CA2379936A1 - Opto-mechanical valve and valve array for fiber-optic communication - Google Patents
Opto-mechanical valve and valve array for fiber-optic communication Download PDFInfo
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- CA2379936A1 CA2379936A1 CA002379936A CA2379936A CA2379936A1 CA 2379936 A1 CA2379936 A1 CA 2379936A1 CA 002379936 A CA002379936 A CA 002379936A CA 2379936 A CA2379936 A CA 2379936A CA 2379936 A1 CA2379936 A1 CA 2379936A1
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Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/3564—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
- G02B6/358—Latching of the moving element, i.e. maintaining or holding the moving element in place once operation has been performed; includes a mechanically bistable system
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/264—Optical coupling means with optical elements between opposed fibre ends which perform a function other than beam splitting
- G02B6/266—Optical coupling means with optical elements between opposed fibre ends which perform a function other than beam splitting the optical element being an attenuator
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0005—Switch and router aspects
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/351—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements
- G02B6/3512—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements the optical element being reflective, e.g. mirror
- G02B6/3514—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements the optical element being reflective, e.g. mirror the reflective optical element moving along a line so as to translate into and out of the beam path, i.e. across the beam path
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/351—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements
- G02B6/353—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements the optical element being a shutter, baffle, beam dump or opaque element
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/354—Switching arrangements, i.e. number of input/output ports and interconnection types
- G02B6/3554—3D constellations, i.e. with switching elements and switched beams located in a volume
- G02B6/3556—NxM switch, i.e. regular arrays of switches elements of matrix type constellation
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/3564—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
- G02B6/3568—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details characterised by the actuating force
- G02B6/357—Electrostatic force
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/3564—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
- G02B6/3584—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
- G02B6/4228—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements
- G02B6/423—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements using guiding surfaces for the alignment
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/0036—Switches making use of microelectromechanical systems [MEMS]
- H01H2001/0084—Switches making use of microelectromechanical systems [MEMS] with perpendicular movement of the movable contact relative to the substrate
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0005—Switch and router aspects
- H04Q2011/0007—Construction
- H04Q2011/0026—Construction using free space propagation (e.g. lenses, mirrors)
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0005—Switch and router aspects
- H04Q2011/0007—Construction
- H04Q2011/0026—Construction using free space propagation (e.g. lenses, mirrors)
- H04Q2011/003—Construction using free space propagation (e.g. lenses, mirrors) using switches based on microelectro-mechanical systems [MEMS]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0005—Switch and router aspects
- H04Q2011/0052—Interconnection of switches
- H04Q2011/0056—Clos
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- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0005—Switch and router aspects
- H04Q2011/0052—Interconnection of switches
- H04Q2011/0058—Crossbar; Matrix
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Micromachines (AREA)
- Mechanical Light Control Or Optical Switches (AREA)
Abstract
A microelectromechanical system optical switch is introduced which includes a mirror (1) constructed on a substrate (3). The mirror (1) is movable paralle l to the surface of the substrate and either allows an input ray incident at a n oblique angle, preferably 45~, to the mirror surface (1) to pass undisturbed through a transparent part of a substrate or reflects the ray to an alternat e output.
Description
OPTO-MECHANICAL VALVE AND VALVE ARRAY
FOR FIBER-OPTIC COMMUNICATION
Field and Background of the Invention The present invention relates to switching in optical networks. such as optical communications networks. to an optomechanical valve. and to arraes of optical valves generally.
An essential component of any communications system is a switch to enable signal routing.
Various types of devices are used for optical switching. Some transform the optical signal into the electrical domain. where switching is done. and then retransfonm back to the optical domain. Others use integrated optics to perform switching. using materials such as lithium niobate. These devices are relatively expensive, their minimum size is limited by the physics of optical wave-guides, they are strongly dependent on wavelength. and they suffer from cross-talk and signal attenuation.
One way to overcome many of these limitations is to use mechanical optical switches (Motamedi M. E. e~ crl. "Micro-opto-electro-mechanical devices and on-clip optical processing". Optical Engirreerirrg vol. 36 No. 5, May 1997. page 1282, and other articles in this issue of the journal). Micro-mechanical switches are not wavelength dependent and can be very compact. Signal loss occurs mainly at the input from and output into the fibers, which is about the same as for other switching technologies. The medium of propagation between fibers. typically air but possibly vacuum or inert gases, accounts for only a very 2~ small portion of the attenuation.
The valves and valve arrays of the present invention overcome the shortfalls of previous ar-t.
FOR FIBER-OPTIC COMMUNICATION
Field and Background of the Invention The present invention relates to switching in optical networks. such as optical communications networks. to an optomechanical valve. and to arraes of optical valves generally.
An essential component of any communications system is a switch to enable signal routing.
Various types of devices are used for optical switching. Some transform the optical signal into the electrical domain. where switching is done. and then retransfonm back to the optical domain. Others use integrated optics to perform switching. using materials such as lithium niobate. These devices are relatively expensive, their minimum size is limited by the physics of optical wave-guides, they are strongly dependent on wavelength. and they suffer from cross-talk and signal attenuation.
One way to overcome many of these limitations is to use mechanical optical switches (Motamedi M. E. e~ crl. "Micro-opto-electro-mechanical devices and on-clip optical processing". Optical Engirreerirrg vol. 36 No. 5, May 1997. page 1282, and other articles in this issue of the journal). Micro-mechanical switches are not wavelength dependent and can be very compact. Signal loss occurs mainly at the input from and output into the fibers, which is about the same as for other switching technologies. The medium of propagation between fibers. typically air but possibly vacuum or inert gases, accounts for only a very 2~ small portion of the attenuation.
The valves and valve arrays of the present invention overcome the shortfalls of previous ar-t.
3 CA 02379936 2002-O1-18 p~/IL00/00425 Summary of the Invention A micro-electromechanical optical switch using a movable mirror constructed on the surface of a substrate and oriented at 4~° to the ray's direction is presented.
The switch either intercepts a light ray and reflects the ray into a changed direction or allows the ray to transit unimpeded. This switch is situated on. above. inside. or below a substrate and actuated parallel to the substrate's surface b~ electrostatic. magnetic. thermal.
piezoelectric. or other means. Some of these bi-stable actuation methods. which may be utilized in other applications, are described below. In the case of electrostatic actuation. an envelope-st,~le electrode may be used to obtain larger forces than are obtained in prior art configurations, such as comb actuators. to produce faster switching. Designing the electrode edges to have a more complicated or irregular shape such as a fractal shape can increase this force even more.
It should be noted that the terms "valve' and "sw itch's are used interchangeably herein.
An NxN switch. that can route any of its N inputs to any of its N outputs. is simple to realize.
There is no interference among the N inputs, since light-ray paths cross without interaction (Hecht .I.. "Optical switching promises cure for telecommunications log jam".
Laser Foczrs 11'orlcl. September 1998. page 69). There is thus almost no cross-talk between data lines.
which allows the utilization of such switches in complicated schemes. Such switches may be incorporated into a three-dimensional array in order to produce compact cross-connects that may switch rays from a plurality of inputs to any of a plurality of outputs, a configuration that ?0 can be utilized in optical computation. They nla~' also be used to switch other than optical waves. for example acoustic waves. ,4 three-dimensional switch array disclosed allows this switchin~~ to he done with shorter ray paths and fewer mirrors than w ith prior art. VNithout limiting the generality of the invention. the examples and embodiments described hereunder will be directed to switching optical w-aves in communications applications.
2~ The task is mainly the production of tiny mirrors to use as switches in these arrays.
Micro-machined devices are capable of fulfilling the task, provided that the micro-machining produces optical-grade mirrors in order to reduce losses. Actuation needs to be fast, simple, and allow reproducible and accurate alignment of the beam inputs and outputs as the mirrors bend the ray. In addition, the abilit, to deploy lame arrays of mirrors is an essential feature 30 of the system. All of these affect switching losses and utiliy. Previous art devices. although ingenious. were not able to achieve all of these requirements together. (See, for example:
Toshivoshi H. m ul_ "Electrostatic micro-torsion mirrors for an optical-switch matrix".
.lnnrnn/ o/ 'llicr~n~le~cnrnnacrlumiwnl.fncloms_ vc,l. ~ No. =t. December 1996. patTe ?;1. and WO 01/09653 CA 02379936 2002-O1-18 p~/II,00/00425 ~lararr O. eml. "Vertical mirrors fabricated by deep reactive ion etching li,r fiber-optic w itclrin'~ appllcatlons". .J1I11!'llcll n~ ~llicmoeloclruntc-olumiwu!
,fv.srem.v, vol. 6_ No. f.
September 1997. page 277.) A device that can separate a multi-wavelength beam into a bundle of parallel single wave-len~th rays and recombine them is also disclosed.
Usual fabrication methods are employed but enhanced mirror alignment and performance are achieved by fabricating mirrors on the surface of a wafer. A novel method is disclosed for fabricating 2D and 3D arrays, by bonding several laterally displaced wafers on top of one another.
According to the present invention there is provided an optical switch for switching a light ray including: (a) a substantially planar substrate havin~~ a portion that is transparent to the li~~ht ray: (h) a switching element havin~~ at least one reflective surface substantially parallel to the substrate: and (c) a mechanism for moving the switching element in a direction parallel to the substrate between (f) a first position wherein the light ray traverses the transparent portion of the substrate and (ii) a second position wherein the light ray is blocked from traversing the transparent portion of the substrate and reflected by the reflective surface.
According to one embodiment of the present invention the mechanism includes:
(f) a first rigid element having two ends. the first end of the first rigid element being flexibly connected to a fined point: (ii) a second rigid element having two ends, the second end of the first rigid element being flexibly connected to the first end of the second rigid element:
and (iii) <t tensile elastic element connecting the first end of the tint rigid element to the second end of the second risid element so that the distance between the first end and the second end when the elastic element is in a relaxed state is less than the sum of the distance between the ends of the first rigid element and the distance between the ends of the second rigid element: both the rigid elements being constrained to be movable only in a plane parallel to the substrate.
According to another embodiment of the present invention the mechanism includes: (f) a first element ha1'In'~ two ends: (ii) a second element havin~~ two ends. the first end of the first element being flexibly connected to the first end of the second element: (iii) a third element having two ends, the second end of the second element being flexibly connected to the first end of the third element: (iv) a fourth element having two ends. the second end of the third element being flexibly connected to the first end of the fourth element: (v) two fixed anchor points. a second the end of the f first element being flexibly cimnected to the first anchor point and the second end ol_tlte ti,llrtlr element being flexibly connected to the second anchor poil:
and l~ i) a tensile el<IStic mechanism fe,r maintainin« the mechani,m for movin~~ the witching element in either of nwo stable states: all the elements being constrained to he movable only in a plane parallel to the substrate.
According to one embodiment of the present invention all the elements are rigid.
S According to a further embodiment of the present invention the tensile elastic mechanism includes: (a) a tensile elastic element connecting the second end of the second element to the first anchor point so that the distance between the second end and the first anchor point when the elastic element is in a relaxed state is less than the sum of the distance between the ends of the first element and the distance between the ends of the second element:
and (b) a tensile elastic element connecting the first end of the third element to the second anchor point so that the distance between the first end and the second anchor point when the elastic element is in a relaxed state is less than the sum of a distance between the ends of the third element and the distance henyeen the ends of the fourth element.
According to another embodiment of the present invention the tensile elastic mechanism includes a tensile elastic element connecting the first end of the second element to the second end of the third element so that the distance between the first end and the second end when the elastic element is in a relaxed state is less than the sum of the distance between the ends of the second element and the distance between the ends of the third element.
According to another embodiment of the present invention the tensile elastic mechanism ?0 includes a spiral spring at each flexible connection.
Accordin~~ to another embodiment of the present invention the tirst element and the fourth element are elastic beams, the second element and the third element are rigid.
the first element is rigidly connected to the first anchor point. and the fourth element is rigidly connected to the second anchor point According to the present invention there is provided a hinge including: (a) a housing having a flat wall. (b) an element free to roll within the housing and haying a connector that protrudes beyond the housings. (c) a mechanism for urgings the rollable element against the wall as the element rolls within the housing so as to maintain rolling contact between the element and the wall.
30 According to one embodiment of the present invention the connector is rigid.
According to one embodiment of the present invention the ur~_in;; mechanism is electrostatic.
-I
:~ccorciin« to another embodiment of the present im-ention the ur~~in'~
mechanism is maenetic.
According to another embodiment the present invention further includes (d) a restoring mechanism for returnin~~ the rollable element to contact with the wall in case of loss of contact.
,According to one embodiment of the present invention the restoring mechanism includes: (a) nvo flexible cables: (i) the first end of the first cable being operationally connected to but electrically insulated from the housing, (ii) the first end of the second cable being operationally connected to but electrically insulated from the housing. (iii) the second end of the first cable being operationally connected to but electrically insulated from the rollable element, and (iv) the second end of the second cable beings operationally connected to but electrically insulated from the rollable element: (h) two electrodes for resettin~~ the rollable element in place: (i) a tirst the electrode being_ situated opposite the tirst cable on a side away from the rollable element. and (ii) the second electrode being situated opposite the second 1 S cable on a side away from the rollable element, (c) a mechanism for charging the electrodes;
and (d) a mechanism for charging the cables.
According to one embodiment of the present invention- in the restoring mechanism (a) the cables are slack while the rollable element is in contact with the wall. and (b) at least one cable is taut when the rollable element loses contact with the wall.
According to the present invention there is provided a travelling wave actuator for moving an object including_ (a) an elastic membrane. (b) a mechanism for maintaining contact beween the object and the membrane. and (c) a mechanism for '~eneratin~~ a travelling wave in the membrane.
According to one embodiment of the present invention the travelling wave actuator further includes (d) a substrate whereupon the elastic membrane is deposited.
According to one embodiment of the present invention the mechanism for maintaining contact is electrostatic.
According to another embodiment of the present invention the mechanism for maintaining contact is magnetic.
Accordin~~ to one embodiment o1' the present invention the mechanism for ';eneratin~~ a travelling wave includes: (i1 a plurality of electrode lairs. eclallv slace<I
alone and W~ ~1/0965~ CA 02379936 2002-O1-18 p~~,p0/00425 stradcllin~~ the nmmhron~_ and Liil ti,r each pair. a respective alternatin;~
electrical power supply.
,4ccording to another embodiment of the present invention the mechanism for generating a travelling wave is magnetic.
W.According to another embodiment of the present invention the mech<rnrsm for ~~enerating a travelling wave is thermal.
According to another embodiment of the present invention the mechanism for generating a travelling wave is piezoelectric.
According to the present invention there is provided an actuator for moving an element comprisin;;: (a) a stationary support for the element. (b) a deflectable support for the element operative to: (i) raise the element from the stationaw support. (ii) advance the element in a required direction of motion. (iii) deposit the element upon the stationary support. and (iv) return to a starting position thereof.
According to one embodiment of the present invention (a) the stationary support includes a 1~ cluster of fingers. the cluster being sufficient to support the element.
and (h) the detlectahle movable support includes at least one cluster of fingers. each cluster being sufficient to support the element.
.According to a further embodiment of the present invention each finger includes a surface at a tip thereof. whereupon the element is supportable.
?U According to a iiirther embodiment of the present invention the element is a planar switchin~~
element.
According to a further embodiment of the present invention the deflectable support is activated electrostaticallv.
,4ccording to a tirrther embodiment of the present invention the deflectable support is 2~ activated piezoelectricallv.
,According to the present invention there is provided an emergency holding device for a movable switching element includin'_: (a) a buckled beam having: (i) a first stable configuration concave towards the switching element. and (ii) a second. tense conti'~uration.
concave towards the w itchin~~ element. wherefrom. if relieved. the beam relaxes to the first ;(1 stable rrmii~zur,uimo: ,rnd (hl a tlexihle strap str,~ddlin'~ the w-itching element. the atrap hein~.~:
(, WO 01/09653 CA 02379936 2002-O1-18 pCT/IL00/00425 ( f 1 attached at a f first enci thereof to a center of the beam anti perpendicular tl~erete~. and ( ii 1 anchored at a second end thereof at a tined point. so that. at the concave stable conti~_uration.
the strap constrains the switching element.
Accordin~T to one embodiment of the present invention the flexible strap is electrically conductive. the device further comprising: (c) an electrode placed opposite the strap.
According to the present invention there is provided a mechanism for lateral realignment of a free movable element with respect to a rectilinear motion path thereof comprising: (a) two alignment pads on opposite sides of the element, (b) a mechanism for bringing the pads into contact with the movable element. thereby nudging the element to the laterally aligned position. and (c) a mechanism for retracting the pads from contact.
According to one embodiment of the present invention each the alignment pad includes an electrode.
According to one embodiment of the present invention the contact mechanism is elastic.
According to another embodiment of the present invention the contact mechanism is 1 ~ electrostatic.
According to another embodiment of the present invention the realignment mechanism further includes: (d) two walls situated on opposite sides of the movable element and outside the alignment pads. and (e) elastic elements attaching each alignment pad to the nearer wall.
,4ccordin~~ to another embodiment of the present invention the realignment mechanism ?0 further includes: (d) two walls situated on opposite sides of the movable element and outside the alignment pads. each wall including an electrode. and (e) elastic elements attaching each alignment pad to the nearer side of the movable element.
According to one embodiment of the present invention the retracting mechanism is electrostatic.
According to another embodiment of the present invention the retracting mechanism is magnetic.
According to the present invention there is provided a mechanism for continuous lateral reali~~nment of a free movable element with respect to a motion path thereof including: (a) a stationary electrode adjacent to and clear of the path. (h) a second_ movable electrode: (i) ,0 attached W tl~e element. (iil at lean partially overlapping tl~e stationary electrode. and (iiil WD 01/09653 CA 02379936 2002-O1-18 p~/1I,00/00425 constrained to remain parallel W the stationary electrode so that a ~~ap remains therehetween_ and (c) a mechanism for electrostaticallv charging the electrocles_ the resulting electrostatic force between the electrodes acting to maintain the element in the motion path.
According to one embodiment of the present invention the motion path is confined to a plane.
i ,4ccording to another embodiment of the present invention the motion path is rectilinear.
According to a further embodiment of the present invention the realignment rlleChanISm.
includes: (d) a second stationary electrode adjacent to and clear of the path, (i) lying in a same plane as and clear of the first stationary electrode, (ii) opposed to the first stationary electrode with respect to the motion path. and (iii) at least partially overlapped by the movable electrode so that a gap remains therebetween_ and (e) a mechanism for electrostaticallv charging the second stationan electrode. the resulting electrostatic force beween the electrodes acting to maintain the element in the motion path.
According to a further embodiment of the present invention the stationary electrodes are shaped as mutual mirror images and are symmetrically disposed about the path.
1 ~ Accordin;~ to a further embodiment of the present invention the charge on the second stationary electrode is of same polarity as the charade on the first stationan electrode.
,4ccording to a further embodiment of the present invention the charge on the movable electrode has the same polarity as the charge on the stationary electrodes.
,4ccordin~~ to another embodiment of the present invention the chary=e on the movable ~'0 electrode is of opposite polarity to the charge on the stationan electrodes.
According to a further embodiment of the present invention the shape of each electrode is an isosceles triangle. an axis of symmetry whereof is oriented perpendicular to the motion path.
,4ccording to the present invention there is provided a method of moving an object including the steps of: (a) ur'~in~; the object to he in contact with an elastic membrane while (b) generating a travelin'; wane in the membrane.
According to the present invention there is provided a method of moving an element including the steps of: (a) providing: (i) a stationary support for the element. and (ii) a deflectable support for the element. and (b) cyclically operating the deflectable support to: (i) raise the element from the stationary support. f ii 1 advance the element in a required direction of motion. pill) deposit the element upon Ilre static~nan support. and livl return to a ;tartin~~
position thereof.
According to the present invention there is provided a method of holding an electrostatically supported switching element in the event of cessation of a supply of power to the switching element. including the steps of: (a) providin~~ a flexible strap straddling the switching element. and having a first configuration wherein the strap constrains the switchin'; element and a second configuration wherein the switching element is free from the constraint: and (b) maintaining the strap in the second configuration only while power is supplied.
According to the present invention there is provided a method of laterally realigning a free movable element in a direction perpendicular to a rectilinear motion path thereof including the steps of: (a) providing a realignment mechanism including two movahle alignment pads on opposite sides of the element. (h) bringing the pads into contact with the movable element.
thereby nud'~in'~ the element to the rectilinear motion path. and (c) retracting the pads.
According to the present invention there is provided a method of continuously laterally I S realigning a free movable element with respect to a motion path thereof comprising the steps of: (a) providin~~: (i) a stationary electrode adjacent to and clear of the path. (ii) a second, movable electrode attached to the element. at least partially overlappin'T the stationary electrode. and constrained to remain parallel to the stationan electrode so that a gap remains therebetwee.n, and: (iii) a mechanism for electrostaticallv charging the electrodes. and (h) electrostaticallv charging the electrodes.
According to one embodiment of the present invention the method includes the further steps of: (c) providin~~: (i) a second stationary electrode adjacent to and clear of the path. lying in a same plane as and clear of first the stationary electrode, opposed to the first stationary electrode with respect to the motion path, and at least partially overlapped by the movable electrode so that a gap remains therebetween. ancf (ii) a mechanism for electrostatically char2inrl the second stationary electrode.
According to a further embodiment of the present invention the method includes the further step of providing that the stationary electrodes are shaped as mutual mirror imagoes and are symmetrically disposed about the path.
According to a further embodiment of the present invention the method includes the further step of char'lin~:, the second stationary electrode with a polarity the same as the charade on the first stationary electrode.
y WO Ol/0965~ CA 02379936 2002-O1-18 pCT/IL00/00425 ~morciine to a f'nrther eml>ociimeW of tl~e present inveWion the nrctho~i includes the further step of charging the movable electrode with a polarity tire same as the charge on the stationan electrodes.
According to another embodiment of the present invention the method includes the further step of charging the movahle electrode with a polarity opposite to the charge on the stationary electrodes.
According to another embodiment of the present invention the method includes the further step of providing that the stationary electrodes are shaped as isosceles triangles.
According to the present invention there is provided a method of fahricating a micro-device having a high-quality smooth mirror surface comprisin~~ the steps of: (a) polishing a substrate surface to a required smoothness. (h) depositing mirror material on the substrate, and (c) removing a superfluous part of the substrate adjacent to a surface of the mirror.
According to the present invention there is provided a method of fabricatin~~
a micro-device having a high-quality smooth mirror surface comprising the steps of: (a) depositing a 1 ~ sacrificial layer on the substrate. (b) polishing a surface of the sacrificial layer to a required smoothness. (c) patternin~~ the sacrificial layer to provide for auxiliary elements. (d) depositing mirror material on the polished surtace of the sacrificial layer.
(e) depositing the au~ilian elements on the patterned portion of the sacriticial layer. and (t~
removing the sacriticial layer.
~'0 According to another embodiment of the present invention the method further include; the step of: ('~) removing a supertluous part of the substrate.
According to the present invention there is provided a method of fabricatin~~
an envelope-actuated micro-device having a high-qualih smooth mirror surface including the steps of: (a) providing a first substrate. (h) depositing an electrode on the first substrate, (c) 2~ depositing a first sacriticial layer on the electrode and the first substrate. (d) polishing a surface of the first sacrificial layer to a required smoothness. (e) patterning the first sacriticial layer to provide for a first set of auxilian elements. (f1 depositing mirror material on the polished surface of the first sacrificial layer. and ('~) depositing the awiliary elements on the patterned portion of the first sacrificial layer.
;0 ,Accordin~~ to another em hodiment of the present invention the method includes the t~mlher step of: (h) providip_ a second elrUrodc.
WO O1/09C)53 CA 02379936 2002-O1-18 p~~L00/00425 ,4crorclin~~ o, anWloer embodiment of the present invention the method ui providing the second electrode is effected by the further steps of: (i) depositing a second sacriticial layer on the mirror material. (ii) patternin~~ the second sacrificial layer to provide for the second electrode and a second set of auriliary elements. and (iii) depositing the second electrode and the second set ofau~:iliarw elements on the patterned portion ofthe second sacrificial layer.
According to another embodiment of the present invention the method of providing the second electrode is effected by the further steps of: (i) providing a second substrate, (ii) depositing the second electrode on the second substrate. (iii) aligning the second electrode opposite the micro-device as fabricated on the first substrate. and (iv) bonding the second substrate to the first substrate.
According to another embodiment of the present invention the method includes the further step of: (h ) removin~~ the first sacriticial layer-According to another embodiment of the present invention the method includes the further step of: (h) removing a superfluous part of the substrate.
According to the present invention there is provided a mechanism for providing a strictly non-blocking 5~~11Chlllg configuration comprising two coupled substantially identical tri-cube complex switchin~~ arrays: (a) each capable of switching any input element to any output element. (b) the first array being capable of allowin'; any input element to transit unswitched to a corresponding input of the second array. and (c) the second array hein'~
capable of ?0 allowing any output element from the tirst array to transit unswitched to a correspondin~~
output of the second array.
According to the present invention there is provided a method of strictly non-blocking switching including the steps of (a) providing two coupled substantially identical tri-cube comple?: switching arrays: (i) each capable of switching any input element to any output 2> element. (ii) the first array being capable of allowing any input element to transit unswitched to a corresponding input of the second array. and (iii) the second array being capable of allowing any output element from the tirst array to transit unsw itched to a corresponding output of the second array. and (h) operating the switching arrays coupled in parallel.
WO 01/09653 CA 02379936 2002-O1-18 pC'1'/IL00/00425 Brief Description of the Drawings The invention is herein described. by way of example only. with reference to the accompanying drawings. wherein:
Figure 1 shows the general switch layout and basic switching motions;
Figure 2 shows switch zones;
Figure 3 shows basic switching actions:
Figure 4 illustrates how a switch can direct Uvo parallel inputs to separate outlets, by operating a switching element entirely within an optically active zone;
Fixture > shows the principles of envelope actuation of a switching element;
Figure 6 presents two different desi~~ns for curved-beam actuation:
Fieure 7 illustrates the use of magnetic actuation:
Figure 8 shows various bistable beam supports;
Figure 9 shows further examples of bistahle beam supports:
Figure 10 presents a representation of the use of bistable beams with a micro-mechanical switching element:
Fi~~ure 1 1 illustrates the action of a frictionless_joint:
Figure 1'' .presents a more complex application of a frictionless joint;
Figure 13 shows a resetting mechanism in the event of power failure:
Figure 14 illustrates travelling-wave actuation;
?Q Fi~~ure I ~ shows the mechanism of fin~~er actuation:
Figure 16 shows a variation on finger actuation Figure 17 presents a mechanism for securing a movable element in the event of power failure;
Fi~_ure I 8 illustrates an electro-mecl~anicol method of ali~~nin~~ a movable element:
I, WO 01/09653 CA 02379936 2002-O1-18 p~/II,00/00425 Fi«ure 19 show; a variant o1-the method oi-ti~~urc I fi:
Figure ?0 shows how electrostatic forces can maintain alignment:
Figure 21 presents applications of electrostatic alignment:
Figure 22 shows some basic switching actions with mo crossed rays:
Figure 23 presents a two variations of a basic ?D switch array:
Figure 24 shows a schematic view of multi-layer switch array:
Figures 25 illustrate 3D switching methods involving two or more multi-layer switch arrays. including a partially blocking confi';uration. a Clos architecture (non-blocking) configuration. and a strictly-non-blocking configuration:
Figure?6 shows a wavelen«th-separationirecombiner device:
Figure ?7 illustrates basic switch fabrication processes:
Figure 28 shows fabrication stages of a pD switch array: and Figure ?9 shows an isometric view of a 3D array cube.
Wo ~l/0965~ CA 02379936 2002-O1-18 p~'/Ii,00/00425 Description of the Preferred Embodiments Introduction The wave valve of the present invention is intended to be used in fiber-optic communications to overcome the above-mentioned shortcomin<~s of previous art. although other applications can be envisioned. It employs mirrors to perform the switching. Mirrors have the advantage of being substantially insensitive to wavelength. The active environment is air. some other gas. or a vacuum. This is a non-blocking environment: i.e. it allows rays to cross unimpeded.
Thus there is no cross-talk and almost no attenuation by the medium. Most losses occur durin~~ light transfer from and into the fiber at the switch/fiber interfaces.
Losses also arise from beam spreading. but use of collimating lenses and short distances can reduce these.
The mirrors should he small. to allow fast response and compactness. The mirrors are generally micro-machined and. in order to reduce losses. are designed to be of optical grade.
Actuation should provide reproducible and accurate alignment of the beam inputs and outputs while the mirror bends the ray. In addition. the ability to forn~ large arrays is an essential 1 ~ requirement of the system. All these requirements retlect on switch loss and utility. Prior art devices, althOllgh IIl''enlOUS. were not able to fulfil all these requirements together [Toshivoshi H. et al.. "Electrostatic micro torsion mirrors for an optical switch matria~.
Journal of A~ioroelecW omechunical Svslems. vol. ~ No. 4 page 231. December 1996, and Marxer C. et al. "Vertical mirrors fabricated by deep reactive ion etching for fiber optic ?0 switching applications~~. vol. 6 No. 3 pa~~e ~,?. September 1997].
These factors are incorporated into the design of the valve. which is ~~enerally planar and fabricated on a smooth wafer substrate. unlike prior art wherein the mirrors are etched into the wafer bulk. In order to enhance switchin~~ speed, the mirror moves parallel to the substrate, thereby reducing air resistance and nlII111111Z1na small deviations of the mirror from ~5 the normal (90°) to the substrate that account for part of the losses introduced in prior art systems. Moreover. the principles presented here are designed to give higher actuating forces, thus allowing a faster response than in prior art switches.
Single valve configuration and operation.
Referring to Fi~~ure 1 a and 1 h, the value consists of a flat mirror 1 situated above. on. inside.
p0 or below. and parallel n> a substrate 2. In tht figure. it is shown at a short distance c1 from the substram. ~'lirror 1 may move n, ditterent position; in a plane 3 parallel to a surface of substrate 2, either substantially curvilinearly. as in a pendulum-like motion s in Fi~~ure Ic. or in a substantially rectilinear motion in any direction, such as 6 or 6A in Figure 1d. or in some combination of these. In a preferred embodiment, motion is generally parallel or normal to a base line 7 (Figure 2). that separates an opaque zone 8 of substrate 2.
wherethrouQh light 10 cannot pass. fr01T1 a transparent zone 9, wfierethrough light 10 can pass and wherein switching takes place. Zone 9 may be transparent because the material of substrate 2, which is present in zone 8. is absent in zone 9, or because the material of substrate 2 in zone 9 is transparent to a relevant wavelength. Different embodiments of the principles disclosed here can be devised by those skilled in the art, wherein it is possible to distinguish the zones in other ways.
One approach is illustrated in Fi'_ure i. Mirror element 1 is located opposite an opaque zone 38 of substrate 2 while li~~ht 10 transits unobstructed throu~~h a transparent zone 39. In thi condition. the system is in an UI=F state 1A. as shown in Figure 3a, b. Mirror I is movable 1 > rectilinearly. parallel to substrate 2, to a position opposite zone 39, as shown by double-headed arrow 3b, to an ON state 1B (Figure 3c, d?. While mirror I is in OFF state 1A.
light 10 can pass from one side 39.4 of surface 3 to another side 39B.
In a preferred embodiment (Figure se, f) ray 10 is inclined at 4>° to mirror 1. In OFF state 1A. ray 10 transits transparent zone 39 unimpeded from IOA to IOB. When mirror 1 is in <)N
state 1B, ray 10 is reflected along an alternate path IOC. Thus ray 10 has one input state IOA
and mo possible. mutually exclusive. output states 10B and IOC.
In 8nother embodiment (Fi~~ure -1). mirror 1 is movable along a line of motion :16 which lies entirely opposite a transparent part 49 of plane 3 and, by so doings.
simultaneously e~chanaes blocking and non-blocking states in different parts of zone 49. Mirror suspension and actuation elements are placed opposite another, opaque zone 48 of plane 3. As previously explained. in a non-blocking state 41A (Figure 4c), light from IOA passes to exit IOB while.
in blocking state 41B. light is reflected to an alternate output IOC. In this configuration.
where mirror 1 is entirely opposite transparent zone 49, either position of mirror 1 can be designated as ON or OFF (Figure -le, f). Thus. it is possible to have a valve with two parallel inputs 10 IA and 10 11A beings in an ON state for the former. retlecting ray 10 IA to output 10 IC. while being in an ~)t=F state for the latter, which passes to output 10 IIB (Fi~zure :fe).
On actuating switch 1. these states reverse and input ray 10 1A is in an OFF
state, transiting to 1;
WO 01/09653 CA 02379936 2002-O1-18 pLT/IL00/00425 output 10113_ while intent rat' 11111A i; in an o1\ state_ retlectin~~ m output 10110. This makes a ( 1 x2 )x2 exchange switch. which may be used. for example. in a Banvan neW ork.
~1ore elaborate applications can be realized by combining two or more switching elements.
It is important to note that the rays can traverse the switch in a reverse direction. In this case, inputs interchange with outputs and the switching options explained above are reversed.
Actuation The valve consists of mirror I which is movable parallel to surface 3 and may be in at least two rest positions. Mirror 1 reflects light at one position and allows its passage at another position. Anv appropriate force may be applied to induce a desired change in mirror position. A number of actuation methods are available: thermal (bimetallic strips). magnetic.
piezoelectric_ mechanical. and electrostatic actuation and methods that rely on shape memom alloys (SM,4) are a few of many known in the art.
Three preferred actuation embodiments are discussed. The first follows a design similar to a comb-drive but designed to produce larger forces than prior-art implementations. It uses an envelope-like electrode into which a mirror is retracted. Larger forces can be obtained with this actuation method by designing the electrode edges to have a large area chancre. such as a fractal form.
Alternatively. a mirror is supported by flexible beams that are actuated by attraction to or repulsion from static. curved electrodes.
I~1a~netic actuation is also described whereby a ma~~netic field is established around a switch and a flowin~~ current induces switching.
Electrostatic envelope actuation A preferred embodiment employs electrostatic actuation. Different schemes of electrostatic actuation can he used. among them a comb-drive mechanism. (Hirano T. et u1.
"Design, 2~ Fabrication. and operation of submicron-gap comb-drive microactuators", .lourrrul of Microelectromochunicul S'vslems. vol. 1 No. 1. A~tarch 1992, page ~2.) In conventional comb-drive actuation. the actuation force depends on the change of the overlapping area between a driver's tingers and a comb. Since usual fabrication methods limit that area to a small value. a large numher of tin~~ers is necessary to produce the required lorce. Therefore Ih tl~i; kind of actuation require; lar«z actuators. :1 di(~lerent approach t«
this actuation principle is disclosed here (Figure >).
Overlapping finger 51 and comb s2 form a capacitor (Figure >b). The attractive force between the movable and static fingers is:
c~(,,, F= -cW
where j,, is the electrical energy stored in the capacitor of capacitance C~'. The capacitance of a parallel-plate capacitor is determined by the geometric parameters thereof and depends directly on the area (A) and inversely on the gap between the electrodes (g").
In the case considered here:
.-1 !y ~.
('=8~i-=E~
~~'o ~~'n The force is. therefore:
s~I'-h~
F=
--g..
1 ~ Where. ~~ is the permittivity of the vacuum, V an electrical potential, lo" is width of the finder_ r is the overlapping length of the finger in the direction of advance thereof.
and g" is the ';ap between the movable finder and each static finger. Thus the force is inversely proportional to the gap between the fingers and proportional to the width of the fingers. It does not depend on the thickness of or the amount of overlap beW eon movahle and static tingers. Based on ?0 this conclusion. a configuration is disclosed wherein the width of the tinger is increased in order to achieve greater force and thus faster switching speed,.
The production of wide fingers is difficult with conventional, prior art. A
fabrication technique is disclosed below wherein the manufacture of wider fingers is easily done using conventional methods. In this way. fewer fingers. or even a single finger, can achieve sufticient force and hence switching times of the order of microseconds, compared to milli-seconds with prior art. The disclosed actuator has an envelope-like configuration in which mirror / tinges (movable electrode) s1 may enter or exit envelope (static actuating electrode) ~2.
In another emhodiment (Figure ~dl. at least two actuatin~~ electrodes are placed in a way that one set s2A actuates to an ON position while another set s2B. C actuates to an OFF position.
:4ctuation can be made bistable: if the actuated mirror is supported by huckled beams (see below). a snap action to each position of the mirror results.
Another possible embodiment to implement bistabilitl. employs electrostatic snap (pull-in) action. An actuated element is attracted to and held by an electrically isolated electrode at an end of its motion. From the equations above. force exerted is given by:
s h'' c~A
F= ° -2go c~Z
Since force depends on the change of area A with displacement x, then, to increase the force, the area change of this actuator should be increased, not only the width of the finger. There-fore. for the actuator presented. the force can be increased further by using a more complex profile than a straight line (~7. Figure >c) that the electrode crosses.
thereby increasing the rate of area change. This line can be designed. for example, to be circular (s7B. Figure ~e), and the force increases correspondingly. Alternatively, or additionally, the leading edge of electrode ~1 may be similarly enlarged.
Another embodiment increases the profile by using an even more complex geometrical form.
Such a form might be an irregular form such as a fractal line designed for the application.
The use of a fractal form can increase the actuatin~~ force by the ratio of its rate of area chance to that of a straight-line profile.
?0 Crrrred electrode artrrntion Another electrostatic actuation method is presented in Figure 6, in which the post-fix A or B
refers respectively to variant embodiments. One or more flexible beams 67A or 67B support a mirror 61. One point of the beams) 68A or 68B is fixed in close proximity to a circular segment stator 69A or 69B attached to a substrate 62. These stators and beams are 2> conductive and respectively chargeable with opposite polarity. Beam 67A or 67B and stator 69A or 69B, respectively, are separated by insulators 6>A or 65B from each other along an entire circular segment of stator 69A or 69B or. at least- at points where contact may otherwise occur. so as to prevent a short circuit (Figure 6a. b. c. and d).
Applying a potential difference between stator 69.A (B) and movable beam 67A
(B) sets 30 charades of opposite polarities on stator 69A (B) and beam 67A (B). so that the latter is attracted to the former. as close as permitted by the insulation (I=i'~ure 6h.
6d). Removing the IS
WO 01/09653 CA 02379936 2002-O1-18 pC'f/IL00/00425 potential dii~fereni:e allows beam 67.4 (B) n, return W the ori;~inal sh<rpe thereof. Since a free end of beam 67A (B) is connected to mirror 61. the consequent advance or retreat of the contact zone around a perimeter of stator 69A (B) moves mirror 61A (B) a distance L in a direction indicated by double-headed arrows 66A (B). This method is especially useful when actuating elements 67A (B), 68A (B), and 69A (B) are completely within substrate 62A (B) with mirror 61 being entirely opposite transparent zone 63. as described previously. It is an alternative where envelope-type actuation is not preferred. Buckled beams are used so that actuation is inherently bistable. In order to move mirror 61 a distance L, the height of stator 69A (B) is preferably approximately L. If stator 69B is a quadrant of a circle, the height should approximate the circle radius and have a value of L.
Another embodiment of this actuation method (Figure 6e, f~ employs opposed-quadrant stators. In this case pairs of quadrant-shaped stators 69C are separated by a beam 67C so that beam 67C is tan~~ential to both quadrants at a point of contact and both quadrants are relatively opposed so that a radial boundary of each quadrant forms a straight line passing through that point of contact. As before, both stators are prevented from contacting beam 67C by insulating material 65C. In this configuration, by use of opposite charges on each member of a stator pair. half of the motion is caused by one member and the other half by the other member. in sequence. This allows a more compact actuator to be constructed.
Magnetic actnafinn ?0 Another embodiment of the valve switch uses magnetic forces. I~'1agnetic tields can produce greater forces and. consequently. faster switching. ,A disadvanta~~e is the larger overall volume of the device. even thou~Th the sva-itching mechanism, itself has the same dimensions whatever the actuation mechanism. In order to use this actuation method (Figure 7). a magnetic field. B, is necessary at the switch. The field can be produced by conducting loops 2~ around each switch, by a permanent magnet, or by an electromagnet with similar field. These are only some of the available magnetic field application possibilities.
In this embodllllent of the switch. mirror 71 is supported by beams, 77A and 77B. These beams are preferably made from buckled beams, to produce bistahle operation.
and are conductive or include a conducting layer wherethrough an electric current I
may be passed.
30 Interaction with the magnetic Held induces a lateral force F on the beams.
The magnetic field is aligned so that current I actuates mirror 71 to a new position (Figure 7a). Reversing current I reverses force F and returns mirror 71 to an original position (Figure 76). Higher Held valuca or hi~=her currents produce stron~~er forces and taster sw itching.
W~ Ol/0965~ CA 02379936 2002-O1-18 pC'1'/IL00/00425 Bi.sluhle su/~Jmrl Realization of the aforementioned systems requires a means of supporting active elements that enables bistable operation. The devices described hereunder relate to the present invention but may also be used in other applications. for example in conveyor systems.
i Translation systems that variously include a frictionless hinge, surface-wave motion. and beams that vibrate in two directions are described. Different actuation methods, including electrostatic or magnetic actuation against elastic restraints or buckled beams. are utilized in order to lock a translated mirror in a newly attained position. A buckled beam is used as a mechanical memory element, a task it can fulfill if the length of the beam is larger than the distance between the anchor points thereof. By applying a force normal to the length of a buckled beam a critical point is reached whereupon the beam transits to another stable configuration. The same effect is also possible if the beam takes other forms.
which are also described.
In Figure 7. each buckled beam, 77A and 77B, is a variation of a bistable buckled element with a bistable, snap mechanical action. The basic principle of the buckled beam is shown in Figure 8a. A beam 80 has intrinsic elasticity and its length is greater than a distance between anchor points 81 and 82. If a lateral force F be applied to beam 80. as known from standard teats. the beam snaps from a stable state 80 to another stable state 80'.
Applications of this principle are illustrated in Figures 8b, c. and d, in which like reference numerals reter to like ?0 parts throughout the figures of the drawing. It is to be understood that the descriptions below are illustrative. and are not intended to restrict the present invention to the specitic details set forth below.
The device of Figure 86 is bistable, analogous to the buckled beam, and the components are correspondingly numbered. The beam includes rigid elements. 80A and 80B
flexibly connected at respective ends 80A, and 80B,. Element 80A is flexibly connected at end 80A2 to fixed anchor point 82 while element 80B is unanchored at end 80B2. Ends 80A,_ and 80B2 are connected by a tensile element represented by a spring 83, although it is obvious that other ways may achieve substantially the same effect, such as using spiral springs at connections 80A, - 80B, and 80AZ - 82, or some other combination easily devised by those skilled in the art. A second stable configuration of this element is represented by the dashed lines denoted by 80A' and 80B'. This device, like that in Figure 8a, may be regarded as an elementary, bistahle building block.
?U
~ snap element tlma has two static contignrations is sh~,wn in Hi«nre Sc.
Ri~~id elements 8(1A
and 80B are tleaihly connected at ends 80A, and 80B, respectively- 80B and 8(1C are tleaihly connected at ends 80B= and 80C~ respectively. at a point 8:1: and 80C and 80D
are flexibly connected at ends 80C, and 80D, respectively. There are two anchor points. 82 and 82A, whereto are tlexihlyconnected ends 80A, and 80D= respectively. A tensile element.
represented by a spring 83A. connects anchor point 82 to the tlexible connection between ends 80B, and 80C: and another tensile element. represented by a spring 83B.
connects anchor point 82A - -to the flexible connection between ends 80B, and 80C,. The whole device is constrained to move within a plane. Applying force F snaps the device to a new stable position. the distance between points 82 and 82A remaining constant while point 8:1 moves to a new location 84'. as shown schematically in Figure 8d.
To show the «enerality of the design another preferred embodiment is shown in Figures 9a and 9h, where elasticity is provided by a spring 90. In this embodiment. force F produces snap action to brim point 84 to a new stable position. 84'. Figure 9c shows an equivalent embodiment wherein elasticity is provided by spiral springs 92A. B. C. D. E.
and F. Another embodiment employs an elastic beam as part or all of the elastic members of the device to produce the elasticity. as shown in Figure 9d. In this embodiment. anchor points 82 and 82A
riaidlwhold fully or partially elastic members 80A and 80D at ends 80A, and 80D, respectively. All other members remain as in the previous example. Figure 9e shows a partially actuated state of this embodiment, showing elastic members 80A and 80D bent.
allowing the transit of point 84 to a new stable state. as before.
To make the device useful. joint 8-1. or any other point or beam in the device-is attached to something that one wishes to move. In one preferred embodiment joint 84. can be replaced with or attached to a usable element, such as a mirror. as shown in Figure 10.
which depicts a double application of the arrangement in Figure 9c and is labeled to show corresponding components. the duplicate part of the mechanism being labeled with primed numbers. In this figure. 84 represents a usable element. Another possible application is as a switch in which different connections are made in each state of the histahle device.
Frictinnless juinfs In micromechanical applications. friction less hin~~es are advantageous.
Dynamic friction is normally a cause of wear. suppression of which is especially important for micromachines.
where lubricants are not ~~enerallv usable. For this reason. pin ,joints are usually replaced by ~l W~ ~l/09653 CA 02379936 2002-O1-18 p~/II,00/00425 spiral spring's where larvae no,vement is required. :another type of hinge is presented wl~i~lr uses static friction but is dynamically friction less.
The hinge in Figure I 1 includes a cylindrical roller I11 from which protrudes a radial arm 112. the movable element thus formed being in contact with a surface 114 contained within a housing 113. Arrn 112 protrudes out of housing 113. Large static friction between roller 111 and surface 114 as 111 rolls on 114 means that no slippage occurs during the rollin;~. This requires that contact be maintained at all times between roller 111 and surface 114. this is termed ''rolling contact" and is achieved by the action of a normal force F
urging contact between roller 111 and surface 114. Force F may include electrostatic and magnetic forces.
Through rolling contact. roller 111 may move between position 111A and position 111B and, consequently. ann 112 moves between position 112A and position 112B. The whole arrangement forms a dynamically frictionless hin~le with center of rotation at a point 11~.
which is not the center of roller 111. and with an angular rankle 2a.
This hinge can be employed more than once in an implementation, as illustrated in Fi~~ure 1?.
1 ~ Nere. the result enables translation of a movable part 122 relative to a stationan~ housing 113 in directions 127+ and 127-. ,4s before. in order for the hin~~e to function.
a normal force is needed to maintain contact between rotor 112 and housings 113 and between rotor 112 and movable part 122. which rotor 112 connects. Again, different types of force may be used, including magnetic and electrostatic forces. In case of a ma~~netic force, movable part 122 and stationary housing 113 of the hinge include permanent magnets or electromagnets. If electrostatic attraction be employed. <r thin insulating layer 123 is deposited to cover at least all of the possible contact surfaces of the hinge so as to prevent a short circuit. as shown in Figure 1?. An electrostatic potential is applied between rotor 112 and embedded electrodes 12~a and 125b. The potential is provided by direct connection of the electrodes to a power 2~ supply or through electrostatic induction, electrodes 125a and 125b being oppositely charged.
The potential difference induces attractive normal forces between rotor 112 and embedded electrodes 125a in housing 113 and 12>b in movable part 122. The same consideration applies if more than one hinge exists. in which case electrostatic attraction may be more suitable than magnetic attraction. Charges may also be applied to stoppers 126a and 126b of the hinge, by means of embedded electrodes 128a and 128b, in order to produce electrostatic forces to actuate rotor 112. which may then be used either to actuate an element or to act as a control device by. for example. detection of capacitance change caused by the induced motion thereof to provide positional information.
If a device relic; on electrostatic attrai lion. cessation of the hover supply may allow a rotor to fall ti-om a workings position. In order to restore to the working position, a mechanism. as shown in Figure 13a is used as one of the options. Figure 1 , shows views of the device of Figure 1 1 from within the plane of Figure 1 1. and relevant parts are similarly numbered. Part of a housing 113 in contact with a rotor 111 is viewed schematically from the plane of motion of protruding part 112. While power is supplied. both elements are in contact but for a separating, insulating layer 123, as described before. Flexible. loose conductive cables 131A
and 131B are anchored to either side of housing 113. In Figure 13a, masts 130A
and 130B, emerging from either side of housing 113, are used to illustrate this. Masts 130A and 130B
also electrically insulate cables 131A and 131B from housing 113. Insulation 133 may be also provided for cables 131A and 1318 from rotor I I1 as is also a means 134A
and 134B of electrically charging the cables. Resetting electrodes 132A and 132B are situated to the sides of the hin~~e. outside cables 131.4 anti 131 B and provided with respective means 13~A and l3sB of being electrostatically charged. In normal operation. cables 131 A and 131B are is relaxed. When power fails, the attraction between rotor 111 and housings 113 ceases and rotor 111 falls until checked by one taut cable. in this case 131A, while other cable 131B
remains slack. as shown in Figure 13b. When power is restored. a resetting procedure is followed to restore the hinge: first. a voltage 13~A is applied to electrode 132.A and an opposite voltage 134A to cable 131A so that electrode 132A attracts cable 131A.
Simultaneously. a voltage 135B is applied to electrode 132B and an opposite volta~~e 13:1B to cable 131B so that electrode 132B attracts cable 131B. The resultant tensing of cables 131A
and 131B returns rotor 111 to a working position. as shown in Figure 13c. Then the electrostatic attraction between housings 113 and rotor 111 is renewed and the mo elements will remain together. Finally. power supply to resetting electrodes 132 and cables 131 is 2~ ceased. leaving cables 131 slack. Operation of the hinge can then be resumed.
Other applications and realizations of the described mechanism can be envisioned by those skilled in the art.
Travelling-n~nve actuation Another method of actuation is now introduced. In Figure 14, a standing wave 140 is induced in an elastic material 141 situated on a substrate 1.12 by any method that can cause a modification of the dlmenSlotlS Of elastic membrane 141. The modification method, which may affect the time constant of standing wave 140. may he thermal.
piezoelectric. magnetic.
or electrustati~. to a preferred en~hociimmt. electrostatic actuation i, used.
.-',n ucillatin'~
WO ~l/09653 CA 02379936 2002-O1-18 p~/IL00/00425 voltage 1-t-t is ahpliecl acrus> <i pair e~i~ electrode; 1=13 placed in substrate 1-t2 and above elastic material 141. causing vibration of elastic membrane 141. Alternating voltage 144 induces a standing wave 140 in elastic membrane 141. if two pairs of electrodes 143A and 143B be laterally separated with their respective cycles 144A and 144B having the right phase difference. as in Figure 146, a traveling wave 14s is produced at a surface of elastic medium 141; a point on elastic material 141 will undergo circular motion 146 (Figure 1 Ic).
This circular, wave-like motion can move an element 148 placed on top of elastic material 141. Changing the phase difference between electrodes 143A and 143B, and thus between the standing waves, can change the velocit<~ and direction of traveling wave 14~ and, with it, the yelociy and direction of element 148 placed on elastic membrane 141. A
plurality of electrodes and generating devices may be used as required. Although such waves are known from prior art this device is innovative. as described in the following.
The functioning of this device requires contact and friction between movable element 1-t8 and elastic membrane 141. in which waves 14s propagate. In prior art. that contact is maintained by virtue of gravih or by springs. The current invention, being intended for elements of small dimensions, introduces other options, including magnetic force and electrostatic force.
For the former. movable element 148 is made of magnetic material, as are the surrounding parts of elastic membrane 141 or substrate 142. By oppositely magnetizing 148 and 141 and/or 142. an attractive normal force holds movable element 148 against elastic membrane 141. even against gravity. and induces friction that will permit the functioning of the device.
Either permanent magnets or electromagnets may be used. Another possibility is electrostatic attraction between movable element 148 and the stationan- part of the device.
Again. the attraction produces a force that induces the static friction that enables the actuator to 2~ function. This enhancement permits the functioning of the device in any orientation, without relying on gravity or springs or other elements that may produce dynamic friction and wear or require the use of bearings that are difticult to fabricate at micro-dimensions. The use of this kind of actuator in the optical cross-connect. the aforementioned mirror and movable part, is an innovative improvement.
In case magnetic actuation is preferred. the electromagnetic attraction of the previous paragraph is caused to van cyclically so as to induce a required travelling wage in the membrane.
In case thermal actuation is preferred. the membrane is selectively heated h~-heater 1-49 in Figure l~(d) to cause periodic deformation so as to induce a required travelling wave in the membrane.
In case piezoelectric actuation is preferred, piezoelectricallv deformable device 149 in Figure 14(d) is caused to change dimensions in contact with the membrane to cause periodic selective deformation therein so as to induce a required travelling wave in the membrane.
Finger uctualion Although the surface wave device is usable in some cases. a more versatile device can be designed. The intention is to produce a rotational motion at the movable element that resembles that of 146 in Figure 1 ~, without actually needing to propagate a surface wave.
The desiUn (FiUure lea) is based on clusters of supportin<~ timers 153. each cluster bein'T
sufficient to support a movable element 152. FinUers 153 can have various configurations.
such as cantilevers protruding from a side wall or posts protruding from a substrate 151.
Although the illustration shows the finger tips aligned in a straight line.
this is not an 1 ~ essential requirement of the invention. Movable element 152 rests on supporting fingers 1,3.
An appropriate movable element 152 for this application is an actuatable mirror. The supporting surfaces of fingers 153 are generally located above the plane of substrate 151. .A
vyorking cycle is illustrated in Figures 15b - I ~e and starts when a first cluster of supporting fingers 153B. D moves away from substrate 151 bearing movable element 152. At this stage_ ?0 a second cluster of supportin~~ fin'~ers 153A. C is stationary and thus out of contact with movable element 152. Neat_ first cluster of supporting tin~~ers 153B, D moves laterally in a required direction of motion to a new position and lowers so that second cluster 153A. C now supports movable element 152. First cluster 153B, D then moves laterally in an opposite direction from the first motion thereof and returns, without touching movable element 152. to 25 a starting position thereof while second cluster 153A. C begins a similar cycle. The displacement in each step depends on the lateral amplitude of the motion of supporting fingers 153. which is normally very small and many cycles may be required to achieve a required translation. Clearly. the lateral displacement may be reversed by reversing the cycles. By using two movable clusters of supporting fin~~ers in succession.
the displacement 30 may be doubled from that of a single-cluster cycle. and so on. It is seen that the resultant effect is similar to that of the travelling wave actuator.
WO 01/09653 CA 02379936 2002-O1-18 pCT/IL00/00425 actuation of the supportin~~ elements can he by various method;. wclr as electrostatic actuation. whereby electrodes are placed around the supportin;~ elements in the horizontal and vertical directions and voltages applied to bend or deflect the supporting elements. as required. Alternatively. the supporting elements can be made of piezoelectric material and.
by applying suitable voltages. these piezoelectric beams rnay be bent in the horizontal and vertical directions. Bv controlling the timing and duration of these voltages it is possible to produce the required motion of the supporting element and rotate its extremity in clockwise or anticlockwise motions to advance or regress the movable part. Since static friction is necessary for the functioning of the device, as in the travelling wave option, the same method of holding and application of the normal force by using electrostatic or magnetic forces is used here.
This approach is particularly suitable in the micro-environment. Use of cumulative small displacements reduces stress on the elements. Mloreover. at this scale. rotary motors would suffer dynamic friction sufficient to render them unusable.
A simpler variation of this actuator uses only one set of supporting fingers at each step, as shown in Figure 16. A movable element 162 is supported by actuated fingers 163A.B.C
while being moved. as previously explained. and. while actuated fingers 163A.B_C return to an original position thereof element 162 rests on stationary posts 16=tA.B.
Again. many cycles are needed to achieve a required lateral displacement.
Other variations and combinations of this device are possible. In another preferred embodiment. while the actuated elements retreat. the movable part is held by side handles instead of restin~~ on top of aforementioned posts 164A_B.
Enrergeney holding In the event that the electrical supply fails. any electrostatic holding force stops and the movable element may fall. Of the various possible mechanisms. a preferred embodiment is presented that is designed having in mind the fabrication methods used in the micro-environment 1n ~~'hlCh the device is used. but can also be applied in other fields. As shown in Figure l7a.b. an element 171 that needs holding in case of power failure is fabricated on a substrate 170. A flexible element 172 is fabricated separated from element 171 by a sacrificial layer 174 that is later removed. Flexible element 172 is anchored at an end A and another end is held by a histahle bucklin~~ element 173 that is anchored at points B
and C~. In pwitic~n 173A hucklin~~ elentem 173 is tri';'~ered by ,rpllvin~~ a suitable force in order m make element 173 snap to anther stable point 17313. as shown in Fi~~ure l7c.d. As a consequence. tlexible element 172 is tensed- as shown in Figure l7c.d, and thus holds free element 171 in position. In order to allow element 171 to move. element 172 is disengaged by an electrode 175, isolated by insulation 176, placed opposite element 172.
An applied voltage difference between element 172 and electrode 175. attracts the former to the latter against the tension from buckling element 173 in position 173C, which is displaced slightly from a stable position 173B but insuffiiciently to cause it to snap to other stable position 173A. In case of power failure, the attraction of electrode 175 ceases and the tension exerted by 173C acts to return 172 to a position in which it holds movable element 171.
Eleelro-meelmnieal aligning mechnnism With practically free movable elements. especially when a stepping motion is involved, there is a possibility of disalignment of the movable element in a direction perpendicular to the element-s direction of motion. A mechanism for lateral realignment is necessary. A basic arrangement is shown in Figure 18. An element 184 to be kept aligned in a lateral direction 188 so that it remains in a rectilinear motion path 187 is situated between two aligning pads 183a and 183b. which are situated between walls 181a and 181b and attached respectively thereto by matched springs or other elastic elements 182. Element 184 is movable in the plane of the drawing, 1v'hlCh IS perpendicular to the walls. Since the force of a spring is greater when displacement from equilibrium is greater, deviation of element 184 from center is corrected by spring action on both sides (Figure 18b). Springs 182 are retracted by electrostatic force betvyeen electrodes 18_>b alld 18:~C Ill allgnlll'~ pads 183a and 183b respectively and correspondin~~ electrodes 185a and 1854 at walls 181a and 181b respectively. Vt'hen aligning elements 183a and 183b are retracted, free movement of movable element 184 is possible. Such aligning elements may also sense as the part of an actuating system that holds a movable element while the movable supporting elements of the finger actuation mechanism described earlier are retracted.
Another aligning option has the same layout as in Figure 18 but acts through electrostatic attraction between element 184 and elements 183a and 183b. One possibiliy is to connect element 184 to one polarity and elements 183a and 183b to an opposite polarity of a power supply. Another. preferred embodiment is to apply opposite polariy charges to elements 183a and 183b. represented generically as V,, and V~, in the figure. Opposite charges are induced in the respective ad-jacent surfaces of neutral element 184. In either case the result is attraction between elements 183a and 183b and element 184. When elements 183a and 183b ~7 are in contact wily 184. spring's 182 will art l balance each other. tl~erehv prcuiucin~! a net force that aliens movable element 184.
A variation of this principle is shown in Figure 19. wherein movable element 184 contains spring parts 182 that support aligning elements 183a and 183b. In one preferred embodiment, opposite electrostatic charges are applied to electrodes 18~a and 185d, which are located at surroundings walls 181a and 181b . As before. these charges induce opposite charges in respective elements 183a and 183b which are attracted to respective walls 181a and 181b. Balanced springs 182 act to align element 184, as before.
These methods are applicable with magnetic or electromagnetic forces employed in place of electrostatic forces. with suitable variations that will be obvious to those experienced in the art. Other actuation methods. such as combined thermal or other action, can be applied.
Eleclroslnlio aliyrinri nrec%anisnr Another electrostatic alignment mechanism follows directly from the envelope-like actuation principle discussed earlier. Aligning a movable element with electrostatic force alone will 1 ~ not work since electrostatic force depends inversely on distance. Thus any misalignment would be increasingly exacerbated. Using repulsive electrostatic torces would mitigate this problem although this is hard to implement in practice.
In the above discussion. however, it was shown that. in an envelope-like actuator with one or nvo eternal static electrodes. the force in the direction of surface motion depends on the ?0 derivative of the area with respect to distance in the direction of motion.
It was also shown that, this being the case. if the profile of the electrode with the actuated element is such as to produce a large area variation, such as in the case of a suitable complex shape or fractal form, an increased force results. Based on this, shapes of the movable or static electrode can be tailored to produce a force depending differently on the distance from a rest position.
2> Using the same calculation as for envelope-like actuation, the electrostatic energy stored in a capacitor formed from two overlapping plates 201 and 202 is (Figure ?0):
~l - ? s~.9 1.=
f the force is then:
t;"t ~- c:~.~
,: - _ __ __ ~~.v ,1 Ifmm plates as slu,wn in Fi~~ure ~tlh ,j re used. the i~r,rce is simply proportional tem". wlri~l~ i;
constant as the plate overlap chan';es. If. however. the protile of one plate be chan~~ect. tier example to a triangle 203 as shown in Figure ?0c. the force varies linearly with distance ~-and increases like -2.x.tan a as the overlap increases. However. in the configuration shown in Figure ?0d. a reversed triangle 20~t the force depends on ~_v" - x~ tan a . It may he seen that when the distance of overlap is .y, the force is zero. as would be expected.
When there is no overlap the force is zero. If the overlap increases towards .u~ the force decreases, and vice oersu. Application of this permits continuous alignment of an object that is movable in a plane parallel to the plane of the diagram, as shown in Figure 21, since displacement from alignment will result in a net attractive force to the central neutral point of the system. Two configurations are discussed, as shown in Figure ? 1 a and b. In Figure 21 a, trian~Tular electrodes 210 are respectively fixed relative to walls 181 and central element 18=1 is mc,vahle: in Figure 21b triangular electrodes 211 are lived to movable element 184 and fixed electrodes 212 mounted on walls 181 have straight leadin~~ edges. C'har'ges may he applied to 1 ~ the electrodes and to the movable plate by some means, shown generically by voltages V".
V,,. V~, and V~ in the figure. By this arrangement, central element 184, which is intended to move along motion path 187. may be constrained from lateral deviation in direction 188.
Other electrode shapes may he tailored to produce different dependencies of the electrostatic force on the overlap distance. Bv combining these forms. complicated actuation effects. even including accelerations and decelerations. can be achieved. .Another use of this concept is in the stahilization of electrostatic actuators such as in the envelope-type actuator. Bv placing shaped electrodes in opposition it is possible to stabilize the movable central electrode and prevent it from sticking to a side electrode as a result of the inherent instability of this actuator.
Valve Array The smale valve disclosed above is capable of switchin« light rays. Switching is possible heaveen a single input and W o outputs or two inputs into one output. The disclosed switch (Figure 22) can incorporate prior art optical devices, such as HEMS (Micro-Electro-Mechanical Systems) switches (e.~,l. mirrors), liquid crystals. and electro-optics.
In order to switch one input to two outputs. one mirror, 222. parallel to a substrate. 223, as disclosed before. moves in a direction parallel to substrate 223. as illustrated by double-beaded arrow 224 1I=i~~nre ~~a. h). If the witch is in an ol-I state.
an input ray. 221:x.
emer~~es at output 22113. It the switch is actuated to an c~N state_ ray 221.4 retlects tom mirror 222 and exits ti-om output 221C. Another embodiment can be desi~~ned (Figure _'2c, d) wherein two inputs. 221A and 221D. are normal to each other and. in an (>FF
state.
continue to respective outputs 221B and 221C. Actuating mirror 222 flips the output rays to emerge at interchanged outputs 221C and 221B respectively. In this latter embodiment.
mirror 222 is reflective on both sides.
These are simple schemes. in which a single switching element is utilized. but the strength of this device - deriving from the compactness thereof - is in switching many inputs among many outputs. within a compact space. Elaborate examples can be produced by employing an array of switches (Figure 23x). (It should be noted that the terms "array"
and "matrix" are used interchangeably herein.) A column of inputs. 231A ... 231D, is situated normal to a coplanar row of outputs. 232A ... 232D. ,At an intersection of each input line with each output line. a switchin'; n~irror_ 233 for example. is placed. at an angle to an intersecting input line 231 and output line 232. depending upon the switching technolo~~y hein'~
used. the angle 1 ~ may have any value up to 180°. It is emphasized that each input can act as an output, and rice oersa, by reversing the respective ray propagation direction. In order to switch any particular input to any desired output. an appropriate switching mirror 233, at an intersection of corresponding input and output axes. is actuated to an ON state. For example, input 231B
may be directed to output 232D by actuating switch 233A. In the simplest case, only a single switch is actuated at any time in each row and in each column. resulting in a one-to-one correspondence between input and output rays; a "non-blockin~~~~ condition is said to exist.
This is a non-broadcasting situation. When partly transmissive mirrors are used to allow broadcasting. '-bloching~~ is allowed. in the sense that a light ray that enters the array along a row of switches naiv traverse, albeit diminished. two or more actuated switches. with a reflected ray being directed along each colunu~ wherein an actuated switch is situated.
Moreover, although inputs and outputs are generally normal to each other, more complicated switching operations. as basically described in Figs 22c and 22d, can be achieved by placing additional inputs 231 or outputs 23s, collinear with the original outputs and inputs respectively. In order to use these additional outputs or inputs. switches such as are illustrated in Figures 22c and 22d are used but none of the switches along the path of a respective ray is actuated. thus allowing unimpeded passable of the ray concerned. Such an array can be used for more complicated switching operations. as well as for controlling the beams.
WO 01/09653 CA 02379936 2002-O1-18 p~~,p0/00425 In Figure ~,h. another embodiment is presented in which only half of an array is needed. In this case. a static retlectin'~ element. such as a mirror 239. as shown. or a wave-guide termination. is placed at a diagonal of the array and that part of the array behind mirror 239 is discarded. All actuatable mirrors are double sided. In this configuration.
fewer actuatable s elements are required to achieve desired output configurations. with the same ray path-length as in the complete array of Figure 23a, although a ray may encounter more reflecting surfaces, leading to greater light loss. The overall switch is smaller, which is an advantage in some fabrication schemes, as will be shown below. In the example of Figure 23b, inputs 236A, B, C, and D, are switched to outputs 237A, C, B, and D respectively.
Input 236A is reflected to output 237A via path ac and input 236D is reflected to output 237D oia path 8: it is seen that these require no switching. Input 2368 is, however, switched to output 237C vin path (3 by reflecting at the back of actuated mirror 238. At the same time.
input 236C is switched to output 2378 oia path y by retlectin~~ at mirror 238. This description refers to mirrors as the actuatable elements but. as already mentioned. other switching elements 1 ~ having similar capabilities may be utilized.
More elaborate effects may be obtained by placing actuatable mirrors at the array diagonal, instead of a fined mirror. As an example, placing two half arrays- as previously described.
back to back with the previously defined reflecting diagonal common to both.
The two half arrays may work independently but, if pan of the reflecting bisecting element is svyitchahle, it is possible for part of the rays to transit from one array to another.
Although the preceding preferred embodiments of valve arrays have no broadcast capability.
these are not restrictive examples. Other embodiments can he devised wherein broadcastin~~
is available by including mirrors that are partially reflective and partially transmissiye, as mentioned above. In such cases, more than one switch is actuated. to produce broadcasting.
Other schemes for broadcasting and multicasting can be designed by those skilled in the art, using the presented building blocks.
Most of the previous features of the array of switches are known from prior art and are applied to the specific embodiments disclosed here. In the case of small arrays, the number of switches is small and the short optical paths cause only small signal losses. Some applications. however, require large numbers of inputs and outputs. For a l Ox 10 array, 100 switches are required. A 50 arm separation between switches will result in a longest path length of -1 mm. In a I00x 100 array, however. there are 10.000 switches and the longest path length is I cm. The large increase in dimensions and number of switches results in increased losses.
a more elaborate swilel~in~~ device is now disclosed in which shorter paths and l~ew-er switches are feasible. Other types of switches. both of the ~~tE~~1S
(microeleetromechanical system) type. like the switch of the present invention, and of other types (lithium niohate.
liquid crystal, etc). are also configurable in the arrays of the present invention, with MEMS
switches being preferred.
An embodiment of this more elaborate device is presented schematically in Figure 24a. In an example of this embodiment, three virtual switching planes, a, b, and c, each having the capability of the arrays described in Figure 23a or 23b, are utilized. These virtual switching planes are, in effect, stacked. with corresponding elements vertically above one another.
Each virtual switching plane operates either independently of the other virtual planes or in conjunction therewith. As will be seen below. these planes are not merely stacked. but may be mutually coupled. to achieve more efficient switching, in a smaller volume than is possihle using prior art switch arrays.
It is important to note that the terminology "virtual plane", "virtual array", "virtual switching plane". "virtual switching arra~~'~, and "logical switching array" has been adopted to stress that. the switching of the present invention is. in reality. done within the physical layers: i.e.
the switches move parallel to the physical layers formed by the suhstrates whereon they are constructed. The virtual planes are only a descriptive artifice for comparison with previous art and better visualization of the overall switching effect. For this purpose, the switches are conceptually grouped in virtual planes independent of the physical layers.
Each virtual switching plane, wherewithin any particular light path advances intersects the physical layers.
The relationship between these two types of layers is shown in Figure 24a.
where physical layers are drawn as vertical planes and labeled a, (3, Y, b, and ~, and virtual layers as horizontal planes labeled u, b, and c. Further details are given below, in the section 2~ ''Fabrication".
Inputs 241 consist of stacked rows, denoted by a, b, c. and vertical columns denoted by I, II, III. Outputs. 242, are similarly denoted. The switch may be regarded as comprising a two-dimensional input array to a three-dimensional switch. leading to a two-dimensional output array. (The previously described device had a one-dimensional input array to a two-dimensional switch. leading to a one-dimensional output array.) With standard fabrication methods. it is difficult to realize the presented configuration:
an easy fabrication method is described below. Those skilled in the art may find other fabrication possibilities.
Other types of switches. beyond the preferred embodiments presented here. may be t~hri~ated by the method presented in the lollowin~~.
;, WO 01/09653 CA 02379936 2002-O1-18 p~/1L00/00425 r1 realization <o tlri: arran~~en~ent i., slrownr in i i~~ur~ ?-Ih. where ,j cut-wvav view of a W o-layer array havin;~ tour switches in each layer is shown. oriented similarly to the schematic view in Figure 2-4a. Inputs 2:13 may lead to outputs 244. The upper layer has inputs 2=13 In and 2:13 lla and outputs 244 In and 2.1.111x. and switches AI.
A2, A3. and A4:
possible light paths are illustrated by dotted lines. The lower layer has inputs 243 Ib and 243 Ilb and outputs 24416 and 24411b, and switches B1. B2. B3. and B4; possible li~~ht paths are illustrated by dashed lines. There is no interaction or correlation between the two layers.
The switches may be of any suitable h-pe.
The same Figure 24b can also illustrate the smallest realization of the half array switch illustrated schematically in Figure 23b. In this case. mirrors A1, A4. B1 and B4 are fixed, mirrors A3 and B3 are absent. and mirrors A2 and B2 are actuatable. as before.
and also reflective on both sides. Light paths beyond mirrors .41. A4, B1 and B4 are no longer possible. As in the previous para~;raph_ there is no interaction hemeen the two layers.
In a first 3D embodiment presented, there is no correlation between input rows. A basic use l~ of this stack is in connecting a number of inputs to outputs within a small space, the only advantage being a saving of space.
A more important use can. however, be envisioned in WDM (wavelength division multiplexing) networking wherein each plane is assi~Tned to a different wavelength, there being a sufficient number of planes for the number of wavelengths in a multiplexed beam.
?0 Previously separated wavelen~~ths are conducted to the respective planes wherein. for each wavelength. a ?D switching matrix routes inputs to desired outputs. These outputs may be subsequently recomhined for further transmission or other use.
Although inputs 241 and 243 and outputs 242 and 244 are illustrated in Figure ?4 as being respectively at right angles to each other. the switch array of the present invention may be ?5 configured with inputs and outputs at any convenient non-zero angle to each other.
Multi-layer .sr,~itching Another use of the sD switching matrix shown in Fi~~ure 2-t is in compact switching of a large number of inputs. The main purpose of this use is the reduction both of a ray path-length and the number of switches necessary compared with a square switching array.
30 Instead of usin~~ a 2D array with a 1 D coltmo of inputs and of outputs. a 2D input matrix is utilized. Each plane. a, h, and c. consist; 01' a non-hlockin~~ array. Such an array can he re'_,rrded as an operator that transform; llte inpm rm~. ~-!1 lo, 2-I1 Ilrr, 2-Il Illo_ at plane a. to output mw. ~'-l2 lu, 2-t2 IIu, 2-t2 //la. W plane a. and su on Ii~r the other planes. since each plane is isolated from nei'~hhorin'~ planes. the only possible operator action is to change a column index. I. II. III, .... beW een input and output.
This is not enough: what is required is the ability to switch any input array element to any output array element. The 3D operator of the preceding paragraph is able to change only a column index of each element in the inprlt matrix. This limitation can be overcome by a double application of the 3D operator wherein rows and columns at the output of a first stage are transposed into columns and rows at the input of a second stage. This second application of the operator will again change only the column index within each row of the second matrix. but this tune the column indices are the former rovy indices. Thus, by applying the 3D operator represented by the 3D switching matrix twice in succession, with intermediate transposition. the necessan switching can be accomplished. Figure ?~a illustrates the disposition of switching elements wherein. for convenience. mirrors are used as switching elements.
1~ Practically. after rays transit a first swrtchrng matrix (251) emerging rays are introduced into a second similar switching matrix (252). rotated 90° with respect to matrix 251. ~-1atrix 252 may be switched differently from matrix 251. Non-blockin~~ switching can be achieved. It can. however. be shown that some switching configurations cannot be achieved.
owing to the non-blocking property of the 2D arrays. A third switching matrix, rotated 90° with respect to matrix 252. is added if the resulting overall svyitching is inadequate. This switch is actually a realization of the well known Clos architecture. With such a conti~~uration, it can be proved that all switching permutations are obtainable. In this case. non-fIIOCkIn'~
states are attain obtained although a non-blocking path that connects any given input to any given output may not be unique so this switch has inherent redundancy. This may be seen from Figure ?>c which depicts a tri-cube complex switching array: a matrix of input beams 255 enters cube 256A, vyherein switching occurs. and the rays emerge as an output matrix 255'.
Matrix 255' enters cube 256B, which is a cube similar to, but with the switching planes thereof rotated with respect to cube 256A. and emerges as transformed matrix 255". A third cuhe 256C is used to make a final transformation of ray matrix 255" into output matrix 255"'. Cuhe 2560 is. again. rotated vyith respect to previous cube 256B.
As an example of the advanta~~e of this design. consider the task of switching am or several of 100 inputs to any or several of 100 outputs (a 100x 100 switch). To pertorm the task. three witchin~T matrices are needed in sednence. each matrix hein~~ rotated 90'' with respect to a preceding matrix. Each switching matrix consists of a I t)p I Oa I t) cnhe.
with I (l00 w itches _ -I
W~ ~l/0965~ CA 02379936 2002-O1-18 p~/IL00/00425 a total of st)On :witches. flee longest optical path. Iur a switch separation of >Oym, is I I(1+10+10+10+10)x>0 ym = 2600 ym =?.~ mm. This compares with 10.000 switches and a 1 cm optical path needed to perform the same task with a conventional 2D
array.
In Figure 2~b is illustrated an equivalent switch array complex to that of Figure 2~a. this time using the halt=array 3D sw-itchin~~ matrix of Figure ?d6. wherein there are tixed mirrors along a diagonal of each matrix. instead of that of Figure 24x. In this case, a 100x 100 switch requires only 1350 switches. not including the 100 fixed switches, along the diagonal.
As in the case of the two-dimensional matrix of Figure 23x, the three-dimensional arrays of Figures 24b and 2~a can be configured with switches such as the switch illustrated in Figures 22c and 22d: providin~~ the option of placing the arrays in switching states in which some or all input rays traverse the array without being reflected. In this case. too.
special options.
such as control elements along the transit paths- can be implemented. :~ 3D
matriweed not be cubic and an input array may be. for example I Ox 10, I0x3, etc. provided that a following.
rotated 3D matrix has a matching number of rows and columns. For example. for a six-input matrix. arranged as a 3x2 array. two planes of 3x3 arrays are needed. The second cube then needs three planes of 2x2 arrays.
In some cases it is necessary to ensure, while switchiny~ some inputs to other outputs, that some or all of the paths connecting the rest of the inputs to outputs are not disturbed. This concern is known as the rearrangement problem. With some configurations, a desired path change for some rays may require, at least momentarily. a switching off of other paths not related to the paths in question, and data intended to transit unaffected may be momentarily affected. This can be overcome with the 3D-block concept using additional cubes or blocks.
together with the bypass capabilities of the switch (as explained before for the basic 2D
arrays). To understand this concept we refer to Figure 2~d, wherein. two identical tri-cube complex switching array sets. of the type shown in Figure 2~c, are aligned each beside the other. Both sets 258A,B.C and 259A,B,C have identical switching capability. If only the first set be activated- switching occurs during the passage of input ray matrix 257 through 258A.B,C exiting as matrix 257"'. The rays then traverse cube 259C.
undisturbed. exiting as matrix 257Y. which matrix is identical to 257"'. Cube 259C is in a bypass (or transparent) configuration. as explained earlier. At this stage. no ray enters cubes 259A
and 259B.
If some change of switching configuration is needed. it can tirst be set up in cubes 259A and 259B. Then, cube 258A is changed to transparent. bypass mode. simultaneously with a chancre of cuter 259C inW a desired witchin~~ mnli'~uratir~n. In thicase ipoul r<3v matrix 2;7 traverse; cube 258A unchan«e<t. witin;~ as identical matrix 2s7a'. ~tatriv 2~7a' neW
enters block 2s9A. is switched therein into matrix 2~7a" and thence by block 2s9B into matrix 2s7a"'. finally emerging. after being switched by block 2s9C. as output matrix ?~7*.
It may he seen that some of the paths linking input to output may pass through one set of cubes while other paths may pass at the same time through a second set of cubes: not all paths need go through the same set of cubes at the same time. The advantage of this design is that it does more than provide a solution to the rearrangement problem: the path redundancy that exists with only three cubes increases dramatically through the use of a second set of three cubes that doubles the system not only for rearrangement purposes but also provides the possibility of backup. Moreover. it can be seen that. even thOllgh the number of cubes has doubled, the path-length increases by only one block traverse thus almost not affecting properties depending on path length. such as loss. This set-up. featuring non-blocking and solvin~~ the rearrangement problem is known as a "strictly-non-hlockin'~
conti'~uration".
As already mentioned, any kind of switch may be incorporated into the design.
but switches 1 ~ including mirrors have many advantages and are a preferred embodiment. It is also emphasized that, although rays are shown as entering and exiting normal to a block, other angles of incidence and output can be designed for, dependin~~ on various considerations pertaining to the required final svvrtchmg arrangements.
In addition to the coupling of two sets of blocks, the same additional states in which the input ray is not reconfigured by any switch (i.e. by-pass or transparent mode) can be utilized in other applications. Such a case or special option could he for implementation of control devices at the output of the bv-pass path.
Again. the 3D matrix need not be cubic and the input array nary he for example IOx4, 10x3, etc. provided that the rotated 3D matrix has a corresponding number of rows and columns.
2s For a six-input matrix arranged as a 3x2 array, two planes of 3x3 arrays are needed. The following cube w-ill need three planes of 2x2 arrays.
Based on the elements presented. those skilled in the an may find other variations covered by this invention. One possible variation is to alter the number of cubes used, applying one, two, three. four. ctc, cubes as required. Not only may the number of cubes change but also their mutual disposition. as required by the specific application. Other wave-shaping or controlling elements can obviously be inserted betore, between. or after the switching cubes.
Such variations include the use of lenses. wave re~~enerators. prisms_ magnets. mc. or addition of a color dc-multiplevin~~ system to the above methods.
(, flan sD blocks explained above have multiple witchin~~ capabilities.
~~Itl~ou'~h ~lescrihed basically as a cross-connect for optical communications. a device having such switching capabilities can serve as a logical component and thus be utilized as part of an optical memory' or as part of an optical computing device.
Wavelength de-multiplexing Another embodiment includes the addition of a wavelength demultiplexing/multiplexing system to the above methods for use of the disclosed switch in WDM (wavelength division multiplexing). In this embodiment. information is transmitted through optical fiber, encoded within a group of different wavelengths. A wavelength de-multiplexing and multiplexing device is necessan' to separate the different wavelengths at the entrance to a switch array and. after processing or use. to recombine these wavelengths. Rays introduced into the described switch are preferably parallel to one another. ,A device that can accomplish this is presented.
Several technologies for wavelength separation exist, among them, the use of diffraction 1 > ~~ratings. The embodiment introduced below uses retlection gratings to separate the wave-lengths into parallel rays that can be introduced into a sD switch. A similar device collects and recombines the output bundle of parallel rays for insertion into a fiber.
The device used (Figure 26) includes two parallel reflection Gratings. 261 and 262. with respective diffracting surfaces that face each other and with rulings also parallel. The ?0 distance between the separated wavelength rays is determined by parameters includin~~ the distance d between parallel gratin ';s 261 and 262 and the pitch of the grating rulings.
A collimated input beam, 263, emerging from a fiber, is incident on a surface of first reflection grating 261 at a predetermined angle a. A simple mirror would reflect this beam at the same angle with respect to a normal to the surface of the mirror. A
grating, however, 2~ reflects different wavelengths (~,,, ~,,, ~,3, ,_,) at different angles (~3,, (3z, (33, ...): the sum of angle of incidence plus an~~le of diffraction is a i~unction of wavelength.
From this. it is clear that different wavelengths will be separated into different angles at reflection grating 261.
Since the relation between the incidence and retlection angles is the same for second reflection gratin's 262 as for first reflection '~ratiny 261. and since the gratings are parallel.
00 the retlected an~~le i~rom second gratin') 262 is equal to the an~.tle of incidence a at first ~_ratine 261. Since this an~zle a is edual ti,r all wwelrn~_ths. rays of all wavelen~~th; emer'=a WO Ol/0965~ CA 02379936 2002-O1-18 p~~L00/00425 parallel. at an~~le a. hut diaplaceJ t~r«n~ une another atier rellectin'r ti-om second ~~ratip= 262.
Thus. wavelem<~ths are separated into parallel rays. with displacement dependin~~ upon inter-grating distance c1_ incident angle a. and the pitch of aerating>
rulings.
Since the ray paths are reversible. reversing direction provides a device capable of recombining wavelengths before insertion into a fiber on output. The use of one device at an input to the matrix and a reversed one at an output allows de-multiplexing.
switching. and multiplexing signals in a WDM network.
The switch presented can thus be used for diverting input rays of different wavelengths from a plurality of inputs to a pluraliy of outputs. The primary use is in communications.
Together with the wavelength separation and combination device presented. the switch is applicable to WDM1. Other applications. such as optical computation. e~c. are also possible.
Fabrication Since the real strength of this device - residing in its compactness - is in switching among many inputs and many outputs. these switches are envisioned to be incorporated in multi-switch devices.
The three-dimensional arrays described in the present invention may he fabricated using prior art technologies. such as conventional macro-. rneso- and micro-machining techniques. In one envisioned application. the switching= of optical paths. the fabrication methods include photo-litho~;raphv. deposition. and etching'_ all methods commonly used in microelectronics ~0 and micro-machining. These methods may. however. be uneconomical or impractical.
Therefore. the scope of the present invention includes an innovative method of fabricatin~~
these arrays. which enhances the advantages thereof.
In this process. 3D arrays are produced usin~~ 2D fabrication methods and stacking to obtain the desired sD switching array. such as an optical cross-connect (OXC). The fabrication ~> technique transfers tire critical steps into tire macro-fabrication realm.
where high quality can be achieved with already-existing mature techniques and much experience exists. The results are applied in the micro-realm.
The basic device is fabricated on top of a wafer surface. in contrast to previous art. where the mirrors are etched into or erected upon a substrate. The mirrors. which require substantially ;p perfect surface quality tlatness. and parallelism. take advantage of high-quality suhstrates ;V
prepared lu,r tile microelectronics industry. Substrates ui various dimensions_ thicknesses.
materials. and surface preparations are available.
Generally. the device can be prepared on any kind of material and the fabrication procedure is independent of substrate material. While the substrate material has no effect on the switches. apart from surface preparation and physical dimensions. it is possible to take advantage of a substrate's properties. For example_ electronic circuitry may be integrated into the substrate or optical fibers may be set therein, in which case advantage can be taken of features such as the cn~stallographic planes of the substrate material, as in silicon. Those skilled in the art may find different materials and techniques for the production of these switches. The fabrication techniques introduced here may be useful for other applications and not just for mirrors or switches as in the disclosed invention.
The fabrication methods disclosed. in many aspects. are enahlin~~
technologies. In other switch array configurations the MEMS methods impose restrictions that impede the functioning and the reliability of the device. The usual HEMS fabrication methods are l~ inherently two-dimensional. That is to say. the device is like a silhouette. If a device should require any out-of plane structure. the elements prepared at the surface have to be raised. In Illally cases this is not a problem but. when dealings with tree-space arrays for optical swrtchmg, this introduces severe restrictions. The principal deficiency is the impossibility of truly positioning the mirrors (a variation of 0.1 degree is enough to spoil the usefulness of the device). Another aspect is mirror quality; mirror smoothness affects signal loss. When dealing with large arrays of mirrors. and especially in pD configurations.
this becomes a disqualifying factor.
Single-.switch fabrication Fabrication is explained with respect to an actuated mirror application. One starts with an 2~ optical quality polished substrate 272 (Figure 27). Mirror material 271, generally a metal such as aluminum, is deposited on substrate 272 and patterned using standard methods such as lithography. Generally. mirror 271 is produced on top of substrate 272 at a zone 273 where substrate material eventually will be removed so that a ray may pass through (Figure 27b).
In a variant fabrication procedure (Figure ?7c. d), a sacrificial layer 274 is deposited on top of substrate 272; patterned. if necessary. to allow the deposition of subsequent layers that must penetrate sacrificial layer 37-1 to reach substrate 272: and polished prior to deposition ;9 and patterning ~,~ mirn,r 271. As well as mirror 271. sup~c~rtin~~ beams 27~
arc deposited and patterned above and tl~rou'~h sacrificial layer 274. Suphortin'~ beams 27s can be made of any material: in many cases they are made of metal or otherwise include conductive material.
Supporting beams 27i are fabricated attached to mirror 271 and substrate 272.
The number and configuration of supporting beams 27~ depend on the application.
After deposition and patterning of mirror 271 and supporting beams 275. these movable elements are released by dissolving sacrificial layer 274 (Figure 27d) or by etching away a non-required, and hence superfluous, part of substrate 272 under minor 271 (Figure 27b).
thus leaving mirror 271 suspended by beams 27~. Further fabrication steps depend on the actuation mechanism. Since the surface on which mirror 271 is deposited was previously polished. the quality of mirror 271 resembles the high quality of the surface on which it was constructed. The use of a surface polished by conventional means to optical mirror grade and the use of this surface as the base for mirror preparation are key innovations of this method.
Fabrication of electrodes and conducting lines can be done together with.
before. or after the above-mentioned steps. Electrodes. conducting lines and the like, as well as the above-mentioned supportin~~ beams 27~. are referred to collectively herein as "awiliary elements".
In case of envelope actuation (Figure 27e. t~. an electrode 276 is deposited on substrate 272 and covered by a sacrificial layer 274. The above-mentioned steps for fabrication of mirror ~0 271 are carried out on top thereof. A second electrode of the envelope can be produced in one of several ways. In one way (Figure 27e. f) mirror 271 is covered by a second sacrificial layer 274A. Second layer 274A is patterned and covered by a second envelope electrode 277. which is also patterned. By removing sacrificial layers, the envelope is formed and minor 271 is released.
Another possibilit, is depositing and patterning a second envelope electrode 277 on another side of substrate 272 or. as illustrated in Figure 27g. on another substrate 272A. By aligning and bringing together a mirror side of substrate 272 and a second-electrode side of substrate 272A. and hondin~~. an envelope is formed (Figure 27h). Bonding is done by one of the known wafer-bonding methods. such as fusion bonding. anodic bonding, or other bonding methods. Spacers and electrical connection paths are deposited and patterned as required prior to alignment and bonding.
-I O
In tl~~ ~.me of curved electrode amnation- the mirror can he pn,cessed directly on a wafer surface at a ray traverse zone. Supporting beams are deposited and patterned on top of the mirror. as previously explained. It is possible to deposit material for the static curved electrode and to do the patternin~~ simultaneously. followed by insulation deposition and patterning over the static electrode. Etching the sacriticial layer and corresponding substrate area releases the movable elements.
In the case of magnetic actuation. the supporting beams may act also as conducting lines, and there is no need for further fabrication steps. The mirror and beams are fabricated and released. as described above.
Other methods for single-switch fabrication can be devised by those skilled in the art. It is emphasized. however, that fabrication on the substrate surface is critical to obtaining good quality mirrors and acquiring better control over alignment of the mirrors.
Switclmrrrrv jnbricmion The construction of a switch array requires more elaborate methods than single-switch 1 > fabrication. The disclosed method is designed to facilitate accurate construction of a ;D
cubic array. Switches are made on wafers in rows and a number of wafers are bonded each on top of another. but displaced laterally. to produce a 3D array. In the following the fabrication is eremplifed by mirrors. although other switching elements can be used instead and formed into a 3D-matrix device. This fabrication method can be applied to other devices that can take advanta~~e of the planarity of the wafers and the ,D
configuration of the completed device.
In order to simplify understanding of the fabrication method. a :lx-Ix.~ array is described (Figure 28). It is to be understood that the descriptions below are illustrative. and are not intended to restrict the present invention to the specific details set forth below Single switches 281 are produced. as described previously. in rows 283, on a surface 282 of a substrate. In our example, there are four rows. These switches are also arranged in groups 28S of regularly spaced columns 284. each group being separated from a neighboring group by an empty column 286 at the same column spacing. The first group of our example consists of one column of four rows ( 1 x4). separated by an empty column from a second ~~roup consisting of two columns of four rows (2x1) followed by another empty column. The I
arran~~ement continues with successive groups of >k-1 ancl -1~-1 to form a set. .fin entire water may be covered with such sets. For our example. at least seven such sets are required.
In order to fabricate a box array. these sets are carefully aligned, each on top of another. and bonded. A first set is placed at the bottom ready for an alignment (Figure 28b). A second wafer is aligned on top of and parallel to the first. with a second group of columns (2x4) centered above a single-column group ( 1 x4) of the first wafer. This alignment is obtained by suitably displacing the second wafer with respect to the first, in a direction parallel to rows 283. This procedure is continued with consecutive wafers, a 3x4 group of columns being centered above the 2x4 group, and a 4x4 group being centered above the 3x4.
Stacking is then continued in a reverse order. a 3x4 group being centered above the 4x4 group, and so on, until a 1 x4 group is placed on top of a second 2x4 group. The stack is then bonded. The wafer surfaces correspond to the physical layers defined earlier. Viewed from the side.
however. the mirrors f01'lll a 2D matrix having column 287 and row 288 directions oriented at ~1~° to the surfaces of substrates 282. The mirrors are oriented at 45° to these column and row directions. In this example, there are four virtual arrays, corresponding to the four rows of switches fabricated on the wafer surfaces.
If the configuration shown in Figure 236 is fabricated. only half of the above array is required. One set of S~'IItChln~~ mirrors_ at a reflecting middle plain, 289, is replaced b~ a plain static mirror substrate and the mirrors on the non-reflective side of plain 289 are not required.
After bonding is completed. the mass is accurately diced. preferably parallel to columns 287 and rows 288 of the mirror array, along dashed lines 280. A cubic array of mirrors results.
This array is further packaged by aligning with input and output fibers. It is possible to align two or more such cubes and to rotate one with respect to another so that a 3D-switching device, as explained before, is produced.
A finished device is represented in Figure 29. There, a finished cube can be seen with aligned substrates 291 bonded at interfaces 29:1. The input and output ports for the rays_ in the case of an optical switch, are represented interchangeably by 292 and 293.
Similar steps are followed to produce arrays of other dimensions, including rectan~~ular arrays other than square ones.
-I , WO 01/09653 CA 02379936 2002-O1-18 pCT/IL00/00425 Operation These switches are actuated by one of the previously specified methods through conducting lines which connect rows. columns, and planes. as appropriate. By applying an appropriate voltage or current to a particular mirror. that mirror may be set or reset into an ON or OFF
state.
Applications The switch presented can be used for switching input rays of different wavelengths from numerous input paths to numerous output paths. It is primarily intended for use in communications. Together with the wavelength separation and re-combination device disclosed above, it is applicable to WDM. Other applications. such as in optical CCllllplltatl011. Wc. will be evident.
While the invention has been described with respect to a limited number of embodiments. it will be appreciated that many variations, modifications and other applications of the invention may be made.
.t ;
The switch either intercepts a light ray and reflects the ray into a changed direction or allows the ray to transit unimpeded. This switch is situated on. above. inside. or below a substrate and actuated parallel to the substrate's surface b~ electrostatic. magnetic. thermal.
piezoelectric. or other means. Some of these bi-stable actuation methods. which may be utilized in other applications, are described below. In the case of electrostatic actuation. an envelope-st,~le electrode may be used to obtain larger forces than are obtained in prior art configurations, such as comb actuators. to produce faster switching. Designing the electrode edges to have a more complicated or irregular shape such as a fractal shape can increase this force even more.
It should be noted that the terms "valve' and "sw itch's are used interchangeably herein.
An NxN switch. that can route any of its N inputs to any of its N outputs. is simple to realize.
There is no interference among the N inputs, since light-ray paths cross without interaction (Hecht .I.. "Optical switching promises cure for telecommunications log jam".
Laser Foczrs 11'orlcl. September 1998. page 69). There is thus almost no cross-talk between data lines.
which allows the utilization of such switches in complicated schemes. Such switches may be incorporated into a three-dimensional array in order to produce compact cross-connects that may switch rays from a plurality of inputs to any of a plurality of outputs, a configuration that ?0 can be utilized in optical computation. They nla~' also be used to switch other than optical waves. for example acoustic waves. ,4 three-dimensional switch array disclosed allows this switchin~~ to he done with shorter ray paths and fewer mirrors than w ith prior art. VNithout limiting the generality of the invention. the examples and embodiments described hereunder will be directed to switching optical w-aves in communications applications.
2~ The task is mainly the production of tiny mirrors to use as switches in these arrays.
Micro-machined devices are capable of fulfilling the task, provided that the micro-machining produces optical-grade mirrors in order to reduce losses. Actuation needs to be fast, simple, and allow reproducible and accurate alignment of the beam inputs and outputs as the mirrors bend the ray. In addition, the abilit, to deploy lame arrays of mirrors is an essential feature 30 of the system. All of these affect switching losses and utiliy. Previous art devices. although ingenious. were not able to achieve all of these requirements together. (See, for example:
Toshivoshi H. m ul_ "Electrostatic micro-torsion mirrors for an optical-switch matrix".
.lnnrnn/ o/ 'llicr~n~le~cnrnnacrlumiwnl.fncloms_ vc,l. ~ No. =t. December 1996. patTe ?;1. and WO 01/09653 CA 02379936 2002-O1-18 p~/II,00/00425 ~lararr O. eml. "Vertical mirrors fabricated by deep reactive ion etching li,r fiber-optic w itclrin'~ appllcatlons". .J1I11!'llcll n~ ~llicmoeloclruntc-olumiwu!
,fv.srem.v, vol. 6_ No. f.
September 1997. page 277.) A device that can separate a multi-wavelength beam into a bundle of parallel single wave-len~th rays and recombine them is also disclosed.
Usual fabrication methods are employed but enhanced mirror alignment and performance are achieved by fabricating mirrors on the surface of a wafer. A novel method is disclosed for fabricating 2D and 3D arrays, by bonding several laterally displaced wafers on top of one another.
According to the present invention there is provided an optical switch for switching a light ray including: (a) a substantially planar substrate havin~~ a portion that is transparent to the li~~ht ray: (h) a switching element havin~~ at least one reflective surface substantially parallel to the substrate: and (c) a mechanism for moving the switching element in a direction parallel to the substrate between (f) a first position wherein the light ray traverses the transparent portion of the substrate and (ii) a second position wherein the light ray is blocked from traversing the transparent portion of the substrate and reflected by the reflective surface.
According to one embodiment of the present invention the mechanism includes:
(f) a first rigid element having two ends. the first end of the first rigid element being flexibly connected to a fined point: (ii) a second rigid element having two ends, the second end of the first rigid element being flexibly connected to the first end of the second rigid element:
and (iii) <t tensile elastic element connecting the first end of the tint rigid element to the second end of the second risid element so that the distance between the first end and the second end when the elastic element is in a relaxed state is less than the sum of the distance between the ends of the first rigid element and the distance between the ends of the second rigid element: both the rigid elements being constrained to be movable only in a plane parallel to the substrate.
According to another embodiment of the present invention the mechanism includes: (f) a first element ha1'In'~ two ends: (ii) a second element havin~~ two ends. the first end of the first element being flexibly connected to the first end of the second element: (iii) a third element having two ends, the second end of the second element being flexibly connected to the first end of the third element: (iv) a fourth element having two ends. the second end of the third element being flexibly connected to the first end of the fourth element: (v) two fixed anchor points. a second the end of the f first element being flexibly cimnected to the first anchor point and the second end ol_tlte ti,llrtlr element being flexibly connected to the second anchor poil:
and l~ i) a tensile el<IStic mechanism fe,r maintainin« the mechani,m for movin~~ the witching element in either of nwo stable states: all the elements being constrained to he movable only in a plane parallel to the substrate.
According to one embodiment of the present invention all the elements are rigid.
S According to a further embodiment of the present invention the tensile elastic mechanism includes: (a) a tensile elastic element connecting the second end of the second element to the first anchor point so that the distance between the second end and the first anchor point when the elastic element is in a relaxed state is less than the sum of the distance between the ends of the first element and the distance between the ends of the second element:
and (b) a tensile elastic element connecting the first end of the third element to the second anchor point so that the distance between the first end and the second anchor point when the elastic element is in a relaxed state is less than the sum of a distance between the ends of the third element and the distance henyeen the ends of the fourth element.
According to another embodiment of the present invention the tensile elastic mechanism includes a tensile elastic element connecting the first end of the second element to the second end of the third element so that the distance between the first end and the second end when the elastic element is in a relaxed state is less than the sum of the distance between the ends of the second element and the distance between the ends of the third element.
According to another embodiment of the present invention the tensile elastic mechanism ?0 includes a spiral spring at each flexible connection.
Accordin~~ to another embodiment of the present invention the tirst element and the fourth element are elastic beams, the second element and the third element are rigid.
the first element is rigidly connected to the first anchor point. and the fourth element is rigidly connected to the second anchor point According to the present invention there is provided a hinge including: (a) a housing having a flat wall. (b) an element free to roll within the housing and haying a connector that protrudes beyond the housings. (c) a mechanism for urgings the rollable element against the wall as the element rolls within the housing so as to maintain rolling contact between the element and the wall.
30 According to one embodiment of the present invention the connector is rigid.
According to one embodiment of the present invention the ur~_in;; mechanism is electrostatic.
-I
:~ccorciin« to another embodiment of the present im-ention the ur~~in'~
mechanism is maenetic.
According to another embodiment the present invention further includes (d) a restoring mechanism for returnin~~ the rollable element to contact with the wall in case of loss of contact.
,According to one embodiment of the present invention the restoring mechanism includes: (a) nvo flexible cables: (i) the first end of the first cable being operationally connected to but electrically insulated from the housing, (ii) the first end of the second cable being operationally connected to but electrically insulated from the housing. (iii) the second end of the first cable being operationally connected to but electrically insulated from the rollable element, and (iv) the second end of the second cable beings operationally connected to but electrically insulated from the rollable element: (h) two electrodes for resettin~~ the rollable element in place: (i) a tirst the electrode being_ situated opposite the tirst cable on a side away from the rollable element. and (ii) the second electrode being situated opposite the second 1 S cable on a side away from the rollable element, (c) a mechanism for charging the electrodes;
and (d) a mechanism for charging the cables.
According to one embodiment of the present invention- in the restoring mechanism (a) the cables are slack while the rollable element is in contact with the wall. and (b) at least one cable is taut when the rollable element loses contact with the wall.
According to the present invention there is provided a travelling wave actuator for moving an object including_ (a) an elastic membrane. (b) a mechanism for maintaining contact beween the object and the membrane. and (c) a mechanism for '~eneratin~~ a travelling wave in the membrane.
According to one embodiment of the present invention the travelling wave actuator further includes (d) a substrate whereupon the elastic membrane is deposited.
According to one embodiment of the present invention the mechanism for maintaining contact is electrostatic.
According to another embodiment of the present invention the mechanism for maintaining contact is magnetic.
Accordin~~ to one embodiment o1' the present invention the mechanism for ';eneratin~~ a travelling wave includes: (i1 a plurality of electrode lairs. eclallv slace<I
alone and W~ ~1/0965~ CA 02379936 2002-O1-18 p~~,p0/00425 stradcllin~~ the nmmhron~_ and Liil ti,r each pair. a respective alternatin;~
electrical power supply.
,4ccording to another embodiment of the present invention the mechanism for generating a travelling wave is magnetic.
W.According to another embodiment of the present invention the mech<rnrsm for ~~enerating a travelling wave is thermal.
According to another embodiment of the present invention the mechanism for generating a travelling wave is piezoelectric.
According to the present invention there is provided an actuator for moving an element comprisin;;: (a) a stationary support for the element. (b) a deflectable support for the element operative to: (i) raise the element from the stationaw support. (ii) advance the element in a required direction of motion. (iii) deposit the element upon the stationary support. and (iv) return to a starting position thereof.
According to one embodiment of the present invention (a) the stationary support includes a 1~ cluster of fingers. the cluster being sufficient to support the element.
and (h) the detlectahle movable support includes at least one cluster of fingers. each cluster being sufficient to support the element.
.According to a further embodiment of the present invention each finger includes a surface at a tip thereof. whereupon the element is supportable.
?U According to a iiirther embodiment of the present invention the element is a planar switchin~~
element.
According to a further embodiment of the present invention the deflectable support is activated electrostaticallv.
,4ccording to a tirrther embodiment of the present invention the deflectable support is 2~ activated piezoelectricallv.
,According to the present invention there is provided an emergency holding device for a movable switching element includin'_: (a) a buckled beam having: (i) a first stable configuration concave towards the switching element. and (ii) a second. tense conti'~uration.
concave towards the w itchin~~ element. wherefrom. if relieved. the beam relaxes to the first ;(1 stable rrmii~zur,uimo: ,rnd (hl a tlexihle strap str,~ddlin'~ the w-itching element. the atrap hein~.~:
(, WO 01/09653 CA 02379936 2002-O1-18 pCT/IL00/00425 ( f 1 attached at a f first enci thereof to a center of the beam anti perpendicular tl~erete~. and ( ii 1 anchored at a second end thereof at a tined point. so that. at the concave stable conti~_uration.
the strap constrains the switching element.
Accordin~T to one embodiment of the present invention the flexible strap is electrically conductive. the device further comprising: (c) an electrode placed opposite the strap.
According to the present invention there is provided a mechanism for lateral realignment of a free movable element with respect to a rectilinear motion path thereof comprising: (a) two alignment pads on opposite sides of the element, (b) a mechanism for bringing the pads into contact with the movable element. thereby nudging the element to the laterally aligned position. and (c) a mechanism for retracting the pads from contact.
According to one embodiment of the present invention each the alignment pad includes an electrode.
According to one embodiment of the present invention the contact mechanism is elastic.
According to another embodiment of the present invention the contact mechanism is 1 ~ electrostatic.
According to another embodiment of the present invention the realignment mechanism further includes: (d) two walls situated on opposite sides of the movable element and outside the alignment pads. and (e) elastic elements attaching each alignment pad to the nearer wall.
,4ccordin~~ to another embodiment of the present invention the realignment mechanism ?0 further includes: (d) two walls situated on opposite sides of the movable element and outside the alignment pads. each wall including an electrode. and (e) elastic elements attaching each alignment pad to the nearer side of the movable element.
According to one embodiment of the present invention the retracting mechanism is electrostatic.
According to another embodiment of the present invention the retracting mechanism is magnetic.
According to the present invention there is provided a mechanism for continuous lateral reali~~nment of a free movable element with respect to a motion path thereof including: (a) a stationary electrode adjacent to and clear of the path. (h) a second_ movable electrode: (i) ,0 attached W tl~e element. (iil at lean partially overlapping tl~e stationary electrode. and (iiil WD 01/09653 CA 02379936 2002-O1-18 p~/1I,00/00425 constrained to remain parallel W the stationary electrode so that a ~~ap remains therehetween_ and (c) a mechanism for electrostaticallv charging the electrocles_ the resulting electrostatic force between the electrodes acting to maintain the element in the motion path.
According to one embodiment of the present invention the motion path is confined to a plane.
i ,4ccording to another embodiment of the present invention the motion path is rectilinear.
According to a further embodiment of the present invention the realignment rlleChanISm.
includes: (d) a second stationary electrode adjacent to and clear of the path, (i) lying in a same plane as and clear of the first stationary electrode, (ii) opposed to the first stationary electrode with respect to the motion path. and (iii) at least partially overlapped by the movable electrode so that a gap remains therebetween_ and (e) a mechanism for electrostaticallv charging the second stationan electrode. the resulting electrostatic force beween the electrodes acting to maintain the element in the motion path.
According to a further embodiment of the present invention the stationary electrodes are shaped as mutual mirror images and are symmetrically disposed about the path.
1 ~ Accordin;~ to a further embodiment of the present invention the charge on the second stationary electrode is of same polarity as the charade on the first stationan electrode.
,4ccording to a further embodiment of the present invention the charge on the movable electrode has the same polarity as the charge on the stationary electrodes.
,4ccordin~~ to another embodiment of the present invention the chary=e on the movable ~'0 electrode is of opposite polarity to the charge on the stationan electrodes.
According to a further embodiment of the present invention the shape of each electrode is an isosceles triangle. an axis of symmetry whereof is oriented perpendicular to the motion path.
,4ccording to the present invention there is provided a method of moving an object including the steps of: (a) ur'~in~; the object to he in contact with an elastic membrane while (b) generating a travelin'; wane in the membrane.
According to the present invention there is provided a method of moving an element including the steps of: (a) providing: (i) a stationary support for the element. and (ii) a deflectable support for the element. and (b) cyclically operating the deflectable support to: (i) raise the element from the stationary support. f ii 1 advance the element in a required direction of motion. pill) deposit the element upon Ilre static~nan support. and livl return to a ;tartin~~
position thereof.
According to the present invention there is provided a method of holding an electrostatically supported switching element in the event of cessation of a supply of power to the switching element. including the steps of: (a) providin~~ a flexible strap straddling the switching element. and having a first configuration wherein the strap constrains the switchin'; element and a second configuration wherein the switching element is free from the constraint: and (b) maintaining the strap in the second configuration only while power is supplied.
According to the present invention there is provided a method of laterally realigning a free movable element in a direction perpendicular to a rectilinear motion path thereof including the steps of: (a) providing a realignment mechanism including two movahle alignment pads on opposite sides of the element. (h) bringing the pads into contact with the movable element.
thereby nud'~in'~ the element to the rectilinear motion path. and (c) retracting the pads.
According to the present invention there is provided a method of continuously laterally I S realigning a free movable element with respect to a motion path thereof comprising the steps of: (a) providin~~: (i) a stationary electrode adjacent to and clear of the path. (ii) a second, movable electrode attached to the element. at least partially overlappin'T the stationary electrode. and constrained to remain parallel to the stationan electrode so that a gap remains therebetwee.n, and: (iii) a mechanism for electrostaticallv charging the electrodes. and (h) electrostaticallv charging the electrodes.
According to one embodiment of the present invention the method includes the further steps of: (c) providin~~: (i) a second stationary electrode adjacent to and clear of the path. lying in a same plane as and clear of first the stationary electrode, opposed to the first stationary electrode with respect to the motion path, and at least partially overlapped by the movable electrode so that a gap remains therebetween. ancf (ii) a mechanism for electrostatically char2inrl the second stationary electrode.
According to a further embodiment of the present invention the method includes the further step of providing that the stationary electrodes are shaped as mutual mirror imagoes and are symmetrically disposed about the path.
According to a further embodiment of the present invention the method includes the further step of char'lin~:, the second stationary electrode with a polarity the same as the charade on the first stationary electrode.
y WO Ol/0965~ CA 02379936 2002-O1-18 pCT/IL00/00425 ~morciine to a f'nrther eml>ociimeW of tl~e present inveWion the nrctho~i includes the further step of charging the movable electrode with a polarity tire same as the charge on the stationan electrodes.
According to another embodiment of the present invention the method includes the further step of charging the movahle electrode with a polarity opposite to the charge on the stationary electrodes.
According to another embodiment of the present invention the method includes the further step of providing that the stationary electrodes are shaped as isosceles triangles.
According to the present invention there is provided a method of fahricating a micro-device having a high-quality smooth mirror surface comprisin~~ the steps of: (a) polishing a substrate surface to a required smoothness. (h) depositing mirror material on the substrate, and (c) removing a superfluous part of the substrate adjacent to a surface of the mirror.
According to the present invention there is provided a method of fabricatin~~
a micro-device having a high-quality smooth mirror surface comprising the steps of: (a) depositing a 1 ~ sacrificial layer on the substrate. (b) polishing a surface of the sacrificial layer to a required smoothness. (c) patternin~~ the sacrificial layer to provide for auxiliary elements. (d) depositing mirror material on the polished surtace of the sacrificial layer.
(e) depositing the au~ilian elements on the patterned portion of the sacriticial layer. and (t~
removing the sacriticial layer.
~'0 According to another embodiment of the present invention the method further include; the step of: ('~) removing a supertluous part of the substrate.
According to the present invention there is provided a method of fabricatin~~
an envelope-actuated micro-device having a high-qualih smooth mirror surface including the steps of: (a) providing a first substrate. (h) depositing an electrode on the first substrate, (c) 2~ depositing a first sacriticial layer on the electrode and the first substrate. (d) polishing a surface of the first sacrificial layer to a required smoothness. (e) patterning the first sacriticial layer to provide for a first set of auxilian elements. (f1 depositing mirror material on the polished surface of the first sacrificial layer. and ('~) depositing the awiliary elements on the patterned portion of the first sacrificial layer.
;0 ,Accordin~~ to another em hodiment of the present invention the method includes the t~mlher step of: (h) providip_ a second elrUrodc.
WO O1/09C)53 CA 02379936 2002-O1-18 p~~L00/00425 ,4crorclin~~ o, anWloer embodiment of the present invention the method ui providing the second electrode is effected by the further steps of: (i) depositing a second sacriticial layer on the mirror material. (ii) patternin~~ the second sacrificial layer to provide for the second electrode and a second set of auriliary elements. and (iii) depositing the second electrode and the second set ofau~:iliarw elements on the patterned portion ofthe second sacrificial layer.
According to another embodiment of the present invention the method of providing the second electrode is effected by the further steps of: (i) providing a second substrate, (ii) depositing the second electrode on the second substrate. (iii) aligning the second electrode opposite the micro-device as fabricated on the first substrate. and (iv) bonding the second substrate to the first substrate.
According to another embodiment of the present invention the method includes the further step of: (h ) removin~~ the first sacriticial layer-According to another embodiment of the present invention the method includes the further step of: (h) removing a superfluous part of the substrate.
According to the present invention there is provided a mechanism for providing a strictly non-blocking 5~~11Chlllg configuration comprising two coupled substantially identical tri-cube complex switchin~~ arrays: (a) each capable of switching any input element to any output element. (b) the first array being capable of allowin'; any input element to transit unswitched to a corresponding input of the second array. and (c) the second array hein'~
capable of ?0 allowing any output element from the tirst array to transit unswitched to a correspondin~~
output of the second array.
According to the present invention there is provided a method of strictly non-blocking switching including the steps of (a) providing two coupled substantially identical tri-cube comple?: switching arrays: (i) each capable of switching any input element to any output 2> element. (ii) the first array being capable of allowing any input element to transit unswitched to a corresponding input of the second array. and (iii) the second array being capable of allowing any output element from the tirst array to transit unsw itched to a corresponding output of the second array. and (h) operating the switching arrays coupled in parallel.
WO 01/09653 CA 02379936 2002-O1-18 pC'1'/IL00/00425 Brief Description of the Drawings The invention is herein described. by way of example only. with reference to the accompanying drawings. wherein:
Figure 1 shows the general switch layout and basic switching motions;
Figure 2 shows switch zones;
Figure 3 shows basic switching actions:
Figure 4 illustrates how a switch can direct Uvo parallel inputs to separate outlets, by operating a switching element entirely within an optically active zone;
Fixture > shows the principles of envelope actuation of a switching element;
Figure 6 presents two different desi~~ns for curved-beam actuation:
Fieure 7 illustrates the use of magnetic actuation:
Figure 8 shows various bistable beam supports;
Figure 9 shows further examples of bistahle beam supports:
Figure 10 presents a representation of the use of bistable beams with a micro-mechanical switching element:
Fi~~ure 1 1 illustrates the action of a frictionless_joint:
Figure 1'' .presents a more complex application of a frictionless joint;
Figure 13 shows a resetting mechanism in the event of power failure:
Figure 14 illustrates travelling-wave actuation;
?Q Fi~~ure I ~ shows the mechanism of fin~~er actuation:
Figure 16 shows a variation on finger actuation Figure 17 presents a mechanism for securing a movable element in the event of power failure;
Fi~_ure I 8 illustrates an electro-mecl~anicol method of ali~~nin~~ a movable element:
I, WO 01/09653 CA 02379936 2002-O1-18 p~/II,00/00425 Fi«ure 19 show; a variant o1-the method oi-ti~~urc I fi:
Figure ?0 shows how electrostatic forces can maintain alignment:
Figure 21 presents applications of electrostatic alignment:
Figure 22 shows some basic switching actions with mo crossed rays:
Figure 23 presents a two variations of a basic ?D switch array:
Figure 24 shows a schematic view of multi-layer switch array:
Figures 25 illustrate 3D switching methods involving two or more multi-layer switch arrays. including a partially blocking confi';uration. a Clos architecture (non-blocking) configuration. and a strictly-non-blocking configuration:
Figure?6 shows a wavelen«th-separationirecombiner device:
Figure ?7 illustrates basic switch fabrication processes:
Figure 28 shows fabrication stages of a pD switch array: and Figure ?9 shows an isometric view of a 3D array cube.
Wo ~l/0965~ CA 02379936 2002-O1-18 p~'/Ii,00/00425 Description of the Preferred Embodiments Introduction The wave valve of the present invention is intended to be used in fiber-optic communications to overcome the above-mentioned shortcomin<~s of previous art. although other applications can be envisioned. It employs mirrors to perform the switching. Mirrors have the advantage of being substantially insensitive to wavelength. The active environment is air. some other gas. or a vacuum. This is a non-blocking environment: i.e. it allows rays to cross unimpeded.
Thus there is no cross-talk and almost no attenuation by the medium. Most losses occur durin~~ light transfer from and into the fiber at the switch/fiber interfaces.
Losses also arise from beam spreading. but use of collimating lenses and short distances can reduce these.
The mirrors should he small. to allow fast response and compactness. The mirrors are generally micro-machined and. in order to reduce losses. are designed to be of optical grade.
Actuation should provide reproducible and accurate alignment of the beam inputs and outputs while the mirror bends the ray. In addition. the ability to forn~ large arrays is an essential 1 ~ requirement of the system. All these requirements retlect on switch loss and utility. Prior art devices, althOllgh IIl''enlOUS. were not able to fulfil all these requirements together [Toshivoshi H. et al.. "Electrostatic micro torsion mirrors for an optical switch matria~.
Journal of A~ioroelecW omechunical Svslems. vol. ~ No. 4 page 231. December 1996, and Marxer C. et al. "Vertical mirrors fabricated by deep reactive ion etching for fiber optic ?0 switching applications~~. vol. 6 No. 3 pa~~e ~,?. September 1997].
These factors are incorporated into the design of the valve. which is ~~enerally planar and fabricated on a smooth wafer substrate. unlike prior art wherein the mirrors are etched into the wafer bulk. In order to enhance switchin~~ speed, the mirror moves parallel to the substrate, thereby reducing air resistance and nlII111111Z1na small deviations of the mirror from ~5 the normal (90°) to the substrate that account for part of the losses introduced in prior art systems. Moreover. the principles presented here are designed to give higher actuating forces, thus allowing a faster response than in prior art switches.
Single valve configuration and operation.
Referring to Fi~~ure 1 a and 1 h, the value consists of a flat mirror 1 situated above. on. inside.
p0 or below. and parallel n> a substrate 2. In tht figure. it is shown at a short distance c1 from the substram. ~'lirror 1 may move n, ditterent position; in a plane 3 parallel to a surface of substrate 2, either substantially curvilinearly. as in a pendulum-like motion s in Fi~~ure Ic. or in a substantially rectilinear motion in any direction, such as 6 or 6A in Figure 1d. or in some combination of these. In a preferred embodiment, motion is generally parallel or normal to a base line 7 (Figure 2). that separates an opaque zone 8 of substrate 2.
wherethrouQh light 10 cannot pass. fr01T1 a transparent zone 9, wfierethrough light 10 can pass and wherein switching takes place. Zone 9 may be transparent because the material of substrate 2, which is present in zone 8. is absent in zone 9, or because the material of substrate 2 in zone 9 is transparent to a relevant wavelength. Different embodiments of the principles disclosed here can be devised by those skilled in the art, wherein it is possible to distinguish the zones in other ways.
One approach is illustrated in Fi'_ure i. Mirror element 1 is located opposite an opaque zone 38 of substrate 2 while li~~ht 10 transits unobstructed throu~~h a transparent zone 39. In thi condition. the system is in an UI=F state 1A. as shown in Figure 3a, b. Mirror I is movable 1 > rectilinearly. parallel to substrate 2, to a position opposite zone 39, as shown by double-headed arrow 3b, to an ON state 1B (Figure 3c, d?. While mirror I is in OFF state 1A.
light 10 can pass from one side 39.4 of surface 3 to another side 39B.
In a preferred embodiment (Figure se, f) ray 10 is inclined at 4>° to mirror 1. In OFF state 1A. ray 10 transits transparent zone 39 unimpeded from IOA to IOB. When mirror 1 is in <)N
state 1B, ray 10 is reflected along an alternate path IOC. Thus ray 10 has one input state IOA
and mo possible. mutually exclusive. output states 10B and IOC.
In 8nother embodiment (Fi~~ure -1). mirror 1 is movable along a line of motion :16 which lies entirely opposite a transparent part 49 of plane 3 and, by so doings.
simultaneously e~chanaes blocking and non-blocking states in different parts of zone 49. Mirror suspension and actuation elements are placed opposite another, opaque zone 48 of plane 3. As previously explained. in a non-blocking state 41A (Figure 4c), light from IOA passes to exit IOB while.
in blocking state 41B. light is reflected to an alternate output IOC. In this configuration.
where mirror 1 is entirely opposite transparent zone 49, either position of mirror 1 can be designated as ON or OFF (Figure -le, f). Thus. it is possible to have a valve with two parallel inputs 10 IA and 10 11A beings in an ON state for the former. retlecting ray 10 IA to output 10 IC. while being in an ~)t=F state for the latter, which passes to output 10 IIB (Fi~zure :fe).
On actuating switch 1. these states reverse and input ray 10 1A is in an OFF
state, transiting to 1;
WO 01/09653 CA 02379936 2002-O1-18 pLT/IL00/00425 output 10113_ while intent rat' 11111A i; in an o1\ state_ retlectin~~ m output 10110. This makes a ( 1 x2 )x2 exchange switch. which may be used. for example. in a Banvan neW ork.
~1ore elaborate applications can be realized by combining two or more switching elements.
It is important to note that the rays can traverse the switch in a reverse direction. In this case, inputs interchange with outputs and the switching options explained above are reversed.
Actuation The valve consists of mirror I which is movable parallel to surface 3 and may be in at least two rest positions. Mirror 1 reflects light at one position and allows its passage at another position. Anv appropriate force may be applied to induce a desired change in mirror position. A number of actuation methods are available: thermal (bimetallic strips). magnetic.
piezoelectric_ mechanical. and electrostatic actuation and methods that rely on shape memom alloys (SM,4) are a few of many known in the art.
Three preferred actuation embodiments are discussed. The first follows a design similar to a comb-drive but designed to produce larger forces than prior-art implementations. It uses an envelope-like electrode into which a mirror is retracted. Larger forces can be obtained with this actuation method by designing the electrode edges to have a large area chancre. such as a fractal form.
Alternatively. a mirror is supported by flexible beams that are actuated by attraction to or repulsion from static. curved electrodes.
I~1a~netic actuation is also described whereby a ma~~netic field is established around a switch and a flowin~~ current induces switching.
Electrostatic envelope actuation A preferred embodiment employs electrostatic actuation. Different schemes of electrostatic actuation can he used. among them a comb-drive mechanism. (Hirano T. et u1.
"Design, 2~ Fabrication. and operation of submicron-gap comb-drive microactuators", .lourrrul of Microelectromochunicul S'vslems. vol. 1 No. 1. A~tarch 1992, page ~2.) In conventional comb-drive actuation. the actuation force depends on the change of the overlapping area between a driver's tingers and a comb. Since usual fabrication methods limit that area to a small value. a large numher of tin~~ers is necessary to produce the required lorce. Therefore Ih tl~i; kind of actuation require; lar«z actuators. :1 di(~lerent approach t«
this actuation principle is disclosed here (Figure >).
Overlapping finger 51 and comb s2 form a capacitor (Figure >b). The attractive force between the movable and static fingers is:
c~(,,, F= -cW
where j,, is the electrical energy stored in the capacitor of capacitance C~'. The capacitance of a parallel-plate capacitor is determined by the geometric parameters thereof and depends directly on the area (A) and inversely on the gap between the electrodes (g").
In the case considered here:
.-1 !y ~.
('=8~i-=E~
~~'o ~~'n The force is. therefore:
s~I'-h~
F=
--g..
1 ~ Where. ~~ is the permittivity of the vacuum, V an electrical potential, lo" is width of the finder_ r is the overlapping length of the finger in the direction of advance thereof.
and g" is the ';ap between the movable finder and each static finger. Thus the force is inversely proportional to the gap between the fingers and proportional to the width of the fingers. It does not depend on the thickness of or the amount of overlap beW eon movahle and static tingers. Based on ?0 this conclusion. a configuration is disclosed wherein the width of the tinger is increased in order to achieve greater force and thus faster switching speed,.
The production of wide fingers is difficult with conventional, prior art. A
fabrication technique is disclosed below wherein the manufacture of wider fingers is easily done using conventional methods. In this way. fewer fingers. or even a single finger, can achieve sufticient force and hence switching times of the order of microseconds, compared to milli-seconds with prior art. The disclosed actuator has an envelope-like configuration in which mirror / tinges (movable electrode) s1 may enter or exit envelope (static actuating electrode) ~2.
In another emhodiment (Figure ~dl. at least two actuatin~~ electrodes are placed in a way that one set s2A actuates to an ON position while another set s2B. C actuates to an OFF position.
:4ctuation can be made bistable: if the actuated mirror is supported by huckled beams (see below). a snap action to each position of the mirror results.
Another possible embodiment to implement bistabilitl. employs electrostatic snap (pull-in) action. An actuated element is attracted to and held by an electrically isolated electrode at an end of its motion. From the equations above. force exerted is given by:
s h'' c~A
F= ° -2go c~Z
Since force depends on the change of area A with displacement x, then, to increase the force, the area change of this actuator should be increased, not only the width of the finger. There-fore. for the actuator presented. the force can be increased further by using a more complex profile than a straight line (~7. Figure >c) that the electrode crosses.
thereby increasing the rate of area change. This line can be designed. for example, to be circular (s7B. Figure ~e), and the force increases correspondingly. Alternatively, or additionally, the leading edge of electrode ~1 may be similarly enlarged.
Another embodiment increases the profile by using an even more complex geometrical form.
Such a form might be an irregular form such as a fractal line designed for the application.
The use of a fractal form can increase the actuatin~~ force by the ratio of its rate of area chance to that of a straight-line profile.
?0 Crrrred electrode artrrntion Another electrostatic actuation method is presented in Figure 6, in which the post-fix A or B
refers respectively to variant embodiments. One or more flexible beams 67A or 67B support a mirror 61. One point of the beams) 68A or 68B is fixed in close proximity to a circular segment stator 69A or 69B attached to a substrate 62. These stators and beams are 2> conductive and respectively chargeable with opposite polarity. Beam 67A or 67B and stator 69A or 69B, respectively, are separated by insulators 6>A or 65B from each other along an entire circular segment of stator 69A or 69B or. at least- at points where contact may otherwise occur. so as to prevent a short circuit (Figure 6a. b. c. and d).
Applying a potential difference between stator 69.A (B) and movable beam 67A
(B) sets 30 charades of opposite polarities on stator 69A (B) and beam 67A (B). so that the latter is attracted to the former. as close as permitted by the insulation (I=i'~ure 6h.
6d). Removing the IS
WO 01/09653 CA 02379936 2002-O1-18 pC'f/IL00/00425 potential dii~fereni:e allows beam 67.4 (B) n, return W the ori;~inal sh<rpe thereof. Since a free end of beam 67A (B) is connected to mirror 61. the consequent advance or retreat of the contact zone around a perimeter of stator 69A (B) moves mirror 61A (B) a distance L in a direction indicated by double-headed arrows 66A (B). This method is especially useful when actuating elements 67A (B), 68A (B), and 69A (B) are completely within substrate 62A (B) with mirror 61 being entirely opposite transparent zone 63. as described previously. It is an alternative where envelope-type actuation is not preferred. Buckled beams are used so that actuation is inherently bistable. In order to move mirror 61 a distance L, the height of stator 69A (B) is preferably approximately L. If stator 69B is a quadrant of a circle, the height should approximate the circle radius and have a value of L.
Another embodiment of this actuation method (Figure 6e, f~ employs opposed-quadrant stators. In this case pairs of quadrant-shaped stators 69C are separated by a beam 67C so that beam 67C is tan~~ential to both quadrants at a point of contact and both quadrants are relatively opposed so that a radial boundary of each quadrant forms a straight line passing through that point of contact. As before, both stators are prevented from contacting beam 67C by insulating material 65C. In this configuration, by use of opposite charges on each member of a stator pair. half of the motion is caused by one member and the other half by the other member. in sequence. This allows a more compact actuator to be constructed.
Magnetic actnafinn ?0 Another embodiment of the valve switch uses magnetic forces. I~'1agnetic tields can produce greater forces and. consequently. faster switching. ,A disadvanta~~e is the larger overall volume of the device. even thou~Th the sva-itching mechanism, itself has the same dimensions whatever the actuation mechanism. In order to use this actuation method (Figure 7). a magnetic field. B, is necessary at the switch. The field can be produced by conducting loops 2~ around each switch, by a permanent magnet, or by an electromagnet with similar field. These are only some of the available magnetic field application possibilities.
In this embodllllent of the switch. mirror 71 is supported by beams, 77A and 77B. These beams are preferably made from buckled beams, to produce bistahle operation.
and are conductive or include a conducting layer wherethrough an electric current I
may be passed.
30 Interaction with the magnetic Held induces a lateral force F on the beams.
The magnetic field is aligned so that current I actuates mirror 71 to a new position (Figure 7a). Reversing current I reverses force F and returns mirror 71 to an original position (Figure 76). Higher Held valuca or hi~=her currents produce stron~~er forces and taster sw itching.
W~ Ol/0965~ CA 02379936 2002-O1-18 pC'1'/IL00/00425 Bi.sluhle su/~Jmrl Realization of the aforementioned systems requires a means of supporting active elements that enables bistable operation. The devices described hereunder relate to the present invention but may also be used in other applications. for example in conveyor systems.
i Translation systems that variously include a frictionless hinge, surface-wave motion. and beams that vibrate in two directions are described. Different actuation methods, including electrostatic or magnetic actuation against elastic restraints or buckled beams. are utilized in order to lock a translated mirror in a newly attained position. A buckled beam is used as a mechanical memory element, a task it can fulfill if the length of the beam is larger than the distance between the anchor points thereof. By applying a force normal to the length of a buckled beam a critical point is reached whereupon the beam transits to another stable configuration. The same effect is also possible if the beam takes other forms.
which are also described.
In Figure 7. each buckled beam, 77A and 77B, is a variation of a bistable buckled element with a bistable, snap mechanical action. The basic principle of the buckled beam is shown in Figure 8a. A beam 80 has intrinsic elasticity and its length is greater than a distance between anchor points 81 and 82. If a lateral force F be applied to beam 80. as known from standard teats. the beam snaps from a stable state 80 to another stable state 80'.
Applications of this principle are illustrated in Figures 8b, c. and d, in which like reference numerals reter to like ?0 parts throughout the figures of the drawing. It is to be understood that the descriptions below are illustrative. and are not intended to restrict the present invention to the specitic details set forth below.
The device of Figure 86 is bistable, analogous to the buckled beam, and the components are correspondingly numbered. The beam includes rigid elements. 80A and 80B
flexibly connected at respective ends 80A, and 80B,. Element 80A is flexibly connected at end 80A2 to fixed anchor point 82 while element 80B is unanchored at end 80B2. Ends 80A,_ and 80B2 are connected by a tensile element represented by a spring 83, although it is obvious that other ways may achieve substantially the same effect, such as using spiral springs at connections 80A, - 80B, and 80AZ - 82, or some other combination easily devised by those skilled in the art. A second stable configuration of this element is represented by the dashed lines denoted by 80A' and 80B'. This device, like that in Figure 8a, may be regarded as an elementary, bistahle building block.
?U
~ snap element tlma has two static contignrations is sh~,wn in Hi«nre Sc.
Ri~~id elements 8(1A
and 80B are tleaihly connected at ends 80A, and 80B, respectively- 80B and 8(1C are tleaihly connected at ends 80B= and 80C~ respectively. at a point 8:1: and 80C and 80D
are flexibly connected at ends 80C, and 80D, respectively. There are two anchor points. 82 and 82A, whereto are tlexihlyconnected ends 80A, and 80D= respectively. A tensile element.
represented by a spring 83A. connects anchor point 82 to the tlexible connection between ends 80B, and 80C: and another tensile element. represented by a spring 83B.
connects anchor point 82A - -to the flexible connection between ends 80B, and 80C,. The whole device is constrained to move within a plane. Applying force F snaps the device to a new stable position. the distance between points 82 and 82A remaining constant while point 8:1 moves to a new location 84'. as shown schematically in Figure 8d.
To show the «enerality of the design another preferred embodiment is shown in Figures 9a and 9h, where elasticity is provided by a spring 90. In this embodiment. force F produces snap action to brim point 84 to a new stable position. 84'. Figure 9c shows an equivalent embodiment wherein elasticity is provided by spiral springs 92A. B. C. D. E.
and F. Another embodiment employs an elastic beam as part or all of the elastic members of the device to produce the elasticity. as shown in Figure 9d. In this embodiment. anchor points 82 and 82A
riaidlwhold fully or partially elastic members 80A and 80D at ends 80A, and 80D, respectively. All other members remain as in the previous example. Figure 9e shows a partially actuated state of this embodiment, showing elastic members 80A and 80D bent.
allowing the transit of point 84 to a new stable state. as before.
To make the device useful. joint 8-1. or any other point or beam in the device-is attached to something that one wishes to move. In one preferred embodiment joint 84. can be replaced with or attached to a usable element, such as a mirror. as shown in Figure 10.
which depicts a double application of the arrangement in Figure 9c and is labeled to show corresponding components. the duplicate part of the mechanism being labeled with primed numbers. In this figure. 84 represents a usable element. Another possible application is as a switch in which different connections are made in each state of the histahle device.
Frictinnless juinfs In micromechanical applications. friction less hin~~es are advantageous.
Dynamic friction is normally a cause of wear. suppression of which is especially important for micromachines.
where lubricants are not ~~enerallv usable. For this reason. pin ,joints are usually replaced by ~l W~ ~l/09653 CA 02379936 2002-O1-18 p~/II,00/00425 spiral spring's where larvae no,vement is required. :another type of hinge is presented wl~i~lr uses static friction but is dynamically friction less.
The hinge in Figure I 1 includes a cylindrical roller I11 from which protrudes a radial arm 112. the movable element thus formed being in contact with a surface 114 contained within a housing 113. Arrn 112 protrudes out of housing 113. Large static friction between roller 111 and surface 114 as 111 rolls on 114 means that no slippage occurs during the rollin;~. This requires that contact be maintained at all times between roller 111 and surface 114. this is termed ''rolling contact" and is achieved by the action of a normal force F
urging contact between roller 111 and surface 114. Force F may include electrostatic and magnetic forces.
Through rolling contact. roller 111 may move between position 111A and position 111B and, consequently. ann 112 moves between position 112A and position 112B. The whole arrangement forms a dynamically frictionless hin~le with center of rotation at a point 11~.
which is not the center of roller 111. and with an angular rankle 2a.
This hinge can be employed more than once in an implementation, as illustrated in Fi~~ure 1?.
1 ~ Nere. the result enables translation of a movable part 122 relative to a stationan~ housing 113 in directions 127+ and 127-. ,4s before. in order for the hin~~e to function.
a normal force is needed to maintain contact between rotor 112 and housings 113 and between rotor 112 and movable part 122. which rotor 112 connects. Again, different types of force may be used, including magnetic and electrostatic forces. In case of a ma~~netic force, movable part 122 and stationary housing 113 of the hinge include permanent magnets or electromagnets. If electrostatic attraction be employed. <r thin insulating layer 123 is deposited to cover at least all of the possible contact surfaces of the hinge so as to prevent a short circuit. as shown in Figure 1?. An electrostatic potential is applied between rotor 112 and embedded electrodes 12~a and 125b. The potential is provided by direct connection of the electrodes to a power 2~ supply or through electrostatic induction, electrodes 125a and 125b being oppositely charged.
The potential difference induces attractive normal forces between rotor 112 and embedded electrodes 125a in housing 113 and 12>b in movable part 122. The same consideration applies if more than one hinge exists. in which case electrostatic attraction may be more suitable than magnetic attraction. Charges may also be applied to stoppers 126a and 126b of the hinge, by means of embedded electrodes 128a and 128b, in order to produce electrostatic forces to actuate rotor 112. which may then be used either to actuate an element or to act as a control device by. for example. detection of capacitance change caused by the induced motion thereof to provide positional information.
If a device relic; on electrostatic attrai lion. cessation of the hover supply may allow a rotor to fall ti-om a workings position. In order to restore to the working position, a mechanism. as shown in Figure 13a is used as one of the options. Figure 1 , shows views of the device of Figure 1 1 from within the plane of Figure 1 1. and relevant parts are similarly numbered. Part of a housing 113 in contact with a rotor 111 is viewed schematically from the plane of motion of protruding part 112. While power is supplied. both elements are in contact but for a separating, insulating layer 123, as described before. Flexible. loose conductive cables 131A
and 131B are anchored to either side of housing 113. In Figure 13a, masts 130A
and 130B, emerging from either side of housing 113, are used to illustrate this. Masts 130A and 130B
also electrically insulate cables 131A and 131B from housing 113. Insulation 133 may be also provided for cables 131A and 1318 from rotor I I1 as is also a means 134A
and 134B of electrically charging the cables. Resetting electrodes 132A and 132B are situated to the sides of the hin~~e. outside cables 131.4 anti 131 B and provided with respective means 13~A and l3sB of being electrostatically charged. In normal operation. cables 131 A and 131B are is relaxed. When power fails, the attraction between rotor 111 and housings 113 ceases and rotor 111 falls until checked by one taut cable. in this case 131A, while other cable 131B
remains slack. as shown in Figure 13b. When power is restored. a resetting procedure is followed to restore the hinge: first. a voltage 13~A is applied to electrode 132.A and an opposite voltage 134A to cable 131A so that electrode 132A attracts cable 131A.
Simultaneously. a voltage 135B is applied to electrode 132B and an opposite volta~~e 13:1B to cable 131B so that electrode 132B attracts cable 131B. The resultant tensing of cables 131A
and 131B returns rotor 111 to a working position. as shown in Figure 13c. Then the electrostatic attraction between housings 113 and rotor 111 is renewed and the mo elements will remain together. Finally. power supply to resetting electrodes 132 and cables 131 is 2~ ceased. leaving cables 131 slack. Operation of the hinge can then be resumed.
Other applications and realizations of the described mechanism can be envisioned by those skilled in the art.
Travelling-n~nve actuation Another method of actuation is now introduced. In Figure 14, a standing wave 140 is induced in an elastic material 141 situated on a substrate 1.12 by any method that can cause a modification of the dlmenSlotlS Of elastic membrane 141. The modification method, which may affect the time constant of standing wave 140. may he thermal.
piezoelectric. magnetic.
or electrustati~. to a preferred en~hociimmt. electrostatic actuation i, used.
.-',n ucillatin'~
WO ~l/09653 CA 02379936 2002-O1-18 p~/IL00/00425 voltage 1-t-t is ahpliecl acrus> <i pair e~i~ electrode; 1=13 placed in substrate 1-t2 and above elastic material 141. causing vibration of elastic membrane 141. Alternating voltage 144 induces a standing wave 140 in elastic membrane 141. if two pairs of electrodes 143A and 143B be laterally separated with their respective cycles 144A and 144B having the right phase difference. as in Figure 146, a traveling wave 14s is produced at a surface of elastic medium 141; a point on elastic material 141 will undergo circular motion 146 (Figure 1 Ic).
This circular, wave-like motion can move an element 148 placed on top of elastic material 141. Changing the phase difference between electrodes 143A and 143B, and thus between the standing waves, can change the velocit<~ and direction of traveling wave 14~ and, with it, the yelociy and direction of element 148 placed on elastic membrane 141. A
plurality of electrodes and generating devices may be used as required. Although such waves are known from prior art this device is innovative. as described in the following.
The functioning of this device requires contact and friction between movable element 1-t8 and elastic membrane 141. in which waves 14s propagate. In prior art. that contact is maintained by virtue of gravih or by springs. The current invention, being intended for elements of small dimensions, introduces other options, including magnetic force and electrostatic force.
For the former. movable element 148 is made of magnetic material, as are the surrounding parts of elastic membrane 141 or substrate 142. By oppositely magnetizing 148 and 141 and/or 142. an attractive normal force holds movable element 148 against elastic membrane 141. even against gravity. and induces friction that will permit the functioning of the device.
Either permanent magnets or electromagnets may be used. Another possibility is electrostatic attraction between movable element 148 and the stationan- part of the device.
Again. the attraction produces a force that induces the static friction that enables the actuator to 2~ function. This enhancement permits the functioning of the device in any orientation, without relying on gravity or springs or other elements that may produce dynamic friction and wear or require the use of bearings that are difticult to fabricate at micro-dimensions. The use of this kind of actuator in the optical cross-connect. the aforementioned mirror and movable part, is an innovative improvement.
In case magnetic actuation is preferred. the electromagnetic attraction of the previous paragraph is caused to van cyclically so as to induce a required travelling wage in the membrane.
In case thermal actuation is preferred. the membrane is selectively heated h~-heater 1-49 in Figure l~(d) to cause periodic deformation so as to induce a required travelling wave in the membrane.
In case piezoelectric actuation is preferred, piezoelectricallv deformable device 149 in Figure 14(d) is caused to change dimensions in contact with the membrane to cause periodic selective deformation therein so as to induce a required travelling wave in the membrane.
Finger uctualion Although the surface wave device is usable in some cases. a more versatile device can be designed. The intention is to produce a rotational motion at the movable element that resembles that of 146 in Figure 1 ~, without actually needing to propagate a surface wave.
The desiUn (FiUure lea) is based on clusters of supportin<~ timers 153. each cluster bein'T
sufficient to support a movable element 152. FinUers 153 can have various configurations.
such as cantilevers protruding from a side wall or posts protruding from a substrate 151.
Although the illustration shows the finger tips aligned in a straight line.
this is not an 1 ~ essential requirement of the invention. Movable element 152 rests on supporting fingers 1,3.
An appropriate movable element 152 for this application is an actuatable mirror. The supporting surfaces of fingers 153 are generally located above the plane of substrate 151. .A
vyorking cycle is illustrated in Figures 15b - I ~e and starts when a first cluster of supporting fingers 153B. D moves away from substrate 151 bearing movable element 152. At this stage_ ?0 a second cluster of supportin~~ fin'~ers 153A. C is stationary and thus out of contact with movable element 152. Neat_ first cluster of supporting tin~~ers 153B, D moves laterally in a required direction of motion to a new position and lowers so that second cluster 153A. C now supports movable element 152. First cluster 153B, D then moves laterally in an opposite direction from the first motion thereof and returns, without touching movable element 152. to 25 a starting position thereof while second cluster 153A. C begins a similar cycle. The displacement in each step depends on the lateral amplitude of the motion of supporting fingers 153. which is normally very small and many cycles may be required to achieve a required translation. Clearly. the lateral displacement may be reversed by reversing the cycles. By using two movable clusters of supporting fin~~ers in succession.
the displacement 30 may be doubled from that of a single-cluster cycle. and so on. It is seen that the resultant effect is similar to that of the travelling wave actuator.
WO 01/09653 CA 02379936 2002-O1-18 pCT/IL00/00425 actuation of the supportin~~ elements can he by various method;. wclr as electrostatic actuation. whereby electrodes are placed around the supportin;~ elements in the horizontal and vertical directions and voltages applied to bend or deflect the supporting elements. as required. Alternatively. the supporting elements can be made of piezoelectric material and.
by applying suitable voltages. these piezoelectric beams rnay be bent in the horizontal and vertical directions. Bv controlling the timing and duration of these voltages it is possible to produce the required motion of the supporting element and rotate its extremity in clockwise or anticlockwise motions to advance or regress the movable part. Since static friction is necessary for the functioning of the device, as in the travelling wave option, the same method of holding and application of the normal force by using electrostatic or magnetic forces is used here.
This approach is particularly suitable in the micro-environment. Use of cumulative small displacements reduces stress on the elements. Mloreover. at this scale. rotary motors would suffer dynamic friction sufficient to render them unusable.
A simpler variation of this actuator uses only one set of supporting fingers at each step, as shown in Figure 16. A movable element 162 is supported by actuated fingers 163A.B.C
while being moved. as previously explained. and. while actuated fingers 163A.B_C return to an original position thereof element 162 rests on stationary posts 16=tA.B.
Again. many cycles are needed to achieve a required lateral displacement.
Other variations and combinations of this device are possible. In another preferred embodiment. while the actuated elements retreat. the movable part is held by side handles instead of restin~~ on top of aforementioned posts 164A_B.
Enrergeney holding In the event that the electrical supply fails. any electrostatic holding force stops and the movable element may fall. Of the various possible mechanisms. a preferred embodiment is presented that is designed having in mind the fabrication methods used in the micro-environment 1n ~~'hlCh the device is used. but can also be applied in other fields. As shown in Figure l7a.b. an element 171 that needs holding in case of power failure is fabricated on a substrate 170. A flexible element 172 is fabricated separated from element 171 by a sacrificial layer 174 that is later removed. Flexible element 172 is anchored at an end A and another end is held by a histahle bucklin~~ element 173 that is anchored at points B
and C~. In pwitic~n 173A hucklin~~ elentem 173 is tri';'~ered by ,rpllvin~~ a suitable force in order m make element 173 snap to anther stable point 17313. as shown in Fi~~ure l7c.d. As a consequence. tlexible element 172 is tensed- as shown in Figure l7c.d, and thus holds free element 171 in position. In order to allow element 171 to move. element 172 is disengaged by an electrode 175, isolated by insulation 176, placed opposite element 172.
An applied voltage difference between element 172 and electrode 175. attracts the former to the latter against the tension from buckling element 173 in position 173C, which is displaced slightly from a stable position 173B but insuffiiciently to cause it to snap to other stable position 173A. In case of power failure, the attraction of electrode 175 ceases and the tension exerted by 173C acts to return 172 to a position in which it holds movable element 171.
Eleelro-meelmnieal aligning mechnnism With practically free movable elements. especially when a stepping motion is involved, there is a possibility of disalignment of the movable element in a direction perpendicular to the element-s direction of motion. A mechanism for lateral realignment is necessary. A basic arrangement is shown in Figure 18. An element 184 to be kept aligned in a lateral direction 188 so that it remains in a rectilinear motion path 187 is situated between two aligning pads 183a and 183b. which are situated between walls 181a and 181b and attached respectively thereto by matched springs or other elastic elements 182. Element 184 is movable in the plane of the drawing, 1v'hlCh IS perpendicular to the walls. Since the force of a spring is greater when displacement from equilibrium is greater, deviation of element 184 from center is corrected by spring action on both sides (Figure 18b). Springs 182 are retracted by electrostatic force betvyeen electrodes 18_>b alld 18:~C Ill allgnlll'~ pads 183a and 183b respectively and correspondin~~ electrodes 185a and 1854 at walls 181a and 181b respectively. Vt'hen aligning elements 183a and 183b are retracted, free movement of movable element 184 is possible. Such aligning elements may also sense as the part of an actuating system that holds a movable element while the movable supporting elements of the finger actuation mechanism described earlier are retracted.
Another aligning option has the same layout as in Figure 18 but acts through electrostatic attraction between element 184 and elements 183a and 183b. One possibiliy is to connect element 184 to one polarity and elements 183a and 183b to an opposite polarity of a power supply. Another. preferred embodiment is to apply opposite polariy charges to elements 183a and 183b. represented generically as V,, and V~, in the figure. Opposite charges are induced in the respective ad-jacent surfaces of neutral element 184. In either case the result is attraction between elements 183a and 183b and element 184. When elements 183a and 183b ~7 are in contact wily 184. spring's 182 will art l balance each other. tl~erehv prcuiucin~! a net force that aliens movable element 184.
A variation of this principle is shown in Figure 19. wherein movable element 184 contains spring parts 182 that support aligning elements 183a and 183b. In one preferred embodiment, opposite electrostatic charges are applied to electrodes 18~a and 185d, which are located at surroundings walls 181a and 181b . As before. these charges induce opposite charges in respective elements 183a and 183b which are attracted to respective walls 181a and 181b. Balanced springs 182 act to align element 184, as before.
These methods are applicable with magnetic or electromagnetic forces employed in place of electrostatic forces. with suitable variations that will be obvious to those experienced in the art. Other actuation methods. such as combined thermal or other action, can be applied.
Eleclroslnlio aliyrinri nrec%anisnr Another electrostatic alignment mechanism follows directly from the envelope-like actuation principle discussed earlier. Aligning a movable element with electrostatic force alone will 1 ~ not work since electrostatic force depends inversely on distance. Thus any misalignment would be increasingly exacerbated. Using repulsive electrostatic torces would mitigate this problem although this is hard to implement in practice.
In the above discussion. however, it was shown that. in an envelope-like actuator with one or nvo eternal static electrodes. the force in the direction of surface motion depends on the ?0 derivative of the area with respect to distance in the direction of motion.
It was also shown that, this being the case. if the profile of the electrode with the actuated element is such as to produce a large area variation, such as in the case of a suitable complex shape or fractal form, an increased force results. Based on this, shapes of the movable or static electrode can be tailored to produce a force depending differently on the distance from a rest position.
2> Using the same calculation as for envelope-like actuation, the electrostatic energy stored in a capacitor formed from two overlapping plates 201 and 202 is (Figure ?0):
~l - ? s~.9 1.=
f the force is then:
t;"t ~- c:~.~
,: - _ __ __ ~~.v ,1 Ifmm plates as slu,wn in Fi~~ure ~tlh ,j re used. the i~r,rce is simply proportional tem". wlri~l~ i;
constant as the plate overlap chan';es. If. however. the protile of one plate be chan~~ect. tier example to a triangle 203 as shown in Figure ?0c. the force varies linearly with distance ~-and increases like -2.x.tan a as the overlap increases. However. in the configuration shown in Figure ?0d. a reversed triangle 20~t the force depends on ~_v" - x~ tan a . It may he seen that when the distance of overlap is .y, the force is zero. as would be expected.
When there is no overlap the force is zero. If the overlap increases towards .u~ the force decreases, and vice oersu. Application of this permits continuous alignment of an object that is movable in a plane parallel to the plane of the diagram, as shown in Figure 21, since displacement from alignment will result in a net attractive force to the central neutral point of the system. Two configurations are discussed, as shown in Figure ? 1 a and b. In Figure 21 a, trian~Tular electrodes 210 are respectively fixed relative to walls 181 and central element 18=1 is mc,vahle: in Figure 21b triangular electrodes 211 are lived to movable element 184 and fixed electrodes 212 mounted on walls 181 have straight leadin~~ edges. C'har'ges may he applied to 1 ~ the electrodes and to the movable plate by some means, shown generically by voltages V".
V,,. V~, and V~ in the figure. By this arrangement, central element 184, which is intended to move along motion path 187. may be constrained from lateral deviation in direction 188.
Other electrode shapes may he tailored to produce different dependencies of the electrostatic force on the overlap distance. Bv combining these forms. complicated actuation effects. even including accelerations and decelerations. can be achieved. .Another use of this concept is in the stahilization of electrostatic actuators such as in the envelope-type actuator. Bv placing shaped electrodes in opposition it is possible to stabilize the movable central electrode and prevent it from sticking to a side electrode as a result of the inherent instability of this actuator.
Valve Array The smale valve disclosed above is capable of switchin« light rays. Switching is possible heaveen a single input and W o outputs or two inputs into one output. The disclosed switch (Figure 22) can incorporate prior art optical devices, such as HEMS (Micro-Electro-Mechanical Systems) switches (e.~,l. mirrors), liquid crystals. and electro-optics.
In order to switch one input to two outputs. one mirror, 222. parallel to a substrate. 223, as disclosed before. moves in a direction parallel to substrate 223. as illustrated by double-beaded arrow 224 1I=i~~nre ~~a. h). If the witch is in an ol-I state.
an input ray. 221:x.
emer~~es at output 22113. It the switch is actuated to an c~N state_ ray 221.4 retlects tom mirror 222 and exits ti-om output 221C. Another embodiment can be desi~~ned (Figure _'2c, d) wherein two inputs. 221A and 221D. are normal to each other and. in an (>FF
state.
continue to respective outputs 221B and 221C. Actuating mirror 222 flips the output rays to emerge at interchanged outputs 221C and 221B respectively. In this latter embodiment.
mirror 222 is reflective on both sides.
These are simple schemes. in which a single switching element is utilized. but the strength of this device - deriving from the compactness thereof - is in switching many inputs among many outputs. within a compact space. Elaborate examples can be produced by employing an array of switches (Figure 23x). (It should be noted that the terms "array"
and "matrix" are used interchangeably herein.) A column of inputs. 231A ... 231D, is situated normal to a coplanar row of outputs. 232A ... 232D. ,At an intersection of each input line with each output line. a switchin'; n~irror_ 233 for example. is placed. at an angle to an intersecting input line 231 and output line 232. depending upon the switching technolo~~y hein'~
used. the angle 1 ~ may have any value up to 180°. It is emphasized that each input can act as an output, and rice oersa, by reversing the respective ray propagation direction. In order to switch any particular input to any desired output. an appropriate switching mirror 233, at an intersection of corresponding input and output axes. is actuated to an ON state. For example, input 231B
may be directed to output 232D by actuating switch 233A. In the simplest case, only a single switch is actuated at any time in each row and in each column. resulting in a one-to-one correspondence between input and output rays; a "non-blockin~~~~ condition is said to exist.
This is a non-broadcasting situation. When partly transmissive mirrors are used to allow broadcasting. '-bloching~~ is allowed. in the sense that a light ray that enters the array along a row of switches naiv traverse, albeit diminished. two or more actuated switches. with a reflected ray being directed along each colunu~ wherein an actuated switch is situated.
Moreover, although inputs and outputs are generally normal to each other, more complicated switching operations. as basically described in Figs 22c and 22d, can be achieved by placing additional inputs 231 or outputs 23s, collinear with the original outputs and inputs respectively. In order to use these additional outputs or inputs. switches such as are illustrated in Figures 22c and 22d are used but none of the switches along the path of a respective ray is actuated. thus allowing unimpeded passable of the ray concerned. Such an array can be used for more complicated switching operations. as well as for controlling the beams.
WO 01/09653 CA 02379936 2002-O1-18 p~~,p0/00425 In Figure ~,h. another embodiment is presented in which only half of an array is needed. In this case. a static retlectin'~ element. such as a mirror 239. as shown. or a wave-guide termination. is placed at a diagonal of the array and that part of the array behind mirror 239 is discarded. All actuatable mirrors are double sided. In this configuration.
fewer actuatable s elements are required to achieve desired output configurations. with the same ray path-length as in the complete array of Figure 23a, although a ray may encounter more reflecting surfaces, leading to greater light loss. The overall switch is smaller, which is an advantage in some fabrication schemes, as will be shown below. In the example of Figure 23b, inputs 236A, B, C, and D, are switched to outputs 237A, C, B, and D respectively.
Input 236A is reflected to output 237A via path ac and input 236D is reflected to output 237D oia path 8: it is seen that these require no switching. Input 2368 is, however, switched to output 237C vin path (3 by reflecting at the back of actuated mirror 238. At the same time.
input 236C is switched to output 2378 oia path y by retlectin~~ at mirror 238. This description refers to mirrors as the actuatable elements but. as already mentioned. other switching elements 1 ~ having similar capabilities may be utilized.
More elaborate effects may be obtained by placing actuatable mirrors at the array diagonal, instead of a fined mirror. As an example, placing two half arrays- as previously described.
back to back with the previously defined reflecting diagonal common to both.
The two half arrays may work independently but, if pan of the reflecting bisecting element is svyitchahle, it is possible for part of the rays to transit from one array to another.
Although the preceding preferred embodiments of valve arrays have no broadcast capability.
these are not restrictive examples. Other embodiments can he devised wherein broadcastin~~
is available by including mirrors that are partially reflective and partially transmissiye, as mentioned above. In such cases, more than one switch is actuated. to produce broadcasting.
Other schemes for broadcasting and multicasting can be designed by those skilled in the art, using the presented building blocks.
Most of the previous features of the array of switches are known from prior art and are applied to the specific embodiments disclosed here. In the case of small arrays, the number of switches is small and the short optical paths cause only small signal losses. Some applications. however, require large numbers of inputs and outputs. For a l Ox 10 array, 100 switches are required. A 50 arm separation between switches will result in a longest path length of -1 mm. In a I00x 100 array, however. there are 10.000 switches and the longest path length is I cm. The large increase in dimensions and number of switches results in increased losses.
a more elaborate swilel~in~~ device is now disclosed in which shorter paths and l~ew-er switches are feasible. Other types of switches. both of the ~~tE~~1S
(microeleetromechanical system) type. like the switch of the present invention, and of other types (lithium niohate.
liquid crystal, etc). are also configurable in the arrays of the present invention, with MEMS
switches being preferred.
An embodiment of this more elaborate device is presented schematically in Figure 24a. In an example of this embodiment, three virtual switching planes, a, b, and c, each having the capability of the arrays described in Figure 23a or 23b, are utilized. These virtual switching planes are, in effect, stacked. with corresponding elements vertically above one another.
Each virtual switching plane operates either independently of the other virtual planes or in conjunction therewith. As will be seen below. these planes are not merely stacked. but may be mutually coupled. to achieve more efficient switching, in a smaller volume than is possihle using prior art switch arrays.
It is important to note that the terminology "virtual plane", "virtual array", "virtual switching plane". "virtual switching arra~~'~, and "logical switching array" has been adopted to stress that. the switching of the present invention is. in reality. done within the physical layers: i.e.
the switches move parallel to the physical layers formed by the suhstrates whereon they are constructed. The virtual planes are only a descriptive artifice for comparison with previous art and better visualization of the overall switching effect. For this purpose, the switches are conceptually grouped in virtual planes independent of the physical layers.
Each virtual switching plane, wherewithin any particular light path advances intersects the physical layers.
The relationship between these two types of layers is shown in Figure 24a.
where physical layers are drawn as vertical planes and labeled a, (3, Y, b, and ~, and virtual layers as horizontal planes labeled u, b, and c. Further details are given below, in the section 2~ ''Fabrication".
Inputs 241 consist of stacked rows, denoted by a, b, c. and vertical columns denoted by I, II, III. Outputs. 242, are similarly denoted. The switch may be regarded as comprising a two-dimensional input array to a three-dimensional switch. leading to a two-dimensional output array. (The previously described device had a one-dimensional input array to a two-dimensional switch. leading to a one-dimensional output array.) With standard fabrication methods. it is difficult to realize the presented configuration:
an easy fabrication method is described below. Those skilled in the art may find other fabrication possibilities.
Other types of switches. beyond the preferred embodiments presented here. may be t~hri~ated by the method presented in the lollowin~~.
;, WO 01/09653 CA 02379936 2002-O1-18 p~/1L00/00425 r1 realization <o tlri: arran~~en~ent i., slrownr in i i~~ur~ ?-Ih. where ,j cut-wvav view of a W o-layer array havin;~ tour switches in each layer is shown. oriented similarly to the schematic view in Figure 2-4a. Inputs 2:13 may lead to outputs 244. The upper layer has inputs 2=13 In and 2:13 lla and outputs 244 In and 2.1.111x. and switches AI.
A2, A3. and A4:
possible light paths are illustrated by dotted lines. The lower layer has inputs 243 Ib and 243 Ilb and outputs 24416 and 24411b, and switches B1. B2. B3. and B4; possible li~~ht paths are illustrated by dashed lines. There is no interaction or correlation between the two layers.
The switches may be of any suitable h-pe.
The same Figure 24b can also illustrate the smallest realization of the half array switch illustrated schematically in Figure 23b. In this case. mirrors A1, A4. B1 and B4 are fixed, mirrors A3 and B3 are absent. and mirrors A2 and B2 are actuatable. as before.
and also reflective on both sides. Light paths beyond mirrors .41. A4, B1 and B4 are no longer possible. As in the previous para~;raph_ there is no interaction hemeen the two layers.
In a first 3D embodiment presented, there is no correlation between input rows. A basic use l~ of this stack is in connecting a number of inputs to outputs within a small space, the only advantage being a saving of space.
A more important use can. however, be envisioned in WDM (wavelength division multiplexing) networking wherein each plane is assi~Tned to a different wavelength, there being a sufficient number of planes for the number of wavelengths in a multiplexed beam.
?0 Previously separated wavelen~~ths are conducted to the respective planes wherein. for each wavelength. a ?D switching matrix routes inputs to desired outputs. These outputs may be subsequently recomhined for further transmission or other use.
Although inputs 241 and 243 and outputs 242 and 244 are illustrated in Figure ?4 as being respectively at right angles to each other. the switch array of the present invention may be ?5 configured with inputs and outputs at any convenient non-zero angle to each other.
Multi-layer .sr,~itching Another use of the sD switching matrix shown in Fi~~ure 2-t is in compact switching of a large number of inputs. The main purpose of this use is the reduction both of a ray path-length and the number of switches necessary compared with a square switching array.
30 Instead of usin~~ a 2D array with a 1 D coltmo of inputs and of outputs. a 2D input matrix is utilized. Each plane. a, h, and c. consist; 01' a non-hlockin~~ array. Such an array can he re'_,rrded as an operator that transform; llte inpm rm~. ~-!1 lo, 2-I1 Ilrr, 2-Il Illo_ at plane a. to output mw. ~'-l2 lu, 2-t2 IIu, 2-t2 //la. W plane a. and su on Ii~r the other planes. since each plane is isolated from nei'~hhorin'~ planes. the only possible operator action is to change a column index. I. II. III, .... beW een input and output.
This is not enough: what is required is the ability to switch any input array element to any output array element. The 3D operator of the preceding paragraph is able to change only a column index of each element in the inprlt matrix. This limitation can be overcome by a double application of the 3D operator wherein rows and columns at the output of a first stage are transposed into columns and rows at the input of a second stage. This second application of the operator will again change only the column index within each row of the second matrix. but this tune the column indices are the former rovy indices. Thus, by applying the 3D operator represented by the 3D switching matrix twice in succession, with intermediate transposition. the necessan switching can be accomplished. Figure ?~a illustrates the disposition of switching elements wherein. for convenience. mirrors are used as switching elements.
1~ Practically. after rays transit a first swrtchrng matrix (251) emerging rays are introduced into a second similar switching matrix (252). rotated 90° with respect to matrix 251. ~-1atrix 252 may be switched differently from matrix 251. Non-blockin~~ switching can be achieved. It can. however. be shown that some switching configurations cannot be achieved.
owing to the non-blocking property of the 2D arrays. A third switching matrix, rotated 90° with respect to matrix 252. is added if the resulting overall svyitching is inadequate. This switch is actually a realization of the well known Clos architecture. With such a conti~~uration, it can be proved that all switching permutations are obtainable. In this case. non-fIIOCkIn'~
states are attain obtained although a non-blocking path that connects any given input to any given output may not be unique so this switch has inherent redundancy. This may be seen from Figure ?>c which depicts a tri-cube complex switching array: a matrix of input beams 255 enters cube 256A, vyherein switching occurs. and the rays emerge as an output matrix 255'.
Matrix 255' enters cube 256B, which is a cube similar to, but with the switching planes thereof rotated with respect to cube 256A. and emerges as transformed matrix 255". A third cuhe 256C is used to make a final transformation of ray matrix 255" into output matrix 255"'. Cuhe 2560 is. again. rotated vyith respect to previous cube 256B.
As an example of the advanta~~e of this design. consider the task of switching am or several of 100 inputs to any or several of 100 outputs (a 100x 100 switch). To pertorm the task. three witchin~T matrices are needed in sednence. each matrix hein~~ rotated 90'' with respect to a preceding matrix. Each switching matrix consists of a I t)p I Oa I t) cnhe.
with I (l00 w itches _ -I
W~ ~l/0965~ CA 02379936 2002-O1-18 p~/IL00/00425 a total of st)On :witches. flee longest optical path. Iur a switch separation of >Oym, is I I(1+10+10+10+10)x>0 ym = 2600 ym =?.~ mm. This compares with 10.000 switches and a 1 cm optical path needed to perform the same task with a conventional 2D
array.
In Figure 2~b is illustrated an equivalent switch array complex to that of Figure 2~a. this time using the halt=array 3D sw-itchin~~ matrix of Figure ?d6. wherein there are tixed mirrors along a diagonal of each matrix. instead of that of Figure 24x. In this case, a 100x 100 switch requires only 1350 switches. not including the 100 fixed switches, along the diagonal.
As in the case of the two-dimensional matrix of Figure 23x, the three-dimensional arrays of Figures 24b and 2~a can be configured with switches such as the switch illustrated in Figures 22c and 22d: providin~~ the option of placing the arrays in switching states in which some or all input rays traverse the array without being reflected. In this case. too.
special options.
such as control elements along the transit paths- can be implemented. :~ 3D
matriweed not be cubic and an input array may be. for example I Ox 10, I0x3, etc. provided that a following.
rotated 3D matrix has a matching number of rows and columns. For example. for a six-input matrix. arranged as a 3x2 array. two planes of 3x3 arrays are needed. The second cube then needs three planes of 2x2 arrays.
In some cases it is necessary to ensure, while switchiny~ some inputs to other outputs, that some or all of the paths connecting the rest of the inputs to outputs are not disturbed. This concern is known as the rearrangement problem. With some configurations, a desired path change for some rays may require, at least momentarily. a switching off of other paths not related to the paths in question, and data intended to transit unaffected may be momentarily affected. This can be overcome with the 3D-block concept using additional cubes or blocks.
together with the bypass capabilities of the switch (as explained before for the basic 2D
arrays). To understand this concept we refer to Figure 2~d, wherein. two identical tri-cube complex switching array sets. of the type shown in Figure 2~c, are aligned each beside the other. Both sets 258A,B.C and 259A,B,C have identical switching capability. If only the first set be activated- switching occurs during the passage of input ray matrix 257 through 258A.B,C exiting as matrix 257"'. The rays then traverse cube 259C.
undisturbed. exiting as matrix 257Y. which matrix is identical to 257"'. Cube 259C is in a bypass (or transparent) configuration. as explained earlier. At this stage. no ray enters cubes 259A
and 259B.
If some change of switching configuration is needed. it can tirst be set up in cubes 259A and 259B. Then, cube 258A is changed to transparent. bypass mode. simultaneously with a chancre of cuter 259C inW a desired witchin~~ mnli'~uratir~n. In thicase ipoul r<3v matrix 2;7 traverse; cube 258A unchan«e<t. witin;~ as identical matrix 2s7a'. ~tatriv 2~7a' neW
enters block 2s9A. is switched therein into matrix 2~7a" and thence by block 2s9B into matrix 2s7a"'. finally emerging. after being switched by block 2s9C. as output matrix ?~7*.
It may he seen that some of the paths linking input to output may pass through one set of cubes while other paths may pass at the same time through a second set of cubes: not all paths need go through the same set of cubes at the same time. The advantage of this design is that it does more than provide a solution to the rearrangement problem: the path redundancy that exists with only three cubes increases dramatically through the use of a second set of three cubes that doubles the system not only for rearrangement purposes but also provides the possibility of backup. Moreover. it can be seen that. even thOllgh the number of cubes has doubled, the path-length increases by only one block traverse thus almost not affecting properties depending on path length. such as loss. This set-up. featuring non-blocking and solvin~~ the rearrangement problem is known as a "strictly-non-hlockin'~
conti'~uration".
As already mentioned, any kind of switch may be incorporated into the design.
but switches 1 ~ including mirrors have many advantages and are a preferred embodiment. It is also emphasized that, although rays are shown as entering and exiting normal to a block, other angles of incidence and output can be designed for, dependin~~ on various considerations pertaining to the required final svvrtchmg arrangements.
In addition to the coupling of two sets of blocks, the same additional states in which the input ray is not reconfigured by any switch (i.e. by-pass or transparent mode) can be utilized in other applications. Such a case or special option could he for implementation of control devices at the output of the bv-pass path.
Again. the 3D matrix need not be cubic and the input array nary he for example IOx4, 10x3, etc. provided that the rotated 3D matrix has a corresponding number of rows and columns.
2s For a six-input matrix arranged as a 3x2 array, two planes of 3x3 arrays are needed. The following cube w-ill need three planes of 2x2 arrays.
Based on the elements presented. those skilled in the an may find other variations covered by this invention. One possible variation is to alter the number of cubes used, applying one, two, three. four. ctc, cubes as required. Not only may the number of cubes change but also their mutual disposition. as required by the specific application. Other wave-shaping or controlling elements can obviously be inserted betore, between. or after the switching cubes.
Such variations include the use of lenses. wave re~~enerators. prisms_ magnets. mc. or addition of a color dc-multiplevin~~ system to the above methods.
(, flan sD blocks explained above have multiple witchin~~ capabilities.
~~Itl~ou'~h ~lescrihed basically as a cross-connect for optical communications. a device having such switching capabilities can serve as a logical component and thus be utilized as part of an optical memory' or as part of an optical computing device.
Wavelength de-multiplexing Another embodiment includes the addition of a wavelength demultiplexing/multiplexing system to the above methods for use of the disclosed switch in WDM (wavelength division multiplexing). In this embodiment. information is transmitted through optical fiber, encoded within a group of different wavelengths. A wavelength de-multiplexing and multiplexing device is necessan' to separate the different wavelengths at the entrance to a switch array and. after processing or use. to recombine these wavelengths. Rays introduced into the described switch are preferably parallel to one another. ,A device that can accomplish this is presented.
Several technologies for wavelength separation exist, among them, the use of diffraction 1 > ~~ratings. The embodiment introduced below uses retlection gratings to separate the wave-lengths into parallel rays that can be introduced into a sD switch. A similar device collects and recombines the output bundle of parallel rays for insertion into a fiber.
The device used (Figure 26) includes two parallel reflection Gratings. 261 and 262. with respective diffracting surfaces that face each other and with rulings also parallel. The ?0 distance between the separated wavelength rays is determined by parameters includin~~ the distance d between parallel gratin ';s 261 and 262 and the pitch of the grating rulings.
A collimated input beam, 263, emerging from a fiber, is incident on a surface of first reflection grating 261 at a predetermined angle a. A simple mirror would reflect this beam at the same angle with respect to a normal to the surface of the mirror. A
grating, however, 2~ reflects different wavelengths (~,,, ~,,, ~,3, ,_,) at different angles (~3,, (3z, (33, ...): the sum of angle of incidence plus an~~le of diffraction is a i~unction of wavelength.
From this. it is clear that different wavelengths will be separated into different angles at reflection grating 261.
Since the relation between the incidence and retlection angles is the same for second reflection gratin's 262 as for first reflection '~ratiny 261. and since the gratings are parallel.
00 the retlected an~~le i~rom second gratin') 262 is equal to the an~.tle of incidence a at first ~_ratine 261. Since this an~zle a is edual ti,r all wwelrn~_ths. rays of all wavelen~~th; emer'=a WO Ol/0965~ CA 02379936 2002-O1-18 p~~L00/00425 parallel. at an~~le a. hut diaplaceJ t~r«n~ une another atier rellectin'r ti-om second ~~ratip= 262.
Thus. wavelem<~ths are separated into parallel rays. with displacement dependin~~ upon inter-grating distance c1_ incident angle a. and the pitch of aerating>
rulings.
Since the ray paths are reversible. reversing direction provides a device capable of recombining wavelengths before insertion into a fiber on output. The use of one device at an input to the matrix and a reversed one at an output allows de-multiplexing.
switching. and multiplexing signals in a WDM network.
The switch presented can thus be used for diverting input rays of different wavelengths from a plurality of inputs to a pluraliy of outputs. The primary use is in communications.
Together with the wavelength separation and combination device presented. the switch is applicable to WDM1. Other applications. such as optical computation. e~c. are also possible.
Fabrication Since the real strength of this device - residing in its compactness - is in switching among many inputs and many outputs. these switches are envisioned to be incorporated in multi-switch devices.
The three-dimensional arrays described in the present invention may he fabricated using prior art technologies. such as conventional macro-. rneso- and micro-machining techniques. In one envisioned application. the switching= of optical paths. the fabrication methods include photo-litho~;raphv. deposition. and etching'_ all methods commonly used in microelectronics ~0 and micro-machining. These methods may. however. be uneconomical or impractical.
Therefore. the scope of the present invention includes an innovative method of fabricatin~~
these arrays. which enhances the advantages thereof.
In this process. 3D arrays are produced usin~~ 2D fabrication methods and stacking to obtain the desired sD switching array. such as an optical cross-connect (OXC). The fabrication ~> technique transfers tire critical steps into tire macro-fabrication realm.
where high quality can be achieved with already-existing mature techniques and much experience exists. The results are applied in the micro-realm.
The basic device is fabricated on top of a wafer surface. in contrast to previous art. where the mirrors are etched into or erected upon a substrate. The mirrors. which require substantially ;p perfect surface quality tlatness. and parallelism. take advantage of high-quality suhstrates ;V
prepared lu,r tile microelectronics industry. Substrates ui various dimensions_ thicknesses.
materials. and surface preparations are available.
Generally. the device can be prepared on any kind of material and the fabrication procedure is independent of substrate material. While the substrate material has no effect on the switches. apart from surface preparation and physical dimensions. it is possible to take advantage of a substrate's properties. For example_ electronic circuitry may be integrated into the substrate or optical fibers may be set therein, in which case advantage can be taken of features such as the cn~stallographic planes of the substrate material, as in silicon. Those skilled in the art may find different materials and techniques for the production of these switches. The fabrication techniques introduced here may be useful for other applications and not just for mirrors or switches as in the disclosed invention.
The fabrication methods disclosed. in many aspects. are enahlin~~
technologies. In other switch array configurations the MEMS methods impose restrictions that impede the functioning and the reliability of the device. The usual HEMS fabrication methods are l~ inherently two-dimensional. That is to say. the device is like a silhouette. If a device should require any out-of plane structure. the elements prepared at the surface have to be raised. In Illally cases this is not a problem but. when dealings with tree-space arrays for optical swrtchmg, this introduces severe restrictions. The principal deficiency is the impossibility of truly positioning the mirrors (a variation of 0.1 degree is enough to spoil the usefulness of the device). Another aspect is mirror quality; mirror smoothness affects signal loss. When dealing with large arrays of mirrors. and especially in pD configurations.
this becomes a disqualifying factor.
Single-.switch fabrication Fabrication is explained with respect to an actuated mirror application. One starts with an 2~ optical quality polished substrate 272 (Figure 27). Mirror material 271, generally a metal such as aluminum, is deposited on substrate 272 and patterned using standard methods such as lithography. Generally. mirror 271 is produced on top of substrate 272 at a zone 273 where substrate material eventually will be removed so that a ray may pass through (Figure 27b).
In a variant fabrication procedure (Figure ?7c. d), a sacrificial layer 274 is deposited on top of substrate 272; patterned. if necessary. to allow the deposition of subsequent layers that must penetrate sacrificial layer 37-1 to reach substrate 272: and polished prior to deposition ;9 and patterning ~,~ mirn,r 271. As well as mirror 271. sup~c~rtin~~ beams 27~
arc deposited and patterned above and tl~rou'~h sacrificial layer 274. Suphortin'~ beams 27s can be made of any material: in many cases they are made of metal or otherwise include conductive material.
Supporting beams 27i are fabricated attached to mirror 271 and substrate 272.
The number and configuration of supporting beams 27~ depend on the application.
After deposition and patterning of mirror 271 and supporting beams 275. these movable elements are released by dissolving sacrificial layer 274 (Figure 27d) or by etching away a non-required, and hence superfluous, part of substrate 272 under minor 271 (Figure 27b).
thus leaving mirror 271 suspended by beams 27~. Further fabrication steps depend on the actuation mechanism. Since the surface on which mirror 271 is deposited was previously polished. the quality of mirror 271 resembles the high quality of the surface on which it was constructed. The use of a surface polished by conventional means to optical mirror grade and the use of this surface as the base for mirror preparation are key innovations of this method.
Fabrication of electrodes and conducting lines can be done together with.
before. or after the above-mentioned steps. Electrodes. conducting lines and the like, as well as the above-mentioned supportin~~ beams 27~. are referred to collectively herein as "awiliary elements".
In case of envelope actuation (Figure 27e. t~. an electrode 276 is deposited on substrate 272 and covered by a sacrificial layer 274. The above-mentioned steps for fabrication of mirror ~0 271 are carried out on top thereof. A second electrode of the envelope can be produced in one of several ways. In one way (Figure 27e. f) mirror 271 is covered by a second sacrificial layer 274A. Second layer 274A is patterned and covered by a second envelope electrode 277. which is also patterned. By removing sacrificial layers, the envelope is formed and minor 271 is released.
Another possibilit, is depositing and patterning a second envelope electrode 277 on another side of substrate 272 or. as illustrated in Figure 27g. on another substrate 272A. By aligning and bringing together a mirror side of substrate 272 and a second-electrode side of substrate 272A. and hondin~~. an envelope is formed (Figure 27h). Bonding is done by one of the known wafer-bonding methods. such as fusion bonding. anodic bonding, or other bonding methods. Spacers and electrical connection paths are deposited and patterned as required prior to alignment and bonding.
-I O
In tl~~ ~.me of curved electrode amnation- the mirror can he pn,cessed directly on a wafer surface at a ray traverse zone. Supporting beams are deposited and patterned on top of the mirror. as previously explained. It is possible to deposit material for the static curved electrode and to do the patternin~~ simultaneously. followed by insulation deposition and patterning over the static electrode. Etching the sacriticial layer and corresponding substrate area releases the movable elements.
In the case of magnetic actuation. the supporting beams may act also as conducting lines, and there is no need for further fabrication steps. The mirror and beams are fabricated and released. as described above.
Other methods for single-switch fabrication can be devised by those skilled in the art. It is emphasized. however, that fabrication on the substrate surface is critical to obtaining good quality mirrors and acquiring better control over alignment of the mirrors.
Switclmrrrrv jnbricmion The construction of a switch array requires more elaborate methods than single-switch 1 > fabrication. The disclosed method is designed to facilitate accurate construction of a ;D
cubic array. Switches are made on wafers in rows and a number of wafers are bonded each on top of another. but displaced laterally. to produce a 3D array. In the following the fabrication is eremplifed by mirrors. although other switching elements can be used instead and formed into a 3D-matrix device. This fabrication method can be applied to other devices that can take advanta~~e of the planarity of the wafers and the ,D
configuration of the completed device.
In order to simplify understanding of the fabrication method. a :lx-Ix.~ array is described (Figure 28). It is to be understood that the descriptions below are illustrative. and are not intended to restrict the present invention to the specific details set forth below Single switches 281 are produced. as described previously. in rows 283, on a surface 282 of a substrate. In our example, there are four rows. These switches are also arranged in groups 28S of regularly spaced columns 284. each group being separated from a neighboring group by an empty column 286 at the same column spacing. The first group of our example consists of one column of four rows ( 1 x4). separated by an empty column from a second ~~roup consisting of two columns of four rows (2x1) followed by another empty column. The I
arran~~ement continues with successive groups of >k-1 ancl -1~-1 to form a set. .fin entire water may be covered with such sets. For our example. at least seven such sets are required.
In order to fabricate a box array. these sets are carefully aligned, each on top of another. and bonded. A first set is placed at the bottom ready for an alignment (Figure 28b). A second wafer is aligned on top of and parallel to the first. with a second group of columns (2x4) centered above a single-column group ( 1 x4) of the first wafer. This alignment is obtained by suitably displacing the second wafer with respect to the first, in a direction parallel to rows 283. This procedure is continued with consecutive wafers, a 3x4 group of columns being centered above the 2x4 group, and a 4x4 group being centered above the 3x4.
Stacking is then continued in a reverse order. a 3x4 group being centered above the 4x4 group, and so on, until a 1 x4 group is placed on top of a second 2x4 group. The stack is then bonded. The wafer surfaces correspond to the physical layers defined earlier. Viewed from the side.
however. the mirrors f01'lll a 2D matrix having column 287 and row 288 directions oriented at ~1~° to the surfaces of substrates 282. The mirrors are oriented at 45° to these column and row directions. In this example, there are four virtual arrays, corresponding to the four rows of switches fabricated on the wafer surfaces.
If the configuration shown in Figure 236 is fabricated. only half of the above array is required. One set of S~'IItChln~~ mirrors_ at a reflecting middle plain, 289, is replaced b~ a plain static mirror substrate and the mirrors on the non-reflective side of plain 289 are not required.
After bonding is completed. the mass is accurately diced. preferably parallel to columns 287 and rows 288 of the mirror array, along dashed lines 280. A cubic array of mirrors results.
This array is further packaged by aligning with input and output fibers. It is possible to align two or more such cubes and to rotate one with respect to another so that a 3D-switching device, as explained before, is produced.
A finished device is represented in Figure 29. There, a finished cube can be seen with aligned substrates 291 bonded at interfaces 29:1. The input and output ports for the rays_ in the case of an optical switch, are represented interchangeably by 292 and 293.
Similar steps are followed to produce arrays of other dimensions, including rectan~~ular arrays other than square ones.
-I , WO 01/09653 CA 02379936 2002-O1-18 pCT/IL00/00425 Operation These switches are actuated by one of the previously specified methods through conducting lines which connect rows. columns, and planes. as appropriate. By applying an appropriate voltage or current to a particular mirror. that mirror may be set or reset into an ON or OFF
state.
Applications The switch presented can be used for switching input rays of different wavelengths from numerous input paths to numerous output paths. It is primarily intended for use in communications. Together with the wavelength separation and re-combination device disclosed above, it is applicable to WDM. Other applications. such as in optical CCllllplltatl011. Wc. will be evident.
While the invention has been described with respect to a limited number of embodiments. it will be appreciated that many variations, modifications and other applications of the invention may be made.
.t ;
Claims (70)
1. An optical switch for switching a light ray comprising:
(a) a substantially planar substrate having a portion that is transparent to the light ray:
(b) a switching element having at least one reflective surface substantially parallel to said substrate: and (c) a bistable mechanism for moving said switching element in a direction parallel to said substrate between:
(i) a first position wherein the light ray traverses said transparent portion of said substrate and (ii) a second position wherein the light ray is blocked from traversing said transparent portion of said substrate and wherein the light ray is reflected by said reflective surface.
(a) a substantially planar substrate having a portion that is transparent to the light ray:
(b) a switching element having at least one reflective surface substantially parallel to said substrate: and (c) a bistable mechanism for moving said switching element in a direction parallel to said substrate between:
(i) a first position wherein the light ray traverses said transparent portion of said substrate and (ii) a second position wherein the light ray is blocked from traversing said transparent portion of said substrate and wherein the light ray is reflected by said reflective surface.
2. The optical switch of claim 1. wherein said mechanism includes:
(i) a first rigid element having two ends a first said end of said first rigid element being flexibly connected to a fixed point:
(ii) a second rigid element having two ends a second said end of said first rigid element being flexibly connected to a first said end of said second rigid element: and (iii) a tensile elastic element connecting said first end of said first rigid element to a second said end of said second rigid element so that a distance between said first end and said second end when said elastic element is in a relaxed state is less than a sum of a distance between said ends of said first rigid element and a distance between said ends of said second rigid element:
both said rigid elements being constrained to be movable only in a plane parallel to said substrate.
(i) a first rigid element having two ends a first said end of said first rigid element being flexibly connected to a fixed point:
(ii) a second rigid element having two ends a second said end of said first rigid element being flexibly connected to a first said end of said second rigid element: and (iii) a tensile elastic element connecting said first end of said first rigid element to a second said end of said second rigid element so that a distance between said first end and said second end when said elastic element is in a relaxed state is less than a sum of a distance between said ends of said first rigid element and a distance between said ends of said second rigid element:
both said rigid elements being constrained to be movable only in a plane parallel to said substrate.
3. The optical switch of claim 1, wherein said mechanism includes:
(i) a first element having two ends:
(ii) a second element having two ends, a first said end of said first element being flexibly connected to a first said end of said second element:
(iii) a third element having two ends, a second said end of said second element being flexibly connected to a first said end of said third element;
(iv) a fourth element having two ends, a second said end of said third element being flexibly connected to a first said end of said fourth element:
(v) two fixed anchor points, a second said end of said first element being flexibly connected to a first said anchor point and a second said end of said fourth element beings flexibly connected to a second said anchor point: and (vi) a tensile elastic mechanism for maintaining said mechanism for moving said switching element in either of two stable states:
all said elements being constrained to be movable only in a plane parallel to said substrate.
(i) a first element having two ends:
(ii) a second element having two ends, a first said end of said first element being flexibly connected to a first said end of said second element:
(iii) a third element having two ends, a second said end of said second element being flexibly connected to a first said end of said third element;
(iv) a fourth element having two ends, a second said end of said third element being flexibly connected to a first said end of said fourth element:
(v) two fixed anchor points, a second said end of said first element being flexibly connected to a first said anchor point and a second said end of said fourth element beings flexibly connected to a second said anchor point: and (vi) a tensile elastic mechanism for maintaining said mechanism for moving said switching element in either of two stable states:
all said elements being constrained to be movable only in a plane parallel to said substrate.
4. The optical switch of claim 3 wherein all said elements are rigid.
5. The optical switch of claim 4 wherein said tensile elastic mechanism includes:
a) a tensile elastic element connecting said second end of said second element to said first anchor point so that a distance between said second end and said first anchor point when said elastic element is in a relaxed state is less than a sum of a distance between said ends of said first element and a distance between said ends of said second element: and b) a tensile elastic element connecting said first end of said third element to said second anchor point so that a distance between said first end and said second anchor point when said elastic element is in a relaxed state is less than a sum of a distance between said ends of said third element and a distance between said ends of said fourth element.
a) a tensile elastic element connecting said second end of said second element to said first anchor point so that a distance between said second end and said first anchor point when said elastic element is in a relaxed state is less than a sum of a distance between said ends of said first element and a distance between said ends of said second element: and b) a tensile elastic element connecting said first end of said third element to said second anchor point so that a distance between said first end and said second anchor point when said elastic element is in a relaxed state is less than a sum of a distance between said ends of said third element and a distance between said ends of said fourth element.
6. The optical switch of claim 4 wherein said tensile elastic mechanism includes a tensile elastic element connecting said first end of said second element to said second end of said third element so that a distance between said first end and said second end when said elastic element is in a relayed state is less than a sum of a distance between said ends of said second element and a distance between said ends of said third element.
7. The optical switch of claim 4 wherein said tensile elastic mechanism includes a spiral spring at each said flexible connection.
8. The optical switch of claim 3 wherein:
a) said first element and said fourth element are elastic beams, b) said second element and said third element are rigid, c) said first element is rigidly connected to said first anchor point, and d) said fourth element is rigidly connected to said second anchor point.
a) said first element and said fourth element are elastic beams, b) said second element and said third element are rigid, c) said first element is rigidly connected to said first anchor point, and d) said fourth element is rigidly connected to said second anchor point.
9. A hinge comprising:
a) a housing having a flat wall, b) an element free to roll within said housing and having a connector that protrudes beyond said housing, and c) a mechanism for urging said rollable element against said wall as said element rolls within said housing so as to maintain rolling contact between said element and said wall.
a) a housing having a flat wall, b) an element free to roll within said housing and having a connector that protrudes beyond said housing, and c) a mechanism for urging said rollable element against said wall as said element rolls within said housing so as to maintain rolling contact between said element and said wall.
10. The hinge of claim 9 wherein said connector is a rigid arm.
11. The hinge of claim 9 wherein said mechanism is electrostatic.
12. The hinge of claim 9 wherein said mechanism is magnetic.
13. The hinge of claim 9 further comprising:
d) a restoring mechanism for returning said rollable element to contact with said wall in case of loss of said contact.
d) a restoring mechanism for returning said rollable element to contact with said wall in case of loss of said contact.
14. The hinge of claim 13, wherein said restoring mechanism includes:
a) two flexible cables:
(i) a first end of a first said cable being operationally connected to but electrically insulated from said housings.
(ii) a first end of a second said cable being operationally connected to but electrically insulated from said housing, (iii) a second end of said first cable being operationally connected to but electrically insulated from said rollable element, and (iv) a second end of said second cable being operationally connected to but electrically insulated from said rollable element:
b) two electrodes for resetting said rollable element in place:
(i) a first said electrode being situated opposite first said cable on a side away from said rollable element, and (ii) a second said electrode being situated opposite second said cable on a side away from said rollable element:
c) a mechanism for charging said electrodes: and d) a mechanism for charging said cables.
a) two flexible cables:
(i) a first end of a first said cable being operationally connected to but electrically insulated from said housings.
(ii) a first end of a second said cable being operationally connected to but electrically insulated from said housing, (iii) a second end of said first cable being operationally connected to but electrically insulated from said rollable element, and (iv) a second end of said second cable being operationally connected to but electrically insulated from said rollable element:
b) two electrodes for resetting said rollable element in place:
(i) a first said electrode being situated opposite first said cable on a side away from said rollable element, and (ii) a second said electrode being situated opposite second said cable on a side away from said rollable element:
c) a mechanism for charging said electrodes: and d) a mechanism for charging said cables.
15. The restoring mechanism of claim 14 wherein:
a) said cables are slack while said rollable element is in contact with said wall, and b) at least one said cable is taut when said rollable element loses contact with said wall.
a) said cables are slack while said rollable element is in contact with said wall, and b) at least one said cable is taut when said rollable element loses contact with said wall.
16. A travelling wave actuator for moving an object comprising:
a) an elastic membrane, b) a mechanism for maintaining contact between the object and said membrane, and c) a mechanism for generating a travelling wave in said membrane.
a) an elastic membrane, b) a mechanism for maintaining contact between the object and said membrane, and c) a mechanism for generating a travelling wave in said membrane.
17. The travelling wage actuator of claim 16 further comprising:
d) a substrate whereupon said elastic membrane is deposited.
d) a substrate whereupon said elastic membrane is deposited.
18. The travelling wave actuator of claim 16 wherein said mechanism for maintaining contact is electrostatic.
19. The travelling wave actuator of claim 16 wherein said mechanism for maintaining contact is magnetic.
20. The travelling wave actuator of claim 16 wherein said mechanism for generating a travelling wave includes:
(i) a plurality of electrode pairs, equally spaced along and straddling said membrane, and (ii) for each said pair, a respective alternating electrical power supply.
(i) a plurality of electrode pairs, equally spaced along and straddling said membrane, and (ii) for each said pair, a respective alternating electrical power supply.
21. The travelling wave actuator of claim 16 wherein said means of generating a travelling wave is magnetic.
22. The travelling wave actuator of claim 16 wherein said means of generating a travelling wave is thermal.
23. The travelling wave actuator of claim 16 wherein said means of generating a travelling wave is piezoelectric.
24. An actuator for moving an element comprising:
a) a stationary support for the element, b) a deflectable support for the element operative to:
(i) raise the element from said stationary support.
(ii) advance the element in a required direction of motion, (iii) deposit the element upon said stationary support, and (iv) return to a starting position thereof.
a) a stationary support for the element, b) a deflectable support for the element operative to:
(i) raise the element from said stationary support.
(ii) advance the element in a required direction of motion, (iii) deposit the element upon said stationary support, and (iv) return to a starting position thereof.
25. The actuator of claim 24 wherein:
a) said stationary support includes a cluster of fingers, said cluster being sufficient to support the element, and b) said deflectable movable support includes at least one cluster of fingers, each said cluster being sufficient to support the element.
a) said stationary support includes a cluster of fingers, said cluster being sufficient to support the element, and b) said deflectable movable support includes at least one cluster of fingers, each said cluster being sufficient to support the element.
26. The actuator of claim 25 wherein each said finger includes a surface at a tip thereof, whereupon said element is supportable.
27. The actuator of claim 24 wherein the element is a planar switching element.
28. The actuator of claim 24 wherein said deflectable support is activated electro-statically.
29. The actuator of claim 24 wherein said deflectable support is activated piezo-electrically.
30. An emergency holding device for a movable switching element comprising:
a) a buckled beam having:
(i) a first stable configuration concave towards the switching element, and (ii) a second, tense configuration, concave towards the switching element, wherefrom, if relieved, said beam relaxes to said first stable configuration: and h) a flexible strap straddling the switching element, said strap being:
(i) attached at a first end thereof to a center of said beam and perpendicular thereto, and (ii) anchored at a second end thereof at a tired point, so that, at said concave stable configuration. said strap constrains the switching element.
a) a buckled beam having:
(i) a first stable configuration concave towards the switching element, and (ii) a second, tense configuration, concave towards the switching element, wherefrom, if relieved, said beam relaxes to said first stable configuration: and h) a flexible strap straddling the switching element, said strap being:
(i) attached at a first end thereof to a center of said beam and perpendicular thereto, and (ii) anchored at a second end thereof at a tired point, so that, at said concave stable configuration. said strap constrains the switching element.
31. The emergency holding device of claim 30 wherein said strap is electrically conductive, the device further comprising:
c) an electrode placed opposite said strap.
c) an electrode placed opposite said strap.
32. A mechanism for lateral realignment of a free movable element with respect to a rectilinear motion path thereof comprising:
a) two alignment pads on opposite sides of the element, b) a mechanism for bringing said pads into contact with the movable element, thereby nudging the element to said laterally aligned position, and c) a mechanism for retracting said pads from said contact.
a) two alignment pads on opposite sides of the element, b) a mechanism for bringing said pads into contact with the movable element, thereby nudging the element to said laterally aligned position, and c) a mechanism for retracting said pads from said contact.
33. The realignment mechanism of claim 32 wherein each said alignment pad includes an electrode.
34. The realignment mechanism of claim 32 wherein said contact mechanism is elastic.
35. The realignment mechanism of claim 32 wherein said contact mechanism is electrostatic.
36. The realignment mechanism of claim 32 further comprising:
d) two walls situated on opposite sides of the movable element and outside said alignment pads, and e) elastic elements attaching each said alignment pad to a nearer said wall.
d) two walls situated on opposite sides of the movable element and outside said alignment pads, and e) elastic elements attaching each said alignment pad to a nearer said wall.
37. The realignment mechanism of claim 32 further comprising:
d) two walls situated on opposite sides of the movable element and outside said alignment pads, each said wall including an electrode, and e) elastic elements attaching each alignment pad to a nearer side of the movable element.
d) two walls situated on opposite sides of the movable element and outside said alignment pads, each said wall including an electrode, and e) elastic elements attaching each alignment pad to a nearer side of the movable element.
38. The realignment mechanism of claim 32 wherein said retracting mechanism is electrostatic.
39. The realignment mechanism of claim 32 wherein said retracting mechanism is magnetic.
40. A mechanism for continuous lateral realignment of a free movable element with respect to a motion path thereof comprising:
a) a stationary electrode adjacent to and clear of the path.
b) a second, movable electrode:
(i) attached to the element.
(ii) at least partially overlapping said stationary electrode, and (iii) constrained to remain parallel to said stationary electrode so that a gap remains therebetween, and c) a mechanism for electrostatically charging said electrodes, the resulting electrostatic force between said electrodes acting to maitain the element in the motion path.
a) a stationary electrode adjacent to and clear of the path.
b) a second, movable electrode:
(i) attached to the element.
(ii) at least partially overlapping said stationary electrode, and (iii) constrained to remain parallel to said stationary electrode so that a gap remains therebetween, and c) a mechanism for electrostatically charging said electrodes, the resulting electrostatic force between said electrodes acting to maitain the element in the motion path.
41. The realignment mechanism of claim 40, wherein the motion path is confined to a plane.
42. The realignment mechanism of claim 41, wherein the motion path is rectilinear.
43. The realignment mechanism of claim 40, further comprising:
d) a second stationary electrode adjacent to and clear of the path, (i) lying in a same plane as and clear of said first stationary electrode, (ii) opposed to said first stationary electrode with respect to the motion path, and (iii) at least partially overlapped by said movable electrode so that a gap remains therebetween, and e) a mechanism for electrostatically charging said second stationary electrode, the resulting electrostatic force between said electrodes acting to maintain the element in the motion path.
d) a second stationary electrode adjacent to and clear of the path, (i) lying in a same plane as and clear of said first stationary electrode, (ii) opposed to said first stationary electrode with respect to the motion path, and (iii) at least partially overlapped by said movable electrode so that a gap remains therebetween, and e) a mechanism for electrostatically charging said second stationary electrode, the resulting electrostatic force between said electrodes acting to maintain the element in the motion path.
44. The realignment mechanism of claim 43 wherein said stationary electrodes are shaped as mutual mirror images and are symmetrically disposed about the path.
45. The realignment mechanism of claim 43 wherein said charge on said second stationary electrode is of a same polarity as said charge on first said stationary electrode.
46. The realignment mechanism of claim 45 wherein said charge on said movable electrode is of a same polarity as said charge on said stationary electrodes.
47. The realignment mechanism of claim 45 wherein said charade on said movable electrode is of opposite polarity to said charge on said stationary electrodes.
48. The realignment mechanism of claim 44 wherein said shape of each said electrode is an isosceles triangle, an axis of symmetry whereof is oriented perpendicular to the motion path.
49. A method of moving an element comprising the steps of:
a) urging the element to be in contact with an elastic membrane while b) generating a travelling wave in said membrane.
a) urging the element to be in contact with an elastic membrane while b) generating a travelling wave in said membrane.
50. A method of moving an element comprising the steps of:
a) providing:
(i) a stationary support for the element, and (ii) a deflectable support for the element, and b) cyclically operating said deflectable support to:
(i) raise the element from said stationary support, (ii) advance the element in a required direction of motion, (iii) deposit the element upon said stationary support, and (iv) return to a starting position thereof.
a) providing:
(i) a stationary support for the element, and (ii) a deflectable support for the element, and b) cyclically operating said deflectable support to:
(i) raise the element from said stationary support, (ii) advance the element in a required direction of motion, (iii) deposit the element upon said stationary support, and (iv) return to a starting position thereof.
51. A method of holding an electrostatically supported switching element upon cessation of a supply of power to the switching element, comprising the steps of:
a) providing a flexible strap straddling the switching; element, and having a first configuration wherein said strap constrains the switching element and a second configuration wherein the switching element is free from said constraint; and b) maintaining said strap in said second configuration only while the power is supplied.
a) providing a flexible strap straddling the switching; element, and having a first configuration wherein said strap constrains the switching element and a second configuration wherein the switching element is free from said constraint; and b) maintaining said strap in said second configuration only while the power is supplied.
52. A method of laterally realigning a free movable element in a direction perpendicular to a rectilinear motion path thereof comprising the steps of:
a) providing a realignment mechanism including two movable alignment pads on opposite sides of the element.
b) bringing said pads into contact with the movable element, thereby nudging the element to the rectilinear motion path, and c) retracting said pads.
a) providing a realignment mechanism including two movable alignment pads on opposite sides of the element.
b) bringing said pads into contact with the movable element, thereby nudging the element to the rectilinear motion path, and c) retracting said pads.
53. A method of continuously laterally realigning a free movable element with respect to a motion path thereof comprising the steps of:
a) providing:
(i) a stationary electrode adjacent to and clear of the path, (ii) a second, movable electrode attached to the element, at least partially overlapping said stationary electrode, and constrained to remain parallel to said stationary electrode so that a gap remains therebetween, and (iii) a mechanism for electrostatically charging said electrodes: and b) electrostatically charging said electrodes.
a) providing:
(i) a stationary electrode adjacent to and clear of the path, (ii) a second, movable electrode attached to the element, at least partially overlapping said stationary electrode, and constrained to remain parallel to said stationary electrode so that a gap remains therebetween, and (iii) a mechanism for electrostatically charging said electrodes: and b) electrostatically charging said electrodes.
54. The method of claim 53, further comprising the step of:
c) providing:
(i) a second stationary electrode adjacent to and clear of the path, lying in a same plane as and clear of said first stationary electrode, opposed to said first stationary electrode with respect to the motion path, and at least partially overlapped by said movable electrode so that a gap remains therebetween, and (ii) a mechanism for electrostatically charging said second stationary electrode.
c) providing:
(i) a second stationary electrode adjacent to and clear of the path, lying in a same plane as and clear of said first stationary electrode, opposed to said first stationary electrode with respect to the motion path, and at least partially overlapped by said movable electrode so that a gap remains therebetween, and (ii) a mechanism for electrostatically charging said second stationary electrode.
55. The method of claim 54 wherein said stationary electrodes are shaped as mutual mirror images and are symmetrically disposed about the path.
56. The method of claim 54 further comprising the step of charging said second stationary electrode with a same polarity as said charge on said first stationary electrode.
57. The method of claim 56 further comprising the step of charging said movable electrode with a same polarity as said charge on said stationary electrodes.
58. The method of claim 56 further comprising the step of charging said movable electrode with a polarity opposite to said charge on said stationary electrodes.
59. The method of claim 55 wherein said stationary electrodes are shaped as isosceles triangles.
60. A method of fabricating a micro-device having a high-quality smooth mirror surface comprising the steps of:
a) polishing a substrate surface to a required smoothness, b) depositing mirror material on said substrate, and c) removing a superfluous part of said substrate adjacent to a surface of said mirror.
a) polishing a substrate surface to a required smoothness, b) depositing mirror material on said substrate, and c) removing a superfluous part of said substrate adjacent to a surface of said mirror.
61. A method of fabricating a micro-device having a high-quality smooth mirror surface comprising the steps of:
a) depositing a sacrificial layer on said substrate, b) polishing a surface of said sacrificial layer to a required smoothness, c) patterning said sacrificial layer to provide for auxiliary elements, d) depositing mirror material on said polished surface of said sacrificial layer, e) depositing said auxiliary elements on said patterned portion of said sacrificial layer, and removing said sacrificial layer.
a) depositing a sacrificial layer on said substrate, b) polishing a surface of said sacrificial layer to a required smoothness, c) patterning said sacrificial layer to provide for auxiliary elements, d) depositing mirror material on said polished surface of said sacrificial layer, e) depositing said auxiliary elements on said patterned portion of said sacrificial layer, and removing said sacrificial layer.
62. The method of claim 61, comprising the further step of:
removing a superfluous part of said substrate.
removing a superfluous part of said substrate.
63. A method of fabricating an envelope-actuated micro-device having a high-quality smooth mirror surface comprising the steps of:
a) providing a first substrate, b) depositing an electrode on said first substrate, c) depositing a first sacrificial layer on said electrode and said first substrate, d) polishing a surface of said first sacrificial layer to a required smoothness, e) patterning said first sacrificial layer to provide for a first set of auxiliary elements.
f) depositing mirror material on said polished surface of said first sacrificial layer, and g) depositing said auxiliary elements on said patterned portion of said first sacrificial layer.
a) providing a first substrate, b) depositing an electrode on said first substrate, c) depositing a first sacrificial layer on said electrode and said first substrate, d) polishing a surface of said first sacrificial layer to a required smoothness, e) patterning said first sacrificial layer to provide for a first set of auxiliary elements.
f) depositing mirror material on said polished surface of said first sacrificial layer, and g) depositing said auxiliary elements on said patterned portion of said first sacrificial layer.
64. The method of claim 63, comprising the further step of:
h) providing a second electrode.
h) providing a second electrode.
65. The method of claim 64 wherein said providing of said second electrode is effected by steps including:
(i) depositing a second sacrificial layer on said mirror material.
(ii) patterning said second sacrificial layer to, provide for said second electrode and a second set of auxiliary elements, and (iii) depositing said second electrode and said second set of auxiliary elements on said patterned portion of said second sacrificial layer.
(i) depositing a second sacrificial layer on said mirror material.
(ii) patterning said second sacrificial layer to, provide for said second electrode and a second set of auxiliary elements, and (iii) depositing said second electrode and said second set of auxiliary elements on said patterned portion of said second sacrificial layer.
66. The method of claim 6-1 wherein said providing of said second electrode is effected by steps including:
(i) providing a second substrate, (ii) depositing said second electrode on said second substrate, (iii) aligning said second electrode opposite the micro-device as fabricated on said first substrate, and (iv) bonding said second substrate to said first substrate.
(i) providing a second substrate, (ii) depositing said second electrode on said second substrate, (iii) aligning said second electrode opposite the micro-device as fabricated on said first substrate, and (iv) bonding said second substrate to said first substrate.
67. The method of claim 63, comprising the further step of:
h) removing said first sacrificial layer.
h) removing said first sacrificial layer.
68. The method of claim 63, comprising the further step of:
h) removing a superfluous part of said substrate.
h) removing a superfluous part of said substrate.
69. A mechanism for providing a strictly non-blocking switching configuration comprising two coupled substantially identical tri-cube complex switching arrays:
a) each said array being operative to switch any input element to any output element, b) a first said array being operative to allow any input element to transit unswitched to a corresponding input of a second said array, and c) said second array being operative to allow any output element from said first array to transit unswitched to a corresponding output of said second array.
a) each said array being operative to switch any input element to any output element, b) a first said array being operative to allow any input element to transit unswitched to a corresponding input of a second said array, and c) said second array being operative to allow any output element from said first array to transit unswitched to a corresponding output of said second array.
70. A method of strictly non-blocking switching including the steps of:
a) providing two coupled substantially identical tri-cube complex switching arrays:
(i) each said array being operative to switch any input element to any output element.
(ii) a first said array being operative to allow any input element to transit unswitched to a corresponding input of a second said array, and (iii) said second array being operative to allow any output element from said first array to transit unswitched to a corresponding output of said second array; and b) operating said switching arrays coupled in parallel.
a) providing two coupled substantially identical tri-cube complex switching arrays:
(i) each said array being operative to switch any input element to any output element.
(ii) a first said array being operative to allow any input element to transit unswitched to a corresponding input of a second said array, and (iii) said second array being operative to allow any output element from said first array to transit unswitched to a corresponding output of said second array; and b) operating said switching arrays coupled in parallel.
Applications Claiming Priority (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US14462899P | 1999-07-20 | 1999-07-20 | |
| US60/144,628 | 1999-07-20 | ||
| US17048299P | 1999-12-13 | 1999-12-13 | |
| US17049299P | 1999-12-13 | 1999-12-13 | |
| US17049499P | 1999-12-13 | 1999-12-13 | |
| US60/170,482 | 1999-12-13 | ||
| US60/170,492 | 1999-12-13 | ||
| US60/170,494 | 1999-12-13 | ||
| PCT/IL2000/000425 WO2001009653A1 (en) | 1999-07-20 | 2000-07-19 | Opto-mechanical valve and valve array for fiber-optic communication |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2379936A1 true CA2379936A1 (en) | 2001-02-08 |
Family
ID=27495626
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002379936A Abandoned CA2379936A1 (en) | 1999-07-20 | 2000-07-19 | Opto-mechanical valve and valve array for fiber-optic communication |
Country Status (5)
| Country | Link |
|---|---|
| AU (1) | AU6012100A (en) |
| CA (1) | CA2379936A1 (en) |
| GB (1) | GB2367906A (en) |
| IL (1) | IL147521A0 (en) |
| WO (1) | WO2001009653A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6647164B1 (en) | 2000-10-31 | 2003-11-11 | 3M Innovative Properties Company | Gimbaled micro-mirror positionable by thermal actuators |
| US6711318B2 (en) | 2001-01-29 | 2004-03-23 | 3M Innovative Properties Company | Optical switch based on rotating vertical micro-mirror |
| US6718084B1 (en) | 2001-05-10 | 2004-04-06 | Axsun Technologies, Inc. | Integrated optical line card protection module |
| JP3952902B2 (en) | 2002-08-09 | 2007-08-01 | 住友電気工業株式会社 | Optical switch, optical add / drop device, optical transmission system, and optical switch manufacturing method |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0325421Y2 (en) * | 1986-03-13 | 1991-06-03 | ||
| JP2616683B2 (en) * | 1993-12-28 | 1997-06-04 | 日本電気株式会社 | Piezoelectric actuator with displacement expansion mechanism |
| US5742712A (en) * | 1996-10-08 | 1998-04-21 | E-Tek Dynamics, Inc. | Efficient electromechanical optical switches |
| US5943454A (en) * | 1997-08-15 | 1999-08-24 | Lucent Technologies, Inc. | Freespace optical bypass-exchange switch |
-
2000
- 2000-07-19 CA CA002379936A patent/CA2379936A1/en not_active Abandoned
- 2000-07-19 AU AU60121/00A patent/AU6012100A/en not_active Abandoned
- 2000-07-19 WO PCT/IL2000/000425 patent/WO2001009653A1/en not_active Ceased
- 2000-07-19 GB GB0201261A patent/GB2367906A/en not_active Withdrawn
- 2000-07-19 IL IL14752100A patent/IL147521A0/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB0201261D0 (en) | 2002-03-06 |
| GB2367906A (en) | 2002-04-17 |
| AU6012100A (en) | 2001-02-19 |
| WO2001009653A1 (en) | 2001-02-08 |
| IL147521A0 (en) | 2002-08-14 |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |