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WO2002097482A2 - Retroreflecteurs diedres a angle droit - Google Patents

Retroreflecteurs diedres a angle droit Download PDF

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Publication number
WO2002097482A2
WO2002097482A2 PCT/CA2002/000777 CA0200777W WO02097482A2 WO 2002097482 A2 WO2002097482 A2 WO 2002097482A2 CA 0200777 W CA0200777 W CA 0200777W WO 02097482 A2 WO02097482 A2 WO 02097482A2
Authority
WO
WIPO (PCT)
Prior art keywords
waveguide
optical component
core
optical
waveguide core
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CA2002/000777
Other languages
English (en)
Other versions
WO2002097482A3 (fr
Inventor
Siegfried Janz
Dan-Xia Xu
Pavel Cheben
Andre Delage
Lynden Erickson
Boris Lamontagne
Sylvain Charbonneau
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LNL TECHNOLOGIES CANADA Inc
Original Assignee
LNL TECHNOLOGIES CANADA Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by LNL TECHNOLOGIES CANADA Inc filed Critical LNL TECHNOLOGIES CANADA Inc
Priority to AU2002257465A priority Critical patent/AU2002257465A1/en
Publication of WO2002097482A2 publication Critical patent/WO2002097482A2/fr
Publication of WO2002097482A3 publication Critical patent/WO2002097482A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/13—Integrated optical circuits characterised by the manufacturing method
    • G02B6/136—Integrated optical circuits characterised by the manufacturing method by etching
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/12—Reflex reflectors
    • 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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/122—Basic optical elements, e.g. light-guiding paths
    • 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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/122—Basic optical elements, e.g. light-guiding paths
    • G02B6/125—Bends, branchings or intersections
    • 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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12083—Constructional arrangements
    • G02B2006/12104—Mirror; Reflectors or the like
    • 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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12166—Manufacturing methods
    • G02B2006/12176—Etching

Definitions

  • This invention relates to the field of photonics, and in particular to right angle corner retroreflectors and retroreflectors with optical taps.
  • TIR total internal reflection
  • Figure 1 illustrates the concept of Snell's Law.
  • a light beam incident beam
  • IB travels along a medium of refractive index n. and impinges on the surface S of a medium of refractive index n-r. Part of the incident light is transmitted into medium T (the refracted beam RFRB) and part is reflected (the reflected beam RFLB) back into medium I. If the angle of incidence is ⁇ i and the angle of reflection is ⁇ R , then the angle of the refracted beam ⁇ T is given by Snell's Law which can be written as: ⁇
  • sin "1 (nj/ni).
  • a prism is one type of refractive and reflective device.
  • a prism 10 is a wedge of optical material that can either refract or totally reflect light, depending on the angle of incidence.
  • the 45° glass prism shown in Figure 2 is especially useful because incident light 12 entering normal to one face will totally reflect out from the other face, having changed direction by 90°. Total reflection occurs because the light strikes the inner surface at 45°, which is greater than the critical angle of about 41° for glass.
  • the line "N" represents a line normal (perpendicular) to a surface.
  • Figure 3 is refracted in part, reflected in part by any internal surface, and refracted again as it emerges as exiting light 14. It has deviated from its original direction to emerge at a new angle. The general result is that the light is bent partly back in the direction from which it came. The deviation depends on the index of refraction of the prism, the angle of incidence, and on the angle in the vertex of the prism. For a symmetrical arrangement of incident and exiting light, 12 and 14 respectively, the angle of deviation is a minimum. More complex prisms use reflections to perform complex changes in image orientation. For example, a corner-cube prism has the geometric property of sending light back exactly in the direction it came (i.e., to "retroreflect" the light).
  • Such existing schemes using dielectric or metal coatings to achieve high reflectivity entail one or more additional process steps.
  • the deposition of multilayer dielectric coatings is not within the capability with conventional silicon fabrication facilities.
  • the use of metal coatings also introduces unwanted polarization dependent loss in the structure.
  • the efficiency of the reflective coating depends on the quality of the deposition.
  • retroreflector in waveguides, and the integrated waveguide are disclosed. Also disclosed is a retroreflector with an optical tap.
  • the invention provides an integrated optical component for use in bidirectional optical transmission and reception.
  • the component comprises a substrate with a waveguide core provided on the substrate.
  • the waveguide has a first end from which lights enters and exits the waveguide core, and a second end.
  • a mirror is at the second end of the waveguide core.
  • the mirror is in the form of a right angle corner reflector arrangement, such that light entering the waveguide core at the first end and travelling to the second end is reflected by the corner reflector so as to exit the waveguide core at the first end.
  • the invention provides an optical transmission network used in bidirectional optical transmission and reception.
  • the network comprises an integrated optical component comprising a substrate, and a waveguide core provided on the substrate.
  • the waveguide core has a first end from which lights enters and exits the waveguide core, and a second end.
  • a waveguide mirror is at the second end of the waveguide core.
  • the mirror is in the form of a right angle corner reflector arrangement, such that light entering the waveguide core at the first end and travelling to the second end is reflected by the corner reflector so as to exit the waveguide core at the first end.
  • the method comprises the steps of preparing a substrate, and fabricating a waveguide on the substrate.
  • the waveguide has a first end from which lights enters and exits the waveguide, and a second end.
  • the method also comprises fabricating a waveguide mirror in the form of a right angle corner reflector arrangement by reactive ion etching at the second end of the waveguide.
  • the waveguide employed may be a silicon-on-insulator (SOI) waveguide, an
  • Corner retroreflectors find application as waveguide mirrors and reflectors for SOI based or InP based echelle grating demultiplexers or any other waveguiding structures/materials. By leaving a small gap at the apex of the retroreflector or at the edge of the retroreflector, a reflector with an optical tap for monitoring purposes can be fabricated.
  • Figure 2 illustrates total internal reflection in a prism
  • Figure 3 illustrates deviation of light as it passes through a prism
  • Figure 4 illustrates a top view of a right angle corner retroreflector in a waveguide according to an embodiment of the present invention
  • Figure 5 illustrates a cross sectional side view of the retroreflector of Figure 4.
  • Figure 6 is a top view of a right angle corner retroreflector with an optical tap in waveguide according to another embodiment of the invention.
  • the optical component 29 illustrated is a planar waveguide.
  • the light travels along a two dimensional core of high-index material embedded in the surface of a substrate.
  • the core may be deposited on top of the substrate.
  • embodiments of this invention contemplate use of a conventional rib-type SOI (Silicon-On-Insulator) optical planar waveguide, which is typically formed on a SOI wafer.
  • Other embodiments utilize InP waveguides, or waveguides of any other suitable material.
  • the SOI manufacturing process two standard silicon wafers are oxidized and then bonded together to form a sandwich with an intermediate layer of silicon dioxide. One of the wafers is then thinned down to form an active layer on the order of a micron in thickness with an underlying silicon dioxide layer. Or, the SOI wafer may be fabricated by silicon direct bonding or the separation by implantation of oxygen (SIMOX) methods. Examples of such known techniques are disclosed in U.S. Pat. No. 5,234,535. This material is commercially available for the manufacture of high speed electronic integrated circuits, and can be obtained at low cost in large substrate sizes from various vendors.
  • SIMOX separation by implantation of oxygen
  • SOI waveguide structures include a buffer layer 30 formed on a silicon substrate 32, a waveguide core layer 34 and a cladding layer (not shown).
  • the invention preferably uses the thin silicon layer 34 of an SOI wafer of SOI substrate as the core of the waveguide.
  • the core layer 34 may be made of a single crystal silicon layer or any material with an index higher than 1.5, such as silicon, silicon oxynitride, silicon nitride, and III-V semiconductors.
  • the buffer layer 30 is made of a silicon oxide layer, and a silicon oxide layer formed by oxidizing the surface of the core layer 34 is used as the cladding layer (not shown).
  • the thickness of the layers is a parameter of the waveguide design and not of the retroreflector operation.
  • the waveguide buffer 30 is of a lower index than the core, which serves to confine the light within the core.
  • the top is exposed to air, which also has a lower refractive index, so the whole core serves as a waveguide for the light. Therefore, an optical waveguide is defined by an extended region of increased index of refraction relative to the surrounding medium. According to Snell's Law, for TIR to occur for light incident on a surface at 45°, (n ⁇ /n ⁇ ) must be greater than 1.42. In other words, a waveguide system with a high refractive index step between the core and air greater than 1.42 is required.
  • the waveguide 29 includes a right angle corner retroreflector 36 used as a waveguide mirror in the optical component.
  • the retroreflector 36 consists of two vertical walls 35, 37 oriented at a right angle to each other as shown.
  • the walls are formed by a dry etching technique, such as reactive ion etching or chemically assisted ion beam etching to form a trench 40 in the waveguide.
  • the trench could be formed by a purely wet etch.
  • the walls forming the retroreflector must be smooth to within 100 nm or less, and vertical to within 1 degree or less.
  • the main problem in corner mirror fabrication is to achieve smooth vertical facets at precisely defined positions.
  • TIR total internal reflection
  • apex 40 of the retroreflector forms an etched facet 42 through which a small amount of light is transmitted to a tap waveguide. Therefore most of the waveguide mode is reflected while a small amount is transmitted through the aperture into the following waveguide. This can be used as an optical tap to split off part of an optical signal for monitoring or other purposes, while leaving the main beam relatively undisturbed.
  • the waveguide may be SOI, InP or any other suitable type.
  • the etched facet 42 is of a length "d” and at an angle " ⁇ ", as seen in Figure 6.
  • the tap may be at any other angle than 90°, depending upon the amount of light to be tapped. As well, the tap may be provided at the side of the waveguide.
  • Embodiments of the waveguide according to the present invention result in a reduction of process steps; once the vertical walls are fabricated no additional process steps or depositions are required.
  • the waveguide also provides a mirror of high reflectivity. Since TIR is used, the mirror should have 100%) efficiency, apart from losses due to roughness and defects in the vertical walls.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Optical Integrated Circuits (AREA)

Abstract

L'invention concerne un composant optique, tel qu'un guide d'ondes, présentant un miroir en guide d'ondes sous la forme d'un réflecteur dièdre à angle droit, de telle sorte qu'un faisceau lumineux entrant dans le guide d'ondes frappe le miroir en guide d'ondes et subisse une réflexion interne totale. L'indice du rapport de réfraction entre l'âme du guide d'ondes et l'air est au moins de 1,42. De préférence, le miroir en guide d'ondes est fabriqué par gravure ionique réactive. Selon une forme d'exécution, le sommet du miroir en guide d'ondes présente une petite facette gravée agissant comme prise optique. L'invention permet de réduire les étapes de traitement, tout en obtenant une réflectivité élevée.
PCT/CA2002/000777 2001-05-28 2002-05-28 Retroreflecteurs diedres a angle droit Ceased WO2002097482A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002257465A AU2002257465A1 (en) 2001-05-28 2002-05-28 Right angle corner waveguide retroreflector

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA 2349014 CA2349014A1 (fr) 2001-05-28 2001-05-28 Retroreflecteurs corniers a angle droit et retroreflecteurs a prises optiques dans des guides d'ondes silicium-sur-isolant
CA2,349,014 2001-05-28

Publications (2)

Publication Number Publication Date
WO2002097482A2 true WO2002097482A2 (fr) 2002-12-05
WO2002097482A3 WO2002097482A3 (fr) 2003-02-20

Family

ID=4169121

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA2002/000777 Ceased WO2002097482A2 (fr) 2001-05-28 2002-05-28 Retroreflecteurs diedres a angle droit

Country Status (3)

Country Link
AU (1) AU2002257465A1 (fr)
CA (1) CA2349014A1 (fr)
WO (1) WO2002097482A2 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7747115B2 (en) * 2007-09-12 2010-06-29 Fuji Xerox Co., Ltd. Optical waveguide device and light outputting module
EP1914584A3 (fr) * 2006-10-19 2010-10-20 Samsung Electronics Co., Ltd. Conduit lumineux de type rétro-réflectif, dispositif d'illumination l'incorporant et dispositif de projection comportant le dispositif d'illumination
EP2518534A4 (fr) * 2009-12-21 2017-04-19 Osaka University Materiau reflechissant et structure optique
EP3460544A1 (fr) * 2017-09-25 2019-03-27 EFFECT Photonics B.V. Ensemble photonique intégré et son procédé de fabrication

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3948583A (en) * 1974-12-09 1976-04-06 Bell Telephone Laboratories, Incorporated Isolation of passive devices and integration with active devices in optical waveguiding circuits
DE9007754U1 (de) * 1990-03-01 1995-03-09 Dr. Johannes Heidenhain Gmbh, 83301 Traunreut Optische Vorrichtung
US6214178B1 (en) * 1998-12-22 2001-04-10 Lucent Technologies, Inc. Focused ion beam formation of angled optoelectronic devices
US6023480A (en) * 1999-02-02 2000-02-08 Lucent Technologies Inc. Fast tunable multiwavelength laser with folded imaging arrangement of nonoverlapping focal regions

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1914584A3 (fr) * 2006-10-19 2010-10-20 Samsung Electronics Co., Ltd. Conduit lumineux de type rétro-réflectif, dispositif d'illumination l'incorporant et dispositif de projection comportant le dispositif d'illumination
US7747115B2 (en) * 2007-09-12 2010-06-29 Fuji Xerox Co., Ltd. Optical waveguide device and light outputting module
EP2518534A4 (fr) * 2009-12-21 2017-04-19 Osaka University Materiau reflechissant et structure optique
EP3460544A1 (fr) * 2017-09-25 2019-03-27 EFFECT Photonics B.V. Ensemble photonique intégré et son procédé de fabrication

Also Published As

Publication number Publication date
WO2002097482A3 (fr) 2003-02-20
CA2349014A1 (fr) 2002-11-28
AU2002257465A1 (en) 2002-12-09

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