JP2008151825A - Optical multiplexer/demultiplexer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce time for optical axis alignment, to facilitate assembly, and to contrive reduction in cost and size, in an optical multiplexer/demultiplexer. <P>SOLUTION: The optical multiplexer/demultiplexer 1 includes: a cylindrical split sleeve 2; a first optical fiber assembly 3 having a ferrule 31 for holding optical fibers 32, 33; a second optical fiber assembly 4 having a ferrule 41 for holding an optical fiber 42; and optical components such as a first and a second lens 5, 6 and an optical filter 7, which are provided with a nearly equal outer diameter. The split sleeve 2 is provided with an inner diameter not more than these outer diameters. The lenses 5, 6 and the optical filter 7 are inserted in internal contact with the split sleeve 2, while the ferrules 31, 41 are each inserted in a manner that their outer diameters are in direct contact with the inner diameter of the split sleeve 2. Consequently, this reduces the diameter of the split sleeve 2, enabling optical axes to be aligned by merely inserting each optical component into the split sleeve 2. Thus, the alignment operation is reduced, making reduction in cost and size possible. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical multiplexer / demultiplexer used for multiplexing / demultiplexing in an optical communication system such as optical wavelength division multiplexing transmission.

  In recent years, in the field of optical communication and the like, an optical communication system adopting a wavelength division multiplexing system for increasing transmission capacity has been spreading. In such a wavelength division multiplexing optical communication system, particularly an access optical communication system, different optical signals from a plurality of optical fibers are combined into one optical fiber, or wavelength division multiplexed signals are wavelength-separated. Thus, an optical multiplexer / demultiplexer for demultiplexing into a plurality of optical fibers is used. Such an optical multiplexer / demultiplexer is usually composed of a plurality of optical components such as a lens for converging light and an optical filter for selecting a wavelength in addition to the optical fiber. Further, in an optical multiplexer / demultiplexer, high accuracy is required for alignment of an optical fiber and optical components such as a lens and an optical filter that are optically coupled to the optical fiber in order to reduce transmission loss. For this reason, when assembling these optical components, they are fixed with resin or the like with their optical axes adjusted and aligned. Therefore, in the manufacturing process, alignment takes time, the manufacturing efficiency is lowered, and expensive adjustment equipment is required.

  By the way, as shown in Patent Document 1, a first member including a lens holding an optical signal input port, and a second member including a lens holding an optical signal output port, which are formed of cylindrical members having an equal radius. There is known an optical multiplexer / demultiplexer having a member and a third member for holding an optical filter element, and inserting and fixing the first to third members with their central axes aligned with each other in a split sleeve. However, in this optical multiplexer / demultiplexer, an optical component such as a lens or an optical filter is built in a cylindrical member serving as a special case, and this cylindrical member is inserted into the split sleeve. A cylindrical member is interposed in the optical member, and the optical axis may be shifted between the optical components due to variations in the outer diameter of the cylindrical member, which deteriorates the characteristics of the optical multiplexer / demultiplexer, such as increasing insertion loss. There was a thing. For this reason, it takes time to align the optical axis, reducing the workability of manufacturing, and the diameter of the split sleeve needs to be thickened by the amount of the cylindrical member. It was high.

Moreover, as shown in Patent Document 2, at least a first optical member, a second optical member, and a third optical member are arranged in this order on the optical path of optical communication, and the third optical member is There is known an optical communication module that is joined to a first optical member and in which first to third optical members are inserted into a sleeve having a slit. However, in this optical communication module, the slit of the sleeve is not a complete split sleeve, and the mounting and alignment of optical components in the sleeve are performed using an adjusting arm for each optical component. The alignment work is complicated, time consuming and expensive.
Japanese Patent Laid-Open No. 2004-12588 Japanese Patent Laid-Open No. 2004-219766

  The present invention has been made to solve the above-described problems, and is an optical multiplexer / demultiplexer that reduces the alignment time of optical axis alignment, is easy to assemble, can be reduced in cost, and can be reduced in size. The purpose is to provide.

  In order to achieve the above object, a first aspect of the present invention provides a cylindrical split sleeve having a slit in the outer wall along an axial direction, an optical fiber, and a ferrule that surrounds and holds one end of the optical fiber. A first optical fiber assembly in which the ferrule is inserted into one side of the split sleeve, an optical fiber, and a ferrule that surrounds and holds one end of the optical fiber, A second optical fiber assembly in which the ferrule is inserted into the other side of the split sleeve; and first and second lenses disposed near end faces of the ferrules in the first and second optical fiber assemblies. And an optical filter disposed between the first and second lenses, wherein at least one of the first and second optical fiber assemblies has a plurality of optical fibers, Ferru The first and second lenses and the optical filter have substantially the same outer diameter, and the split sleeve has a diameter equal to or less than the outer diameter of each of the ferrule, the first and second lenses, and the optical filter. The first and second lenses and the filter are abutted and inserted into the split sleeve, and the ferrules of the first and second optical fiber assemblies are arranged on the outer diameter side thereof. It is inserted so as to be in direct contact with the inner diameter side of the split sleeve.

  A second aspect of the present invention is the optical multiplexer / demultiplexer according to the first aspect, wherein cylindrical drum lenses are used for the first and second lenses.

  According to a third aspect of the present invention, in the optical multiplexer / demultiplexer according to the first or second aspect, each space between the first and second lenses and each ferrule of the first and second fiber assemblies. Is filled with an optical adhesive.

  According to a fourth aspect of the present invention, in the optical multiplexer / demultiplexer according to the first or second aspect of the present invention, the non-reflection is performed to suppress the reflection of light on at least the end surfaces of the ferrules and the surfaces of the first and second lenses. It has been coated.

  According to a fifth aspect of the present invention, in the optical multiplexer / demultiplexer according to any one of the first to fourth aspects, the ferrules, the first and second lenses, and the optical filter are inserted. A metal cylinder for storing and fixing the split sleeve therein is further provided.

  According to a sixth aspect of the present invention, in the optical multiplexer / demultiplexer according to the fifth aspect, each optical fiber that goes out of the metal tube from each ferrule housed and fixed in the metal tube is disposed at both ends in the metal tube. The space through which the optical fiber passes is filled with an adhesive and fixed.

  According to a seventh aspect of the present invention, in the optical multiplexer / demultiplexer according to any one of the first to sixth aspects, the optical filter comprises an optical thin film filter formed of a multilayer film made of a thin film. is there.

  According to an eighth aspect of the present invention, in the optical multiplexer / demultiplexer according to any one of the first to seventh aspects, at least one of the first and second lenses is covered with a metal lens barrel. In addition to the lens barrel integrated lens, the split sleeve is a metal split sleeve, and the lens barrel integrated lens is inserted into the metal split sleeve.

  According to the first aspect of the present invention, since there are no conventional intervening members between the split sleeve and each ferrule, the first and second lenses, and each optical component of the optical filter, the size can be reduced. In addition, there is no component variation due to the intervening members, and the optical axes of the optical components can be arranged with high accuracy along the central axis of the split sleeve, and the optical axis shift between the optical components can be suppressed. . Thereby, since the adjustment of the optical axis alignment in the manufacturing process can be simplified, the alignment time can be reduced, and the cost can be reduced without requiring an advanced adjustment facility. In addition, the slit of the split sleeve is used as an adhesive application groove into which the adhesive is poured, and the optical component can be inserted while being viewed from the outside of the split sleeve and positioned in the split sleeve, so that the optical component can be easily fixed in the split sleeve. It can be performed with high accuracy.

  According to the second aspect of the present invention, since the contact surface with the inner surface of the split sleeve is increased as compared with a spherical lens or the like, the lens can be fixed simply and reliably. Further, when the drum lens is inserted into the split sleeve, it does not rotate in the direction of the optical axis as in the case of the ball lens, so that it can be positioned without scratching the light transmitting surface of the lens through which light passes. In addition, since the drum lens is obtained by cylindrical processing of a spherical lens, the diameter can be reduced and the split sleeve diameter can be reduced, so that the whole can be reduced in size and cost.

  According to the invention of claim 3, since the light transmission space between the lens and the ferrule end face is filled with the optical adhesive having a refractive index close to that of the glass material, the optical fiber, the space between the optical fiber and the lens, In addition, since each refractive index of the lens can be substantially matched, reflection of light at the optical fiber end face and the lens end face can be suppressed, deterioration of light transmittance can be reduced, and optical characteristics can be improved.

  According to the invention of claim 4, surface reflection on the ferrule end face and the lens surface can be reduced by the non-reflective coating, so that deterioration of light transmittance can be reduced and optical characteristics can be improved. it can.

  According to the invention of claim 5, since the optical component can be protected against a physical load such as an impact from the outside, fluctuation and deterioration of the optical characteristics can be prevented, and stable characteristics are maintained. be able to.

  According to the sixth aspect of the present invention, since resistance to a tensile load or bending load to the optical fiber from the outside can be increased, it is possible to prevent deterioration of the optical transmission characteristics and to prevent moisture inside the split sleeve. In addition, it is possible to prevent intrusion of harmful gases and the like, protect internal optical components, and maintain stable quality.

  According to the invention of claim 7, the optical filter characteristics can be changed only by changing the thin film specification conditions, and the size of the optical filter is hardly affected. Therefore, the optical filter characteristics are substantially the same for different characteristics of the optical multiplexer / demultiplexer. It can be formed in a unified manner, and the cost can be reduced.

  According to the eighth aspect of the present invention, the lens barrel-integrated lens can be fixed to the split sleeve by metal welding, and the adhesive strength is less deteriorated due to thermal expansion and moisture absorption than the adhesive fixing, thereby improving the reliability. be able to. Moreover, joining by soldering is also possible, and lens fixation can be performed at low cost.

  The optical multiplexer / demultiplexer according to the first embodiment of the present invention will be described below with reference to FIGS. The optical multiplexer / demultiplexer 1 includes a split sleeve 2, a first optical fiber assembly 3, a second optical fiber assembly 4, a first lens 5, a second lens 6, an optical filter 7, and a metal tube 8.

  The split sleeve 2 is formed of a cylindrical tube formed of resin or the like, and a slit 2a is provided on the outer wall along the direction of the central axis X. The inner diameter of the split sleeve 2 has substantially the same outer diameter, the ferrules 31 and 41 of the first optical fiber assembly 3 and the second optical fiber assembly 4, the first lens 5 and the second lens 6, The inner diameter of each of the optical filters 7 is equal to or smaller than the outer diameter. The split sleeve 2 and the ferrules 31 and 41 have a fitting tolerance dimensional relationship in which the ferrules 31 and 41 are press-fitted.

  The first optical fiber assembly 3 includes two optical fibers 32 and 33 and a two-core ferrule 31 that surrounds and holds one end of each of the optical fibers 32 and 33. The ferrule 31 is a split sleeve. 2 is inserted into one side.

  As shown in FIG. 2, the ferrule 31 is formed of a ceramic material having a cylindrical shape and excellent polishing properties, and the fiber insertion holes 31 b and 31 c through which the two optical fibers 32 and 33 are inserted. Each end of the optical fibers 32 and 33 is inserted into the fiber insertion holes 31b and 31c and fixed to the ferrule 31 with an adhesive. At this time, each short surface of one end of the optical fibers 32 and 33 is disposed so as to be flush with the end surface 31a of the ferrule 31, and is fixed to the ferrule 31 with an adhesive in the fiber insertion holes 31b and 31c. The optical fibers 32 and 33 are formed by covering the core wires 32 a and 33 a with the covering portions 32 b and 33 b, and only the core wires 32 a and 33 a are wired in the ferrule 31. The ferrule 31 is inserted and fixed so that the outer diameter side thereof is in direct contact with the inner diameter side of the split sleeve 2. Thereby, the core wires 32 a and 33 a of the optical fibers 32 and 33 are arranged so as to be parallel to the central axis X of the split sleeve 2. The end face 31a has an inclination angle of several degrees with respect to the optical transmission direction (the central axis X direction) of the optical fibers 32 and 33 in order to prevent the reflected light from returning.

  The second optical fiber assembly 4 has basically the same configuration as the first optical fiber assembly 3, and includes a single optical fiber 42 and a ferrule that surrounds and holds one end side of the optical fiber 42. The ferrule 41 is inserted into the other side of the split sleeve 2.

  The ferrule 41 has the same configuration as the ferrule 31, and has a fiber insertion hole 41b (see FIG. 4) into which one optical fiber 42 is inserted, and one end of the optical fiber 42 has a fiber insertion hole. It is inserted into 41b and fixed to the ferrule 41 with an adhesive. At this time, the short surface of one end of the optical fiber 42 is disposed so as to be flush with the end surface 41a of the ferrule 41, and is fixed to the ferrule 41 with an adhesive at the fiber insertion hole 41b. In the ferrule 41, only the core wire 42a of the optical fiber 42 is wired. Here, the ferrule 41 is the same two-core as the ferrule 31 having two fiber insertion holes, and only one fiber insertion hole 41b is used.

  The first lens 5 and the second lens 6 are made of a spherical lens using a glass material or a resin material, and the central axis of the split sleeve 2 is arranged in the vicinity of the end faces 31a and 41a of the ferrules 31 and 41 in the split sleeve 2. It is arranged at a right angle to X. The lenses 5 and 6 are inserted into contact with the split sleeve 2 having an inner diameter equal to or smaller than the outer diameter thereof. Thereby, the optical axes of the lenses 5 and 6 can be arranged so as to coincide with the central axis X of the split sleeve 2. Further, these lenses 5 and 6 are parallel to each other along the central axis X with respect to the light emitted from the optical fibers 32 and 33 on the end face 31 a of the ferrule 31 and the light emitted from the optical fiber 42 on the end face 41 a of the ferrule 41. Focus on light.

  The optical filter 7 is composed of, for example, a disk-shaped thin film filter formed by laminating a plurality of dielectric thin films on a glass substrate by vapor deposition or the like, and has an outer diameter equivalent to that of the lenses 5 and 6. Between the first and second lenses 5 and 6 in the sleeve 2, they are fitted at a right angle to the central axis X of the split sleeve 2. The optical filter 7 selectively transmits or reflects incident light depending on the wavelength. Since the optical filter 7 does not require a large area, it can be formed in a rectangular shape and attached to a disc-shaped transparent substrate or the like.

  The assembly of the optical multiplexer / demultiplexer 1 will be described with reference to FIG. In these assembling, first, the optical filter 7 is fitted and inserted in the vicinity of the center in the longitudinal direction at a right angle to the center axis X of the split sleeve 2, and an adhesive is inserted through the slit 2 a of the split sleeve 2. Secure in the sleeve 2. Next, the first and second lenses 5 and 6 are respectively inserted from both ends of the split sleeve 2 at right angles to the central axis X, fitted into predetermined positions, and inserted in the same manner. 2a is fixed in the split sleeve 2 with an adhesive. At this time, since the outer diameters are adjusted so that the lenses 5 and 6 are fitted in the split sleeve 2, the center axis X of the split sleeve 2 and the optical axes of the lenses 5 and 6 are matched with high accuracy. be able to.

  Next, the ferrules 31, 41 of the first and second optical fiber assemblies 3, 4 are inserted from both ends of the split sleeve 2, fitted into a predetermined position and inserted, and the slits of the split sleeve 2 are inserted. Fix with adhesive from 2a. At this time, by fitting and fixing the ferrules 31 and 41 in the split sleeve 2, the center axis X of the split sleeve 2 and the center axes of the ferrules 31 and 41 can be aligned with extremely high accuracy. The fibers 32, 33 and 42 can be arranged parallel to the central axis X.

  Further, the entire split sleeve 2 is inserted into a metal cylinder 8 having an inner diameter larger than the outer diameter of the split sleeve 2 and fixed with an adhesive. Thereby, each optical component in the split sleeve 2 can be protected from an external load, and the reliability can be further improved. Further, the optical fibers 32, 33, and 42 that go out of the metal tube 8 from the ferrules 31 and 41 that are housed and fixed in the metal tube 8 are connected to the optical fibers 32, 33, and the optical fiber 42 at both ends in the metal tube 8. An adhesive 9 for fixing the optical fiber is filled in the space through which the optical fiber passes, and these are fixed. As a result, the optical fibers 32, 33 and 42 can be protected from the influence of the physical external load, and the resistance to the tensile load and the bending load to the optical fiber from the outside can be strengthened, and the optical transmission characteristic is deteriorated. Can be prevented. Moreover, the penetration | invasion of the water | moisture content, harmful gas, etc. to the split sleeve 2 inside can be prevented, an internal optical component can be protected and the stable quality can be maintained.

  The optical multiplexing / demultiplexing operation of the optical multiplexer / demultiplexer 1 will be described with reference to FIG. Wavelengths λ1 and λ2 from the optical fiber 32 of the optical fiber assembly 3 on the input side are radiated from the front end surface of the optical fiber 32 on the end surface 31a toward the first lens 5 through the optical fiber 32 in the ferrule 31. . Here, the optical fibers 32 and 33 are arranged in parallel at positions separated from the optical axis by D and −D, respectively. The light emitted from the optical fiber 32 enters the lens 5 that forms an angle θ with the optical axis and faces the end surface 31 a, is refracted along the optical axis by the lens 5, and enters the optical filter 7. The light incident on the optical filter 7 passes only λ1 due to the transmission characteristics of the optical filter 7, and λ2 is reflected. The reflected λ2 passes through the lens 5 again to form an angle −θ with the central axis, passes through the end face of the optical fiber 33 on the end face 31a, and is reflected as a reflected wave λ2 from the optical fiber 33 of the optical fiber assembly 3. It is taken out. Further, the transmitted wave λ1 transmitted through the optical filter 7 is inclined by an angle θ with respect to the optical axis, enters the second lens 6 and is refracted along the optical axis, and −D from the optical axis of the end surface 41a of the ferrule 41. The light enters the remote optical fiber 42 and is taken out from the optical fiber assembly 4. When the wavelengths λ2 and λ1 are input from the optical fiber 33 of the optical fiber assembly 3 and the optical fiber 42 of the optical fiber assembly 4, respectively, the wavelengths λ1 and λ2 are combined and extracted from the optical fiber 32 of the optical fiber assembly 3. Can do.

  In the optical multiplexer / demultiplexer 1 having the above configuration, each of the optical fibers 32, 33, and 42 has a diameter of about 10 μm, and emits or enters light from each end face. Accordingly, since the arrangement of the ferrules 31 and 41 directly affects the optical path position of light, the strictest positional accuracy is required, so that the optical axis needs to be adjusted strictly. On the other hand, in the lenses 5 and 6, since the light expanded by the lens itself has a diameter of about 0.4 mm, for example, the allowable range of position error set in comparison with the ferrules 31 and 41 is large. Further, since the optical filter 7 is also formed in a plane by the optical thin film filter, the incident surface is easy to match and is thin, so that the allowable range of the position error set in comparison with the ferrules 31 and 41 is large. Therefore, in the optical multiplexer / demultiplexer 1, optical components of the ferrules 31 and 41, the first and second lenses 5 and 6 and the optical filter 7 having substantially the same outer diameter are divided into inner diameters equal to or smaller than these outer diameters. The ferrules 31 and 41 are inserted in contact with the sleeve 2 so that the outer diameter side of the ferrules 31 and 41 is in direct contact with the inner diameter side of the split sleeve 2. Thereby, in the insertion between these optical components (lenses 5 and 6 and optical filter 7, each ferrule 31,41) and the split sleeve, there is no split sleeve 2 and no components intervening between the respective optical components, and the size is small. In addition, since each optical component abuts and is fixed to the split sleeve 2, the influence of the dimensional variation of the intervening components can be eliminated. It can be accurately arranged at a predetermined position.

  As described above, according to the optical multiplexer / demultiplexer 1 of the first embodiment, the ferrules 31 and 41, the first and second lenses 5 and 6, and the light in the split sleeve 2 along the central axis X thereof. Since the optical axes of the optical parts of the filter 7 can be arranged with high accuracy, the optical axis shift between the optical parts can be reduced. As a result, the adjustment of the optical axis alignment in the manufacturing process can be simplified, so that the alignment time can be reduced or the alignment operation can be omitted, and the cost can be reduced without the need for advanced adjustment equipment as well as downsizing. it can. Moreover, since the slit 2a of the split sleeve 2 can be used as an adhesive application groove into which an adhesive is poured, an optical component can be inserted while looking through the slit 2a from the outside of the split sleeve 2. As a result, the optical components in the split sleeve 2 can be easily positioned and can be fixed with high accuracy.

  FIG. 5 shows a modification of the first embodiment. Each of the ferrules 31 and 41 of the first and second optical fiber assemblies 3 and 4 and each of the first and second lenses 5 and 6 are shown in FIG. The space is filled with an optical adhesive 10 having a refractive index close to that of a glass material. The optical adhesive 10 has a refractive index close to that of the optical fibers 32, 33, 42 and the lenses 5, 6, so that the optical adhesive 10 has the optical fibers 32, 33 on the end faces 31 a, 41 a and the lenses 5, 6. Can be optically coupled with substantially the same medium. Accordingly, in the optical transmission path from the end faces 31a, 41a of the ferrules 31, 41 to the lenses 5, 6, the refractive indexes of the optical fibers 32, 33, 42, the optical adhesive 10, and the lenses 5, 6 are made substantially equal. Can be consistent. Thereby, reflection of light on the lens surface and the end face of the optical fiber can be suppressed, deterioration of light transmittance can be reduced, and optical characteristics can be improved. Further, when the refractive indexes of the optical fibers 32, 33 and 42 and the lenses 5 and 6 are n1 and n2, the refractive index n3 of the optical adhesive 10 is a refractive index between n1 and n2, for example, n3 = (n1 + n2) By making it / 2, consistency can be improved.

  FIG. 6 shows another modified example of the first embodiment. The antireflection coating agent 31d for suppressing the reflection of light is applied to the end surfaces 31a and 41a of the ferrules 31 and 41 and the surfaces of the lenses 5 and 6, respectively. 41c and 5a, 6a are applied. Usually, a glass, a crystal material, a plastic, or the like generates reflected light of several percent with respect to incident light on its surface. On the other hand, since each non-reflective coating agent 31d, 41c, 5a, 6a is coated, each end surface 31a, 41a of the ferrules 31, 41 and each reflection on the lens surface in the lenses 5, 6 can be reduced. Deterioration of light transmittance can be reduced, and optical characteristics can be improved.

  Next, an optical multiplexer / demultiplexer 1 according to a second embodiment of the present invention will be described with reference to FIG. In the optical multiplexer / demultiplexer 1 of the present embodiment, the first and second lenses 50 and 60 are formed not by spherical lenses but by cylindrical drum lenses. These drum lenses are obtained by cylindrical processing of spherical lenses.

  As described above, according to the optical multiplexer / demultiplexer 1 according to the second embodiment, the first and second lenses 50 and 60 are cylindrical drum lenses, so that the drum lens is inserted into the split sleeve 2. At this time, unlike the spherical lens, there is no possibility of rotating in the direction of the central axis X, so that it can be arranged at a predetermined position without damaging the light transmitting surfaces of the first and second lenses 50 and 60 through which light passes. Further, the first and second lenses 50 and 60 can be fixed easily and stably by increasing the contact surface with the inner surface of the split sleeve 2 on the side surface of the first lens 50 and the second lens 60 compared to a spherical lens or the like. Can do. In addition, since the first and second lenses 50 and 60 are obtained by cylindrical processing for cutting a spherical lens, the diameter thereof can be made smaller than the diameter of the spherical lens, and thereby the diameter of the split sleeve 2 can be reduced. The whole can be reduced in size and cost.

  Next, an optical multiplexer / demultiplexer 1 according to a third embodiment of the present invention will be described with reference to FIGS. 8 (a) and 8 (b). In the optical multiplexer / demultiplexer 1 of the present embodiment, as shown in FIG. 8B, the first lens 51 is formed as a lens barrel-integrated lens in which a spherical lens 51a is covered with a metal lens barrel 51b. The Similarly, the second lens 61 is also formed as a lens barrel-integrated lens in which the spherical lens 61a is covered with a metal lens barrel 61b. The optical multiplexer / demultiplexer 1 of this embodiment is configured by using the split sleeve 2 as a metal split sleeve 20 and inserting these lens barrel integrated lenses into the metal split sleeve 20.

  Thus, according to the optical multiplexer / demultiplexer 1 according to the third embodiment, the first and second lenses 51 and 61 can be fixed to the metal split sleeve 20 by metal welding. Compared to the above, there is little deterioration of adhesive strength due to thermal expansion and moisture absorption, and the reliability of bonding can be improved. Moreover, joining by soldering is also possible, and lens fixation can be performed at low cost. Further, if a drum lens is used for the spherical lenses 51a and 61a of the first and second lenses 51 and 61, the lens diameter can be reduced, so that the lens barrel diameter can be reduced. Thereby, the diameter of the first and second lenses 51 and 61 and the diameter of the ferrules 31 and 41 can be formed, and the optical multiplexer / demultiplexer 1 having a strong lens joint strength can be configured without increasing the overall size. can do. Note that the optical filter 7 can be formed in the same manner.

  According to the optical multiplexer / demultiplexer 1 of the various embodiments described above, the alignment operation for aligning the optical axes of the optical components in the manufacturing process is facilitated, and an expensive and sophisticated facility for alignment is not required. Improvement, cost reduction, and downsizing can be achieved.

  In addition, this invention is not limited to the structure of the said embodiment, A various deformation | transformation is possible suitably in the range which does not change the meaning of invention. For example, a plurality of optical fibers of the first and second fiber assemblies can be provided to provide a multi-channel multiplexing / demultiplexing function.

1 is a side sectional view of an optical multiplexer / demultiplexer according to a first embodiment of the present invention. The elements on larger scale of an optical multiplexer / demultiplexer same as the above. The exploded perspective view of an optical multiplexer / demultiplexer same as the above. The figure explaining the relationship between the incident light, reflected light, and transmitted light of an optical multiplexer / demultiplexer same as the above. The fragmentary sectional side view of the modification of the said embodiment. The fragmentary sectional side view of the other modification of the said embodiment. The sectional side view of the optical multiplexer / demultiplexer which concerns on the 2nd Embodiment of this invention. (A) is a sectional side view of the optical multiplexer / demultiplexer according to the third embodiment of the present invention, and (b) is an enlarged view of the lens of the optical multiplexer / demultiplexer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical multiplexer / demultiplexer 20 Split sleeve 2a Slit 3 1st optical fiber assembly 4 2nd optical fiber assembly 5, 50, 51 1st lens 5a, 6a, 31d, 41c Antireflective coating agent (antireflective coating)
6, 60, 61 Second lens 7 Optical filter, optical thin film filter 8 Metal tube 9 Adhesive 10 Optical adhesive 20 Metal split sleeve 31, 41 Ferrule 31a, 41a End face

Claims (8)

A cylindrical split sleeve provided with slits in the outer wall along the axial direction;
A first optical fiber assembly having an optical fiber and a ferrule that surrounds and holds one end of the optical fiber, the ferrule being inserted into one side of the split sleeve;
A second optical fiber assembly having an optical fiber and a ferrule that surrounds and holds one end of the optical fiber, the ferrule being inserted into the other side of the split sleeve;
First and second lenses disposed near end faces of the ferrules in the first and second optical fiber assemblies;
An optical filter disposed between the first and second lenses;
With
At least one of the first and second optical fiber assemblies has a plurality of optical fibers,
Each of the ferrules, the first and second lenses, and the optical filter have substantially the same outer diameter,
The split sleeve has an inner diameter equal to or less than an outer diameter of each of the ferrule, the first and second lenses, and the optical filter,
The first and second lenses and the filter are inserted into contact with the split sleeve, and the ferrules of the first and second optical fiber assemblies are arranged on the outer diameter side of the split sleeve. An optical multiplexer / demultiplexer, wherein the optical multiplexer / demultiplexer is inserted so as to be in direct contact with the side.   The optical multiplexer / demultiplexer according to claim 1, wherein cylindrical drum lenses are used for the first and second lenses.   3. The optical coupling according to claim 1, wherein spaces between the first and second lenses and the ferrules of the first and second fiber assemblies are filled with an optical adhesive. Duplexer.   3. The optical multiplexer / demultiplexer according to claim 1, wherein an antireflective coating that suppresses reflection of light is applied to at least an end face of each ferrule and each surface of the first and second lenses. .   The metal tube which accommodates and fixes the said split sleeve which inserted each said ferrule, the said 1st and 2nd lens, and the said optical filter in an inside is further provided. The optical multiplexer / demultiplexer as described in any one of Claims.   Each optical fiber that goes out of the metal cylinder from each of the ferrules housed and fixed in the metal cylinder is fixed by filling the space through which the optical fiber passes at both ends in the metal cylinder. The optical multiplexer / demultiplexer according to claim 5.   The optical multiplexer / demultiplexer according to any one of claims 1 to 6, wherein the optical filter includes an optical thin film filter formed of a multilayer film made of a thin film.   At least one of the first and second lenses is a lens barrel integrated lens covered with a metal lens barrel, the split sleeve is a metal split sleeve, and the lens barrel integrated lens is the metal lens. The optical multiplexer / demultiplexer according to any one of claims 1 to 7, wherein the optical multiplexer / demultiplexer is inserted into a split sleeve.

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