JP2010032584A - Optical waveguide, optical module, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide having high mass productivity and a branch, and an optical module using the optical waveguide. <P>SOLUTION: A tool 100 composed of two optical fibers 102, 103 which are made to cross each other and coalesce with each other and a connector 150 which holds the optical fibers 102, 103; a tool 200 composed of an optical fiber 201 and a connector 250 which holds the optical fiber 201; and a tool 300 composed of an optical fiber 301 and a connector 350 which holds the optical fiber 301, are mounted on a case 50 (shown in the figure). The case 50 is filled with a liquefied photocurable resin 420, and curing light is introduced from the optical fibers 102 and 201, therefore the core 412 of a trunk part is formed. The case 50 is filled with a liquefied photocurable resin 430, and curing light is introduced from the optical fibers 103 and 301, thus the core 413 of a branch part is formed. When a clad 45 is formed, and an optical fiber 10, a light receiving element 20 and a light emitting element 30 are mounted, the optical module 1000 is manufactured. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical module having a branch core.

The present inventors have developed, filed, and patented many self-forming optical waveguides (Patent Documents 1 to 4 and others). Here, the self-forming optical waveguide utilizes the fact that the resin is cured in a self-condensing manner by irradiating a liquid photocurable resin with light having a wavelength capable of curing the resin from an optical fiber, for example. An optical waveguide using an axial core.
It is well known that an optical waveguide having a branch whose core forms, for example, a Y-shape in an optical fiber communication or an optical fiber sensor can be used as an optical coupler for coupling a plurality of lights to an optical fiber or branching in reverse. It has been. An element (optical module) that is used in combination with an optical waveguide having this branch and a light emitting / receiving element is also known. Patent documents 5 to 11 and non-patent document 1 are cited as publications of these conventional examples.
Japanese Patent No. 3444352 Japanese Patent No. 3841656 JP 2004-149579 A JP 2007-72129 A JP 62-291604 A JP-A-8-334644 Japanese Patent Laid-Open No. 9-318829 JP-A-9-101428 JP 2000-304954 A JP 205-84347 A JP-A-11-183743 S. Shoji and S. Kawata, "Optically-induced growth of fiber patterns into a photopolymerizable resin," Applied Physics Letters, vol. 75, no. 5, pp. 737-739, 1999

Patent Document 5 discloses an optical branching coupler. An optical waveguide having a branch in which a single mode waveguide is connected to a side surface of a clad of a multimode waveguide is disclosed. By the action of the clad, the propagation light of the multimode waveguide is prevented from being coupled to the single mode optical waveguide.
Patent Document 6 discloses a plastic optical branching / coupling device and a manufacturing method thereof. An optical waveguide having a plastic branch using a molding technique using a mold is disclosed.
Patent Document 7 discloses an optical branching device and a manufacturing method thereof. Optical waveguides with plastic branches by photolithography and etching techniques are disclosed.
Patent Document 8 discloses an optical branching coupler. An optical branching coupler in which different numerical apertures are fused to each other is disclosed.
Patent Document 9 discloses a branching ratio adjusting method and a manufacturing method of an optical waveguide having a branch. A means for adjusting a branching ratio by irradiating light to a branching part and adjusting a refractive index after producing an optical waveguide having a branching is disclosed.
Patent Document 10 discloses an optical waveguide having a branch. There has been disclosed a method of providing a low-loss branching waveguide by forming a part of a coupling portion of an optical waveguide having a branch into a tapered structure.
Patent Document 11 discloses an optical branching coupler and an optical transmission device using the same. An optical waveguide having a branch, in which the optical coupling efficiency with a light receiving element is improved by making the optical waveguide for reception down-tapered, and a method for manufacturing the optical waveguide are disclosed.

For example, the following two examples of the branching waveguide manufacturing technique using a self-forming optical waveguide are given.
Patent Document 4 is based on the inventors of the present application, and discloses a method of manufacturing an optical waveguide having a branch by controlling the transmission mode of a single mode fiber.
Non-Patent Document 1 reports that an optical waveguide having a branch can be manufactured by irradiation with intersecting light beams.

Various techniques as described above have been proposed for an optical module using a light receiving and emitting element in combination with a branched optical waveguide. As a method for producing a branched optical waveguide, resin molding, reactive ion etching, wet etching, fiber fusion, and the like are considered, but in order to promote cost reduction of optical transmission / reception devices, mass production is required. There is a need for further improvement.
In addition, in order to improve optical crosstalk, the refractive index structure of the optical waveguide having a branch is used, for example, when the refractive index of the core on the branch side with a small diameter is made smaller than the refractive index of the core on the trunk side with a large diameter. It is difficult to produce with high productivity by conventional methods.
Also, in order to fabricate a branched optical waveguide using self-forming optical waveguide technology, the core often intersects to form an X shape and a Y shape when fabricated by crossed light beam irradiation. It ’s difficult. Further, in the method of manufacturing an optical waveguide having a branch by inserting an optical filter into the waveguide path and dividing the core-forming light in the middle, an optical filter is necessary, which causes a problem of increasing costs.

  The present invention provides an optical waveguide having a branch having a structure for reducing optical crosstalk in optical transmission / reception, a method for manufacturing the same, and a bidirectional optical communication module using the optical waveguide having the branch. The purpose is to provide.

The invention according to claim 1 is an optical waveguide in which the first, second and third light input / output ends, each of which is a circular region, are connected by a branching core,
The branch core has a columnar trunk core connecting the first and second light input / output ends, a diameter smaller than the trunk core, and a refractive index smaller than the refractive index of the trunk core, A cylindrical branch core connecting the first and third light input / output ends;
The branching of the trunk core and the branch core starts from the first light input / output end. When the side surface of the branch core extends in the direction of the first light input / output end, the first light input It reaches the inside of a circular area at the output end.
The invention according to claim 2 is characterized in that the core of the trunk portion and the core of the branch portion of the branch core are each made of a cured product of a photocurable resin.
According to a third aspect of the present invention, in the optical waveguide according to the first or second aspect, an optical fiber is provided at the first light input / output end, a light receiving element is provided at the second light input / output end, and a third light is provided. An optical module characterized in that a light emitting element is connected to an input / output terminal.

The invention according to claim 4 is a method of manufacturing an optical waveguide in which the first, second and third optical input / output ends, each of which is a circular region, and connected by a branch core,
Using photo-curing resin,
Two optical waveguides capable of irradiating light having a wavelength capable of curing the photocurable resin in the second light input / output end direction and the third light input / output end direction are combined with the first light input / output end. Connect the jig
Irradiation of the curing wavelength light from the first light input / output end to the second light input / output end direction and the third light input / output end direction causes the first light input / output end and the second light input to enter. A trunk core connecting the output end, a first optical input / output end and a third optical input / output end are connected to form a branch core narrower than the trunk core. .

The invention according to claim 5 irradiates the curing wavelength light in the direction from the first light input / output end to the second light input / output end, and provides the first light input / output end and the second light input / output end. After forming the core of the trunk portion connecting the first light input / output end and the third light input / output end, the curing wavelength light is irradiated from the first light input / output end to the third light input / output end and the third light. A branch core connecting the input / output terminals is formed.
The invention according to claim 6 irradiates the curing wavelength light from the first light input / output end in the direction of the second light input / output end, and provides the first light input / output end and the second light input / output end. The photo-curing resin for the trunk when forming the core of the trunk for connecting the first and the first light input and output light is irradiated from the first light input / output end toward the third light input / output end. The branch portion photo-curing resin is different when forming the core of the branch portion connecting the output end and the third light input / output end.
The invention according to claim 7 is characterized in that the refractive index of the cured product of the photocurable resin for the branch portion is smaller than the refractive index of the cured product of the photocurable resin for the trunk portion.
According to an eighth aspect of the present invention, the branch photocurable resin has a refractive index smaller than that of the first photocurable resin and the first photocurable resin, a maximum curable wavelength is small, and 1 photocurable resin is a mixture with a second photocurable resin having a different curing mechanism,
By irradiating light of a wavelength that can cure the first photocurable resin but not the second photocurable resin from the first light input / output end toward the third light input / output end, After forming the core of the branch part which connects the 1st light input / output end and the 3rd light input / output end which consist of hardened | cured material of 1st photocurable resin,
All of the remaining photocurable resin for the branch part is cured to form a trunk core and a clad for the branch core.

  The invention according to claim 9 is introduced from the first optical input / output end when the core of the trunk portion is formed in the optical waveguide manufacturing method according to any one of claims 4 to 8. When the curing wavelength light is also introduced from the second light input / output end and the branch core is formed, the curing wavelength light introduced from the first light input / output end is also input from the third light input / output end. It is characterized by introducing.

  According to a tenth aspect of the present invention, after an optical waveguide is obtained by the method for manufacturing an optical waveguide according to any one of the fourth to ninth aspects, an optical fiber is provided at the first light input / output end. A light receiving element is connected to the light input / output end of the light source, and a light emitting element is connected to the third light input / output end of the optical module manufacturing method.

According to the first aspect of the present invention, the first, second and third light input / output ends, each of which is a circular region, are connected by the branch core, and the first and second light input / output ends are connected to each other. The cylindrical branch core connecting the first and third light input / output ends has a lower refractive index and a smaller diameter than the connecting cylindrical trunk core. Therefore, the trunk core is used as a core for guiding light from an external optical waveguide such as an optical fiber to the light receiving element, and the branch core is used as a core for guiding light from the light emitting element to an external optical waveguide such as an optical fiber. Is preferred. That is, it is difficult for light from the outside to enter the branch core due to the difference in refractive index, and since the diameter is thin, the total loss can be reduced. On the other hand, the branching of the trunk core and the branch core starts from the first light input / output end. When the side surface of the branch core extends in the first light input / output end direction, Since it reaches the inside of the circular region at the light input / output end, it is possible to reliably guide all the light from the light emitting element to an external optical waveguide such as an optical fiber. At this time, since transmission / reflection by the optical filter is not performed, transmission loss can be suppressed (claims 1 and 3).
Each of the trunk core and the branch core of the branch core can be easily formed by curing a photocurable resin (claims 2 and 4 to 10).

  According to the fourth aspect of the present invention, the second light input / output terminal is formed by connecting a jig in which two optical waveguides are combined to the first light input / output terminal using a liquid photocurable resin. It becomes possible to irradiate light having a wavelength capable of curing the photocurable resin in the direction and the third light input / output end direction. Thereby, an optical waveguide having a branch can be easily produced. In addition, in order to hold | maintain liquid photocurable resin, it is not limited to using a transparent housing | casing, for example. As will be described in the following examples, for example, by connecting an optical fiber or the like for irradiating curing light with a connector or the like, a hole can be formed in an optical fiber connecting portion so that a region capable of holding a liquid material is formed for the first time. The housing | casing which has may be sufficient. In this case, the casing can be formed of an opaque resin or ceramic if it has a hole in a portion where an optical fiber or a light emitting / receiving element is attached.

  For example, when forming an optical waveguide having a branch by irradiating light from two optical fibers installed facing each other so that the optical axes intersect, as in the conventional self-forming optical waveguide, For example, even when a T-shaped branch is desired, it may be formed in an X shape. On the other hand, according to the present invention, the branch point is the first light input / output end, and the core of the optical waveguide (branch core) can be formed in a V shape, so that the branch core of a desired angle can be formed reliably.

According to the fifth aspect of the present invention, since the trunk core is formed after the trunk core is formed, the trunk core can be corrected or washed before the branch core is formed, for example. . Further, since the two cores are not formed at the same time, they can be formed under optimum conditions and growth rates, respectively.
According to the invention of claim 6, the refractive index of the core of the trunk portion and the core of the branch portion can be made different. For example, as in the invention according to claim 7, a branch core having a refractive index smaller than that of the trunk core can be formed.
According to the invention according to claim 8, after forming the core of the branch portion with a small diameter, the clad portion having a low refractive index can be formed without removing the uncured liquid photocurable resin and adding the clad material. Can be formed. Thereby, damage of the core at the time of resin replacement can be avoided. The invention according to claim 8 is a technique described in Patent Documents 1 and 2.
According to the ninth aspect of the present invention, since the core formation is performed from both directions, the formation time can be shortened for both the trunk core and the branch core. Further, since the core starts to be formed from the three light input / output ends, the cores in the vicinity of at least the three light input / output ends can form the positions and diameters as designed. Even if the optical axis is slightly deviated, the united portion of the cylindrical core is formed as a smooth columnar object due to the so-called optical solder effect.
The optical module according to claim 3 can be formed, for example, by the manufacturing method according to claim 10.

  Two optical waveguides that can irradiate light having a wavelength capable of curing the photocurable resin in the second light input / output end direction and the third light input / output end direction, used for the first light input / output end. The united jig can be easily manufactured with reference to the attached drawings. If necessary, the relationship between the refractive index of the cured / uncured photocurable resin and the refractive index of the core of the jig may be taken into consideration when designing the irradiation direction.

  As the light emitting element, a light source with high light directivity (light emission angle is narrow) such as VCSEL (surface emitting laser) is preferable. Thereby, it is possible to introduce light into the branch core having a small diameter. The same applies to irradiation with curing light.

In the practice of the present invention, any material may be used as the housing material for holding the liquid photocurable resin. Preferably, engineering plastics can be used.
The manufacturing method of the self-forming optical waveguide according to the present invention may use any technique described in Patent Documents 1 to 4, and does not exclude any known technique. In addition, any material described in Patent Document 3 may be used as the photocurable resin, and any known material is not excluded. The photocurable resin described in Patent Document 3 is as follows.

When a structural unit containing at least one aromatic ring such as a phenyl group consists of a high refractive index and an aliphatic group only, the refractive index is low. In order to lower the refractive index, a part of hydrogen in the structural unit may be substituted with fluorine.
Aliphatic ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, neopentyl glycol, 1,3-propanediol, 1,4-butanediol And polyhydric alcohols such as 1,5-pentanediol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, and dipentaerythritol.
Examples of the aromatic group include various phenol compounds such as bisphenol A, bisphenol S, bisphenol Z, bisphenol F, novolak, o-cresol novolak, p-cresol novolak, and p-alkylphenol novolak.
The following functional groups or the like are added as reactive groups to a relatively low molecular (molecular weight of about 3000 or less) skeleton having the structure of an oligomer (polyether) of these, or one or more polyhydric alcohols arbitrarily selected from these. The introduced one can be used.
[Radical polymerizable material]
As the radically polymerizable material, a photopolymerizable monomer and / or oligomer having one or more, preferably two or more ethylenically unsaturated reactive groups such as an acryloyl group capable of radical polymerization in a structural unit can be used. Examples of those having an ethylenically unsaturated reactive group include conjugate acid esters such as (meth) acrylic acid esters, itaconic acid esters, and maleic acid esters.
[Cationically polymerizable material]
Examples of the cationic polymerizable material include photopolymerizable monomers and / or oligomers having one or more, preferably two or more reactive ether structures such as an oxirane ring (epoxide) or an oxetane ring capable of cationic polymerization in a structural unit. Can be used. Examples of the oxirane ring (epoxide) include an oxiranyl group and a 3,4-epoxycyclohexyl group. The oxetane ring is a 4-membered ether.

[Radical polymerization initiator]
The radical polymerization initiator is a compound that is activated by light and initiates a polymerization reaction of a radical polymerizable material composed of a radical polymerizable monomer and / or oligomer. Specific examples include benzoins such as benzoin, benzoin methyl ether and benzoin propyl ether, acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, Acetophenones such as 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropan-1-one and N, N-dimethylaminoacetophenone, 2-methylanthraquinone, 1- Anthraquinones such as chloroanthraquinone and 2-amylanthraquinone, thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,4-diisopropylthioxanthone, acetophenone dimethyl ketal and benzyldimethyl ketal Ketter Benzophenones, such as benzophenone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone and 4-benzoyl-4'-methyldiphenyl sulfide, and 2,4,6-trimethyl Examples include benzoyldiphenylphosphine oxide. In addition, a radical polymerization initiator may be used independently, or may use 2 or more types together, and is not limited to these.
(Cationic polymerization initiator)
The cationic polymerization initiator is a compound that is activated by light and initiates a polymerization reaction of a cationic polymerizable material composed of a cationic polymerizable monomer and / or oligomer. Specific examples include diazonium salts, iodonium salts, sulfonium salts, selenium salts, pyridinium salts, ferrocenium salts, phosphonium salts, and thiopyrinium salts, but diphenyliodonium, ditolyliodonium, phenyl ( Aromatic iodonium salts such as p-anisyl) iodonium, bis (pt-butylphenyl) iodonium, bis (p-chlorophenyl) iodonium, diphenylsulfonium, ditolylsulfonium, phenyl (p-anisyl) sulfonium, bis (pt-butylphenyl) ) Preferable are onium salt photopolymerization initiators such as aromatic sulfonium salts such as sulfonium and bis (p-chlorophenyl) sulfonium. When using an onium salt photoinitiator such as aromatic iodonium salts and aromatic sulfonium salts, as the anion _{^{BF 4 -, AsF 6 -,}} SbF 6 -, PF 6 -, B (C 6 F 5) 4 - Etc. In addition, a cationic polymerization initiator may be used individually or may use 2 or more types together, and is not limited to these.

  A release agent or a release agent may be applied to the surface of the jig used for photocuring. An appropriate one may be selected in consideration of the relationship between the photocurable resin, the connector, and the optical fiber. For example, a coating agent made of a fluororesin (such as one having a perfluoroalkyl group), particularly a fully fluorinated polymer such as Teflon (registered trademark) may be applied. Thereby, scattering due to roughness of the end surfaces of the core and the clad facing the light emitting / receiving element is reduced.

  FIG. A is a cross-sectional view showing a configuration of an optical module 1000 according to a specific embodiment of the present invention. The optical module 1000 has a V-shaped branch core composed of a trunk core 412 and a branch core 413 and a clad 45 inside the casing 50, and the optical fiber 10 is connected using a connector 15. 20 and the light emitting element 30 are attached. The optical axis (center axis) of the optical fiber 10 substantially coincides with the optical axis (center axis) of the core 412 of the trunk, and the light receiving center of the light receiving element 20 is positioned on the extension. The light emission center of the light emitting element 30 is located on one extension of the optical axis (center axis) of the branch core 413, and the core of the optical fiber 10 is located on the other extension.

  FIG. As shown in A, light emitted from the light emitting element 30 is guided to the optical fiber 10 via the core 413 of the branch part (solid arrow) and sent out to the external device. On the other hand, light from the external device is guided from the optical fiber 10 to the light receiving element 20 through the core 412 of the trunk (broken arrow).

  FIG. B is shown in FIG. It is sectional drawing which shows an example of the manufacturing method of the optical module 1000 of A. FIG. B uses a jig 100 comprising two optical fibers 102 and 103 crossed together and a connector 150 for holding the optical fibers 102 and 103, and a light receiving element 20 and a light emitting element 30 are attached in advance to form a core 412 and a branch part. The case where the core 413 and the clad 45 are formed is shown. The optical axis (center axis) of the optical fiber 102 substantially coincides with the optical axis (center axis) of the trunk core 412. If the refractive indexes of the branch core 413, trunk core 412, optical fiber 102 core, and optical fiber 103 core all match, the optical axis (center axis) of the branch core 413 is the optical fiber 103. Coincides with the optical axis (center axis). If some of these four refractive indices are different, the two optical axes make an angle accordingly.

  FIG. C is the same as FIG. FIG. 6 is a cross-sectional view showing a configuration of a branched optical waveguide 1100 in which an optical fiber 10, a connector 15, a light receiving element 20, and a light emitting element 30 are removed from an A optical module 1000. Both ends of the trunk core 412 are a first light input / output end 10 c to which the optical fiber 10 is connected and a second light input / output end 20 c to which the light receiving element 20 is connected. One end of the branch core 413 is a third light input / output end 30 c to which the light emitting element 30 is connected. FIG. An optical waveguide 1100 having C branches is shown in FIG. As shown in B, after the light receiving element 20 and the light emitting element 30 are attached, a branched core is formed from the photocurable resin, and as shown in the process diagram of FIG. A branched core can also be formed from a functional resin.

FIG. A to FIG. G is a process diagram illustrating another method for manufacturing the optical module 1000. FIG.
First, a jig 100 including two optical fibers 102 and 103 and a connector 150 for holding the optical fibers 102 and 103 which are cross-coupled to the casing 50, a jig 200 including an optical fiber 201 and a connector 250 for holding the optical fiber 301, and an optical fiber 301. And the jig | tool 300 which consists of the connector 350 holding it is attached. The jigs 100, 200, and 300 are respectively shown in FIG. In the optical module 1000 indicated by A, the optical fiber 10 and the connector 150, the light receiving element 20, and the light emitting element 30 are attached at positions to be attached. The holes are closed by the jigs 100, 200, and 300, and the interior 50v of the housing 50 becomes an area capable of holding the liquid material (FIG. 2.A).

FIG. Like B, the case 50 is filled with a liquid photo-curable resin 420 for forming the core 412 of the trunk.
FIG. As in C, when light having a wavelength capable of curing the liquid photocurable resin 420 is introduced from the optical fibers 102 and 201 whose optical axes coincide with each other, an axial core grows, for example, near the center. Together, a core core 412 is formed.
FIG. As in D, the uncured photo-curing resin 420 is removed, and the housing 50 is filled with a liquid photo-curing resin 430 to form the branch core 413 and the clad 45 after washing, for example. The The liquid photocurable resin 430 has a refractive index smaller than that of the first photocurable resin and the first photocurable resin, a maximum curable wavelength is small, and the first photocurable resin. It is a mixture with a second photocurable resin having a different curing mechanism. For example, an acrylic uncured resin is used as the first photocurable resin, and an epoxy uncured resin is used as the second photocurable resin. A cured product having a refractive index lower than that of the trunk core 412 is selected as the first photocurable resin.

  FIG. As in E, the first photocurable resin of the liquid photocurable resin 430 can be cured from the optical fibers 103 and 301 whose optical axes coincide with each other in consideration of the refractive index. When light having a wavelength that does not cure the photo-curable resin is introduced, an axial core mainly composed of a cured product of the first photo-curable resin grows. Is formed. At this time, it is assumed that all of the curing light from the optical fibers 103 and 301 passes through a circular region where the core 412 of the trunk and the optical fiber 102 are in contact with each other and does not leak in the other direction.

  FIG. Like F, when the first photocurable resin and the second photocurable resin are cured together by irradiating the entire uncured liquid photocurable resin 430 with, for example, ultraviolet rays from the upper surface, A clad 45 made of a mixed cured product having a lower refractive index than that of the branch core 413 is formed.

  After that, the optical module 1000 can be manufactured by removing the jigs 100, 200, and 300 and attaching the optical fiber 10, the connector 150, the light receiving element 20, and the light emitting element 30 (FIG. 2.G).

When two photo-curing resins having different curing mechanisms are not used as the liquid photo-curing resin 430, FIG. After forming the branch core 413 as in E, the uncured photocurable resin 430 may be removed and filled with a clad material.
In addition, FIG. A to FIG. In G, when the core is self-formed, light irradiation is performed from both directions. However, the jig 200 may be formed using only the jig 100 without using the jigs 200 and 300. At that time, the branch core and the clad may be cured and formed with the light receiving element 20 and the light emitting element 30 attached, or the branch core and the clad may be cured and formed by attaching a lid to a position where they should be attached.

3 is the same as FIG. A to FIG. The case where the refractive index of the branch core 413 is smaller than the refractive index of the trunk core 412 indicated by G is shown.
FIG. The change in the refractive index at the position indicated by 1-1 ′ of A, that is, the position crossing the clad 45, the trunk core 412, the branch core 413, and the clad 45 is shown in FIG. B. In the contact portion between the trunk core 412 and the branch core 413, the branch core 413 acts as a weak clad with respect to the trunk core 412. FIG. B shows a case where the refractive index changes stepwise.
Or FIG. It may be like C. That is, FIG. D to FIG. In step E, the second photocurable resin, which is a low refractive index component of the liquid photocurable resin 430, permeates the surface of the trunk core 412 and the refractive index of the trunk core 412 surface decreases. Then, FIG. As in C, the change in refractive index can be smooth. At this time, the contact portion 412 s between the trunk core 412 and the branch core 413 may be smaller than the refractive index of the branch core 413.

  In any case, FIG. A optical module 1000 of FIG. A to FIG. It is clear that it can be produced by a mass production method such as G. The jigs 100, 200, and 300 can be used repeatedly while performing appropriate cleaning or the like. Further, although slight core bending may occur, the optical waveguide 1100 and the optical module 1000 having branches having practically identical characteristics can be produced in large quantities continuously. Moreover, optical crosstalk can be reduced.

4 is similar to FIG. It is a block diagram which shows the structure of the single core bidirectional | two-way optical communication system incorporating the optical module 1000 of A and using two optical transmitter-receivers 1500.
The optical transceiver 1500 of FIG. The current-voltage conversion circuit 21 and the demodulation circuit 22 are connected to the light receiving element 20 of the optical module 1000 of A, and the light emitting element drive circuit 31 and the modulation circuit 32 are connected to the light emitting element 30. The demodulation circuit 22 and the modulation circuit 32 are further connected to a terminal device.
On the other hand, an optical transceiver 1500-2 having substantially the same configuration as that of the optical transceiver 1500 is connected to the other end of the optical fiber 10 connected to the optical module 1000 of the optical transceiver 1500. According to the present invention, since the optical crosstalk is reduced, the used light wavelength bands of the light emitting element 30 and the light receiving element 20 may be made the same or partially overlapped. Of course, it is also possible to use light receiving and emitting elements in the corresponding wavelength band in the optical transceiver 1500-2 as different (not overlapping).

Sectional drawing which shows the structure of the optical module 1000 which concerns on one specific Example of this invention. Sectional drawing which shows 1 process of the manufacturing method of the optical module 1000. FIG. FIG. 3 is a cross-sectional view illustrating a configuration of an optical waveguide 1100 in which an optical fiber 10, a light receiving element 20, and a light emitting element 30 are removed from an optical module 1000. Process drawing (sectional drawing) of the other manufacturing method of the optical module 1000. FIG. Process drawing (sectional drawing) of the other manufacturing method of the optical module 1000. FIG. Process drawing (sectional drawing) of the other manufacturing method of the optical module 1000. FIG. Process drawing (sectional drawing) of the other manufacturing method of the optical module 1000. FIG. Process drawing (sectional drawing) of the other manufacturing method of the optical module 1000. FIG. Process drawing (sectional drawing) of the other manufacturing method of the optical module 1000. FIG. Process drawing (sectional drawing) of the other manufacturing method of the optical module 1000. FIG. FIG. 4 is an explanatory diagram showing an example of the relationship between refractive indexes of a trunk core 412 and branch portions 413 and a clad 45 of the optical waveguide 1100. 1 is a block diagram showing a configuration of a single-core bidirectional optical communication system using two optical transceivers 1500 incorporating an optical module 1000. FIG.

Explanation of symbols

1000: optical module 1100: optical waveguide 1500: optical transceiver 10: communication optical fiber 10c: first optical input / output end 15, 150, 250, 350: connector 100, 200, 300: jigs 102, 103, 201 , 301: optical fiber 20: light receiving element 20c: second light input / output terminal 21: current-voltage conversion circuit 22: demodulation circuit 30: light emitting element 30c: third light input / output terminal 31: light emitting element driving circuit 32: modulation Circuit 412: Trunk core 413: Branch core 420, 430: Liquid photocurable resin 45: Clad 50: Housing

Claims (10)

An optical waveguide in which first, second and third light input / output ends, each of which is a circular region, are connected by a branch core,
The branch core is
A cylindrical trunk core connecting the first and second light input / output ends;
The diameter of the trunk is smaller than that of the trunk, the refractive index of the trunk is smaller than the refractive index of the trunk, and a cylindrical branch core that connects the first and third light input / output ends.
The branch of the trunk core and the branch core starts from the first light input / output end,
An optical waveguide characterized in that when the side surface of the core of the branch portion is extended in the direction of the first light input / output end, it reaches the inside of a circular region of the first light input / output end. 2. The optical waveguide according to claim 1, wherein the trunk core and the branch core of the branch core are each made of a cured product of a photocurable resin. The optical waveguide according to claim 1 or 2,
An optical fiber at the first light input / output end;
A light receiving element at the second light input / output terminal,
A light emitting element at the third light input / output terminal;
An optical module characterized by being connected. A method of manufacturing an optical waveguide in which first, second, and third optical input / output ends, each of which is a circular region, are connected by a branching core,
Using photo-curing resin,
The first light input / output end can be irradiated with light having a wavelength capable of curing the photocurable resin in the second light input / output end direction and the third light input / output end direction. Connect a jig that combines optical waveguides,
Irradiating the curing wavelength light from the first light input / output end to the second light input / output end direction and the third light input / output end direction, A trunk core that connects the second optical input / output end, and a branch core that connects the first optical input / output end and the third optical input / output end and is narrower than the trunk core. And a method of manufacturing an optical waveguide. The curing light is irradiated from the first light input / output end toward the second light input / output end to connect the first light input / output end and the second light input / output end. After forming the core of the trunk portion, the curing wavelength light is irradiated from the first light input / output end toward the third light input / output end to thereby form the first light input / output end and the third light input / output end. 5. The method of manufacturing an optical waveguide according to claim 4, wherein a core of a branch portion connecting the optical input / output ends of the optical waveguide is formed. The curing light is irradiated from the first light input / output end toward the second light input / output end to connect the first light input / output end and the second light input / output end. Photocuring resin for the trunk when forming the core of the trunk,
Irradiating the curing wavelength light in the direction of the third light input / output end from the first light input / output end to connect the first light input / output end and the third light input / output end. 6. The method of manufacturing an optical waveguide according to claim 5, wherein the photo-curing resin for the branch portion when forming the core of the branch portion is different. Than the refractive index of the cured product of the photocurable resin for the trunk,
The method of manufacturing an optical waveguide according to claim 6, wherein a refractive index of a cured product of the photocurable resin for branch portions is small. The branch photocurable resin includes a first photocurable resin, a refractive index smaller than that of the first photocurable resin, a maximum curable maximum wavelength, and the first photocurable resin. Is a mixture with a second photocurable resin having a different curing mechanism,
Irradiation of light having a wavelength that can cure the first photocurable resin but does not cure the second photocurable resin from the first light input / output end toward the third light input / output end. And after forming the core of the branch part which mainly connects the 1st light input / output end and the 3rd light input / output end which consist of a hardened material of the 1st photocurable resin,
8. The optical waveguide according to claim 6, wherein the remaining core photocurable resin is cured to form a core of the trunk and a clad of the core of the branch. 9. Production method. When forming the core of the trunk, the curing wavelength light introduced from the first light input / output end is also introduced from the second light input / output end,
5. The curing wavelength light introduced from the first light input / output end is also introduced from the third light input / output end when the branch core is formed. 9. The method for producing an optical waveguide according to any one of 8 above. After obtaining an optical waveguide by the method for manufacturing an optical waveguide according to any one of claims 4 to 9,
An optical fiber at the first light input / output end;
A light receiving element at the second light input / output terminal,
A light emitting element at the third light input / output terminal;
An optical module manufacturing method comprising connecting the optical modules.

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