JP2005128407A - Optical waveguide module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To contrive optical coupling with a small loss between an optical fiber and an optical waveguide, and to reduce manufacturing time, in an optical waveguide module. <P>SOLUTION: The optical module 1 is structured by optically coupling an optical waveguide plate 2 and an optical fiber 3. The optical waveguide plate 2 is provided with a core 4 for light to be guided, a clad 5 which, covering the core 4, is composed of a material having a refractive index lower than that of the core 4, and an optical fiber guiding groove 6 which has a cross section in nearly the same shape as that of the core 4 and which is formed near the end face of the clad 5. The optical fiber 3 has, near the end face, a small diameter part 33 with a diameter smaller than that of other areas, and is fixed by fitting the small diameter part 33 to the optical fiber guiding groove 6 of the optical waveguide plate 2. Alignment positioning is completed in a short period of time by fitting the small diameter part 33 to the optical fiber guiding groove 6. A large difference in level is eliminated between the core 4 and the optical fiber guiding groove 6, thereby suppressing positional deviation between the core 4 and the optical fiber 3 caused by change in temperature, and realizing optical coupling with a small loss. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical waveguide module in which an optical waveguide and an optical fiber are coupled.

Conventionally, an optical waveguide module in which an optical waveguide and an optical fiber are coupled is used in an optical information communication system. The following is known as one of the manufacturing methods of an optical waveguide module (for example, refer patent document 1). As shown in FIG. 15, first, an optical waveguide 92 made of a silica glass-based glass film is formed on a silicon substrate 91 such that the distance between the center of the core of the optical waveguide 92 and the silicon substrate is within the radius of the optical fiber plus 2 μm. To do. Next, a part of the glass film is removed to form the silicon substrate exposed surface 93, and the outer peripheral surface of the optical fiber 94 is brought into contact with the exposed upper surface of the silicon substrate exposed surface 93. In this state, the optical fiber 94 is moved in two directions, ie, the optical axis direction of the core and the direction perpendicular to the direction and parallel to the upper surface of the silicon substrate 91 to align the optical fiber 94 with respect to the core. 94 is fixed to the optical waveguide 91 with an ultraviolet curable adhesive 95.
JP-A-8-36118

  However, in the method of manufacturing an optical waveguide module as described above, an alignment process of an optical fiber and an optical waveguide that requires time and accuracy is required. Also, since the end faces are bonded together, the optical axis shift that causes optical coupling loss occurs due to changes in the alignment position due to curing shrinkage of the adhesive, temperature changes, etc. in the bonding process after alignment. there is a possibility.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical waveguide module that solves the above-described problems and can be manufactured in a reduced manufacturing time and in which an optical fiber and an optical waveguide are optically coupled with low loss.

  In order to achieve the above object, the invention according to claim 1 is an optical waveguide module in which an optical waveguide plate and an optical fiber are coupled, wherein the optical waveguide plate includes a core through which light is guided, and the core covers the core. A clad made of a material having a lower refractive index, and an optical fiber guide groove formed in the vicinity of the end face of the clad and having a cross section substantially the same shape as the cross section of the core. The optical waveguide module includes a small-diameter portion having a smaller diameter than the region, and the optical fiber is fixed by fitting the small-diameter portion into an optical fiber guide groove of the optical waveguide plate.

  According to a second aspect of the present invention, in the optical waveguide module according to the first aspect, the optical fiber guide groove is provided in close proximity to a part of the core of the optical waveguide plate, and is fixed to the core and the optical fiber guide groove. The optical fiber is optically coupled by directional coupling.

  According to a third aspect of the present invention, in the optical waveguide module according to the second aspect, the diameter of the small diameter portion of the optical fiber is 9 to 50 μm.

  According to a fourth aspect of the present invention, in the optical waveguide module according to the first aspect, the outer shape of the small diameter portion of the optical fiber is eccentric with respect to the optical axis center of the optical fiber.

  According to a fifth aspect of the present invention, in the optical waveguide module according to the first aspect, the small diameter portion of the optical fiber is formed by irradiating a short pulse laser beam near the end face of the optical fiber.

  According to the first aspect of the present invention, the alignment is completed with high accuracy by fitting the small-diameter portion of the optical fiber into the optical fiber guide groove formed in substantially the same shape as the core of the optical waveguide plate. Time can be shortened, and since there is no large step between the core of the optical waveguide plate and the optical fiber guide groove, there is almost no occurrence of displacement between the core and the optical fiber due to temperature change in the usage state of the optical waveguide module. Light intensity coupling loss can be suppressed.

  According to the invention of claim 2, since the light guided in the optical fiber is transferred to the core of the optical waveguide plate by directional coupling, the optical loss due to the difference in cross-sectional shape between the optical fiber and the core of the optical waveguide plate is reduced. And coupling loss can be suppressed.

  According to the third aspect of the present invention, optical coupling can be achieved by good directional coupling without a problem that the propagation loss of the optical signal is large when the diameter of the small diameter portion is 9 μm or less, and directional coupling hardly occurs when the diameter is 50 μm or more. It is.

  According to the fourth aspect of the present invention, the optical fiber is rotated around the optical axis when the optical waveguide plate and the optical fiber are joined, and fine adjustment of the axial center positions of the core of the optical waveguide plate and the core of the optical fiber is easily performed. Therefore, the position accuracy of the core in the optical waveguide plate can be relaxed.

  According to the fifth aspect of the present invention, processing can be performed without contact without applying stress to the optical fiber, and three-dimensional processing shape control is possible.

  Hereinafter, an optical waveguide module according to an embodiment of the present invention will be described with reference to the drawings. 1A and 1B show an optical waveguide module 1 and an optical fiber coupling portion structure. The optical waveguide module 1 is configured by optically coupling an optical waveguide plate 2 and an optical fiber 3, and the optical waveguide plate 2 covers the core 4 and covers the core 4 and has a lower refractive index than the core 4. A clad 5 (substrate clad 51, cover clad 52) made of the above material, and an optical fiber guide groove 6 formed in the vicinity of the end face of the clad 5 with a cross section substantially the same shape as the cross section of the core 4. 3 includes a small-diameter portion 33 having a smaller diameter than other regions in the vicinity of the end face, and the optical fiber 3 is fixed by fitting the small-diameter portion 33 into the optical fiber guide groove 6 of the optical waveguide plate 2.

  As shown in FIG. 1B, the above-described optical fiber 3 includes a clad 31 and a core 32 at a central portion having a refractive index larger than that of the clad 31, and a small-diameter portion 33 is formed at an end thereof. ing. The width a of the core groove 41 is, for example, a = 7 μm, and the width c of the optical fiber guide groove 6 is, for example, c = 15 μm. The dimensions b, c, and h of the optical fiber small-diameter portion 33 and the fiber guide groove 6 are determined so that there is no gap between them and the optical axes of the core 4 and the optical fiber 3 are fitted with no deviation. The formation of the small-diameter portion 33 and the substrate cladding 51, the optical fiber guide groove 6 and the like will be described in the description of the manufacturing process below.

  A manufacturing process of the optical waveguide module 1 will be described. FIG. 2 shows a method of forming the small diameter portion 33 of the optical fiber 3, and FIG. 3 shows a manufacturing process of the optical waveguide module 1. [Optical Fiber Small Diameter Forming Step] As shown in FIG. 2A, the small diameter section 33 of the optical fiber 3 is formed by immersing the end of the quartz-based optical fiber 3 in the hydrofluoric acid solution 7 and etching it. This is formed by removing the portion and reducing the fiber diameter in the vicinity of the end face of the optical fiber 3. In the case of a single mode optical fiber, the fiber diameter of the region from which a part of the cladding 31 is removed (cladding removal portion) is about 9 to 50 μm. The region to be etched can be controlled, for example, by not immersing the portion other than the portion to be removed in hydrofluoric acid, or by protecting the surface of the clad 31 other than the removed portion with a Ni—Cr—Mo alloy or the like. When the concentration of hydrofluoric acid is 50%, the etching rate is 0.6 μm / min. Therefore, it takes about 80 minutes to etch an optical fiber of 125 μmφ to 30 μm. Is possible.

  [Substrate Clad Forming Step] The substrate clad 51 is press-molded or injection-molded using a mold having convex portions at the portions to be the core groove and the optical fiber guide groove. As shown to (a), the core groove 41 and the optical fiber guide groove 6 are provided in the surface, and it forms. The mold used here can be manufactured using a LIGA (Lithography Galvanoformung Abformung) method or the like. The LIGA method is a process in which a three-dimensional depth is obtained by a photoelectroplating method. For example, after a photoresist is deeply three-dimensionally carved, a metal mold can be made by electroplating (electrocasting).

  The cross-sectional shape of the core groove 41 is a square, and the width a shown in FIG. 1B is 5 to 20 μm in the case of the single mode. Further, the shape of the optical fiber guide groove 6, that is, the groove width c, the groove height h, and the groove length b shown in FIG. It is formed according to the dimensions to be combined. As representative examples of dimensions, the width a of the core groove 41 is 7 μm, and the width c of the optical fiber guide groove 6 is 15 μm.

  As the resin used for the substrate clad 51, PMMA, epoxy resin, acrylic resin, fluorine resin, or the like having high light transmittance can be used. In the embodiment, for example, in the case of PMMA, a light having a refractive index n of 1.492 is used.

  [Optical Fiber Arrangement Step] In the subsequent step, the optical fiber 3 is fitted and arranged in the optical fiber guide groove 6 of the substrate clad 51 described above. At this time, if the shape of the optical fiber guide groove 6 is substantially the same as the shape of the small-diameter portion 33 of the optical fiber 3 or about 0.5 to 1 μm larger, damage to the end portion of the optical fiber can be avoided during fitting.

  [Adhesive Application Step] As shown in FIG. 3B, an adhesive 43 having a refractive index (n = 1.497) equivalent to that of the core 32 of the optical fiber 3 is replaced with an optical fiber guide by using a dispenser 42. It is applied to the periphery of the optical fiber small-diameter portion 33 fitted in the groove 6. At this time, the core groove 41 can be filled with the adhesive 43 to simultaneously form the optical waveguide (core 4) and bond the optical fiber.

  When using a resin having a different refractive index between the resin forming the waveguide core 4 and the resin used for bonding the optical fiber, the core groove 41 is filled with, for example, a resin having a refractive index n = 1.497, and then the optical fiber guide. A resin having the same refractive index n = 1.492 as that of the substrate cladding 51 is applied to the groove 6. That is, the refractive index of the core through which light is guided is increased, and a low refractive index adhesive is used as an adhesive so as not to adversely affect light propagation. For example, the adhesive has the same effect as that of the cladding region of the optical fiber by using an adhesive having a refractive index lower by 0.001 to 0.05 than the refractive index of the core of the optical fiber. As a result, the optical signal can be prevented from leaking from the small diameter portion of the optical fiber, and the optical signal can be transferred with high efficiency.

  [Cover Cladding Step] As shown in FIG. 3C, a cover clad 52 having a thickness of about 100 μm is disposed on the substrate clad subjected to the above resin filling and adhesive application and pressed from above. . The resin liquid for core formation spreads over the entire surface between the cover clad 52 and the substrate clad 51 by pressing. Thereafter, the core resin and the adhesive are cured by irradiating light from the upper part of the cover clad 52. As a result, the substrate clad 51, the cover clad 52, and the optical fiber 3 are joined to form a core, and the optical waveguide module 1 is completed.

  As the resin used for the cover clad 52, a resin similar to the resin used for the substrate clad 51 described above can be used. In this embodiment, a resin having a refractive index n = 1.492 is used.

  As described above, the optical waveguide module 1 includes the small-diameter portion 33 of the optical fiber 3 in the optical fiber guide groove 6 formed in substantially the same shape as the core 4 of the optical waveguide plate 2 as shown in FIGS. Since the alignment for matching the optical axes of the core 4 and the optical fiber 3 is completed, the alignment positioning time can be shortened. Further, since there is no large step between the core 4 of the optical waveguide plate 2 and the optical fiber guide groove 6, there is almost no displacement between the core 4 and the optical fiber 3 due to temperature change, and the light intensity due to temperature change is reduced. Low-loss optical coupling with reduced coupling loss is realized, and a stable use state of the optical waveguide module 1 is realized.

  Next, an optical waveguide module according to another embodiment of the present invention will be described. 4 shows the optical waveguide module 1, and FIGS. 5A to 5D show the manufacturing process thereof. As shown in FIGS. 4A and 4B, the optical fiber guide groove 6 of the optical waveguide module 1 is provided in parallel and close to a part (end portion) of the core 4 of the optical waveguide plate 2. 4 and the optical fiber 3 (the small diameter portion thereof) fixed to the optical fiber guide groove 6 are optically coupled by directional coupling.

  In the optical waveguide module 1 using such directional coupling, the one having a diameter of the small diameter portion 33 of the optical fiber 3 of 9 to 50 μm is used. This is because if the diameter of the small diameter portion 33 is 9 μm or less, an optical signal cannot be transmitted, and if it is 50 μm or more, directional coupling is unlikely to occur. Further, when the diameter of the small diameter portion 33 of the optical fiber 3 is about 9 to 20 μm, the directional coupling phenomenon is further easily induced, and the coupling property is further improved.

  Further, the distance e between the centers of the core groove 41 and the optical fiber guide groove 6 and the length (transition distance) d of the portion running in parallel with each other have a shorter transition distance d as the distance e between the centers is shorter. Can be transferred (directly coupled). For example, light is transferred from the optical fiber to the waveguide (core 4) with respect to the core groove 41 having a cross-sectional shape of □ 6 μm when d = 0.95 mm when a = 8 μm and d = 1 mm when a = 10 μm. It was.

  By arranging the optical fiber 3 in the vicinity of the core 4 in this way, an optical signal is transmitted by directional coupling between the optical waveguide (core 4) and the optical fiber 3, which is the conventional example. Such an alignment process becomes unnecessary. In addition, since the light guided in the optical fiber is transferred to the core of the optical waveguide plate by directional coupling, there is no optical loss due to the difference in cross-sectional shape between the optical fiber and the core of the optical waveguide plate, and the coupling loss is suppressed. it can. The substrate clad 51 can be easily formed by a method using exposure / development using lithography or a method using a mold as described above. The manufacturing process will be described below.

  [Optical Fiber Small Diameter Portion / Substrate Cladding Forming Step] The small diameter portion 33 of the optical fiber 3 is formed in the same manner as the optical fiber small diameter portion forming step. In the case of a single mode optical fiber, the diameter of the optical fiber small diameter portion 33 is about φ9 to 50 μm. The formation of the substrate cladding 51 is performed in the same manner as described above. Further, the cross-sectional shape of the core groove 41 is set to □ 5 to 20 μm in the case of the single mode. The shape (width / height of the groove) of the optical fiber mounting structure is formed so that the small diameter portion 33 of the optical fiber is fitted.

  [Core Forming Step] As shown in FIG. 5A, using a dispenser 42, the core groove 41 is filled with a methacrylate resin (refractive index 1.497) so that the resin 43 liquid slightly overflows from the core groove 41. To do. Further, as shown in the drawing, the entire periphery of the core groove 41 is surrounded by the substrate clad 51, so that the resin 43 can be damped by the end surface, and the resin liquid does not overflow from the end surface of the substrate clad, so that a post process is performed. In the optical fiber arranging step, it is possible to prevent the resin liquid from adhering to the optical fiber. Therefore, with this core groove 41 structure, it is possible to ensure the positioning accuracy of the optical fiber 3 and prevent problems due to resin liquid adhesion.

  [Optical Fiber Arrangement Step] As shown in FIG. 5B, the optical fiber 3 is fitted and arranged in the optical fiber guide groove of the substrate clad 51.

  [Adhesive Application Step] As shown in FIG. 5 (c), using a dispenser 44, a photocurable acrylate adhesive 45 having the same refractive index n = 1.492 as that of the substrate clad 51 is applied to the optical fiber small diameter portion. Apply to. Thereafter, as described above, a cover clad bonding process is performed to complete the optical waveguide module 1.

  Next, another optical waveguide module using the same directional coupling as described above will be described. FIG. 6 shows the structure of the directional coupling portion of the optical waveguide module. As shown in FIGS. 6A1 and 6A2, the substrate clad 51 is not provided with the above-described optical fiber guide groove. The optical fiber 3 is disposed in parallel to the core 4 directly in the region 60 on the core 4 formed in the substrate cladding 51. Then, as shown in FIGS. 6 (b1) and 6 (b2), an optical waveguide module is formed by covering the cover clad 52 having the optical fiber guide groove 6 from above.

  Note that the cover clad can be formed directly on the substrate clad by using a mold or coating without using the cover clad 52 having the optical fiber guide groove 6. In this way, by eliminating the optical fiber guide groove from the substrate clad and arranging the small diameter portion of the optical fiber directly above the core portion of the optical waveguide plate, the optical signal can be transmitted by the directional coupling phenomenon as described above. is there.

  Next, an optical waveguide module according to still another embodiment of the present invention will be described. FIG. 7 shows an alignment method when manufacturing the optical waveguide module. As shown in FIGS. 7B and 7C, the outer diameter of the small-diameter portion 33 of the optical fiber used in this optical waveguide module is eccentric with respect to the optical axis center of the optical fiber 3, that is, the center of the core 31. The formation of the optical fiber having the eccentric small diameter portion 33 will be described later.

  After the optical fiber 3 having the eccentric small-diameter portion is used, the same process as that shown in FIG. 3 is performed, and the cover clad 51 is placed and pressed as shown in FIG. 7A. Fine adjustment for alignment is performed. The light L0 is incident on the left optical fiber 3 in the figure, and the intensity of the light L1 and L2 emitted from the right optical fiber 3 in the figure is measured, and the light that hardens the adhesive from the upper surface of the cover clad. Irradiate. At this time, the optical fiber 3 is rotated about each axis, and the rotation is stopped at the point where the intensity of the emitted light is the highest, and the adhesive is completely cured in this state. Since the fine adjustment of the axial center position can be easily performed at the time of coupling the optical waveguide plate and the optical fiber, the position accuracy of the core in the optical waveguide plate can be relaxed.

  Next, a method of forming the small-diameter portion 33 of the optical fiber with laser light will be described with reference to FIG. When the core portion of the optical fiber 3 is shaped, according to a method by machining such as cutting or grinding, the fiber may break because the quartz fiber is a brittle material. Therefore, when non-contact processing is performed with laser light, stress load during processing can be suppressed. The laser beam is preferably a short pulse laser beam so that thermal stress is not applied. For example, a laser beam having a pulse width of 1 to 200 nsec can be used. A similar effect can be obtained with a ps and fs laser having a pulse width of ns order or less. However, the shorter the pulse, the lower the removal amount per pulse, and the lower the productivity.

In addition, in the case of a quartz fiber, since it has transparency with respect to light in the visible or infrared region, the absorption efficiency of laser light may become a problem. Considering these matters, for example, processing was performed using an excimer laser. Since the wavelength of ArF (argon fluorine) laser light is absorbed by quartz, this is used, and the laser light LB from the laser light source 8 is converted into a mirror 81 and a condenser lens 82 as shown in FIG. through, as the energy density of ^{1.0J / cm 2 ~5J / cm 2} , it was irradiated to the fiber 3. Since the excimer laser is a pulse laser, the amount of clad removal in the small diameter portion 33 can be controlled by the number of pulses. The irradiation size of the laser beam was shaped to 1 to 100 μmφ using a shielding mask. By scanning the laser beam LB and rotating the optical fiber 3 about its axis, the shape of the small fiber diameter portion 33 can be shaped into a desired shape. For example, an optical fiber having the above-mentioned eccentric small diameter portion 33 can be formed by the method shown in FIG.

  Next, an optical waveguide module according to still another embodiment of the present invention will be described. FIG. 9 shows the tip of an optical fiber and its fitted state, and FIG. 10 shows the tip of an optical fiber of another shape and its fitted state. The optical waveguide module having these fitting states is obtained by forming a shape corresponding to the fiber tip shape in the waveguide portion of the optical waveguide plate with respect to the optical fiber having the fiber tip portion formed in the target shape. When connecting to the optical waveguide plate, the connection reliability is improved. As shown in FIGS. 9A and 9B, the core 31 in the region 3B in the middle of the regions 3A, 3B, 3C at the tip of the optical fiber 3 is exposed to form a small diameter portion. Further, shapes corresponding to the tip shape are formed as optical fiber guide grooves 6A, 6B, 6C at the end of the core groove 41 of the substrate clad 51 as shown in FIG. 9C. Then, as shown in FIG. 9D, the optical waveguide module is formed by fitting the regions 3A, 3B, 3C of the optical fiber 3 and the fiber guide grooves 6A, 6B, 6C, respectively. In the optical fiber 3 shown in FIG. 10, the small-diameter portion 33 at the tip thereof is tapered, and the shape of the optical fiber guide groove 6 is a corresponding shape. The optical fiber guide groove and the core groove 41 can be formed by photolithography using a mask having a pattern corresponding to both the optical fiber guide groove and the core groove 41, for example.

  A method for manufacturing the optical fiber having the tip shown in FIGS. 9 and 10 will be described with reference to FIGS. As shown in FIG. 11 (a), masks M1 and M2 are applied to two locations at the tip of the optical fiber 3 and immersed in an etching solution 7, whereby an optical fiber having a core exposed at the small diameter portion 3B is obtained. . Further, as shown in FIG. 11 (b), a mask M3 is provided at a position away from the tip of the optical fiber 3 and immersed in the etching solution 7, so that the tip has a small diameter portion with a tapered shape. A fiber is obtained.

  The etching will be described in detail. For example, when a hydrofluoric acid solution is used as the etching solution 7, the etching rate is relatively slow, and the dissolution amount of the clad of the optical fiber can be easily controlled. The etching rate can be controlled by changing the hydrofluoric acid concentration. The masks M1 to M3 are formed by forming a coating film of Au on the outer end portion of the optical fiber by a sputtering method. The coating film may be formed by metallization using a Ni—Cr—Mo alloy. In the case of etching using a hydrofluoric acid solution, a fluororesin film may be used as the coating film.

  Also, the optical fiber having a small diameter portion with a tapered tip is heated and cut by the burner 9 while applying tensile stress to the optical fiber 3 as shown in FIGS. 12 (a) to 12 (c). Is obtained. In the case of quartz fiber, when the optical fiber is cut at a temperature of 1600 ° C. to 2000 ° C. and the minimum value of the fiber outer diameter becomes 20 μmφ, the end of the optical fiber becomes a tapered shape, and a desired shape is obtained. This shape can be controlled by the region in which the optical fiber is heated, the tensile stress, and the strain rate. The optical fiber can be heated locally by an infrared laser such as an oxyhydrogen burner or a carbon dioxide laser, and a desired taper shape can be formed using these.

  Next, an optical waveguide module according to still another embodiment of the present invention will be described. FIG. 13 shows the tip of the optical fiber and its fitted state, and FIG. 10 shows yet another fitted state. In the optical fiber placement step described with reference to FIGS. 3A and 3B, the optical fiber guide groove is formed to have a size larger than the outer diameter of the optical fiber by about 0.5 to 1 μm, and the optical fiber is broken when fitted. However, in the case of a polymer waveguide, it is possible to reduce the size of the optical fiber guide groove and perform positioning accurately without damaging the optical fiber. That is, when the optical waveguide (core and clad) is made of a material whose hardness is lower than that of the fiber material such as a polymer or the like, when aligning the optical fiber with the optical fiber guide groove, FIGS. As shown, the groove width d2 of the optical fiber guide groove 6 is made smaller than the outer diameter d1 of the optical fiber small diameter portion 33. When the optical fiber small-diameter portion 33 is fitted into the optical fiber guide groove 6 under such a dimensional relationship, the side wall of the optical fiber guide groove is deformed as shown in FIG. A force F that clamps the optical fiber small-diameter portion 33 is generated. Due to the force F, the optical fiber small-diameter portion 33 is accurately placed and held in the center of the optical fiber guide groove, and the occurrence of displacement is also suppressed in the subsequent manufacturing process such as bonding.

  For example, in the case of the substrate clad 51 made of PMMA and the optical fiber made of quartz (outer diameter φ125 μm, core diameter φ9 μm), the waveguide (core) is taken into consideration when the mode matching between the optical fiber core and the waveguide core is considered. The cross-sectional shape of the groove 41) is preferably 5 to 7 μm. When the outer diameter d1 of the optical fiber small-diameter portion 33 is the same as the diameter φ9 μm of the optical fiber core, if the width d2 of the optical fiber guide groove 6 is set to about 7 to 8 μm, the resin fiber is not damaged. The optical fiber can be held by elastic force.

  14A and 14B, a notch 61 is formed along one side wall of the optical fiber guide groove 6 so that the side wall 62 is easily deformed. The optical fiber small-diameter portion 33 can be disposed with the other side wall 63 as a reference plane. Such a structure can be applied even when the substrate cladding 51 is not made of polymer. The present invention is not limited to the above-described configuration, and various modifications can be made. For example, the above description has been made mainly with reference to the drawings showing the Y-branch waveguide. However, the present invention is not limited to the optical waveguide module having such a Y-branch waveguide, and the optical fiber of the optical waveguide plate. All optical waveguide modules having a configuration in which a small-diameter portion of an optical fiber is fitted and fixed in a guide groove are included.

(A) is a perspective view of the optical waveguide module which concerns on one Embodiment of this invention, (b) is a perspective view explaining the coupling | bond part structure of the optical waveguide module. (A) (b) is a figure explaining formation of the small diameter part of the optical fiber used for an optical waveguide module same as the above. (A) (b) is a perspective view explaining an optical waveguide module manufacturing process same as the above, (c) is a perspective view of the completed optical waveguide module same as the above. (A) is a perspective view of the optical waveguide module which concerns on other one Embodiment of this invention, (b) is a perspective view explaining the coupling | bond part structure of the optical waveguide module. (A)-(c) is a perspective view explaining an optical waveguide module manufacturing process same as the above, (d) is a perspective view of the completed optical waveguide module same as the above. (A1) (b1) is a perspective view explaining the coupling | bond part structure of the optical waveguide module which concerns on another one Embodiment of this invention, (a2) (b2) is a step | planar view explaining the same coupling | bond part structure. (A) is a perspective view for explaining alignment in an optical waveguide module according to still another embodiment of the present invention, (b) is a perspective view of an optical fiber used in the optical waveguide module, and (c) is (b) AA step view of the small diameter portion of the optical fiber in FIG. The figure explaining formation of the small diameter part of the optical fiber used for the optical waveguide module of this invention. (A) is a perspective view of the front-end | tip part of the optical fiber used for the optical waveguide module which concerns on another one Embodiment of this invention, (b) is sectional drawing of the front-end | tip part of the same optical fiber, (c) is the same light The top view of the optical fiber guide groove part of the optical waveguide with which the front-end | tip part of a fiber fits, (d) is a fitting state top view of the same optical fiber and optical fiber guide groove in the same optical waveguide module. The perspective view explaining the coupling | bond part structure of the optical waveguide module which concerns on another one Embodiment of this invention. (A) (b) is a schematic diagram explaining formation of the small diameter part of the optical fiber used for the optical waveguide module of this invention. (A)-(c) is a schematic diagram explaining formation of the small diameter part of the optical fiber used for the optical waveguide module of this invention. (A) is a perspective view explaining the other coupling | bond part structure of the optical waveguide module which concerns on one Embodiment of this invention, (b) (c) is sectional drawing explaining the same coupling | bond part structure. (A) is a perspective view explaining other coupling part structure of the optical waveguide module concerning one embodiment of the present invention, and (b) is a sectional view explaining the coupling part structure. The perspective view explaining the coupling | bond part structure of the conventional optical waveguide module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical waveguide module 2 Optical waveguide board 3 Optical fiber 4 Core (of optical waveguide board) 5, 51, 52 Cladding 6 Optical fiber guide groove 33 Small diameter part

Claims (5)

In an optical waveguide module that combines an optical waveguide plate and an optical fiber,
The optical waveguide plate includes a core through which light is guided, a clad made of a material having a lower refractive index than the core covering the core, and a cross section substantially in the same shape as the cross section of the core, and in the vicinity of the end face of the clad. An optical fiber guide groove formed,
The optical fiber includes a small-diameter portion having a smaller diameter than other regions in the vicinity of the end surface,
The optical fiber module, wherein the optical fiber is fixed by fitting the small diameter portion into an optical fiber guide groove of the optical waveguide plate.   The optical fiber guide groove is provided in parallel and close to a part of the core of the optical waveguide plate, and the core and the optical fiber fixed in the optical fiber guide groove are optically coupled by directional coupling. The optical waveguide module according to claim 1, wherein:   The optical waveguide module according to claim 2, wherein a diameter of the small diameter portion of the optical fiber is 9 to 50 μm.   The optical waveguide module according to claim 1, wherein an outer shape of the small-diameter portion of the optical fiber is eccentric with respect to the optical axis center of the optical fiber.   2. The optical waveguide module according to claim 1, wherein the small-diameter portion of the optical fiber is formed by irradiating a short pulse laser beam in the vicinity of the end face of the optical fiber.

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