Optical coupling module and optical coupler

Abstract

This optical coupling module comprises a substrate, an optical coupler, and an adhesive member. The optical coupler includes a base portion having a first main surface and a second main surface, a first support portion supporting an optical fiber, a second support portion disposed with a gap from the first support portion along the longitudinal direction of the optical fiber, and a metal reflection mirror including a heat transfer portion that has a facing surface facing the substrate. The second support portion has an inclined portion. The metal reflection mirror is at least partially disposed along the inclined portion, and reflects emitted light. The heat transfer portion is positioned on the substrate side in the arrangement direction of the first main surface and the second main surface with respect to the reflection position of the emitted light, and the thickness of the heat transfer portion along the normal direction of the inclined portion increases toward the substrate. The adhesive member is disposed between the facing surface and the substrate. The thermal conductivity of the heat transfer portion and the thermal conductivity of the adhesive member are each higher than the thermal conductivity of the second support portion.

Description

Optical coupling module and optical coupler

[0001] The present invention relates to an optical coupling module and an optical coupler.

[0002] A known prior invention relating to an optical coupling module is, for example, the optical circuit described in Patent Document 1. The optical circuit described in Patent Document 1 comprises a Si substrate, an optical waveguide formed on the Si substrate, and a reflective mirror having a reflective surface that reflects light emitted from the optical waveguide. An inclined surface is formed on the Si substrate. The reflective mirror is formed on the inclined surface. The reflective mirror has a layered structure of a reflow-treated silica-based film and a reflective member on the inclined surface.

[0003] Japanese Patent Application Publication No. 9-197179

[0004] In optical coupling modules used for optical communication, high-intensity lasers of approximately 100 mW to 300 mW are emitted from the optical waveguide. This can cause localized heating of the reflective surface of the reflective mirror. When the optical waveguide is fixed to a Si substrate with a thermosetting resin such as epoxy resin, the heat generated on the reflective surface may be transferred to the thermosetting resin, causing it to overheat. In this case, thermal stress may cause the thermosetting resin to deform, potentially leading to a misalignment of the optical waveguide's position and optical axis.

[0005] Furthermore, heat generated on the reflective surface can be transmitted to the boundary between the surface of the Si substrate where the optical waveguide is formed and the inclined surface, potentially causing thermal stress that could lead to the delamination of the reflow-treated silica-based film.

[0006] Therefore, the object of the present invention is to provide an optical coupling module and an optical coupler that suppress overheating caused by heat generated when reflecting light.

[0007] An optical coupling module according to one embodiment of the present invention comprises a substrate, an optical coupler provided on the substrate, and an adhesive member, wherein the optical coupler includes a base having opposing first and second main surfaces, a first support portion provided on the first main surface for supporting an optical fiber, a second support portion provided on the first main surface and spaced apart from the first support portion along the longitudinal direction of the optical fiber, and a metal reflector including a heat transfer portion having an opposing surface facing the substrate, wherein the second support portion has an inclined portion that is inclined toward the longitudinal direction with respect to the direction in which the first and second main surfaces are aligned, the second support portion or the metal reflector collects the emitted light from the optical fiber or the substrate, and at least a part of the metal reflector is provided along the inclined portion and reflects the emitted light. The heat transfer portion is located on the substrate side in the direction in which the first main surface and the second main surface are aligned, relative to the reflection position of the emitted light, the thickness of the inclined portion along the normal direction increases as it approaches the substrate, the adhesive member is provided between the opposing surface and the substrate, and the thermal conductivity of the heat transfer portion and the thermal conductivity of the adhesive member are each higher than the thermal conductivity of the second support portion.

[0008] The thermal conductivity of the heat transfer section and the adhesive member are both higher than the thermal conductivity of the second support section. Furthermore, the adhesive member is provided between the opposing surface and the substrate. Therefore, heat generated at the reflection position is easily transferred from the opposing surface to the adhesive member via the heat transfer section, and then to the substrate via the adhesive member. In other words, the heat transfer section, adhesive member, and substrate form a heat transfer path for the heat generated at the reflection position. Here, the thickness of the heat transfer section increases as it approaches the substrate. Therefore, heat generated at the reflection position is easily transferred from the heat transfer section to the substrate. This suppresses the transfer of heat generated at the reflection position to the first support section and to the boundary between the first main surface and the inclined section. Therefore, the optical coupling module can suppress overheating caused by heat generated when reflecting light.

[0009] An optical coupler according to one embodiment of the present invention includes: a base having opposing first main surface and second main surface; a first support portion provided on the first main surface for supporting an optical fiber; a second support portion provided on the first main surface and spaced apart from the first support portion along the longitudinal direction of the optical fiber; and a metal reflector including a heat transfer portion having a surface facing a substrate, wherein the second support portion has an inclined portion that is inclined toward the longitudinal direction with respect to the direction in which the first and second main surfaces are aligned, the second support portion or the metal reflector collects the emitted light from the optical fiber or the substrate, at least a part of the metal reflector is provided along the inclined portion and reflects the emitted light, the heat transfer portion is located on the substrate side in the direction in which the first and second main surfaces are aligned more than the reflection position of the emitted light, the thickness along the normal direction of the inclined portion becomes thicker as it approaches the substrate, and the thermal conductivity of the heat transfer portion is higher than the thermal conductivity of the second support portion.

[0010] The thermal conductivity of the heat transfer section is higher than that of the second support section. Therefore, heat generated at the reflection position is more easily transferred from the opposing surface to the substrate via the heat transfer section. In other words, the heat transfer section serves as a heat transfer path for heat generated at the reflection position to the substrate. Here, the thickness of the heat transfer section increases as it approaches the substrate. Therefore, heat generated at the reflection position is more easily transferred from the heat transfer section to the substrate. This suppresses the transfer of heat generated at the reflection position to the first support section and to the boundary between the first main surface and the inclined section. Therefore, the optical coupler can suppress overheating caused by heat generated when reflecting light.

[0011] According to the present invention, it is possible to suppress overheating caused by heat generated when reflecting light.

[0012] Figure 1 is a perspective view of the optical coupling module 100. Figure 2 is a perspective view of the optical coupler 1. Figure 3 is a side view of the optical coupling module 100. Figure 4 is a cross-sectional view of the optical coupling module 100 in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4. Figure 5 is a side view of the optical coupling module 100 showing the direction of propagation of the emitted light L and the heat transfer path H. Figure 6 is a cross-sectional view of the plurality of second support parts 16 and plurality of metal reflectors 17 in a plane passing through the reflection position RP and parallel to the fourth direction DIR4 and the fifth direction DIR5. Figure 7 is a side view of the optical coupling module 100a. Figure 8 is a cross-sectional view of the optical coupling module 100a in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4. Figure 9 is a side view of the optical coupling module 100a showing the direction of propagation of the emitted light L and the heat transfer path H. Figure 10 is a perspective view of a hypothetical first ellipsoid EL1. Figure 11 is a side view of the optical coupling module 100b. Figure 12 is a side view of the optical coupling module 100b in which the metal reflector 17 includes two layers of metal films 17a and 17b. Figure 13 is a side view of the optical coupling module 100c. Figure 14 is a cross-sectional view of the optical coupling module 100d in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4. Figure 15 is a cross-sectional view of the optical coupling module 100e in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4.

[0013] [First Embodiment] Below, an optical coupling module 100 according to the first embodiment of the present invention will be described with reference to the drawings. Figure 1 is a perspective view of the optical coupling module 100. Figure 2 is a perspective view of the optical coupler 1. In Figure 2, reference numerals are given only to representative first support parts 15, second support parts 16, metal reflectors 17, and grooves G among the plurality of first support parts 15, plurality of second support parts 16, plurality of metal reflectors 17, and plurality of grooves G. Figure 3 is a side view of the optical coupling module 100. In Figure 3, reference numerals are given only to representative fillers F among the plurality of fillers F. Figure 4 is a cross-sectional view of the optical coupling module 100 in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4. Figure 5 is a side view of the optical coupling module 100 showing the direction of propagation of emitted light L and the heat transfer path H. In Figures 3 to 5, the side wall portion 12 is omitted. Furthermore, in Figures 3 and 5, for illustrative purposes, only the cross-section of the metal reflector 17 in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4 is shown. Figure 6 is a cross-sectional view of the multiple second support parts 16 and the multiple metal reflectors 17 in a plane passing through the reflection position RP and parallel to the fourth direction DIR4 and the fifth direction DIR5.

[0014] In this specification, directions are defined as follows: As shown in Figure 3, the direction in which the second main surface S2 and the first main surface S1 are aligned in this order is defined as the first direction DIR1. The opposite direction of the first direction DIR1 is defined as the second direction DIR2. The direction in which the optical fiber 20 and the metal reflector 17 are aligned in this order is defined as the third direction DIR3. The direction in which the optical fiber 20 extends is defined as the fourth direction DIR4. In this embodiment, the third direction DIR3 is the opposite direction of the fourth direction DIR4. As shown in Figure 2, the direction in which the plurality of second support parts 16 are aligned is defined as the fifth direction DIR5. The first direction DIR1, the fourth direction DIR4, and the fifth direction DIR5 are orthogonal to each other. However, the first direction DIR1, second direction DIR2, third direction DIR3, fourth direction DIR4, and fifth direction DIR5 in this embodiment are directions defined for the convenience of explanation and do not necessarily coincide with the first direction DIR1, second direction DIR2, third direction DIR3, fourth direction DIR4, and fifth direction DIR5 when the optical coupling module 100 is in use.

[0015] In this specification, "surface roughness" means the arithmetic mean height Sa measured in accordance with ISO 25178.

[0016] The optical coupling module 100 is a device that changes the direction of propagation of light emitted from a photoelectric conversion circuit or the like (not shown), and transmits it by having it enter an optical fiber, or transmits light through an optical fiber, emits the transmitted light from the optical fiber, changes the direction of propagation of the light emitted from the optical fiber, and outputs it to a photoelectric conversion circuit or the like. In this embodiment, the case in which the optical coupling module 100 transmits light through an optical fiber, emits the transmitted light from the optical fiber, changes the direction of propagation of the emitted light L from the optical fiber from the third direction DIR3 to the second direction DIR2, and outputs it to a photoelectric conversion circuit or the like will be described.

[0017] As shown in Figure 1, the optical coupling module 100 comprises an optical coupler 1, a plurality of optical fibers 20, an adhesive member 30, and a substrate 50. The substrate 50 is plate-shaped. The material of the substrate 50 is silicon or the like. The substrate 50 has an optical waveguide OW. The optical waveguide OW will be described later. The optical coupler 1 is mounted on the substrate 50. Therefore, the optical coupler 1 is supported by the substrate 50.

[0018] Multiple optical fibers 20 are arranged along the fifth direction DIR 5. The optical fibers 20 are cylindrical in shape and extend along the fourth direction DIR 4. That is, the third direction DIR 3 and the fourth direction DIR 4 are the longitudinal directions of the optical fibers 20, respectively. Multiple optical fibers 20 are supported by the optical coupler 1. Each of the multiple optical fibers 20 transmits light and emits the transmitted light toward the optical coupler 1. Note that the number of optical fibers 20 is not limited to multiple, but may be one or more.

[0019] As shown in Figure 2, the optical coupler 1 includes a side wall portion 12, a base portion 14, a plurality of first support portions 15, a plurality of second support portions 16, and a plurality of metal reflectors 17.

[0020] The materials of the side wall portion 12, the base portion 14, the first support portion 15, and the second support portion 16 are glass, glass containing fillers, or resin, etc. The glass is a material that is amorphous and exhibits a glass transition phenomenon. The glass is a simple oxide glass such as SiO ２ , B ２ O ３ , P ２ O ５ , GeO ２ , AS3O ３ , etc., a silicate glass such as Li ２ -SiO ２ , Na ２ O - SiO ２ , K ２ O - SiO ２ , etc., an aluminosilicate glass such as Na ２ O - Al ２ O ３ -SiO ２ , CaO - Al[[ID=--35]] ２ O ３ -SiO[[ID=3--9]] ２ , etc., a borate glass such as Li ２ O - B ２ O ３ , Na ２ O - B ２ O ３ , etc., an aluminoborate glass such as CaO - Al ２ O ３ -B ２ O ３ , etc., or a borosilicate glass such as Na ２ O - Al ２ O ３ -B ２ O ３ -SiO ２ , etc. The filler is metal oxide particles such as crystalline silica, amorphous silica, alumina, magnesium oxide, titanium oxide, etc.

[0021] It should be noted that there may be some inaccuracies in the original text such as "AS3O" which might be an incorrect chemical formula. Also, there seem to be some hyphens in the translated text that might not be in the correct position in the original due to the format in the source text. You may want to double-check the original for accuracy.The side wall portion 12, base portion 14, multiple first support portions 15, and multiple second support portions 16 are integrally molded from glass containing a filler. The method of integral molding from glass containing a filler is compression molding or chemical etching. The optical coupler 1 is a single component. Here, a single component means a component that has a structure that cannot be separated without damaging it. Therefore, a component in which two resin pieces are fixed by screws is not a single component. The thermal conductivity of the side wall portion 12, base portion 14, first support portions 15, and second support portions 16 is lower than that of the substrate 50. That is, the thermal conductivity of the substrate 50 is higher than the thermal conductivity of the base portion 14, first support portions 15, and second support portions 16. When the material of the base portion 14, first support portions 15, and second support portions 16 is resin, the method of integral molding from resin is resin molding using a mold. Furthermore, the side wall portion 12, the base portion 14, the plurality of first support portions 15, and the plurality of second support portions 16 do not necessarily have to be integrally molded.

[0022] The side wall portion 12 is provided around a plurality of first support portions 15 and a plurality of second support portions 16. The side wall portion 12 has a first side wall portion 121, a second side wall portion 122, and a third side wall portion 123. The first side wall portion 121, the second side wall portion 122, and the third side wall portion 123 are each plate-shaped. The first side wall portion 121 is located at the end of the third direction DIR 3 of the optical coupler 1. The first side wall portion 121 extends along the fifth direction DIR 5. The second side wall portion 122 is located at the end of the fifth direction DIR 5 of the optical coupler 1. The second side wall portion 122 extends along the third direction DIR 3. The third side wall portion 123 is located at the end of the optical coupler 1 in the opposite direction to the fifth direction DIR 5. The third side wall portion 123 extends along the third direction DIR 3. The end of the fifth direction DIR 5 of the first side wall portion 121 is connected to the end of the third direction DIR 3 of the second side wall portion 122. Also, the opposite end of the fifth direction DIR 5 of the first side wall portion 121 is connected to the end of the third direction DIR 3 of the third side wall portion 123. As a result, the first side wall portion 121 is connected to the end of the third direction DIR 3 of the second side wall portion 122 and to the end of the third direction DIR 3 of the third side wall portion 123.

[0023] Each of the multiple first support sections 15 is provided corresponding to each of the multiple optical fibers 20. Therefore, the multiple first support sections 15 are arranged along the fifth direction DIR 5. Each of the multiple second support sections 16 is provided corresponding to each of the multiple first support sections 15. Therefore, the multiple second support sections 16 are arranged along the fifth direction DIR 5. Each of the multiple metal reflectors 17 is provided corresponding to each of the multiple second support sections 16. Therefore, the multiple metal reflectors 17 are arranged along the fifth direction DIR 5. Adjacent metal reflectors 17 are not connected. Note that the number of first support sections 15, the number of second support sections 16, and the number of metal reflectors 17 are not limited to multiple, but may be one. Below, one set including one first support section 15, one second support section 16, and one metal reflector 17 will be described.

[0024] The base portion 14 is plate-shaped. As shown in Figure 3, the base portion 14 has a first main surface S1 and a second main surface S2. The first main surface S1 and the second main surface S2 are opposite to each other. The second main surface S2 and the first main surface S1 are aligned in this order along the first direction DIR1. That is, the first direction DIR1 and the second direction DIR2 are the directions in which the first main surface S1 and the second main surface S2 are aligned, respectively. The base portion 14 is connected to the second side wall portion 122 and the third side wall portion 123, respectively. The base portion 14 supports the first support portion 15 and the second support portion 16.

[0025] Each of the plurality of first support portions 15 is provided on the first main surface S1. The first support portion 15 is provided in the fourth direction DIR4 rather than the second support portion 16. The first support portion 15 is plate-shaped and extends along the fourth direction DIR4. On the end surface of the first support portion 15 in the first direction DIR1, a groove G having a V shape is provided when viewed in the third direction DIR3. The groove G extends along the fourth direction DIR4. The first support portion 15 supports the optical fiber 20 by the groove G. Thereby, when viewed in the third direction DIR3, the first support portion 15 supports the optical fiber 20 at two points. Note that the groove G may have a U shape when viewed in the third direction DIR3. Also, the groove G may not be provided on the end surface of the first support portion 15 in the first direction DIR1. The first support portion 15 may support the optical fiber 20 by an adhesive such as an epoxy resin, for example.

[0026] As shown in FIG. 4, in a cross section passing through the reflection position RP and orthogonal to the fourth direction DIR4, the length L1 along the first direction DIR1 of the first support portion 15 is equal to or greater than the radius R20 of the optical fiber 20. In the present embodiment, as shown in FIG. 1, the coating at the tip of the optical fiber 20 is removed. Therefore, the radius R20 of the optical fiber 20 is half of the cladding diameter of the optical fiber 20. Also, in a cross section orthogonal to the fourth direction DIR4, the length L1 along the first direction DIR1 of the first support portion 15 is the distance along the first direction DIR1 between the vertex V of the groove G and the first main surface S1.

[0027] As shown in FIG. 5, the end surface of the optical fiber 2 in the third direction DIR3 is the light emission surface. The emitted light L of the optical fiber 20 travels toward the third direction DIR3 and enters the second support portion 16.

[0028] As shown in FIG. 3, the second support portion 16 is provided on the first main surface S1. The second support portions 16 are arranged at intervals along the third direction DIR3 and alongside the first support portion 15. In the present embodiment, each of the plurality of second support portions 16 is connected to both the first main surface S1 and the second main surface S2. More specifically, the second support portion 16 is provided at both the end portion in the third direction DIR3 of the first main surface S1 and the end portion in the third direction DIR3 of the second main surface S2, and connects the end portion in the third direction DIR3 of the first main surface S1 and the end portion in the third direction DIR3 of the second main surface S2.

[0029] The end surface of the second support portion 16 in the fourth direction DIR4 is orthogonal to the third direction DIR3. Also, as shown in FIG. 5, the end surface of the second support portion 16 in the fourth direction DIR4 faces the end surface of the optical fiber 20 in the third direction DIR3. The end surface of the second support portion 16 in the fourth direction DIR4 is the incident surface of the outgoing light L.

[0030] As shown in FIG. 3, the second support portion 16 has an inclined portion SL. The inclined portion SL is inclined toward the fourth direction DIR4 with respect to the first direction DIR1. The inclined portion SL is inclined at an acute angle with respect to the second main surface S2. The inclined portion SL is located in the third direction DIR3 rather than the end surface of the second support portion 16 in the fourth direction DIR4. The inclined portion SL is a convex curved surface curved so as to protrude in the combined direction of the first direction DIR1 and the third direction DIR3. By being a convex curved surface, the inclined portion SL functions as a condenser lens (condensing portion). Thereby, the second support portion 16 condenses the outgoing light L that has traveled within the second support portion 16. The shape of the convex curved surface is designed such that the focal point of the condenser lens becomes the end surface of the optical fiber 20 in the third direction DIR3. Thereby, the coupling efficiency can be improved. The method of forming the convex curved surface is precision cutting using a mold die or chemical etching or the like. Note that the inclined portion SL may be a flat surface.

[0031] In addition, by making the end surface of the second support portion 16 in the fourth direction DIR4 a curved surface, the end surface of the second support portion 16 in the fourth direction DIR4 may function as a condenser lens (condensing portion). Even in this case, the second support portion 16 condenses the outgoing light L.

[0032] The metal reflector 17 is provided along the inclined portion SL. In this embodiment, the entire metal reflector 17 is provided along the inclined portion SL. Furthermore, the end of the metal reflector 17 with respect to the second direction DIR2 is connected to the second main surface S2. Note that only a part of the metal reflector 17 may be provided along the inclined portion SL. That is, it is sufficient that at least a part of the metal reflector 17 is provided along the inclined portion SL.

[0033] As shown in Figure 5, the emitted light L that enters the second support portion 16 from the end face of the fourth direction DIR 4 of the second support portion 16 travels within the second support portion 16. The metal reflector 17 reflects the emitted light L focused by the second support portion 16. Specifically, the metal reflector 17 reflects the emitted light L focused by the second support portion 16 to the optical waveguide OW of the substrate 50. The joint surface between the metal reflector 17 and the inclined portion SL is the reflection surface of the emitted light L. The reflection position RP of the emitted light L is the intersection of the straight line extending the central axis CA 20 of the optical fiber 20 and the metal reflector 17. The direction of travel of the emitted light L is changed from the third direction DIR 3 to the second direction DIR 2 by the metal reflector 17.

[0034] The material of the metal reflector 17 is a metal such as gold, platinum, or copper. The metal reflector 17 can be installed along the inclined portion SL by sputtering or plating the inclined portion SL. The thermal conductivity of the metal reflector 17 is higher than that of the base portion 14, the first support portion 15, and the second support portion 16, respectively.

[0035] As shown in Figure 3, the thickness T17 of the metal reflector 17 is not uniform. The thickness T17 of the metal reflector 17 is the length along the normal direction of the inclined portion SL of the metal reflector 17. In this embodiment, the thickness T17 of the metal reflector 17 increases as you move toward the second direction DIR2. In other words, the thickness T17 of the metal reflector 17 decreases as you move toward the first direction DIR1. Therefore, in the first direction DIR1, the thickness T17 of the metal reflector 17 decreases as you move away from the substrate 50. More specifically, the thickness T17 of the metal reflector 17 decreases as it moves away from the substrate 50, both in the first direction DIR1 (the side further from the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) relative to the reflection position RP, and in the second direction DIR2 (the side closer to the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) relative to the reflection position RP. Furthermore, the thickness T17 of the metal reflector 17 increases as it moves toward the third direction DIR3 (away from the first support portion 15). In the case of sputtering, the thickness T17 of the metal reflector 17 can be controlled by tilting the target beam obliquely with respect to the inclined portion SL. In the case of plating, the thickness T17 of the metal reflector 17 can be controlled by making the thickness of the seed layer uneven.

[0036] The metal reflector 17 has a heat transfer section HTP. In this embodiment, the heat transfer section HTP is a part of the metal reflector 17. That is, the material of the heat transfer section HTP is a metal such as gold, platinum, or copper. The thermal conductivity of the heat transfer section HTP is higher than the thermal conductivity of the base 14, the first support section 15, and the second support section 16, respectively. In this embodiment, the entire heat transfer section HTP is provided along the inclined section SL. The heat transfer section HTP is located in the second direction DIR2 (towards the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) from the reflection position RP, and is adjacent to the reflection position RP. The heat transfer section HTP also has a facing surface OS that faces the substrate 50. The facing surface OS is located in the second direction DIR2 (towards the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) from the optical fiber 20. In other words, the optical fiber 20 is located in the first direction DIR1 (the side further from the substrate 50 in the direction in which the first main surface S1 and the second main surface S2 are aligned) from the opposing surface OS. Furthermore, only a portion of the heat transfer section HTP may be provided along the inclined section SL. That is, it is sufficient that at least a portion of the heat transfer section HTP is provided along the inclined section SL.

[0037] The reflection position RP is located in the second direction DIR2 (towards the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) rather than in the first direction DIR1, where CSL is the center of the inclined portion SL.

[0038] As described above, the thickness T17 of the metal reflector 17 increases as it moves toward the second direction DIR2. Therefore, the thickness TH of the heat transfer section HTP increases as it approaches the substrate 50. Also, the thickness TH of the heat transfer section HTP increases as it moves toward the third direction DIR3 (away from the first support section 15). The thickness TH of the heat transfer section HTP is the length along the normal direction of the inclined section SL of the heat transfer section HTP.

[0039] The adhesive member 30 is provided between the opposing surface OS and the substrate 50. In this embodiment, the adhesive member 30 is provided not only between the opposing surface OS and the substrate 50, but also between the second main surface S2 and the substrate 50. The adhesive member 30 adheres the optical coupler 1 to the substrate 50. The thermal conductivity of the adhesive member 30 is higher than the thermal conductivity of the base portion 14, the first support portion 15, and the second support portion 16, respectively.

[0040] The adhesive member 30 has an adhesive GL and a plurality of fillers F. The plurality of fillers F are mixed in the adhesive GL. The material of the adhesive GL is a thermosetting resin such as epoxy resin. The fillers F are metal oxide particles such as crystalline silica, amorphous silica, alumina, magnesium oxide, and titanium oxide. The fillers F have an aspherical shape. The plurality of fillers F are dispersed throughout the adhesive GL. The thermal conductivity of the fillers F is higher than that of the adhesive GL. Note that the adhesive member 30 does not necessarily have to contain fillers F.

[0041] The adhesive member 30 consists of a network structure in which multiple polymerized adhesive molecules are intertwined. The size of this network structure is approximately 10 to 100 μm. To ensure sufficient adhesive strength, the thickness of the adhesive member 30 along the first direction DIR1 is preferably approximately 10 to 100 μm. Furthermore, since heat is transmitted through this network structure, from the viewpoint of thermal conductivity, the thickness of the adhesive member 30 along the first direction DIR1 is also preferably approximately 10 to 100 μm. In other words, the substrate 50 is in very close proximity to the optical coupler 1.

[0042] The optical waveguide OW of the substrate 50 is provided in a second direction DIR2 from the reflection position RP, and in a third direction DIR3 from the reflection position RP. The optical waveguide OW is provided in the third direction DIR3 from the second support portion 16. Furthermore, the optical waveguide OW extends along the third direction DIR3. In this embodiment, the optical waveguide OW is hollow. The emitted light L, reflected by the metal reflector 17 and traveling through the second support portion 16, enters the adhesive member 30 and travels through the adhesive member 30. The emitted light L that has traveled through the adhesive member 30 travels through the optical waveguide OW and enters the photoelectric conversion circuit, etc., mounted on the substrate 50. Note that the optical waveguide OW is not limited to a hollow space. In this case, the material of the optical waveguide OW includes, for example, SiO2 (silicon dioxide).

[0043] As shown in Figure 6, a connecting portion CP is provided between adjacent second support portions 16. The connecting portion CP connects adjacent inclined portions SL. The metal reflector 17 is not provided at the boundary BO between the inclined portion SL and the connecting portion CP.

[0044] The optical coupling module 100 can suppress overheating caused by heat generated when reflecting light. More specifically, the thermal conductivity of the heat transfer section HTP and the thermal conductivity of the adhesive member 30 are both higher than the thermal conductivity of the second support section 16. The adhesive member 30 is provided between the opposing surface OS and the substrate 50. Therefore, the heat H generated at the reflection position RP is easily transferred from the opposing surface OS to the adhesive member 30 via the heat transfer section HTP, and then to the substrate 50 via the adhesive member 30. In other words, the heat transfer section HTP, the adhesive member 30, and the substrate 50 become the heat transfer paths for the heat H generated at the reflection position RP. Here, the thickness TH of the heat transfer section HTP increases as it approaches the substrate 50. Therefore, the heat H generated at the reflection position RP is easily transferred from the heat transfer section HTP to the substrate 50. This prevents the heat H generated at the reflection position RP from being transmitted to the first support portion 15 and to the boundary between the first main surface S1 and the inclined portion SL. Therefore, the optical coupling module 100 can suppress overheating caused by the heat generated when reflecting light.

[0045] Furthermore, the thickness T17 of the metal reflector 17 decreases as it moves away from the substrate 50 in the first direction DIR1 (the side further from the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) from the reflection position RP. This makes it easier for the heat H generated at the reflection position RP to be directed from the heat transfer section HTP to the adhesive member 30 and the substrate 50.

[0046] Furthermore, the reflection position RP is located in the second direction DIR2 (the substrate side in the direction where the first main surface S1 and the second main surface S2 are aligned) rather than in the first direction DIR1, where CSL is the center of the inclined portion SL. As a result, the reflection position RP is closer to the adhesive member 30 and the substrate 50. Consequently, the heat H generated at the reflection position RP is more easily directed from the heat transfer section HTP to the adhesive member 30 and the substrate 50.

[0047] Furthermore, the thermal conductivity of the substrate 50 is higher than that of the base portion 14, the first support portion 15, and the second support portion 16. This makes it easier for the heat H generated at the reflection position RP to be transferred to the substrate 50.

[0048] Furthermore, the adhesive member 30 includes an adhesive GL and a plurality of fillers F. The thermal conductivity of the fillers F is higher than that of the adhesive GL. This makes it possible to further increase the thermal conductivity of the adhesive member 30. As a result, the heat H generated at the reflection position RP is more easily transferred from the opposing surface OS to the adhesive member 30 via the heat transfer section HTP, and then to the substrate 50 via the adhesive member 30.

[0049] Furthermore, stress concentrates in the portion of the second support portion 16 where the curvature changes significantly. Specifically, stress concentrates at the boundary BO between the inclined portion SL and the connecting portion CP. If the metal reflector 17 is provided at the location where stress is concentrated, there is a risk that the metal reflector 17 will be damaged by the stress. Therefore, in the optical coupling module 100, the metal reflector 17 is not provided at the boundary BO between the inclined portion SL and the connecting portion CP. This suppresses damage to the metal reflector 17 due to stress concentration.

[0050] Furthermore, in a cross-section passing through the reflection position RP and perpendicular to the fourth direction DIR4, the length L1 of the first support portion 15 along the first direction DIR1 is greater than or equal to the radius R20 of the optical fiber 20. As a result, the optical fiber 20 is moved away from the first main surface S1. That is, the optical fiber 20 is moved away from the substrate 50. Therefore, the transfer of heat H generated at the reflection position RP to the optical fiber 20 via the substrate 50 and the base portion 14 is suppressed, and overheating of the optical fiber 20 can be suppressed.

[0051] Furthermore, the optical fiber 20 is located in the first direction DIR1 (the side further from the substrate 50 in the direction in which the first main surface S1 and the second main surface S2 are aligned) relative to the opposing surface OS. As a result, the optical fiber 20 is farther from the first main surface S1. In other words, the optical fiber 20 is farther from the substrate 50. Therefore, the transfer of heat H generated at the reflection position RP to the optical fiber 20 via the substrate 50 and the base 14 is suppressed, and overheating of the optical fiber 20 can be suppressed.

[0052] Furthermore, the thickness TH of the heat transfer section HTP increases as it moves away from the first support section 15. Therefore, the heat transfer path of the heat H generated at the reflection position RP by the heat transfer section HTP, adhesive member 30, and substrate 50 can be made farther away from the first support section 15.

[0053] Furthermore, because the optical waveguide OW is hollow, even if heat H is transferred to the substrate 50, the position and optical axis of the optical waveguide OW are less likely to shift. In addition, the substrate 50 may include a heat bath such as a heat sink. This allows the heat H transferred to the substrate 50 to be quickly released into the heat bath.

[0054] The direction of propagation of the emitted light L may be the opposite of the direction shown in this embodiment. That is, the optical coupling module 100 may change the direction of propagation of the emitted light L, which is emitted from the photoelectric conversion circuit, etc. and has traveled through the optical waveguide OW, from the first direction DIR1 to the fourth direction DIR4, and emit it into the optical fiber 20. In this case, the second support portion 16 collects the emitted light L from the photoelectric conversion circuit, etc., mounted on the substrate 50, which has traveled through the second support portion 16.

[0055] [Second Embodiment] Below, an optical coupling module 100a according to a second embodiment of the present invention will be described with reference to the drawings. Figure 7 is a side view of the optical coupling module 100a. In Figure 7, only a representative filler F among the multiple fillers F is given a reference numeral. Figure 8 is a cross-sectional view of the optical coupling module 100a in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4. Figure 9 is a side view of the optical coupling module 100a showing the direction of propagation of the emitted light L and the heat transfer path H. In Figures 7 to 9, the side wall portion 12 is omitted. Also, in Figures 7 and 9, for explanatory purposes, only the cross-section of the metal reflector 17 in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4 is shown. Figure 10 is a perspective view of a hypothetical first ellipsoid EL1.

[0056] The optical coupling module 100a includes an optical coupler 1a. As shown in Figure 7, in the optical coupler 1a, the second support portion 16 is provided on the first main surface S1. The second support portion 16 is arranged along the third direction DIR 3 with a gap between it and the first support portion 15. The second support portion 16 is perpendicular to the third direction DIR 3 and does not have an end face of the fourth direction DIR 4 that is opposite to the end face of the third direction DIR 3 of the optical fiber 20. On the other hand, the second support portion 16 has an end face of the third direction DIR 3 that is perpendicular to the third direction DIR 3.

[0057] The inclined portion SL is located in the fourth direction DIR4 rather than the end face of the second support portion 16 in the third direction DIR3. The second support portion 16 is not present between the inclined portion SL and the optical fiber 20. The inclined portion SL is inclined toward the third direction DIR3 with respect to the first direction DIR1. The inclined portion SL is inclined at an acute angle with respect to the first main surface S1. The inclined portion SL is a concave curved surface that is concave toward the combined direction of the second direction DIR2 and the third direction DIR3. Methods for forming the concave curved surface include precision cutting using a mold or chemical etching. Note that the concave curved surface is not limited to an ellipsoid, but may also be a parabolic surface, etc.

[0058] As shown in Figure 8, in this embodiment as well, in a cross section passing through the reflection position RP and perpendicular to the fourth direction DIR4, the length L1 of the first support portion 15 along the first direction DIR1 is greater than or equal to the radius R20 of the optical fiber 20. In this embodiment as well, the coating at the tip of the optical fiber 20 is removed. Therefore, the radius R20 of the optical fiber 20 is half the cladding diameter of the optical fiber 20. Furthermore, in a cross section perpendicular to the fourth direction DIR4, the length L1 of the first support portion 15 along the first direction DIR1 is the distance along the first direction DIR1 between the apex V of the groove G and the first main surface S1.

[0059] As shown in Figure 9, the light L emitted from the optical fiber 20 enters the adhesive member 30 and travels through the adhesive member 30 toward the third direction DIR3.

[0060] As shown in Figure 7, a portion of the metal reflector 17 is provided along the inclined portion SL. The surface S17 of the metal reflector 17 is the incident surface of the emitted light L. The metal reflector 17 is a concave curved surface that is concave in the direction of the composite direction of the second direction DIR2 and the third direction DIR3. Due to its concave curved surface, the surface S17 of the metal reflector 17 functions as a focusing lens (focusing portion). As a result, the surface S17 of the metal reflector 17 focuses the emitted light L that has traveled through the adhesive member 30. The shape of the surface S17 of the metal reflector 17 is designed so that the focal point of the focusing lens is the end face of the third direction DIR3 of the optical fiber 20. This improves the coupling efficiency.

[0061] As shown in Figure 9, the metal reflector 17 reflects the emitted light L focused by the surface S17 of the metal reflector 17. Specifically, the metal reflector 17 reflects the emitted light L focused by the surface S17 of the metal reflector 17 to the optical waveguide OW of the substrate 50. The joint surface between a part of the metal reflector 17, which is provided along the inclined portion SL, and the adhesive member 30 is the reflection surface of the emitted light L. The reflection position RP of the emitted light L is the intersection of the straight line extending the central axis CA20 of the optical fiber 20 and the metal reflector 17. The direction of propagation of the emitted light L is changed from the third direction DIR3 to the first direction DIR1 by the metal reflector 17.

[0062] As shown in Figure 7, the thickness T17 of the metal reflector 17 is not uniform. The thickness T17 of the metal reflector 17 increases as you move toward the first direction DIR1. In other words, the thickness T17 of the metal reflector 17 decreases as you move toward the second direction DIR2. Therefore, in the first direction DIR1, the thickness T17 of the metal reflector 17 decreases as you move away from the substrate 50. More specifically, the thickness T17 of the metal reflector 17 decreases as you move away from the substrate 50, both in the first direction DIR1 (the side further from the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) relative to the reflection position RP, and in the second direction DIR2 (the side closer to the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) relative to the reflection position RP. Furthermore, the thickness T17 of the metal reflector 17 increases as you move toward the third direction DIR3 (away from the first support portion 15).

[0063] The heat transfer section HTP is part of the metal reflector 17. That is, the material of the heat transfer section HTP is a metal such as gold, platinum, or copper. The thermal conductivity of the heat transfer section HTP is higher than the thermal conductivity of the base 14, the first support 15, and the second support 16, respectively. In this embodiment, a part of the heat transfer section HTP is provided along the inclined section SL. The heat transfer section HTP is located in the first direction DIR1 (towards the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) from the reflection position RP. The heat transfer section HTP also has a facing surface OS that faces the substrate 50. The facing surface OS is located in the second direction DIR2 (towards the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) from the optical fiber 20. In other words, the optical fiber 20 is located in the first direction DIR1 (the side further from the substrate 50 in the direction in which the first main surface S1 and the second main surface S2 are aligned) relative to the opposing surface OS. The entire heat transfer section HTP may be provided along the inclined section SL. That is, at least a portion of the heat transfer section HTP may be provided along the inclined section SL.

[0064] The reflection position RP is located in the first direction DIR1 (on the substrate 50 side in the direction where the first main surface S1 and the second main surface S2 are aligned) more than the center CSL of the inclined portion SL in the first direction DIR1.

[0065] As described above, the thickness T17 of the metal reflector 17 increases as it moves toward the first direction DIR1. Therefore, the thickness TH of the heat transfer section HTP increases as it approaches the substrate 50. Also, the thickness TH of the heat transfer section HTP increases as it moves toward the third direction DIR3 (away from the first support section 15). The thickness TH of the heat transfer section HTP is the length along the normal direction of the inclined section SL of the heat transfer section HTP.

[0066] As shown in Figure 10, in this embodiment, at least a portion of the surface S17 of the metal reflector 17 is a portion of the first ellipsoid SEL1 of a hypothetical first ellipsoid EL1. Also, at least a portion of the surface of the inclined portion SL is a portion of the second ellipsoid of a hypothetical second ellipsoid. Here, the second ellipsoid is not an ideal ellipsoid. An ideal ellipsoid is a spheroid in which, among the three diameters a, b, and c, where diameter a is the length in the major axis direction and diameter b is the length in the minor axis direction, diameter b and diameter c are equal. The first ellipsoid EL1 is more ideal than the second ellipsoid. Therefore, in the first ellipsoid EL1, diameter b is approximately equal to diameter c.

[0067] In this embodiment, the surface S17 (reflection position RP) of the metal reflector 17 focuses and reflects the light L emitted from the optical fiber 20. Therefore, by applying a metal coating so that at least a portion of the surface S17 of the metal reflector 17 becomes part of the ellipsoidal surface of a more ideal ellipsoid, the focusing efficiency can be improved and the coupling efficiency can be further improved.

[0068] In the first embodiment, the surface (reflection position RP) of the inclined portion SL of the second support portion 16 focuses and reflects the emitted light L of the optical fiber 20. Therefore, in the first embodiment, by forming the surface of the inclined portion SL of the second support portion 16 so that at least a part of it becomes part of the ellipsoidal surface of a more ideal ellipsoid, the focusing efficiency can be improved and the coupling efficiency can be further improved.

[0069] As shown in Figure 7, the heat transfer section HTP has a facing section OP. At least a portion of the facing section OP is provided on the end face of the second support section 16 in the first direction DIR1 (the substrate 50 side in the direction where the first main surface S1 and the second main surface S2 are aligned). The facing section OP faces the substrate 50. The portion of the facing section OP that faces the substrate 50 extends in the third direction DIR3 (the direction away from the first support section 15). In this embodiment, the facing section OP covers the end face of the second support section 16 in the first direction DIR1. The length L2 of the facing section OP along the third direction DIR3 is equal to or greater than the length L3 along the inclined section SL from the reflection position RP of the heat transfer section HTP to the facing surface OS. Note that the facing section OP does not have to cover the end face of the second support section 16 in the first direction DIR1.

[0070] The thickness TOP of the opposing portion OP along the first direction DIR1 (the direction from the end face of the first direction DIR1 of the second support portion 16 toward the substrate 50) is greater than the maximum thickness TH of the heat transfer portion HTP along the normal direction of the inclined portion SL. The surface roughness of the opposing surface OS is greater than the surface roughness of the metal reflector 17 at the reflection position RP. More specifically, the surface roughness of the opposing surface OS is between 1 / 1000 and 1 / 10 of the thermal diffusion length of the adhesive member 30.

[0071] The optical fiber 20 is located in the second direction DIR2 (the side further from the substrate 50 in the direction in which the first main surface S1 and the second main surface S2 are aligned) rather than the opposing surface OS.

[0072] The adhesive member 30 is provided between the opposing surface OS and the substrate 50. In this embodiment, the adhesive member 30 is not limited to the space between the opposing surface OS and the substrate 50, but is also provided between the surface S17 of the metal reflector 17 and the substrate 50, between the surface of the second support portion 16 and the substrate 50, between the first main surface S1 and the substrate 50, between the end face of the first direction DIR1 of the first support portion 15 exposed from the optical fiber 20 and the substrate 50, and between the surface of the optical fiber 20 exposed in the first direction DIR1 and the substrate 50. The adhesive member 30 adheres the optical coupler 1a to the substrate 50. The thermal conductivity of the adhesive member 30 is higher than the thermal conductivity of the base portion 14, the first support portion 15, and the second support portion 16, respectively.

[0073] The optical waveguide OW of the substrate 50 is provided in a first direction DIR1 of the reflection position RP and in a third direction DIR3 of the reflection position RP. The optical waveguide OW is provided on the side of the second support portion 16 in the third direction DIR3. The optical waveguide OW also extends along the third direction DIR3. The emitted light L reflected by the metal reflector 17 travels through the adhesive member 30. The emitted light L that has traveled through the adhesive member 30 travels through the optical waveguide OW and is incident on the photoelectric conversion circuit, etc., mounted on the substrate 50.

[0074] In this embodiment as well, in a plane passing through the reflection position RP and parallel to the fourth direction DIR4 and the fifth direction DIR5, adjacent metal reflectors 17 (heat transfer section HTP) in the fifth direction DIR5 are not connected.

[0075] The optical coupling module 100a also suppresses overheating caused by heat generated when reflecting light. More specifically, the thermal conductivity of the heat transfer section HTP and the thermal conductivity of the adhesive member 30 are each higher than the thermal conductivity of the second support section 16. The adhesive member 30 is provided between the opposing surface OS and the substrate 50. Therefore, the heat H generated at the reflection position RP is easily transferred from the opposing surface OS to the adhesive member 30 via the heat transfer section HTP, and then to the substrate 50 via the adhesive member 30. In other words, the heat transfer section HTP, the adhesive member 30, and the substrate 50 become heat transfer paths for the heat H generated at the reflection position RP. Here, the thickness TH of the heat transfer section HTP increases as it approaches the substrate 50. Therefore, the heat H generated at the reflection position RP is easily transferred to the substrate 50. This prevents the heat H generated at the reflection position RP from being transmitted to the first support portion 15 and to the boundary between the first main surface S1 and the inclined portion SL. Therefore, the optical coupling module 100a can suppress overheating caused by the heat generated when reflecting light.

[0076] Furthermore, the thickness T17 of the metal reflector 17 decreases as it moves away from the substrate 50 in the second direction DIR2 (the side further from the substrate 50 in the direction where the first main surface S1 and the second main surface S2 are aligned) compared to the reflection position RP. This makes it easier for the heat H generated at the reflection position RP to be directed from the heat transfer section HTP to the adhesive member 30 and the substrate 50.

[0077] Furthermore, the reflection position RP is located in the first direction DIR1 (on the substrate side in the direction where the first main surface S1 and the second main surface S2 are aligned) more than the center CSL of the inclined portion SL in the first direction DIR1. As a result, the reflection position RP is closer to the adhesive member 30 and the substrate 50. Consequently, the heat H generated at the reflection position RP is more easily directed from the heat transfer section HTP to the adhesive member 30 and the substrate 50.

[0078] Furthermore, the thermal conductivity of the substrate 50 is higher than that of the base portion 14, the first support portion 15, and the second support portion 16. This makes it easier for the heat H generated at the reflection position RP to be transferred to the substrate 50.

[0079] Furthermore, the adhesive member 30 includes an adhesive GL and a plurality of fillers F. The thermal conductivity of the fillers F is higher than that of the adhesive GL. This makes it possible to further increase the thermal conductivity of the adhesive member 30. As a result, the heat H generated at the reflection position RP is more easily transferred from the opposing surface OS to the adhesive member 30 via the heat transfer section HTP, and then to the substrate 50 via the adhesive member 30.

[0080] Furthermore, stress concentrates in the portion of the second support portion 16 where the curvature changes significantly. Specifically, stress concentrates at the boundary BO between the inclined portion SL and the connecting portion CP. If the metal reflector 17 is provided at the location where stress is concentrated, there is a risk that the metal reflector 17 will be damaged by the stress. Therefore, in the optical coupling module 100a, the metal reflector 17 is not provided at the boundary BO between the inclined portion SL and the connecting portion CP. This suppresses damage to the metal reflector 17 due to stress concentration.

[0081] Furthermore, in a cross-section passing through the reflection position RP and perpendicular to the fourth direction DIR4, the length L1 of the first support portion 15 along the first direction DIR1 is greater than or equal to the radius R20 of the optical fiber 20. As a result, the optical fiber 20 is moved away from the first main surface S1. That is, the optical fiber 20 is moved away from the substrate 50. Therefore, the transfer of heat H generated at the reflection position RP to the optical fiber 20 via the substrate 50 and the base portion 14 is suppressed, and overheating of the optical fiber 20 can be suppressed.

[0082] Furthermore, the optical fiber 20 is located in the first direction DIR1 (the side further from the substrate 50 in the direction in which the first main surface S1 and the second main surface S2 are aligned) relative to the opposing surface OS. As a result, the optical fiber 20 is farther from the first main surface S1. In other words, the optical fiber 20 is farther from the substrate 50. Therefore, the transfer of heat H generated at the reflection position RP to the optical fiber 20 via the substrate 50 and the base 14 is suppressed, and overheating of the optical fiber 20 can be suppressed.

[0083] Furthermore, the thickness TH of the heat transfer section HTP increases as it moves away from the first support section 15. Therefore, the heat transfer path of the heat H generated at the reflection position RP by the heat transfer section HTP, adhesive member 30, and substrate 50 can be made farther away from the first support section 15.

[0084] Furthermore, at least a portion of the opposing portion OP facing the substrate 50 is provided on the end face of the second support portion 16 in the first direction DIR1 (the substrate 50 side in the direction where the first main surface S1 and the second main surface S2 are aligned). Also, the thickness TOP of the opposing portion OP along the first direction DIR1 (the direction from the end face of the first direction DIR1 of the second support portion 16 toward the substrate 50) is greater than the maximum thickness TH of the heat transfer portion HTP along the normal direction of the inclined portion SL. By providing such an opposing portion OP, the contact area between the opposing surface OS and the adhesive member 30 can be increased. Therefore, the heat H generated at the reflection position RP is more easily transferred to the substrate 50, and the transfer of heat H generated at the reflection position RP to the first support portion 15 and to the boundary between the first main surface S1 and the inclined portion SL can be further suppressed.

[0085] Furthermore, the portion where the opposing portion OP and the substrate 50 face each other extends in the third direction DIR3 (the direction away from the first support portion 15). Therefore, the heat transfer path for the heat H generated at the reflection position RP by the heat transfer portion HTP, the adhesive member 30, and the substrate 50 can be secured at a position far from the first support portion 15.

[0086] Furthermore, in this embodiment, the opposing portion OP covers the end face of the first direction DIR1 of the second support portion 16. This prevents ambient light from entering from the end face of the first direction DIR1 of the second support portion 16.

[0087] Furthermore, the length L2 of the opposing portion OP along the third direction DIR3 is greater than or equal to the length L3 along the inclined portion SL from the reflection position RP of the heat transfer portion HTP to the opposing surface OS. This ensures that the heat transfer path for the heat H generated at the reflection position RP by the heat transfer portion HTP, adhesive member 30, and substrate 50 is located further away from the first support portion 15. However, even if the length L2 of the opposing portion OP along the third direction DIR3 is made longer than necessary, the heat dissipation effect does not significantly improve with increasing the length L2 of the opposing portion OP along the third direction DIR3. On the other hand, if the length L2 of the opposing portion OP along the third direction DIR3 is made longer than necessary, the length of the optical coupling module 100a along the third direction DIR3 will increase, leading to an increase in the size of the optical coupling module 100a. The length L2 of the opposing portion OP along the third direction DIR3 is preferably five times or less the length L3 of the inclined portion SL from the reflection position RP of the heat transfer portion HTP to the opposing surface OS.

[0088] Furthermore, the surface roughness of the opposing surface OS is greater than the surface roughness of the metal reflector 17 at the reflection position RP. This allows for a larger contact area between the opposing surface OS and the adhesive member 30. Consequently, the heat H generated at the reflection position RP is more easily transferred from the opposing surface OS to the adhesive member 30 and the substrate 50.

[0089] Furthermore, the surface roughness of the opposing surface OS is 1 / 1000 to 1 / 10 of the heat diffusion length of the adhesive member 30. This suppresses the accumulation of heat H generated at the reflection position RP in the heat transfer section HTP, and facilitates the transfer of heat H generated at the reflection position RP from the opposing surface OS to the adhesive member 30 and the substrate 50.

[0090] [First Modification] Below, an optical coupling module 100b according to the first modification of the present invention will be described with reference to the drawings. Figure 11 is a side view of the optical coupling module 100b. Figure 12 is a side view of the optical coupling module 100b in which the metal reflector 17 includes two layers of metal films 17a and 17b. In Figures 11 and 12, for explanatory purposes, only the cross-section of the metal reflector 17 in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4 is shown. Furthermore, only the parts of the optical coupling module 100b that differ from the optical coupling module 100a will be described, and the rest will be omitted.

[0091] The optical coupling module 100b is equipped with an optical coupler 1b. As shown in Figure 11, the inclined portion SL of the optical coupler 1b has irregularities. In other words, the inclined portion SL is rough. Therefore, the surface roughness of the inclined portion SL is greater than the surface roughness of the metal reflector 17. Note that in Figure 11, the irregularities are shown magnified for illustrative purposes. The actual irregularities are smaller than the thinnest part of the metal reflector 17. Also, the irregularities of the inclined portion SL become larger as you move toward the second direction DIR2. Methods for forming the irregularities on the inclined portion SL include utilizing the irregularities of the material of the second support portion 16, or applying sputtering to the inclined portion SL. The irregularities on the inclined portion SL are made of glass containing filler.

[0092] The optical coupling module 100b also produces the same effect as the optical coupling module 100a. If the thickness T17 of the metal reflector 17 is thinner than the irregularities of the inclined portion SL, scattering occurs when the metal reflector 17 reflects the emitted light L, and the coupling efficiency decreases. On the other hand, with the optical coupling module 100b, the irregularities of the inclined portion SL are smaller than the thinnest part of the metal reflector 17. Therefore, scattering occurs when the metal reflector 17 reflects the emitted light L, and the decrease in coupling efficiency can be suppressed. In addition, the surface roughness of the inclined portion SL is greater than the surface roughness of the metal reflector 17. In other words, the irregularities of the inclined portion SL are flattened by the metal reflector 17. Therefore, the anchoring effect can suppress the separation of the metal reflector 17 from the inclined portion SL.

[0093] Furthermore, the irregularities of the inclined portion SL are made of glass containing filler. Therefore, in addition to the anchoring effect, the occurrence of migration phenomena can be suppressed, and the adhesion between the inclined portion SL and the metal reflector 17 can be further improved.

[0094] Furthermore, the irregularities of the inclined portion SL increase as you move toward the second direction DIR2. On the other hand, the thickness T17 of the metal reflector 17 decreases as you move toward the second direction DIR2. Therefore, the thinner the metal reflector 17 becomes, the larger the irregularities of the inclined portion SL become. Consequently, the anchoring effect can further suppress the separation of the metal reflector 17 from the inclined portion SL.

[0095] As shown in Figure 12, the metal reflector 17 may have two layers of metal films 17a and 17b. In this case as well, the anchoring effect can suppress the separation of the metal reflector 17 from the inclined portion SL.

[0096] [Second Modification] Below, an optical coupling module 100c according to a second modification of the present invention will be described with reference to the drawings. Figure 13 is a side view of the optical coupling module 100c. In Figure 13, for explanatory purposes, only the cross-section of the metal reflector 17 in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4 is shown. Furthermore, only the parts of the optical coupling module 100c that differ from the optical coupling module 100a will be described, and the rest will be omitted.

[0097] The optical coupling module 100c includes an optical coupler 1c. Furthermore, as shown in Figure 13, the optical coupling module 100c also includes a glass plate 40. The glass plate 40 is an example of a plate-shaped member according to the present invention. The glass plate 40 is sandwiched between the adhesive member 30 and the substrate 50. The thermal conductivity of the glass plate 40 is higher than that of the adhesive member 30.

[0098] The optical coupling module 100c also produces the same effect as the optical coupling module 100a. In addition, in the optical coupling module 100c, the glass plate 40 is sandwiched between the adhesive member 30 and the substrate 50. The thermal conductivity of the glass plate 40 is higher than that of the adhesive member 30. As a result, the heat H generated at the reflection position RP is more easily transferred to the substrate 50 via the glass plate 40. Consequently, the heat H generated at the reflection position RP is more easily transferred from the adhesive member 30 to the substrate 50.

[0099] [Third Modification] Below, an optical coupling module 100d according to a third modification of the present invention will be described with reference to the drawings. Figure 14 is a cross-sectional view of the optical coupling module 100d in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4. Note that the side wall portion 12 is omitted in Figure 14. Furthermore, only the parts of the optical coupling module 100d that differ from the optical coupling module 100 will be described, and the rest will be omitted.

[0100] The optical coupling module 100d includes an optical coupler 1d. As shown in Figure 14, in this modified example, the filler F is not mixed into the adhesive GL in the portion located in the optical path, which is the path of the emitted light L. The adhesive member 30 also has adhesive GL in the portion located in the optical path, which is the path of the emitted light L. There may be portions around the portion located in the optical path, which is the path of the emitted light L, where the filler F is not mixed into the adhesive GL.

[0101] The optical coupling module 100d also produces the same effect as the optical coupling module 100. Furthermore, the optical coupling module 100d can suppress the obstruction of the propagation of the emitted light L by the filler F within the adhesive member 30.

[0102] [Fourth Modification] Below, an optical coupling module 100e according to a fourth modification of the present invention will be described with reference to the drawings. Figure 15 is a cross-sectional view of the optical coupling module 100e in a plane passing through the reflection position RP and parallel to the first direction DIR1 and the fourth direction DIR4. Note that the side wall portion 12 is omitted in Figure 15. Furthermore, only the parts of the optical coupling module 100e that differ from the optical coupling module 100a will be described, and the rest will be omitted.

[0103] The optical coupling module 100e includes an optical coupler 1e. As shown in Figure 15, in this modified example, the filler F is not mixed into the adhesive GL in the portion located in the optical path, which is the path of the emitted light L. The adhesive member 30 also has adhesive GL in the portion located in the optical path, which is the path of the emitted light L. There may be portions around the portion located in the optical path, which is the path of the emitted light L, where the filler F is not mixed into the adhesive GL.

[0104] The optical coupling module 100e also produces the same effect as the optical coupling module 100a. Furthermore, the optical coupling module 100e can suppress the obstruction of the propagation of the emitted light L by the filler F within the adhesive member 30.

[0105] [Other Embodiments] The optical coupling module according to the present invention is not limited to optical coupling modules 100, 100a to 100e, but can be modified within the scope of its gist. Furthermore, the structures of optical coupling modules 100, 100a to 100e may be combined in any way.

[0106] 1, 1a-1e: Optical coupler 12: Side wall 14: Base 15: First support 16: Second support 17: Metal reflector 17a: Metal film 17b: Metal film 20: Optical fiber 30: Adhesive member 40: Glass plate 50: Substrate 100, 100a-100e: Optical coupling module 121: First side wall 122: Second side wall 123: Third side wall CA20: Central axis CP: Connection part CSL: Center DIR1: First direction DIR2: Second direction DIR3: Third direction DIR4: Fourth direction DIR5: Fifth direction EL1: First ellipsoid F: Filler G: Groove GL: Adhesive H: Heat HTP: Heat transfer part L: Emitted light OS: Opposing surface OP: Opposing part R20: Radius RP: Reflection position S1: First principal surface S17: Surface S2: Second principal surface SEL1: First ellipsoid SL: Inclined part Sa: Arithmetic mean height T17, TH: Thickness V: Vertex a, b, c: Diameter

Claims

1. The optical coupler comprises a substrate, an optical coupler provided on the substrate, and an adhesive member, wherein the optical coupler includes a base having opposing first and second main surfaces, a first support portion provided on the first main surface for supporting an optical fiber, a second support portion provided on the first main surface and spaced apart from the first support portion along the longitudinal direction of the optical fiber, and a metal reflector including a heat transfer portion having an opposing surface facing the substrate, wherein the second support portion has an inclined portion that is inclined toward the longitudinal direction with respect to the direction in which the first and second main surfaces are aligned, the second support portion or the metal reflector collects the emitted light from the optical fiber or the substrate, and the metal reflector has at least a portion provided along the inclined portion and reflects the emitted light. The heat transfer portion is located on the substrate side in the direction in which the first main surface and the second main surface are aligned, relative to the reflection position of the emitted light, the thickness of the inclined portion along the normal direction increases as it approaches the substrate, the adhesive member is provided between the opposing surface and the substrate, and the thermal conductivity of the heat transfer portion and the thermal conductivity of the adhesive member are each higher than the thermal conductivity of the second support portion, in an optical coupling module.

2. The optical coupling module according to claim 1, wherein the heat transfer portion has an opposing portion that faces the substrate, and at least a part of it is provided on the substrate-side end face of the second support portion, the portion where the opposing portion and the substrate face each other extends in a direction away from the first support portion, and the thickness of the opposing portion along the direction toward the substrate from the substrate-side end face of the second support portion is greater than the maximum thickness of the heat transfer portion along the normal direction.

3. The portion where the opposing portion and the substrate face each other extends in a direction away from the first support portion, the optical coupling module according to claim 2.

4. The optical coupling module according to claim 3, wherein the length of the opposing portion along the longitudinal direction is greater than or equal to the length along the inclined portion from the reflection position of the heat transfer portion to the opposing surface, and is less than or equal to five times the length along the inclined portion from the reflection position of the heat transfer portion to the opposing surface.

5. The optical coupling module according to any one of claims 2 to 4, wherein the surface roughness of the opposing surface is greater than the surface roughness of the metal reflector at the reflection position.

6. The optical coupling module according to any one of claims 2 to 5, wherein the surface roughness of the opposing surfaces is 1 / 1000 or more and 1 / 10 or less of the thermal diffusion length of the adhesive member.

7. The optical coupling module according to any one of claims 1 to 6, wherein the thickness of the metal reflector along the normal direction is thinner on the side further from the substrate in the direction in which the first main surface and the second main surface are aligned, relative to the reflection position, as the distance from the substrate increases.

8. The optical coupling module according to any one of claims 1 to 7, wherein the reflection position is located on the substrate side of the center of the inclined portion in the direction in which the first main surface and the second main surface are aligned.

9. The optical coupling module according to any one of claims 1 to 8, wherein the material of the base, the first support, and the second support is glass.

10. The optical coupling module according to any one of claims 1 to 9, wherein the thermal conductivity of the substrate is higher than the thermal conductivity of the base, the first support portion, and the second support portion.

11. The optical coupling module according to any one of claims 1 to 10, wherein the adhesive member comprises an adhesive and a plurality of fillers, and the thermal conductivity of the fillers is higher than the thermal conductivity of the adhesive.

12. The optical coupling module according to any one of claims 1 to 11, further comprising a plate-shaped member sandwiched between the adhesive member and the substrate, wherein the thermal conductivity of the plate-shaped member is higher than that of the adhesive member.

13. The optical coupling module according to any one of claims 1 to 12, wherein a plurality of first support portions are provided, the second support portion is provided corresponding to each of the plurality of first support portions, a connecting portion is provided between adjacent second support portions to connect each of the inclined portions, the metal reflector is provided corresponding to each of the plurality of second support portions, and the metal reflector is not provided at the boundary between the inclined portion and the connecting portion.

14. The optical coupling module according to any one of claims 1 to 13, further comprising the optical fiber.

15. The optical coupling module according to claim 14, wherein, in a cross section passing through the reflection position and perpendicular to the longitudinal direction, the length along the direction in which the first main surface and the second main surface of the first support portion are aligned is greater than or equal to the radius of the optical fiber.

16. The optical coupling module according to claim 14 or 15, wherein the optical fiber is located on the side further from the substrate in the direction in which the first main surface and the second main surface are aligned, relative to the opposing surface.

17. The optical coupling module according to any one of claims 1 to 16, wherein the thickness of the heat transfer section increases as it moves away from the first support section, with the thickness along the normal direction increasing as it moves away from the first support section.

18. An optical coupler comprising: a base having opposing first and second main surfaces; a first support portion provided on the first main surface for supporting an optical fiber; a second support portion provided on the first main surface and spaced apart from the first support portion along the longitudinal direction of the optical fiber; and a metal reflector including a heat transfer portion having an opposing surface facing a substrate, wherein the second support portion has an inclined portion that is inclined toward the longitudinal direction with respect to the direction in which the first and second main surfaces are aligned, the second support portion or the metal reflector collects the emitted light from the optical fiber or the substrate, at least a part of the metal reflector is provided along the inclined portion and reflects the emitted light, the heat transfer portion is located on the substrate side in the direction in which the first and second main surfaces are aligned more than the reflection position of the emitted light, the thickness along the normal direction of the inclined portion becomes thicker as it approaches the substrate, and the thermal conductivity of the heat transfer portion is higher than the thermal conductivity of the second support portion.

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