Optical waveguide package and light source module

Abstract

An optical waveguide package (2) comprises: a substrate (9) having a first surface (8) and a first recess (31) that opens on the first surface; cladding (12) positioned on the first surface, and having a second surface (10) facing the first surface, a third surface (11) positioned on the opposite side of the second surface, and an element housing space (3) that penetrates between the second surface and the third surface; a core (5) positioned inside the cladding, and having an incident surface (13) facing the element housing space, and an emission surface (15) exposed from an end surface of the cladding; and an electrode layer (33) positioned on the bottom surface of the first recess.

Description

Optical waveguide package and light source module

[0001] The present disclosure relates to an optical waveguide package and a light source module.

[0002] A prior art optical waveguide package and light source module is described, for example, in US Pat. No. 6,244,999.

[0003] Japanese Patent Application Laid-Open No. 2007-133011

[0004] The optical waveguide package according to the present disclosure comprises: a substrate having a first surface and a first recess that opens onto the first surface; a clad located on the first surface, the clad having a second surface facing the first surface, a third surface located opposite the second surface, and an element accommodating space that penetrates between the second surface and the third surface; a core located within the clad, the core having an incident surface facing the element accommodating space and an exit surface exposed from an end surface of the clad; and an electrode layer located on the bottom surface of the first recess.

[0005] The optical waveguide package according to the present disclosure comprises a substrate having a first surface and a first recess that opens on the first surface; a clad located above the first surface, the clad having a second surface facing the first surface, a third surface located opposite the second surface, and an opening that opens on the third surface; a core located within the clad, the core having an incident surface exposed within the opening and an exit surface exposed at an end surface of the clad; and an electrode layer located within the opening, wherein the opening has a bottom, the first recess has a bottom surface, the bottom and the bottom surface overlap in a planar view, and the electrode layer is located on the bottom.

[0006] The optical waveguide package according to the present disclosure comprises a substrate having a first surface and a first recess opening on the first surface, a clad located above the first surface and having a sidewall, a core located within the clad and having an incident surface exposed on the sidewall and an exit surface exposed at an end surface of the clad, and an electrode layer located on the bottom surface of the first recess, the clad being spaced from the first recess.

[0007] The light source module according to the present disclosure includes the optical waveguide package, a light emitting element mounted on the electrode layer of the optical waveguide package, and a lid positioned above the light emitting element.

[0008] Objects, features, and advantages of the present disclosure will become clearer from the detailed description and drawings below. FIG. 1 is an exploded perspective view showing a light source module including an optical waveguide package according to a first embodiment of the present disclosure. FIG. 2 is a plan view showing the light source module. FIG. 3 is an enlarged cross-sectional view of the light source module taken along the section line III-III in FIG. 2. FIG. 4 is a diagram for explaining a manufacturing procedure of the light source module. FIG. 5 is a diagram for explaining a manufacturing procedure of the light source module. FIG. 6 is a diagram for explaining a manufacturing procedure of the light source module. FIG. 7 is a diagram for explaining a manufacturing procedure of the light source module. FIG. 8 is a diagram for explaining a manufacturing procedure of the light source module. FIG. 9 is a diagram for explaining a manufacturing procedure of the light source module. FIG. 10 is a cross-sectional view showing the configuration of a light source module according to a second embodiment of the present disclosure. FIG. 11 is a cross-sectional view showing the configuration of a light source module according to a third embodiment of the present disclosure. FIG. 12 is a cross-sectional view showing the configuration of a light source module according to a fourth embodiment of the present disclosure. FIG. 13 is a cross-sectional view showing the configuration of a light source module according to a fifth embodiment of the present disclosure. FIG. 14 is a cross-sectional view showing the configuration of a light source module according to a sixth embodiment of the present disclosure. FIG. 15 is a cross-sectional view showing the configuration of a light source module according to a seventh embodiment of the present disclosure. Fig. 1 is a cross-sectional view showing the configuration of a light source module according to an eighth embodiment of the present disclosure. Fig. 2 is a plan view showing the configuration of a light source module according to a ninth embodiment of the present disclosure. Fig. 3 is a plan view showing the configuration of a light source module according to a tenth embodiment of the present disclosure. Fig. 4 is a cross-sectional view showing the configuration of a light source module according to an eleventh embodiment of the present disclosure. Fig. 5 is a cross-sectional view showing the configuration of a light source module according to a twelfth embodiment of the present disclosure. Fig. 6 is a cross-sectional view showing the configuration of a light source module according to a thirteenth embodiment of the present disclosure. Fig. 7 is a cross-sectional view showing the configuration of a light source module according to a fourteenth embodiment of the present disclosure. Fig. 8 is a cross-sectional view showing the configuration of a light source module according to a fifteenth embodiment of the present disclosure.

[0009] A light source module that combines and outputs light emitted from a plurality of light-emitting elements has been known. In the conventional technology described in Patent Document 1, the light source module includes light-emitting elements and an optical waveguide layer that includes a clad and a core located within the clad.

[0010] In the conventional technology described in Patent Document 1, when a waveguide and an element mounting portion are formed on a substrate, the heat generated when the light-emitting element emits light can be dissipated through the substrate, but there is a need to dissipate the heat more efficiently.

[0011] Hereinafter, embodiments of the optical waveguide package and light source module of the present disclosure will be described with reference to the drawings. The drawings used in the following description are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones. The optical waveguide package 2 and light source module 1 of the present disclosure may be used with either direction defined as up or down. However, for convenience, this specification defines a Cartesian coordinate system X, Y, and Z, and terms such as top surface and bottom surface are used, with the positive direction of the Z axis defined as up. The X direction is also referred to as the width direction. The Y direction is also referred to as the length direction. The Z direction is also referred to as the thickness direction. Note that parts common to each embodiment are designated by the same reference numerals, and redundant descriptions may be omitted.

[0012] <First Embodiment> Fig. 1 is an exploded perspective view showing a light source module including an optical waveguide package according to a first embodiment of the present disclosure, Fig. 2 is a plan view showing the light source module, and Fig. 3 is an enlarged cross-sectional view of the light source module taken along the section line III-III in Fig. 2. The light source module 1 of this embodiment includes an optical waveguide package 2 and a light emitting element 4 mounted in an element accommodating space 3 of the optical waveguide package 2.

[0013] The optical waveguide package 2 includes a substrate 9 having a first surface 8 and a first recess 31 opening on the first surface 8, a clad 12 located on the first surface 8, the clad 12 having a second surface 10 facing the first surface 8, a third surface 11 located on the opposite side of the second surface 10, and an element accommodating space 3 penetrating the second surface 10 and the third surface 11, a core 5 located within the clad 12 and having an incident surface 13 facing the element accommodating space 3 and an exit surface 15 exposed from an end surface 14 of the clad 12, and an electrode layer 33 located on a bottom surface 32 of the first recess 31. The core 5 and the clad 12 constitute an optical waveguide layer 19.

[0014] The light-emitting elements 4 may be, for example, laser diodes (LDs) or vertical cavity surface-emitting lasers (VCSELs). In this embodiment, the light source module 1 includes a red light-emitting element 4R that emits red light, a green light-emitting element 4G that emits green light, and a blue light-emitting element 4B that emits blue light. The light-emitting elements 4 are not limited to LDs and VCSELs, and may also be, for example, light-emitting diodes (LEDs). The light-emitting elements 4R, 4G, and 4B are positioned and arranged so that the optical axes of the emission ends of the light of each color are located at the centers of the incident surfaces 13R, 13G, and 13B of the core 5.

[0015] The substrate 9 may be, for example, an organic wiring substrate whose dielectric layer is made of an organic material. Examples of organic wiring substrates include printed wiring boards, build-up wiring boards, and flexible wiring boards. Examples of organic materials used in organic wiring substrates include epoxy resin, polyimide resin, polyester resin, acrylic resin, phenolic resin, and fluororesin. The substrate 9 may also be a ceramic wiring substrate whose dielectric layer is made of a ceramic material. Examples of ceramic materials used in ceramic wiring substrates include aluminum oxide sintered compacts, mullite sintered compacts, silicon carbide sintered compacts, aluminum nitride sintered compacts, and glass ceramic sintered compacts. The substrate 9 is a rectangular plate-like body in a planar view. That is, the shape of the first surface 8 of the substrate 9 is rectangular. The substrate 9 may be rectangular, square, or another polygonal shape in a planar view.

[0016] The clad 12 is located on the first surface 8 of the substrate 9, and has an element accommodating space 3 that penetrates between the second surface 10 and the third surface 11. The core 5 is located within the clad 12, and has a plurality of split paths 51R, 51G, 51B that connect the incident surfaces 13R, 13G, 13B, a combining section 17 where the split paths 51R, 51G, 51B meet, and a combining path 18 that extends between the combining section 17 and the output surface 15.

[0017] In the optical waveguide layer 19, for example, the core 5 and the clad 12 have different refractive indices, with the core 5 having a higher refractive index than the clad 12. This difference in refractive index is utilized to cause light to be totally reflected at the interface between the core 5 and the clad 12. In other words, if an optical waveguide is made of a material with a high refractive index and is surrounded by a material with a low refractive index, light can be confined within the core 5 with a high refractive index. The core 5 is made of, for example, silicon oxynitride (SiON), also known as silicon oxynitride, and the clad 12 is made of silicon oxide (SiO ２ The material of the electrode layer 33 may be, for example, a single-layer structure of Al (aluminum) or a three-layer structure of Ti (titanium), Pt (platinum), and Au (gold).

[0018] The first recess 31 opens to a portion of the first surface 8 exposed within the element accommodating space 3 (the bottom surface of the element accommodating space 3). An electrode layer 33 is provided on the bottom surface of the first recess 31, and the light-emitting element 4 is mounted on the electrode layer 33. In this embodiment, three first recesses 31 are provided, corresponding to the number, shape, and size of the light-emitting elements 4R, 4G, and 4B to be mounted. The first recess 31 has a bottom surface 32 and an inner wall surface 34 extending in a direction intersecting the bottom surface 32 (a direction including a Z-direction component) and surrounding the space within the first recess 31. The inner wall surface 34 has two flat inner wall surfaces 34a and 34b extending in a direction perpendicular to the optical axis of the light emitted from the light-emitting element 4 (the X-direction). The inner wall surfaces extending in the X-direction include one inner wall surface 34a close to the incident surface 13 of the core 5 and the other inner wall surface 34b away from the incident surface 13. The inner wall surface 34 also has two flat inner wall surfaces 34 c extending in a direction parallel to the optical axis of the light emitted from the light emitting element 4 (Y direction).

[0019] With this configuration, the bottom of the first recess 31, on which each light-emitting element 4R, 4G, 4B is mounted, has a small thickness T2, resulting in high heat dissipation and efficient dissipation of heat generated by each light-emitting element 4R, 4G, 4B. While heat dissipation can be improved by reducing the thickness T1 of the substrate 9 without providing the first recess 31, this reduces the strength and rigidity of the substrate, potentially causing distortion in the optical waveguide thereon. In contrast, the optical waveguide package 2 of this embodiment provides the first recess 31, which only partially reduces the thickness of the substrate 9, thereby minimizing the reduction in the strength and rigidity of the substrate 9 and achieving both heat dissipation and strength. Furthermore, the optical axis can be adjusted by setting the depth of the first recess 31 (thickness T2 of the bottom of the first recess 31) according to the element height. While the optical axis can be adjusted by adjusting the thickness of the cladding 12, the thickness of the cladding 12 affects the emitted light, limiting the range of adjustment.

[0020] The depth of the first recess 31 may be set to satisfy the relationship 0.4T1≦T2<T1. If the thickness T2 of the bottom portion is within this range, it is possible to improve heat dissipation while suppressing a decrease in strength.

[0021] The electrode layer 33 includes a first electrode layer 33a and a second electrode layer 33b. The first electrode layer 33a is located on the bottom surface of the first recess 31, and the light-emitting element 4 is mounted thereon. The second electrode layer 33b is connected to the first electrode layer 33a and extends from the inner wall surface 34 (34b) of the first recess 31 to the outside of the element accommodating space 3. The second electrode layer 33b passes between the peripheral wall portion of the optical waveguide layer 19 and the first surface 8 of the substrate 9, and extends to an exposed portion of the first surface 8 located outside the element accommodating space 3. The first electrode layer 33a is primarily used as an electrode pad connected to each of the light-emitting elements 4R, 4G, and 4B. The portion of the second electrode layer 33b located outside the element accommodating space 3 is primarily used as an external terminal electrode, and the portion between the first electrode layer 33a and the external terminal electrode may be used as a lead-out wiring. The first electrode layer 33a may be larger than one or both of the width (dimension in the X direction) and length (dimension in the Y direction) of the bottom surface 32 and may extend to the inner wall surfaces 34 (34a, 34b, 34c) of the first recess 31. Alternatively, the first electrode layer 33a may be smaller than one or both of the width (dimension in the X direction) and length (dimension in the Y direction) of the bottom surface 32, and a portion of the bottom surface 32 may be located between the bottom surface 32 and the inner wall surfaces 34 (34a, 34b, 34c) of the first recess 31. In this case, the second electrode layer 33b may extend from the bottom surface 32 of the first recess 31 to an exposed portion of the first surface 8 located outside the element accommodating space 3. The first electrode layer 33a and the second electrode layer 33b may have the same width or different widths, and their shapes are not limited. One electrode of each of the light-emitting elements 4R, 4G, 4B is connected to the first electrode layer 33a of the electrode layer 33, and the other electrode is connected to each of the lead wires 61R, 61G, 61B by a wire 60. Each of the lead wires 61R, 61G, 61B extends parallel to the second electrode layer 33b on the first surface 8 of the substrate 9, passes from inside the element accommodating space 3 between the peripheral wall of the optical waveguide layer 19 and the first surface 8 of the substrate 9, and extends to the outside of the element accommodating space 3. The portion of each of the lead wires 61R, 61G, 61B located outside the element accommodating space 3 may be mainly used as an external terminal electrode.

[0022] When mounting each of the light-emitting elements 4R, 4G, and 4B, the optical axis of light emitted from the emission portion of each of the light-emitting elements 4R, 4G, and 4B is positioned to coincide with the center of each of the incident surfaces 13R, 13G, and 13B of the core 5. In other words, the thickness T2 of the bottom is determined so that the height from the surface (bottom surface) 38 opposite the first surface 8 of the substrate 9 to the center of each of the incident surfaces 13R, 13G, and 13B of the core 5 coincides with the height from the bottom surface 38 of the substrate 9 to the emission portion of each of the light-emitting elements 4R, 4G, and 4B. Therefore, the bottom surface 32 is located at a position obtained by subtracting the dimension L1 from the center of each of the incident surfaces 13R, 13G, and 13B to the mounting surface of the light-emitting elements 4R, 4G, and 4B and the thickness T3 of the electrode layer 33 (first electrode layer 33a) from the height position from the bottom surface 38 of the substrate 9 to the center of each of the incident surfaces 13R, 13G, and 13B. That is, the thickness T2 of the bottom portion is determined by adjusting the depth of the first recess 31 to a dimension corresponding to the thickness of each of the light-emitting elements 4R, 4G, 4B and the thickness T3 of the electrode layer 33. The thickness T2 of the bottom portion of the first recess 31 of such a substrate 9 is set to satisfy the relationship 0.4T1≦T2<T1 as described above.

[0023] The bottom surface 32 of the first recess 31 may have a surface roughness Ra2 (Ra2>Ra1) that is greater than the surface roughness Ra1 of the first surface 8 in arithmetic mean roughness.

[0024] Because the surface roughness Ra2 of the bottom surface 32 of the first recess 31 is greater than the surface roughness Ra1 of the first surface 8, when the electrode layer 33 is directly formed on the bottom surface 32, the adhesion strength of the electrode layer 33 to the substrate 9 can be improved and peeling of the electrode layer 33 can be suppressed. Furthermore, when the electrode layer 33 is directly formed on the bottom surface 32, the fine irregularities of the bottom surface 32 are transferred to the upper surface of the electrode layer 33, and the contact area between the electrode layer 33 and the light-emitting element 4B increases, thereby improving the adhesion strength between the substrate 9, the electrode layer 33, and the light-emitting element 4B. Furthermore, because the surface of the electrode layer 33 also has a large surface roughness, the possibility that stray light that does not enter the core 5 from the incident surface 13 will be re-reflected by the surface of the electrode layer 33 and enter the core 5 can be reduced. Furthermore, since the surface area of ​​the electrode layer 33, which is most affected by thermal expansion, is increased, heat dissipation can be improved and peeling of the electrode layer 33 can be reduced.

[0025] The inner wall surface 34 surrounding the space within the first recess 31 may have a surface roughness Ra3 greater than the surface roughness Ra1 of the first surface 8. If the other inner wall surface 34b of the first recess 31 is parallel to the inner surface 19a, the thickness T5 of the electrode layer 33 on the other inner wall surface 34b is small, which may result in a disconnection. In contrast, by making the surface roughness Ra3 of the inner wall surface 34 greater than the surface roughness Ra1 of the first surface 8, the adhesion strength between the electrode layer 33 and the inner wall surface 34 can be improved, and film peeling can be suppressed. Furthermore, since the inner wall surface 34 and the surface of the electrode layer 33 thereon also have a large surface roughness, the possibility of stray light being re-reflected by the surface of the electrode layer 33 and entering the core 5 can be reduced. If the first electrode layer 33a of the electrode layer 33 does not extend to the inner wall surface 34 (34a, 34b, 34c) of the first recess 31, only the other inner wall surface 34b on which the second electrode layer 33b is located may have a surface roughness Ra3 greater than the surface roughness Ra of the first surface 8.

[0026] In this embodiment, for example, the surface roughness Ra1 of the first surface 8 may be 0.1 nm or more and 10 nm or less, the surface roughness Ra2 of the bottom surface 32 may be 1 μm or more and 100 μm or less, and the surface roughness Ra3 of the inner wall surface 34 may be 10 μm or more and 500 μm or less. In the example shown in Fig. 3, both the surface roughness Ra2 of the bottom surface 32 and the surface roughness Ra3 of the inner wall surface 34 are greater than the surface roughness Ra1 of the first surface 8, but only one of the surface roughness Ra2 of the bottom surface 32 and the surface roughness Ra3 of the inner wall surface 34 may be greater than the surface roughness Ra1 of the first surface 8. When the surface roughness Ra1 of the first surface 8 is within the above range, a high-precision optical waveguide layer 19 can be formed thereon. By having the surface roughness Ra2 of the bottom surface 32 and the surface roughness Ra3 of the inner wall surface 34 within the above range relative to the surface roughness Ra1 of the first surface 8, the above effects can be obtained more effectively and cracks originating from the rough surface due to thermal stress, etc. are less likely to occur.

[0027] The inner wall surface 34 surrounding the space within the first recess 31 may be flat and inclined with respect to the bottom surface 32 of the first recess 31. The inner wall surface 34 being inclined with respect to the bottom surface 32 means that the inner wall surface 34 is not perpendicular to the bottom surface 32, and the angle between the bottom surface 32 and the inner wall surface 34 is an obtuse angle. Furthermore, the inner wall surface 34 being inclined with respect to the bottom surface 32 means that the inner wall surface 34 is inclined with respect to the inner surface 19a of the optical waveguide layer 19 that faces the element accommodating space 3. In a plan view, the opening edge of the first recess 31 is located outside the edge of the bottom surface 32 of the first recess 31, and the inner wall surface 34 is inclined outward from the first recess 31. If the other inner wall surface 34b of the first recess 31 is parallel to the inner surface 19a, the thickness T5 of the electrode layer 33 on the other inner wall surface 34b is small, which may result in a disconnection. In contrast, by inclining the other inner wall surface 34b, the thickness T5 of the electrode layer 33 can be increased, making it possible to suppress the occurrence of disconnections. Furthermore, since the angle between the bottom surface 32 and the inner wall surface 34 is an obtuse angle, stress is less likely to concentrate compared to when this angle is a right angle or an acute angle, and the possibility of cracks originating from the corner being generated is reduced.

[0028] The inclination angles of the inner wall surfaces 34a, 34b, and 34c of the first recess 31 may all be the same or different. For example, as shown in the example in Fig. 3, one inner wall surface 34a has an angle θ1 with respect to an imaginary plane including the inner surface 19a of the optical waveguide layer 19 facing the element accommodating space 3, and the other inner wall surface 34b has an angle θ2 with respect to an imaginary plane parallel to the inner surface 19a, where θ1 < θ2. In the example shown in Fig. 2, the two inner wall surfaces 34c extending in the Y direction are approximately perpendicular to the bottom surface 32, and thus some of the inner wall surfaces 34a and 34b among the multiple inner wall surfaces 34a, 34b, and 34c may be inclined with respect to the bottom surface 32.

[0029] The angle θ1 may be, for example, 5° or greater and 60° or less. The angle θ2 may be, for example, 5° or greater and 60° or less. In this case, the angle between the bottom surface 32 of the first recess 31 and the inner wall surfaces 34a, 34b is an obtuse angle of 95° or greater and 150° or less. The angle θ1 of one inner wall surface 34a and the angle θ2 of the other inner wall surface 34b may be the same or different.

[0030] The light source module 1 includes the aforementioned optical waveguide package 2, a focusing lens 6 located on the optical path of the light emitted from the core 5, a box-shaped lid body 7 with one side open, for example, that covers the element accommodating space 3, and a ring-shaped metal film 22 interposed between the lid body 7 and the clad 12.

[0031] The condenser lens 6 may collimate or condense the light emitted from the core 5. The condenser lens 6 may be, for example, a plano-convex lens having a flat entrance surface and a convex exit surface.

[0032] The lid body 7 is not limited to a box shape, and may be, for example, a plate shape, and other shapes can be adopted as appropriate. The lid body 7 may be made of a glass material such as quartz, borosilicate, or sapphire. The bonding material may be any material that can bond the cladding 12 and the lid body 7 and hermetically seal them, and examples thereof include Au-Sn or Sn-Ag-Cu solder, metal nanoparticle pastes such as Ag or Cu, or glass paste. The lid body 7 may be hermetically bonded by the bonding material with the metal film 22 sandwiched between it and the cladding 12, and therefore the element housing space 3 may be hermetically sealed from the outside.

[0033] 4A to 4L are diagrams illustrating an example of a manufacturing procedure for a light source module. As shown in FIG. 4A , a substrate 9 is prepared. As shown in FIG. 4B , a resist 40 is applied to a first surface 8 of the substrate 9. The first surface 8 is exposed from the portion where the resist 40 is not applied, and a first recess 31 is formed by etching, for example, by laser light irradiation. Next, a bottom surface 32 of the first recess 31 is roughened by isotropic etching, for example, dry etching, so that the surface roughness Ra2 is greater than the surface roughness Ra1 of the first surface 8. If the surface roughness of the bottom surface 32 is sufficiently increased by the etching process for forming the first recess 31, this roughening etching process may be omitted.

[0034] Next, as shown in FIG. 4C , all of the resist 40 is removed, and then, as shown in FIG. 4D , a portion of the electrode layer 33 is formed on the first surface 8, and the clad 12 is partially laminated. Then, as shown in FIG. 4E , a core layer 5a is formed on the clad 12, and a resist 41 for patterning is laminated on the core layer 5a, as shown in FIG. 4F . The core layer 6a is then etched from above the resist 41 to pattern the core layer 5a, forming the core 5, as shown in FIG. 4G . Then, as shown in FIG. 4H , a resist 42 for forming the element accommodating space 3 is laminated on the clad 12, as shown in FIG. 4I . The clad 12 is then etched until the first surface 8 of the substrate 9 is exposed along with the bottom surface 32, forming the element accommodating space 3, as shown in FIG. 4J . Finally, as shown in FIG. 4K , an electrode layer 33 is formed on the exposed bottom surface 32, thereby forming the optical waveguide package 2. 4L, the light emitting element 4 is mounted, for example, by flip-chip mounting on the electrode layer 33 of the optical waveguide package 2, and the opening of the element accommodating space 3 is closed with the lid 7 to manufacture a light source module. In the step shown in Fig. 4D, the electrode layer 33 may be formed up to the inside of the first recess 31. As described above, by separately forming the electrode layer 33 on the first surface 8 and in the first recess 31, the surface roughness in the first recess 31 can be made even greater by the etching step of Fig. 4J.

[0035] Second Embodiment Fig. 5 is a cross-sectional view showing the configuration of a light source module according to a second embodiment of the present disclosure. In the light source module 1a of this embodiment, the inner wall surface 34 of the first recess 31 of the substrate 9 is flat and connected to the bottom surface 32 via a curved surface 34a1. In the example shown in Fig. 5, one of the inner wall surfaces 34a of the first recess 31 of the substrate 9 has a curved surface 34a1 that is convexly curved outward toward the side away from the opening of the first recess 31, i.e., the lower left in Fig. 5, and is connected to the bottom surface 32 via the curved surface 34a1. This is not limited to one of the inner wall surfaces 34a; all of the inner wall surfaces 34 (34a, 34b, 34c), including the other inner wall surface 34b and two other inner wall surfaces 34c extending in the Y direction, may be connected to the bottom surface 32 via the curved surface 34a1. In other words, the corner between the inner wall surface 34 and the bottom surface 32 may be a curved surface (concave surface). Furthermore, the inner wall surface 34 that is continuous with the bottom surface 32 via the curved surface 34 a 1 may be inclined with respect to the bottom surface 32 .

[0036] With this configuration, stress generated at the corners between the bottom surface 32 and the inner wall surface 34 is dispersed, reducing the occurrence of cracks originating from the corners due to stress concentration and reducing damage to the substrate 9. In addition, the curved corners of the electrode layer 33 located from the bottom surface 32 to the inner wall surface 34 also reduce the possibility of fracture at the corners.

[0037] Third Embodiment Fig. 6 is a cross-sectional view showing the configuration of a light source module according to a third embodiment of the present disclosure. In a light source module 1b according to this embodiment, the inner wall surface 34 of the first recess 31 of the substrate 9 is concave and continues to the bottom surface 32 via a curved surface 34a1. In the example shown in Fig. 6, both the one inner wall surface 34a and the other inner wall surface 34b are concavely curved surfaces that are entirely curved from the first surface 8 of the substrate 9 to the bottom surface 32. Therefore, although the curved surface 34a1 between the inner wall surfaces 34a, 34b and the bottom surface 32 is not clear, it can be said that the inner wall surface 34 continues to the bottom surface 32 via the curved surface 34a1. In this case, all of the inner wall surfaces 34 (34a, 34b, 34c), including the other two inner wall surfaces 34c extending in the Y direction, may continue to the bottom surface 32 via the curved surface 34a1.

[0038] According to this configuration, by providing the curved surfaces 34a1 at the corners between the inner wall surface 34 and the bottom surface 32, stress generated at the corners between the bottom surface 32 and the inner wall surface 34 is dispersed, reducing the occurrence of cracks originating from the corners due to stress concentration and reducing damage to the substrate 9. Furthermore, the curved corners of the electrode layer 33 located from the bottom surface 32 to the inner wall surface 34 also reduce the possibility of fracture at the corners. Furthermore, because the entire inner wall surface 34 is curved, the stress dispersion effect is further enhanced, further increasing the effect of reducing damage to the substrate 9 and the electrode layer 33.

[0039] 7 is a cross-sectional view showing the configuration of a light source module according to a fourth embodiment of the present disclosure. In the light source module 1c of this embodiment, a step portion 39 is disposed between the first recess 31 and the inner surface 19a of the cladding 12 and the core 5 that faces the element accommodating space 3. The step portion 39 is formed by the intersection of the first surface 8 and one of the inner wall surfaces 34a. In other words, the first recess 31 opens to the first surface 8 at a position separated from the inner surface 19a. Furthermore, there is a portion between the first recess 31 and the inner surface 19a where the first surface 8 of the substrate 9 is exposed.

[0040] With this configuration, when mounting the light-emitting elements 4R, 4G, and 4B, they must be positioned with high precision relative to the optical waveguide layer 19. For example, by observing the step portion 39 from the underside 38 of the substrate 9 using infrared (IR) light or the like while transmitting through the substrate 9, the visibility of the positions of the light-emitting elements 4R, 4G, and 4B is improved. Based on the relative positional relationship between the step portion 39 and the light-emitting elements 4R, 4G, and 4B, the amount of misalignment of the light-emitting elements 4R, 4G, and 4B can be confirmed, and the mounting positions can be adjusted, allowing for high-precision mounting. In particular, since the step portion 39 is provided on the inner surface 19a of the first recess 31, the positions of the light-emitting elements 4R, 4G, and 4B relative to the step portion 39 from the underside 38 of the substrate 9 can be easily confirmed, resulting in good positioning. Furthermore, because the bottom of the first recess 31 is thin, the visibility of the light-emitting elements 4R, 4G, and 4B can be improved during element mounting.

[0041] 8 is a cross-sectional view showing the configuration of a light source module according to a fifth embodiment of the present disclosure. In a light source module 1d of this embodiment, the bottom surface 32 of the first recess 31 is deepest on the incident surface 13B side relative to the first surface 8 and becomes shallower as it moves away from the incident surface 13B. Therefore, the bottom surface 32 slopes upward as it moves away from the inner surface 19a of the optical waveguide layer 19 that faces the element accommodating space 3. The inner surface 19a of the optical waveguide layer 19 that faces the element accommodating space 3 is perpendicular to the bottom surface 32 of the first recess 31 and is sloped with respect to the first surface 8.

[0042] With this configuration, the thickness of the bottom portion constituting the bottom surface 32 of the first recess 31 is reduced in thickness T2a on the side of the light-emitting element 4B where heat generation is greatest, thereby improving heat dissipation, and the thickness T2b in the portion farther from the light-emitting element 4B is increased in thickness, thereby improving strength. Therefore, both improved heat dissipation and improved strength can be achieved. Furthermore, by adjusting the inclination of the bottom surface 32 in accordance with the inclination of the inner surface 19a of the optical waveguide layer 19, light from the light-emitting element 4B can be made to perpendicularly enter the inner surface 19a of the optical waveguide layer 19, thereby improving the optical coupling efficiency between the incident surface 13B of the core 5 and the light-emitting element 4B.

[0043] Sixth Embodiment Fig. 9 is a cross-sectional view showing the configuration of a light source module according to a sixth embodiment of the present disclosure. The light source module 1e may include a second recess 35 recessed further from the bottom surface 32 of the first recess 31. The light source module 1e of this embodiment includes the second recess 35 between the light-emitting element 4 and the other inner wall surface 34b that is farther from the incident surface 13B. The thickness T2c of the bottom of the second recess 35 is thinner than the thickness T2 of the bottom of the first recess 31. The electrode layer 33 includes a first electrode layer 33a located on the bottom surface 32 closer to the incident surface 13B than the second recess 35, and a second electrode layer 33b that is continuous with the first electrode layer 33a, passes through the second recess 35 and the inner wall surface 34 (34b) of the first recess 31, and extends outward from the element accommodating space 3.

[0044] With this configuration, when bonding the light-emitting element 4B to the electrode layer 33 with the bonding material 47, unnecessary bonding material 47 is likely to flow into the second recess 35, reducing the possibility of the bonding material 47 creeping up the side of the light-emitting element 4B and causing a short circuit between one electrode located on the lower surface of the light-emitting element 4B and the other electrode located on the upper surface. Furthermore, with this configuration, the thickness T2c of the bottom of the second recess 35 is even thinner than the thickness T2 of the bottom of the first recess 31, and the second electrode layer 33b of the electrode layer 33 is located closer to the lower surface 38 of the substrate 9, opposite the first surface 8. Therefore, heat generated by the light-emitting element 4B can be efficiently dissipated via the second electrode layer 33b located on the bottom of the second recess 35, further improving heat dissipation. Furthermore, when the bonding material 47, which has a relatively high thermal conductivity, accumulates in the second recess 35, a large heat conduction path is formed between the light-emitting element 4B and the electrode layer 33, thereby improving heat dissipation.

[0045] Seventh Embodiment Fig. 10 is a cross-sectional view showing the configuration of a light source module according to a seventh embodiment of the present disclosure. The light source module 1f of this embodiment differs from the light source module 1e of the sixth embodiment in the position of the second recess 35. The light source module 1f of this embodiment includes the second recess 35 closer to the incident surface 13B than the light-emitting element 4B. The second recess 35 can also be said to be located between the light-emitting element 4B and one of the inner wall surfaces 34a. The thickness T2c of the bottom of the second recess 35 is thinner than the thickness T2 of the bottom of the first recess 31. Furthermore, the bottom surface 32 of the first recess 31 is not located between the second recess 35 and one of the inner wall surfaces 34a, and one of the inner wall surfaces 34a of the first recess 31 and the inner wall surface of the second recess 35 are continuous. The first electrode layer 33a located directly below the light-emitting element 4B may extend into the second recess 35.

[0046] This configuration reduces the thickness of the substrate 9 near the light-emitting element 4B's emission portion, where heat generation is greatest, thereby further improving heat dissipation. When the light-emitting element 4B is bonded to the electrode layer 33 with the bonding material 47, unnecessary bonding material 47 flows into the second recess 35, reducing the possibility of the bonding material 47 creeping up the side of the light-emitting element 4B and causing a short circuit between one electrode located on the lower surface and the other electrode located on the upper surface. Even if the bonding material 47 does not creep up and cause a short circuit, if it creeps up to the emission portion of the light-emitting element 4B, it can prevent light from emitting from the light-emitting element 4B. In the light source module 1f of this embodiment, the second recess 35 is located closer to the incident surface 13B than the light-emitting element 4B and closer to the emission portion of the light-emitting element 4B, effectively reducing the possibility of the bonding material 47 creeping up to the side where the emission portion of the light-emitting element 4B is located. When the first electrode layer 33a extends into the second recess 35, the bonding material 47 easily spreads onto the extended first electrode layer 33a, making it easier to guide unnecessary bonding material 47 into the second recess 35 and more likely to prevent the bonding material 47 from creeping up onto the side surface of the light-emitting element 4B. Furthermore, at the emission portion side where heat generation from the light-emitting element 4B is greatest, heat can be conducted to a thinner portion of the substrate 9 via the bonding material 47, further improving heat dissipation.

[0047] Eighth Embodiment FIG. 11 is a cross-sectional view showing the configuration of a light source module according to an eighth embodiment of the present disclosure. The light source module 1g of this embodiment has second recesses 35 on the light-incident surface 13B side of the light-emitting element 4B and on the opposite side of the light-incident surface 13B from the light-emitting element 4B. In other words, the second recesses 35 are provided between the light-emitting element 4B (or the first electrode layer 33a on which the light-emitting element 4B is mounted) and one of the inner wall surfaces 34a, and between the light-emitting element 4B (or the first electrode layer 33a on which the light-emitting element 4B is mounted) and the other inner wall surface 34b. Second recesses 35 may also be provided between the light-emitting element 4B and two other inner wall surfaces 34c extending in the Y direction. The second recesses 35 may be annular grooves surrounding the light-emitting element 4B in a plan view. Furthermore, the second inner wall surface 35a of the second recess 35 of the light source module 1g of this embodiment is inclined, similar to the inner wall surface 34 of the first recess 31. The second inner wall surface 35a of the second recess 35 may be inclined with respect to the bottom surface of the second recess 35. This inclination is such that the angle between the second inner wall surface 35a and the bottom surface of the second recess 35 is an obtuse angle. In plan view, the opening edge of the second recess 35 is located outside the edge of the bottom surface of the second recess 35, and the second inner wall surface 35a is inclined outward from the second recess 35. The angle between the second inner wall surface 35a and the bottom surface of the second recess 35 may be 95° to 150°.

[0048] This configuration achieves the same effects as those of Embodiments 6 and 7. Furthermore, because the second inner wall surface 35a of the second recess 35 is inclined relative to the bottom surface of the second recess 35, the thickness transition from the thickness T2 from the bottom surface 32 of the first recess 31 to the underside 38 of the substrate 9 to the thickness T2c from the bottom surface of the second recess 35 to the underside 38 of the substrate 9 is gradual, thereby dispersing thermal stress and reducing the occurrence of cracks. Furthermore, because the corner between the second inner wall surface 35a and the bottom surface of the second recess 35 is obtuse, stress applied to this corner and the electrode layer 33 located above this corner is dispersed, reducing the occurrence of cracks in the substrate 9 and the electrode layer 33. Furthermore, when heat generated in the light-emitting element 4 (4B) is conducted to the underside 38 of the substrate 9, it is diffused in both the width direction (X direction) and the length direction (Y direction) along which the second inner wall surface 35a is inclined, thereby further improving heat dissipation efficiency. Furthermore, the corner between the bottom surface of the second recess 35 and the second inner wall surface 35 a may be a curved concave surface, or the entire second inner wall surface 35 a may be a curved concave surface. In this case, the effect of reducing cracks in the substrate 9 and the electrode layer 33 due to stress dispersion is further enhanced.

[0049] 12 is a plan view showing the configuration of a light source module according to a ninth embodiment of the present disclosure. In the light source module 1h of the present embodiment, the three light-emitting elements 4R, 4G, and 4B are individually housed in the first recesses 31 in the above-described embodiments. However, in the present embodiment, as shown in FIG. 12 , the three light-emitting elements 4R, 4G, and 4B may be housed in a single first recess 31.

[0050] Even in this configuration, as in the above-described embodiments, the heat dissipation performance of each of the light-emitting elements 4R, 4G, 4B is improved by the thin portion of the bottom of the first recess 31 of the substrate 9. Also in this embodiment, when the bottom surface 32 of the first recess 31 has a surface roughness Ra2 that is greater than the surface roughness Ra1 of the first surface 8 of the substrate 9, the adhesion strength between the substrate and the electrode layer is improved, and peeling of the electrode layer can be reduced. Furthermore, the characteristic configurations in the first to eighth embodiments can also be applied to this embodiment.

[0051] Tenth Embodiment Fig. 13 is a plan view showing the configuration of a light source module according to a tenth embodiment of the present disclosure. Note that parts corresponding to the previously described embodiments are assigned the same reference numerals, and redundant description will be omitted. The previously described embodiments are configured such that three cores 5 are combined at a multiplexing section 17 to form a single waveguide that extends to the output end. In contrast, the light source module 1i of the tenth embodiment is similar in that the three input surfaces 13R, 13G, and 13B are positioned apart from one another, in accordance with the centers of the input surfaces 13R, 13G, and 13B of each core 5 (5R, 5G, and 5B) and the positions of the light-emitting elements 4R, 4G, and 4B. Meanwhile, the output end surfaces 15R, 15G, and 15B of the three cores 5 are positioned close to one another but apart from one another. In this way, the three cores 5 may be concentrated close to each other between each incident surface 13R, 13G, 13B and each output end face 15R, 15G, 15B, and may extend parallel from there to each output end face 15R, 15G, 15B. The three cores 5 do not have to be parallel, but may be arranged approximately parallel with the spacing decreasing toward the output end. The cores 5 may be bent significantly to be close to each other and arranged so the spacing decreases toward the output end. The cores 5 may be bent significantly to be close to each other and extend approximately parallel toward the output end. In this case, the spacing between adjacent cores 5 may decrease from the close portion toward the output end. The light beams emitted from the output end faces 15R, 15G, 15B of each core 5 may be multiplexed by, for example, a condenser lens 6. The light beams emitted from each core 5 may be emitted in parallel by, for example, a condenser lens 6. In this case, images or the like formed by the light emitted from the three emission end faces 15R, 15G, and 15B may be synthesized by, for example, an external device.

[0052] Eleventh Embodiment Figure 14 is a cross-sectional view showing the configuration of a light source module according to an eleventh embodiment of the present disclosure. The light source module 1j according to the eleventh embodiment differs from the previous embodiments in that the substrate 9 has a back surface 8a located opposite the first surface 8, and the electrode layer 33 extends to the back surface 8a. This configuration eliminates the need to provide the electrode layer 33 behind the element accommodating space 3 (i.e., in the positive direction of the X axis), thereby reducing the dimension of the light source module 1j in the X direction. Furthermore, this configuration allows the light source module 1j to be connected to a printed circuit board or the like using a conductive bonding material such as solder. More specifically, as shown in Figure 14, the electrode layer 33 may include a through conductor 33c located within the substrate 9 and a back surface electrode 33d located on the back surface 8a. 14, the through conductor 33c is located at a position overlapping with the element accommodating space 3 in a plan view, but for example, the electrode layer 33 may extend to between the clad 12 and the substrate 9, and the through conductor 33c may overlap with the clad 12 in a plan view. Furthermore, when the optical waveguide package 2 has a plurality of wiring conductors, it is not necessary for all of the wiring conductors to extend to the rear surface 8a of the substrate 9, and only some of the wiring conductors may extend to the rear surface 8a of the substrate 9. The rear surface electrode 33d may overlap with the element accommodating space 3.

[0053] Twelfth Embodiment FIG. 15 is a cross-sectional view illustrating the configuration of a light source module according to a twelfth embodiment of the present disclosure. The light source module 1k according to the twelfth embodiment differs from the previous embodiments in that it further includes an insulating film 43 positioned between the bottom surface 32 and the electrode layer 33. Examples of materials for the insulating film 43 include resin, glass, quartz, and ceramic. This configuration reduces the possibility of shorting between the electrode layers 33 on the substrate 9, even when the substrate 9 is made of a conductive material such as silicon. Furthermore, by adjusting the thickness of the insulating film 43 (i.e., the dimension in the Z direction), the positional relationship between the light-emitting element 4 and the incident surface 13 in the Z direction can be easily adjusted. Furthermore, the thickness of the insulating film 43 may be different for each light-emitting element 4.

[0054] 13th Embodiment Fig. 16 is a cross-sectional view showing the configuration of a light source module according to a thirteenth embodiment of the present disclosure. The light source module 1l according to the thirteenth embodiment differs from the previous embodiments in that the clad 12 has a portion that does not penetrate from the second surface 10 to the third surface 11. The light source module 1l includes a substrate 9, a clad 12, a core 5, and an electrode layer 33. The substrate 9 has a first surface 8 and a first recess 31 that opens on the first surface 8. The clad 12 is located above the first surface 8. The clad 12 has a second surface 10 facing the first surface 8, a third surface 11 located on the opposite side of the second surface 10, and an opening 3a that opens on the third surface 11. The core 5 is located within the clad 12 and has an incident surface 13 exposed within the opening 3a and an exit surface 15 exposed at an end face of the clad 12. The electrode layer 33 is located within the opening 3a. The opening 3a has a bottom 12b. The first recess 31 has a bottom surface 32. In a plan view, the bottom 12b and the bottom surface 32 overlap each other. The electrode layer 33 is located on the bottom 12b.

[0055] 16 , in a cross-sectional view of the cladding 12 perpendicular to the first surface 8 from the second surface 10 to the third surface 11, at least a portion of the electrode layer 33 may be located within the first recess 31. More specifically, the dimension in the Z direction of the portion of the electrode layer 33 located at the bottom 12 b may be smaller than the depth of the first recess 31 (i.e., the distance in the Z direction from the first surface 8 to the back surface 8 a).

[0056] The bottom surface 32 may have a surface roughness greater than that of the first surface 8. Furthermore, the bottom portion 12b may have a surface roughness greater than that of the first surface 8. The inner wall surface 34a of the first recess 31 may be flat and inclined with respect to the bottom portion 12b.

[0057] 14th Embodiment Fig. 17 is a cross-sectional view showing the configuration of a light source module according to a fourteenth embodiment of the present disclosure. In a light source module 1m according to the fourteenth embodiment, the first recess 31 may have a second recess 35 further recessed from the bottom surface 32. The second recess 35 may be located between the light-emitting element 4 and the incident surface 13, or may be located behind the light-emitting element 4 at the opening 3a (in other words, in the positive direction of the X-axis in the drawings). Alternatively, as shown in Fig. 17, the second recess 35 may be located between the light-emitting element 4 and the incident surface 13 and behind the light-emitting element 4 at the opening 3a. When the light source module 1m further has the second recess 35, the cladding 12 does not need to be located on the bottom surface of the second recess 35.

[0058] The bottom 12b may include a hole 12o that reaches the second surface 10. The first recess 31 may be exposed within the hole 12o. Furthermore, the second recess 35 may also be exposed within the hole 12o.

[0059] Fifteenth Embodiment Figure 18 is a cross-sectional view showing the configuration of a light source module according to a fifteenth embodiment of the present disclosure. The light source module 1n according to the fifteenth embodiment differs from the previous embodiments in that the clad 12 does not include either an element accommodating space 3 or an opening 3a. That is, in a light source module 1l in which a light emitting element 4 is mounted, the light emitting element 4 faces the sidewall 19b of the clad 12. The light source module 1l includes a substrate 9, a clad 12, a core 5, and an electrode layer 33. The substrate 9 has a first surface 8 and a first recess 31 that opens on the first surface 8. The clad 12 is located above the first surface 8 and has a sidewall 19b. The core 5 is located within the clad 12. The core 5 has an incident surface 13 exposed at the sidewall 19b and an exit surface 15 exposed at an end face of the clad. The electrode layer 33 is located on the bottom surface 32 of the first recess 31. The cladding 12 is spaced from the first recess 31. With this configuration, the positional relationship in the Z direction between the light-emitting element 4 and the incident surface 13 can be easily adjusted by adjusting the depth of the first recess 31. In addition, an insulating film 43 located between the bottom surface 32 and the electrode layer 33 may be further provided.

[0060] The optical waveguide package 2 in each embodiment includes a light emitting element 4 mounted on an electrode layer 33 and a lid 7 positioned above the light emitting element 4 .

[0061] According to the present disclosure, it is possible to provide an optical waveguide package and a light source module that can improve heat dissipation and reduce damage to the substrate.

[0062] The optical waveguide package according to the present disclosure can be implemented in the following aspects (1) to (19).

[0063] (1) A waveguide package comprising: a substrate having a first surface and a first recess that opens onto the first surface; a clad located on the first surface, the clad having a second surface facing the first surface, a third surface located on the opposite side of the second surface, and an element accommodating space that penetrates between the second surface and the third surface; a core located within the clad, the core having an incident surface facing the element accommodating space and an exit surface exposed from an end surface of the clad; and an electrode layer located on a bottom surface of the first recess.

[0064] (2) The optical waveguide package according to the above aspect (1), wherein the bottom surface has a surface roughness greater than the surface roughness of the first surface.

[0065] (3) The optical waveguide package according to the above aspect (1) or (2), wherein an inner wall surface surrounding the space in the first recess has a surface roughness greater than the surface roughness of the first surface.

[0066] (4) An optical waveguide package according to any one of the above aspects (1) to (3), wherein the inner wall surface surrounding the space within the first recess is flat and inclined relative to the bottom surface.

[0067] (5) An optical waveguide package according to any one of the above aspects (1) to (4), wherein the inner wall surface surrounding the space within the first recess is flat and connects to the bottom surface via a curved surface.

[0068] (6) An optical waveguide package according to any one of the above aspects (1) to (5), further including a step portion disposed between the first recess and the inner surfaces of the cladding and the core facing the element accommodating space.

[0069] (7) An optical waveguide package according to any one of the above aspects (1) to (6), wherein the bottom surface is deepest on the side of the incident surface relative to the first surface and slopes upward as it moves away from the incident surface.

[0070] (8) The optical waveguide package according to any one of the above aspects (1) to (7), wherein the first recess has a second recess that is further recessed from the bottom surface.

[0071] (9) The optical waveguide package according to the above aspect (8), wherein the second inner wall surface of the second recess is inclined with respect to the bottom surface.

[0072] (10) The optical waveguide package according to the above aspect (1), further comprising an insulating film positioned between the bottom surface and the electrode layer.

[0073] (11) An optical waveguide package comprising: a substrate having a first surface and a first recess that opens on the first surface; a clad located above the first surface, the clad having a second surface facing the first surface, a third surface located opposite the second surface, and an opening that opens on the third surface; a core located within the clad, the core having an incident surface exposed within the opening and an exit surface exposed at an end surface of the clad; and an electrode layer located within the opening, wherein the opening has a bottom, the first recess has a bottom surface, the bottom and the bottom surface overlap in a planar view, and the electrode layer is located on the bottom.

[0074] (12) The optical waveguide package according to the above aspect (11), wherein at least a portion of the electrode layer is located within the first recess in a cross-sectional view perpendicular to the first surface.

[0075] (13) The optical waveguide package according to the above aspect (11), wherein the bottom surface has a surface roughness greater than the surface roughness of the first surface.

[0076] (14) The optical waveguide package according to the above aspect (11), wherein the bottom portion has a surface roughness greater than the surface roughness of the first surface.

[0077] (15) The optical waveguide package according to the above aspect (10), wherein the inner wall surface of the first recess is flat and inclined relative to the bottom.

[0078] (16) The optical waveguide package according to the above aspect (10), wherein the first recess has a second recess that is further recessed from the bottom surface.

[0079] (17) The optical waveguide package according to the above aspect (10), wherein the bottom portion includes a hole that reaches the second surface, and the first recess is exposed within the hole.

[0080] (18) An optical waveguide package comprising: a substrate having a first surface and a first recess that opens onto the first surface; a clad located above the first surface and having a sidewall; a core located within the clad and having an incident surface exposed to the sidewall and an exit surface exposed at an end surface of the clad; and an electrode layer located on the bottom surface of the first recess, wherein the clad is spaced from the first recess.

[0081] (19) The optical waveguide package according to the above aspect (1), further comprising an insulating film positioned between the bottom surface and the electrode layer.

[0082] The light source module according to the present disclosure can be implemented in the following aspect (20).

[0083] (20) A light source module comprising: an optical waveguide package according to any one of aspects (1), (11), and (18); a light emitting element mounted on the electrode layer of the optical waveguide package; and a lid body positioned above the light emitting element.

[0084] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments, and various modifications and improvements are possible within the scope of the gist of the present disclosure. It goes without saying that all or part of the components constituting each of the above-described embodiments can be combined as appropriate within the scope of not contradicting each other.

[0085] REFERENCE SIGNS LIST 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i Light source module 2 Optical waveguide package 3 Element accommodating space 3a Opening 4, 4R, 4G, 4B Light emitting element 5 Core 6 Lens 7 Lid 8 First surface 8a Back surface 9 Substrate 10 Second surface 11 Third surface 12 Cladding 12b Bottom 12o Hole 13, 13R, 13G, 13B Incident surface 14 End surface 15 Emitting surface 17 Wave-combining section 19 Optical waveguide layer 19a Inner surface 19b Side wall 31 First recess 32 Bottom surface 33 Electrode layer 33a First electrode layer 33b Second electrode layer 33c Through conductor 33d Back electrode 34, 34a, 34b, 34c Inner wall surface 34a1 Curved surface 35 Second recess 35a Second inner wall surface 39 Step portion 40 Resist 41 Resist 42 Resist 43 Insulating film 51R, 51G, 51B Dividing path Ra1, Ra2, Ra3 Surface roughness T1, T2 Thickness θ1, θ2 Angle

Claims

1. a substrate having a first surface and a first recess opening on the first surface; a clad located on the first surface, the clad having a second surface facing the first surface, a third surface located on the opposite side of the second surface, and an element accommodating space penetrating between the second surface and the third surface; a core located within the cladding, the core having an incident surface exposed to the element accommodating space and an exit surface exposed from an end face of the cladding; an electrode layer located on a bottom surface of the first recess.

2. The optical waveguide package of claim 1 , wherein the bottom surface has a surface roughness greater than a surface roughness of the first surface.

3. 3. The optical waveguide package according to claim 1, wherein an inner wall surface of said first recess has a surface roughness greater than a surface roughness of said first surface.

4. 3. The optical waveguide package according to claim 1, wherein an inner wall surface of the first recess is flat and inclined relative to the bottom surface.

5. 3. The optical waveguide package according to claim 1, wherein an inner wall surface of the first recess is flat and connects to the bottom surface via a curved surface.

6. 3. The optical waveguide package according to claim 1, further comprising a step portion disposed between the first recess and an inner surface facing the element accommodating space.

7. 3. The optical waveguide package according to claim 1, wherein the bottom surface is deepest on the side of the incident surface relative to the first surface, and slopes upward as it moves away from the incident surface.

8. 3. The optical waveguide package according to claim 1, wherein the first recess has a second recess that is further recessed from the bottom surface.

9. The optical waveguide package according to claim 8 , wherein a second inner wall surface of the second recess is inclined with respect to the bottom surface.

10. The optical waveguide package according to claim 1 , further comprising an insulating film located between the bottom surface and the electrode layer.

11. a substrate having a first surface and a first recess opening on the first surface; a clad located above the first surface, the clad having a second surface facing the first surface, a third surface located on the opposite side of the second surface, and an opening opening into the third surface; a core located within the cladding, the core having an incident surface exposed within the opening and an exit surface exposed at an end surface of the cladding; an electrode layer located within the opening, the opening has a bottom; The first recess has a bottom surface, The bottom portion and the bottom surface overlap each other in a plan view, The electrode layer is located on the bottom.

12. The optical waveguide package according to claim 11 , wherein at least a portion of the electrode layer is located within the first recess in a cross-sectional view perpendicular to the first surface.

13. The optical waveguide package of claim 11 , wherein the bottom surface has a surface roughness greater than a surface roughness of the first surface.

14. The optical waveguide package of claim 11 , wherein the bottom portion has a surface roughness greater than a surface roughness of the first surface.

15. The optical waveguide package according to claim 11 , wherein an inner wall surface of the first recess is flat and inclined relative to the bottom surface.

16. The optical waveguide package according to claim 11 , wherein the first recess has a second recess further recessed from the bottom surface.

17. the bottom portion includes a hole that reaches the second surface; The optical waveguide package according to claim 11 , wherein the first recess is exposed within the hole.

18. a substrate having a first surface and a first recess opening on the first surface; a cladding located above the first surface and having a sidewall; a core located within the cladding, the core having an incident surface exposed to the side wall and an exit surface exposed to an end surface of the cladding; an electrode layer located on a bottom surface of the first recess, The cladding is spaced from the first recess.

19. 20. The optical waveguide package of claim 18, further comprising an insulating film located between the bottom surface and the electrode layer.

20. an optical waveguide package according to any one of claims 1, 11, and 18; a light emitting element mounted on the electrode layer of the optical waveguide package; a cover body positioned above the light emitting element.