Optical waveguide package and light source module

Abstract

An optical waveguide package (2) comprises: a substrate (9) that has a first surface (8); cladding (12) that is located above the first surface (8), that has a second surface (10) facing the first surface (8), that has a third surface (11) located on the side opposite the second surface (10), that has a fourth surface (14) located on the third surface (11) side between the second surface (10) and the third surface (11), and that has an element mounting region (3) opening in the third surface (11); a core (5) that is located within the cladding (12) and has an incidence surface (13) exposed in the element mounting region (3) and an emission surface (15) exposed from an end surface of the cladding (12); and a metal film (22) that is positioned so as to surround the element mounting region (3) above the cladding (12). The metal film (22) includes a first section (22a) positioned above the third surface (11), and a second section (22b) positioned above the fourth surface (14).

Description

Optical waveguide package and light source module

[0001] The present disclosure relates to optical waveguide packages and light source modules.

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

[0003] Japanese Patent Application Publication No. 10-54917

[0004] The optical waveguide package according to the present disclosure comprises a substrate having a 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 a fourth surface located on the third surface side between the second surface and the third surface, the clad having an element mounting area that opens to the third surface, a core located within the clad and having an incident surface exposed to the element mounting area and an exit surface exposed from an end face of the clad, and a metal film located on the clad surrounding the element mounting area, the metal film having a first portion located on the third surface and a second portion located on the fourth surface.

[0005] The light source module according to the present disclosure comprises the optical waveguide package described above, a light-emitting element mounted in the element mounting area of ​​the optical waveguide package, and a lid body bonded to the metal film and covering the element mounting area.

[0006] Objects, features, and advantages of the present disclosure will become clearer from the following detailed description and drawings.

[0023] FIG. 1 is an exploded perspective view showing a light source module including an optical waveguide package according to an embodiment of the present disclosure.

[0024] FIG. 2 is a plan view of the light source module shown in FIG. 1.

[0025] FIG. 3 is a cross-sectional view taken along the section line III-III in FIG. 2.

[0026] FIG. 4 is a partially enlarged perspective view of section IV in FIG. 2 showing the mounting structure of a metal film on a clad.

[0027] FIG. 5 is a partially enlarged perspective view showing the configuration of a metal film of an optical waveguide package according to another embodiment of the present disclosure.

[0028] FIG. 6 is an enlarged cross-sectional view schematically showing the layered structure of metal films used in an optical waveguide package according to yet another embodiment of the present disclosure.

[0029] FIG. 7 is an enlarged perspective view of a portion of an optical waveguide package according to yet another embodiment of the present disclosure.

[0007] The above-mentioned Patent Document 1 discloses a configuration in which an optical waveguide consisting of a core and a cladding surrounding the core is formed on a substrate, a groove is provided in a direction crossing the optical waveguide, and a light-shielding film is provided on the inner wall of the groove, thereby suppressing leakage of radiation modes generated within the optical waveguide element into the core facing the light-emitting element in cladding mode.

[0008] In the conventional technology of Patent Document 1, heat generated when mounting a light emitting element on a substrate can deform the substrate, causing the optical axis of the light emitting element to become misaligned with the axis of the core of the optical waveguide, potentially reducing the efficiency of light propagation between the core and the light emitting element. Therefore, there has been a demand for an optical waveguide package and a light source module with improved light propagation efficiency.

[0009] FIG. 1 is an exploded perspective view showing a light source module 1 including an optical waveguide package 2 according to an embodiment of the present disclosure. FIG. 2 is a plan view of the light source module 1 shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. 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 designated as up or down. However, for convenience, this specification defines a Cartesian coordinate system (X, Y, Z), and terms such as top and bottom are used, with the positive side of the Z-axis direction designated as up. The X-axis direction is also referred to as the length direction. The Y-axis direction is also referred to as the width direction. The Z-axis direction is also referred to as the thickness direction.

[0010] The light source module 1 of this embodiment comprises an optical waveguide package 2, a light-emitting element 4 mounted in an element mounting area 3 of the optical waveguide package 2, a metal film 22 surrounding the element mounting area 3, and a lid body 7 joined to the metal film 22 and covering the element mounting area 3.

[0011] The optical waveguide package 2 comprises a substrate 9 having a first surface 8, a clad 12 located on the first surface 8, the clad 12 having a fourth surface 14 located on the third surface 11 side between the second surface 10 and the third surface 11, and having an element mounting area 3 opening onto the third surface 11, a core 5 located within the clad 12 and having an incident surface 13 facing the element mounting area 3 and an exit surface 15 exposed from an end face of the clad 12, and a metal film 22 located on the substrate 9 surrounding the element mounting area 3.

[0012] The metal film 22 has a first portion 22a having a closed loop shape and located on the third surface 11, and a second portion 22b located on the fourth surface 14 located on the third surface 11 side between the second surface 10 and the third surface 11. The core 5 and the clad 12 constitute an optical waveguide layer 19. The substrate 9 may be a rectangular plate-like body in a plan view.

[0013] The light source module 1 includes the above-mentioned optical waveguide package 2, a light emitting element 4 located in an element mounting area 3, a lens 6 located on the optical path of light emitted from the core 5, and a box-shaped lid 7, for example, with one side open, that covers the element mounting area 3. The lid 7 is not limited to being box-shaped, and may be, for example, plate-shaped, and different shapes can be adopted as appropriate.

[0014] The optical waveguide layer 19 may be made of, for example, glass such as quartz, resin, or the like. The materials constituting the optical waveguide layer 19 may both be glass or resin, or one of the core 5 and the clad 12 may be glass and the other resin. 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, by creating an optical waveguide using a material with a high refractive index and surrounding it with a material with a low refractive index, light can be confined within the core 5 with a high refractive index.

[0015] The light source module 1 further includes a first electrode 20 located within the element mounting area 3 and on which the light emitting element 4 is mounted, and a second electrode 21 connected to the first electrode 20 and extending outward from the element mounting area 3. The lens 6 is located on the optical path of the light emitted from the core 5, and may collimate or focus the light emitted from the core 5. The lens 6 may be, for example, a plano-convex lens having a flat entrance surface and a convex exit surface.

[0016] The substrate 9 may be, for example, an organic wiring substrate in which a dielectric layer contains an organic material. Examples of the organic wiring substrate include a printed wiring board, a build-up wiring board, a flexible wiring board, etc. Examples of organic materials used for the organic wiring substrate include epoxy resin, polyimide resin, polyester resin, acrylic resin, phenol resin, and fluororesin.

[0017] The substrate 9 may be a ceramic wiring substrate in which the dielectric layer contains a ceramic material. Examples of ceramic materials used in ceramic wiring substrates include aluminum oxide sintered bodies, mullite sintered bodies, silicon carbide sintered bodies, aluminum nitride sintered bodies, and glass ceramic sintered bodies. The substrate 9 may also be a wiring substrate containing, for example, a silicon material or a glass material.

[0018] The light-emitting elements 4 include a light-emitting element 4R that emits red light, a light-emitting element 4G that emits green light, and a light-emitting element 4B that emits blue light. These light-emitting elements 4R, 4G, and 4B are, for example, light-emitting diodes (LEDs) or laser diodes. Each light-emitting element 4R, 4G, and 4B is arranged so that its light-emitting end faces incident surfaces 13R, 13G, and 13B that are exposed in the element mounting area 3 of the core 5. The core 5 has a plurality of split paths 41R, 41G, and 41B each having an incident surface 13R, 13G, and 13B, a multiplexing section 17 where the multiple split paths 41R, 41G, and 41B converge, and an integration path 18 that extends between the multiplexing section 17 and the exit surface 15. Each light-emitting element 4R, 4G, 4B is positioned within the element mounting region 3 so that the optical axis of each light-emitting element 4R, 4G, 4B coincides with the center of the incident surface 13R, 13G, 13B of the optical axis dividing path 41R, 41G, 41B. In the core 5, the divided paths 41R, 41G, 41B do not necessarily need to be joined by the multiplexing section 17; for example, the divided paths 41R, 41G, 41B may be independent of each other. When the divided paths 41R, 41G, 41B are independent, the divided path 41G may be linear, and the divided paths 41R, 41B may be positioned so as to approach the divided path 41G toward the exit surface 15. In other words, the distance between the divided paths 41R and 41G in the X-axis direction may decrease toward the exit surface 15, and the distance between the divided paths 41B and 41G in the X-axis direction may decrease toward the exit surface 15.

[0019] The element mounting region 3 may be a recess or a through-hole opening to the third surface 11 of the cladding 12. In another embodiment, the element mounting region 3 may be a through-hole penetrating from the third surface 11 to the second surface 10 of the cladding 12. Also, as shown in FIG. 3 , the element mounting region 3 does not completely penetrate the cladding 12, and a first electrode 21 and / or a second electrode 22 (described later) may be located on the cladding 12. In plan view, a bonding material is annularly located on the third surface 11 of the cladding 12 so as to surround the opening of the element mounting region 3, and the lid 7 is bonded to the third surface 11 of the cladding 12 by the bonding material. The inside of the element mounting region 3 is hermetically sealed by the lid 7, protecting the light-emitting element 4. The lid 7 may be bonded to the metal film 22 by the bonding material.

[0020] The lid 7 is made of a glass material such as quartz, borosilicate, sapphire, etc. The bonding material may be any material that can bond the cladding 12 and the lid 7 and provide an airtight seal, and examples of such materials include Au-Sn or Sn-Ag-Cu solder, metal nanoparticle paste such as Ag or Cu, or glass paste.

[0021] The core 5 contains silicon oxynitride (SiON), also known as silicon oxynitride, and the cladding 12 contains silicon oxide (SiO ２ ) may be contained.

[0022] Here, an example of a method for forming the element mounting region 3 will be described. In this example of the formation method, the second electrode 21 is formed on the first surface 8 of the substrate 9, and an optical waveguide layer 19 made of the cladding 12 and the core 5 is provided on the first surface 8 including the second electrode 21. The portion of the cladding 12 corresponding to the element mounting region 3 is removed by etching to expose the second electrode 21, and the region of the first surface 8 on which the first electrode 20 is to be formed is exposed. The first electrode 20 is formed and connected to the second electrode 21. The formation of the element mounting region 3 is not limited to the above method. For example, the substrate 9 on which the second electrode 21 is formed and the optical waveguide layer 19 on which the element mounting region 3 is provided may be separately prepared and then bonded together.

[0023] 4 is a partially enlarged perspective view of section IV in FIG. 2 , showing the mounting structure of the metal film 22 on the clad 12. The clad 12 has a recess 12a that opens to the third surface 11 and the side surface 27, and the fourth surface 14 serves as a side surface of the recess 12a. The first portion 22a and the second portion 22b of the metal film 22 are electrically disconnected from each other and are configured separately. Therefore, the first portion 22a and the second portion 22b have small heat capacity and high heat dissipation properties. Therefore, even if the first portion 22a and the second portion 22b are heated by heat, for example, during mounting of the light-emitting element 4, the amount of heat transferred to the clad 12 is small, which has the advantage of reducing the thermal load on the clad 12.

[0024] 5 is a partially enlarged perspective view showing the configuration of a metal film 122 of an optical waveguide package according to another embodiment of the present disclosure. Note that parts corresponding to those in the previously described embodiment are designated by the same reference numerals, and redundant description will be omitted. The optical waveguide package of this embodiment includes a substrate 9, a cladding 12, a core 5, and a metal film 122. The metal film 122 has a first portion 122a and a second portion 122b that are connected to each other. The metal film 122 is bent in a generally L-shape from the third surface 11 to the fourth surface 14 in a cross section perpendicular to the direction in which the fourth surface 14 extends, and the first portion 122a and the second portion 122b are integrally formed. The metal film 122 is provided on the third surface 11 and the fourth surface 14, surrounding the element mounting area 3.

[0025] With this configuration, the second portion 122b is located closer to the substrate 9 than the first portion 122a, and therefore the heat generated when the light-emitting element 4 is mounted causes the metal film 122 to melt and shrink as shown by arrow B. The stress caused by the shrinkage of the metal film 122 counteracts the stress that causes the substrate 9 to warp due to heat as shown by arrow A, thereby reducing the warping of the substrate 9.

[0026] Warpage in the Y-axis direction is likely to cause misalignment between the optical axis of each light-emitting element 4 and the optical axis of the incident surfaces 13R, 13G, and 13B of the core 5. Because the metal film 122 reduces this warpage in the Y-axis direction, misalignment between the optical axis of each light-emitting element 4 and the optical axis of the incident surfaces 13R, 13G, and 13B of each dividing path 41R, 41G, and 41B is suppressed, thereby improving light propagation efficiency. The second portion 122b extending in the YZ plane direction is resistant to warpage (bending) in the Y-axis direction and is therefore effective in suppressing warpage. In particular, the metal film 122 has a first portion 122a and a second portion 122b, and these first portion 122a and second portion 122b are connected to form a bent L-shape, which generates a higher resistance to warpage (bending) and makes the device stronger.

[0027] As shown in FIGS. 1 to 5 , the optical waveguide package may have no recess parallel to the third surface 11, and therefore no fifth surface 16. In this case, the fourth surface 14 is the third surface 11 side (upper side) of the side surface 27 of the cladding 12. The fourth surface 14 is a surface extending in the Y-Z axis direction intersecting the third surface 11. In this case, the same effect can be achieved. Fabrication is easier when the fifth surface 16 is included. For example, when fabricating a large number of optical waveguide packages at once, the fifth surface 16 can be formed in advance, and the first and second portions 122 a and 122 b of the metal film 122 can be formed, followed by cutting to form the side surface 27. This allows for more efficient manufacturing than cutting to form the side surface 27 and then forming the second portion 122 b.

[0028] 6 is a partially enlarged perspective view showing the configuration of a metal film 222 of an optical waveguide package according to another embodiment of the present disclosure. Note that parts corresponding to those in the previously described embodiment are designated by the same reference numerals, and redundant description will be omitted. The optical waveguide package of this embodiment includes a substrate 9, a clad 12, a core 5, and a metal film 222. The clad 12 further includes a side surface 27 and a fifth surface 16 formed between the fourth surface 14 and the side surface 27 and parallel to the third surface 11. The fifth surface 16 also serves as the bottom surface of the recess. The metal film 222 includes a first metal film 222a integrally formed across the third surface 11 to the fourth surface 14 and the fifth surface 16 of the clad 12, and a second metal film 222b overlapping the first metal film 222a and having a substantially L-shaped cross section perpendicular to the direction in which the fourth surface 14 extends.

[0029] The first metal film 222a may be formed of, for example, TiPt, and the second metal film 222b may be formed of, for example, AuSn. In this manner, the thermal expansion coefficients of the first metal film 222a and the second metal film 222b, where α1 is the thermal expansion coefficient of the cladding 12, α2 is the thermal expansion coefficient of the first metal film 222a, and α3 is the thermal expansion coefficient of the second metal film 222b, satisfy the relationship α1<α2<α3, thereby preventing peeling of the metal film 222 during contraction. In other words, if the difference in thermal expansion coefficients between the cladding 12, the first metal film 222a, and the second metal film 222b is too large, peeling of the metal film 222 may occur during contraction. In order to reduce such peeling of the first metal film 222a and the second metal film 222b, the materials are prepared so that the relationship between the thermal expansion coefficients of the clad 12, the first metal film 222a, and the second metal film 222b satisfies α1 < α2 < α3, thereby reducing deterioration of durability due to heat.

[0030] Therefore, in a configuration in which the metal film 222 includes a first metal film 222a arranged on the clad 12 and a second metal film 222b arranged on the first metal film 222a, the occurrence of film peeling as described above can be suppressed by using a material for the second metal film 222b whose thermal expansion coefficient is higher than that of the first metal film 222a.

[0031] 7 is an enlarged cross-sectional view schematically illustrating a laminated structure of a metal film 322 used in an optical waveguide package according to another embodiment of the present disclosure. The third surface 11 of the cladding 12 has a convex portion 12b formed at a position overlapping the second electrode 21, and a portion adjacent to the convex portion 12b has a relatively concave portion 12c, resulting in an uneven shape. The convex portion 12b and the concave portion 12c of the cladding 12 may be formed, for example, by etching the cladding 12. One side of the metal film 22 (322) extending in the X-axis direction, which intersects with the direction in which the second electrode 21 extends (the Y-axis direction), overlaps with the convex portion 12b. The first metal film 322a on the cladding 12 has an uneven shape with convex portions 322ab and concave portions 322ac, due to the transfer of the concave and convex portions of the third surface 11 of the cladding 12.

[0032] The surface of the first metal film 322a facing the third surface 11 of the clad 12 is aligned with the convex portions 12b and concave portions 12c of the clad 12, and the bonding interface between the clad 12 and the first metal film 322a, i.e., the bonding interface between the metal film 322 and the clad 12, has an uneven shape. The second metal film 322b has the same uneven shape as the first metal film 322a, including convex portions 322bb and concave portions 322bc, due to the transfer of the convex portions and concave portions of the first metal film 322a. The bonding interface between the first metal film 322a and the second metal film 322b also has an uneven shape. The third surface 11 of the clad 12 has the convex portions 12b at positions overlapping the second electrode 21, resulting in the formation of the convex portions 322ab of the first metal film 322a and the convex portions 322bb of the second metal film 322b.

[0033] Another side portion of the metal film 22 (322) extending in the X-axis direction is located at a position overlapping with the core 5 extending in the Y-axis direction. The third surface 11 of the cladding 12 also has a convex portion 12b at a position overlapping with the core 5. The convex portions 322ab of the first metal film 322a and the convex portions 322bb of the second metal film 322b are also located at positions corresponding to the core 5. That is, the convex portions 12b of the cladding 12, the convex portions 322ab of the first metal film 322a, and the convex portions 322bb of the second metal film 322b are located at positions overlapping with the core 5 located in front of each light-emitting element 4 (in the -Y-axis direction) and at positions overlapping with the second electrode 21 located behind each light-emitting element 4 (in the Y-axis direction). Even in front of each light-emitting element 4 (in the -Y axis direction), the bonding interface between the second metal film 322b and the first metal film 322a, and the bonding interface between the first metal film 322a and the clad 12 have an uneven shape, i.e., the bonding interface between the metal film 322 and the clad 12 has an uneven shape.

[0034] In this way, since the third surface 11 of the clad 12 has the convex portion 12b, the bonding area between the third surface 11 of the clad 12 and the first metal film 322a and the bonding area between the first metal film 322a and the second metal film 322b are increased, thereby realizing a high bonding strength between them. Note that, even when the metal film 22 is a single layer, the bonding strength between the metal film 22 and the clad 12 is similarly increased.

[0035] When the portions of the metal film 22 located to the sides (in the X-axis direction) of each light-emitting element 4 extend to the fourth surface 14 (when the first portion 122a and the second portion 122b are connected), the bonding strength between the portions located to the sides of the metal film 22 and the clad 12 is increased. In this case, if the protrusions 12b are provided on the third surface 11 of the clad 12 as described above to increase the bonding strength between the portions of the metal film 22 located before and after each light-emitting element 4 and the clad 12, the bonding strength between the metal film 22 and the clad 12 is increased over the entire area of ​​the frame-shaped metal film 22. This reduces the unevenness in the bonding strength of the metal film 22 to the clad 12 compared to when the clad 12 does not have the protrusions 12b, making it less likely that peeling of the metal film 22 will occur starting from areas of weak bonding strength.

[0036] The cross-sectional shape perpendicular to the longitudinal direction (Y-axis direction) of the protrusions 12b, 322ab, 322bb is not limited to a rectangle but may be a trapezoid. When the cross-sectional shape is a trapezoid, the corners of the protrusions 12b, 322ab, 322bb (the corners between the top surface and the side surface of the protrusions 12b, 322ab, 322bb and the corners between the side surface and the bottom surface of the recesses 12c, 322ac, 322bc) are obtuse angles, which makes it difficult for stress to concentrate and reduces the occurrence of cracks originating from the corners.

[0037] 8 is an enlarged perspective view of a portion of an optical waveguide package according to yet another embodiment of the present disclosure. Note that parts corresponding to those in the above-described embodiment are given the same reference numerals, and duplicated explanations will be omitted. The optical waveguide package of this embodiment has a hard layer 400 containing the same material as the core 5 inside the clad 12 that surrounds the element mounting area 3. This hard layer 400 may contain a material harder than the clad 12. For example, the core 5 may contain silicon oxynitride (SiON), also known as silicon oxynitride, and the clad 12 may contain silicon oxide (SiO ２ ) may be contained.

[0038] The shape of the hard layer 400 can be formed by etching, for example, simultaneously with the etching of the core 5. By forming the cladding 12 on the hard layer 400, the cladding 12 can be formed to have a shape conforming to the hard layer 400, i.e., a recess 12a (step). Therefore, additional processing such as etching or cutting to form the recess 12a after forming the cladding 12 is not required. The hard layer 400 for forming the recess 12a may be provided at a position sandwiching the element mounting region 3 in the X-axis direction (side). Furthermore, it may also be provided at a position sandwiching the element mounting region 3 in the Y-axis direction (front and rear). In this way, when the hard layer 400 is positioned surrounding the element mounting region 3, deformation of the element mounting region 3 and the cladding 12 around it can be suppressed. This further reduces the misalignment between the optical axis of each light-emitting element 4 and the optical axis of the incident surfaces 13R, 13G, and 13B of the core 5 due to warping of the element mounting region 3. Furthermore, by reducing the warp of the third surface 11 of the cladding 12, defects are less likely to occur in the bond between the metal film 22 located thereon and the lid 7, making it easier to maintain airtightness.

[0039] In yet another embodiment of the present disclosure, the surface of the clad 12 on which the metal film 322 is deposited may be roughened by a roughening treatment, such as a chemical treatment by etching or a mechanical treatment by blasting. The roughened surface may have an arithmetic mean roughness of, for example, approximately 5 to 100 nm. By depositing a first metal film 322a on the roughened surface to a thickness of, for example, 1 μm to 50 μm, the first metal film 322a is formed on the roughened surface of the clad 12, and the first metal film 322a is also formed to have a rough surface. Furthermore, by depositing a second metal film 322b on the roughened first metal film 322a, the rough surface is transferred to the second metal film 322b, which is also formed to have a rough surface.

[0040] By forming the clad 12, the first metal film 322a, and the second metal film 322b in a rough surface in this manner, the mutual contact area can be increased, thereby improving the bonding strength between the clad 12, the first metal film 322a, and the second metal film 322b and reducing film peeling.

[0041] In still another embodiment of the present disclosure, the light-emitting element 4 is not limited to a light-emitting diode, and may be, for example, a vertical cavity surface emitting laser (VCSEL).

[0042] According to the optical waveguide package according to the present disclosure, an optical waveguide package with improved light propagation efficiency can be obtained.

[0043] According to the light source module according to the present disclosure, a light source module with improved light propagation efficiency can be obtained.

[0044] The optical waveguide package according to the present disclosure can be implemented in the following configurations (1) to (9).

[0045] (1) An optical waveguide package comprising: a substrate having a 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 a fourth surface located on the third surface side between the second surface and the third surface, the clad having an element mounting area that opens to the third surface; a core located within the clad, the core having an incident surface exposed to the element mounting area and an exit surface exposed from an end face of the clad; and a metal film located on the clad surrounding the element mounting area, the metal film having a first portion located on the third surface and a second portion located on the fourth surface.

[0046] (2) The optical waveguide package according to the above configuration (1), wherein the clad has a recess that opens to the third surface and a side surface, and the fourth surface is an inner surface of the recess.

[0047] (3) An optical waveguide package according to the above configuration (1) or (2), wherein the first portion and the second portion are connected, and the metal film is bent from the third surface to the fourth surface.

[0048] (4) The optical waveguide package according to any one of the above configurations (1) to (3), wherein the cladding surrounding the element mounting region has a layer containing the same material as the core inside.

[0049] (5) An optical waveguide package according to any one of the above configurations (1) to (3), having a hard layer made of a material harder than the cladding inside the cladding surrounding the element mounting area.

[0050] (6) An optical waveguide package according to any one of the above configurations (1) to (5), wherein the metal film includes a first metal film disposed on the clad and a second metal film disposed on the first metal film, and the thermal expansion coefficient of the second metal film is higher than the thermal expansion coefficient of the first metal film.

[0051] (7) An optical waveguide package described in any one of the above configurations (1) to (6), wherein the third surface of the clad has a convex portion at a position overlapping the metal film, and the surface of the metal film facing the clad is along the convex portion.

[0052] (8) The optical waveguide package according to the above configuration (7), wherein the convex portion is located at a position overlapping with a side portion of the metal film extending in a direction intersecting the direction in which the core extends from the incident surface.

[0053] (9) The optical waveguide package according to the above configuration (7) or (8), wherein the cross-sectional shape of the convex portion is trapezoidal.

[0054] The light source module according to the present disclosure can be implemented in the following configuration (10).

[0055] (10) A light source module comprising: an optical waveguide package according to any one of the above configurations (1) to (9); a light emitting element mounted in the element mounting area of ​​the optical waveguide package; and a lid body bonded to the metal film and covering the element mounting area.

[0056] 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.

[0057] REFERENCE SIGNS LIST 1 light source module 2 optical waveguide package 3 element mounting area 4, 4R, 4G, 4B light emitting element 5 core 6 lens 7 lid 8 first surface 9 substrate 10 second surface 11 third surface 12 clad 13, 13R, 13G, 13B incident surface 14 fourth surface 15 emission surface 16 fifth surface 19 optical waveguide layer 20 first electrode 21 second electrode 22, 122, 222, 322 metal film 22a, 122a first portion 22b, 122b second portion 222a, 322a first metal film 222b, 322b second metal film

Claims

1. An optical waveguide package comprising: a substrate having a first surface; a cladding located on the first surface and having a second surface facing the first surface, a third surface located on the opposite side of the second surface, and a fourth surface located on the third surface side between the second and third surfaces, the cladding having an element mounting area opening to the third surface; a core located within the cladding and having an incident surface exposed to the element mounting area and an exit surface exposed from an end face of the cladding; and a metal film located on the cladding surrounding the element mounting area, wherein the metal film has a first portion located on the third surface and a second portion located on the fourth surface.

2. The optical waveguide package according to claim 1, wherein said cladding has a recessed portion that opens to said third surface and a side surface, and said fourth surface is the inner surface of said recessed portion.

3. The optical waveguide package according to claim 1 or 2, wherein the first portion and the second portion are connected, and the metal film is bent from the third surface to the fourth surface.

4. The optical waveguide package according to any one of claims 1 to 3, wherein the cladding surrounding the element mounting region has a layer containing the same material as the core inside.

5. The optical waveguide package according to any one of claims 1 to 3, further comprising a hard layer containing a material harder than the cladding inside the cladding surrounding the element mounting area.

6. An optical waveguide package according to any one of claims 1 to 5, wherein the metal film includes a first metal film disposed on the cladding, and a second metal film disposed on the first metal film, and the thermal expansion coefficient of the second metal film is higher than the thermal expansion coefficient of the first metal film.

7. An optical waveguide package according to any one of claims 1 to 6, wherein the third surface of the cladding has a convex portion at a position overlapping the metal film, and the surface of the metal film facing the cladding is aligned along the convex portion.

8. The optical waveguide package according to claim 7, wherein the convex portion is positioned so as to overlap a side portion of the metal film that extends in a direction intersecting the direction in which the core extends from the incident surface.

9. The optical waveguide package according to claim 7 or 8, wherein the cross section of the convex portion is trapezoidal.

10. A light source module comprising: an optical waveguide package according to any one of claims 1 to 9; a light emitting element located in the element mounting area of ​​the optical waveguide package; and a lid located on the metal film and above the element mounting area.