Optical waveguide package and light source module

Abstract

An optical waveguide package (100) according to the present disclosure comprises: a substrate (1) having a first surface (1a); a clad layer (2) which is positioned on the first surface (1a) and in which the surface opposite to the surface facing the first surface (1a) has a recess (21); a plurality of element mounting regions (3) positioned inside the recess (21); and a core (4) including a plurality of light entry parts (41) which have entry end surfaces (41a) in the inner surface of the recess (21), a synthesis part (42) at which the light entry parts (41) meet together, and a light emission part (43) which has an emission end surface (43a) in the outer surface of the clad layer (2) and is positioned at the subsequent stage of the synthesis part (42). In a plan view, the first surface (1a) is exposed on at least the lateral side of the synthesis unit (42).

Description

Technical Field

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

Background Art

[0002] A conventional optical waveguide is described, for example, in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The optical waveguide package of the present disclosure includes a substrate having a first surface, a cladding layer located on the first surface and having a concave portion on a surface opposite to the surface facing the first surface, a plurality of element mounting regions located in the concave portion, a core located in the cladding layer and including a plurality of light incident portions each having an incident end face on an inner surface of the concave portion, a multiplexing portion where the plurality of light incident portions converge, and a light emitting portion located at a subsequent stage of the multiplexing portion and having an emission end face on an outer surface of the cladding layer, In a plan view, at least laterally of the multiplexing portion, the first surface is exposed.

[0005] The light source module of the present disclosure includes the above optical waveguide package and a plurality of light emitting elements respectively mounted on the plurality of element mounting regions.

Brief Description of the Drawings

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

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DETAILED DESCRIPTION OF THE INVENTION

[0007] Conventionally, as described in Patent Document 1 above, various devices such as a light source module and an optical circuit that combine and emit light emitted from a plurality of light-emitting elements have been proposed. Such a device has an optical waveguide composed of a cladding located on the main surface of a substrate and a core located within the cladding.

[0008] In conventional devices, light leaking from the core or incident on the cladding from the surrounding environment becomes stray light and is emitted from the emission end portion of the optical waveguide, which may reduce the quality of the emitted light.

[0009] Hereinafter, embodiments of the optical waveguide package and the light source module of the present disclosure will be described with reference to the accompanying drawings. The drawings used in the following description are schematic. The dimensional ratios and the like on the drawings do not necessarily match the actual ones. In the present disclosure, the term "multiplexing" includes not only the case where lights with different wavelengths are superimposed, but also the case where lights are individually guided through a plurality of optical paths and then the lights emitted from each emission end face are multiplexed, for example, in a lens. The optical waveguide package and the light source module of the present disclosure may be used with any direction being defined as upward or downward. In this specification, for convenience, a rectangular coordinate system (X, Y, Z) is defined, and the positive side in the Z-axis direction is defined as upward, and terms such as the upper surface or the lower surface are used. The X direction is also referred to as the first direction or the length direction. The Y direction is also referred to as the second direction or the width direction. The Z direction is also referred to as the third direction or the height direction.

[0010] FIG. 1 is an exploded perspective view showing an optical waveguide package according to an embodiment of the present disclosure, and FIG. 2 is an exploded perspective view showing the optical waveguide package according to an embodiment of the present disclosure, viewed from a direction different from that of FIG. 1. FIG. 3 is a plan view of the optical waveguide package of FIG. 1, FIG. 4 is a cross-sectional view taken along the cutting plane line IV-IV of FIG. 3, and FIG. 5 is an end view taken along the cutting plane line V-V of FIG. 3. FIG. 6 is an end view showing a modified example of the optical waveguide package of FIG. 1, FIG. 7 is an end view showing a modified example of the optical waveguide package of FIG. 1, and FIG. 8 is a plan view showing a modified example of the optical waveguide package of FIG. 1. In FIGS. 3 to 4 and 8, the lid body and the seal ring are omitted from the illustration. Further, the end views shown in FIGS. 6 and 7 correspond to the end view shown in FIG. 5, and the plan view shown in FIG. 8 corresponds to the plan view shown in FIG. 3.

[0011] The optical waveguide package 100 of the present embodiment includes a substrate 1, a cladding layer 2, a plurality of element mounting regions 3, and a core 4.

[0012] As shown in FIGS. 1 to 3, the substrate 1 has a main surface (first surface) 1a and a side surface 1b continuous with the main surface 1a. The cladding layer 2 is located on the first surface 1a of the substrate 1. As shown in FIG. 4, the cladding layer 2 has a lower surface 2a facing the substrate 1 and an upper surface 2b opposite to the lower surface 2a. The upper surface 2b has a recess 21. A plurality of element mounting regions 3 are located within the recess 21. A plurality of light-emitting elements 10 are respectively mounted on the plurality of element mounting regions 3. The core 4 is located within the cladding layer 2. The core 4 extends from the recess 21 of the cladding layer 2 to the outer surface.

[0013] The substrate 1 may be a ceramic wiring substrate made of a ceramic material. Examples of the ceramic material used for the ceramic wiring substrate include an aluminum oxide-based sintered body, a mullite-based sintered body, a silicon carbide-based sintered body, a aluminum nitride-based sintered body, a glass ceramic-based sintered body, and the like. Conductors such as connection pads, internal wiring conductors, and external connection terminals for electrically connecting the light-emitting element 10 and an external circuit may be disposed on the ceramic wiring substrate. Note that the ceramic wiring substrate may be a laminate formed by laminating a plurality of ceramic layers.

[0014] The substrate 1 may be an organic wiring substrate made of an organic material. The organic wiring substrate may be, for example, a printed wiring substrate, a build-up wiring substrate, a flexible wiring substrate, or the like. Examples of the organic material used for the organic wiring substrate include an epoxy resin, a polyimide resin, a polyester resin, an acrylic resin, a phenol resin, a fluororesin, and the like. The organic wiring substrate may be composed of a single resin layer, or may be a laminate formed by laminating a plurality of resin layers.

[0015] The substrate 1 may be made of a compound semiconductor such as gallium nitride (GaN), gallium arsenide (GaAs), indium phosphide (InP), or may be made of silicon (Si), germanium (Ge), sapphire (Al2O3), or the like.

[0016] The cladding layer 2 may be made of, for example, quartz (SiO2) or the like. The cladding layer 2 may be a laminate. The cladding layer 2 may be made by laminating a lower cladding layer located on the first surface 1a of the substrate 1 and an upper cladding layer located on the upper surface of the lower cladding layer. The core 4 may be formed on the upper surface of the lower cladding layer. The recess 21 may penetrate the cladding layer 2 in the height direction (Z direction).

[0017] Each of the multiple element mounting regions 3 has a first electrode pad 31 and a second electrode pad 32. The first electrode pad 31 and the second electrode pad 32 are located on the first surface 1a and are connected to a first wiring conductor 33 and a second wiring conductor 34, respectively, which extend from inside the recess 21 to outside the recess 21. Ends of the first wiring conductor 33 and the second wiring conductor 34 located outside the recess 21 are connected to an external power supply.

[0018] The light emitting element 10 mounted on the element mounting region 3 is, for example, a semiconductor laser (Laser Diode; L The light emitting elements 10 may be red light emitting elements 10r having a peak of emission intensity in a red wavelength region (approximately 600 to 700 nm), green light emitting elements 10g having a peak of emission intensity in a green wavelength region (approximately 500 to 600 nm), and blue light emitting elements 10b having a peak of emission intensity in a blue wavelength region (approximately 400 to 500 nm).

[0019] The element mounting regions 3 may be separated from one another by a plurality of walls erected in the height direction (Z direction). The walls may be formed integrally with the cladding layer 2.

[0020] The core 4 is made of, for example, silicon oxynitride (SiON), silicon oxide (SiO X) may be composed of the like. In the optical waveguide package 100 of the present embodiment, the cladding layer 2 is made of SiO2, and the core 4 is made of SiON. The refractive index of the core 4 is higher than that of the cladding layer 2. The refractive index difference between the core 4 and the cladding layer 2 may be, for example, about 0.05 to 0.30. The optical waveguide package 100 surrounds the core 4 with a high refractive index by the cladding layer 2 with a low refractive index, and the light propagating through the core 4 is totally reflected at the boundary between the core 4 and the cladding layer 2, so that the light can be confined within the core 4. The core 4 and the cladding layer 2 can be formed, for example, using photolithography technology and etching technology used in the semiconductor device manufacturing process.

[0021] The cladding layer 2 and the core 4 constitute an optical waveguide 5 through which light emitted from a plurality of light-emitting elements mounted on a plurality of element mounting regions 3 propagates. As shown in FIGS. 1 to 3, the core 4 has a plurality of light incident portions 41, a multiplexing portion 42, and a light emitting portion 43. Each of the plurality of light incident portions 41 has an incident end face 41a located on the inner surface of the recess 21. Light emitted from each of the plurality of light-emitting elements 10 is incident on the plurality of incident end faces 41a. The plurality of light incident portions 41 meet at the multiplexing portion 42. The multiplexing portion 42 may be a portion between a location where adjacent cores 4 (light incident portions 41) are in contact with each other and a location located at a subsequent stage of the location and where the width of the core 4 is constant. The light emitting portion 43 is located at the subsequent stage of the multiplexing portion 42, that is, downstream of the multiplexing portion 42 in the light propagation direction. The light emitting portion 43 extends in the first direction and has an emission end face 43a located on the outer surface of the cladding layer 2. The width of the light emitting portion 43 (dimension in the Y direction) may be, for example, about 1 to 10 μm. The light emitted from the plurality of light-emitting elements 10 is multiplexed at the multiplexing portion 42 and then emitted from the emission end face 43a. The emission end face 43a of the light emitting portion 43 and the outer surface of the cladding layer 2 where the emission end face 43a is located constitute an emission end portion 51 of the optical waveguide 5. The emission end portion 51 of the optical waveguide 5 may be flush with the side face 1b of the substrate 1. In this case, since the light emitted from the emission end portion 51 is not kicked by the first face 1a, the light propagating through the light emitting portion 43 can be efficiently extracted.

[0022] In the optical waveguide package 100, the first surface 1a of the substrate 1 is exposed at least laterally of the multiplexing portion 42 in a plan view. In this specification, "lateral" refers to a direction perpendicular to the extending direction of the light emitting portion 43 and along the first surface 1a. The multiplexing portion 42 is a location where a plurality of light incident portions 41 converge. Since the propagation direction of the light propagating through each light incident portion 41 changes in the multiplexing portion 42, the light is likely to leak from the core 4 in the multiplexing portion 42. In the optical waveguide package 100, since the cladding layer 2 is not located in the region lateral to the multiplexing portion 42, the light leaked from the core 4 (hereinafter, also simply referred to as leakage light) can be easily emitted to the outside, so that it is possible to suppress the leakage light from becoming stray light propagating through the cladding layer 2. Note that FIG. 3 shows an example in which the first surface 1a is exposed laterally of the multiplexing portion 42 and the light emitting portion 43, but the first surface 1a may be exposed only laterally of the multiplexing portion 42 and not laterally of the light emitting portion 43.

[0023] Further, in the optical waveguide package 100, since the optical waveguide 5 is narrowed at least laterally of the multiplexing portion 42, the light emitted from the light emitting element 10 and directly incident on the cladding layer 2 can be easily emitted to the outside from the narrowed portion in the optical waveguide 5. As a result, it is possible to suppress the light emitted from the light emitting element 10 and directly incident on the cladding layer 2 from being emitted from the emission end portion 51 of the optical waveguide 5.

[0024] Further, in the optical waveguide package 100, since the cladding layer 2 is not located on at least a part of the first surface 1a, it is possible to suppress the light from the surrounding environment (also referred to as external light) from being incident on the cladding layer 2. Therefore, it is possible to suppress the external light from becoming stray light propagating through the cladding layer 2 and being emitted from the emission end portion 51 of the optical waveguide 5.

[0025] As described above, the optical waveguide package 100 can suppress the stray light from being emitted from the emission end portion 51 of the optical waveguide 5 and improve the quality of the emitted light.

[0026] The cladding layer 2 of the optical waveguide package 100 may be formed by removing a part of the cladding layer precursor formed over substantially the entire area of the first surface 1a. The portion of the cladding layer precursor to be removed can be removed using photolithography technology and etching technology.

[0027] As shown in FIG. 3, the core 4 has a plurality of light incident portions 41 with curvature. The optical waveguide package 100 may be configured such that the first surface 1a is exposed on the side of the location where the curvature of each of the plurality of light incident portions 41 is maximum. The two-dot chain line L in FIG. 3 shows an example where the exposed portion of the first surface 1a extends to the side of the location where the curvature of each of the plurality of light incident portions 41 is maximum. The light propagating through the core 4 is likely to leak into the cladding layer 2 at locations where the curvature of the core 4 is large. In the optical waveguide package 100, the first surface 1a is exposed on the side of the location where light is most likely to leak, and the cladding layer 2 is not located over the entire side area of the location, making it easy to release the light leaked from the core 4 to the outside. As a result, the light leaked from the core 4 becomes stray light propagating through the cladding layer 2, and it is possible to suppress the light from being emitted from the emission end portion 51 of the optical waveguide 5, thus making it possible to improve the quality of the emitted light.

[0028] The plurality of light incident portions 41 may have different lengths in their extending direction (the light propagation direction). In this case, the degree of freedom in arranging the plurality of element mounting regions 3 can be increased. Consequently, it becomes possible to miniaturize the optical waveguide package 100. Further, it is possible to reduce the curvature of the light incident portion 41 and suppress the leakage of light in the light incident portion 41.

[0029] The optical waveguide package 100 may be configured such that the first surface 1a is exposed on the sides of the multiplexing section 42 and the light emitting section 43. Since the multiplexing section 42 and the light emitting section 43 are located downstream of the light incident section 41, the light leaking from the light incident section 41 propagates through the portion of the cladding layer 2 that covers the multiplexing section 42 and the light emitting section 43. When the first surface 1a is exposed on the sides of the multiplexing section 42 and the light emitting section 43, it becomes easier to release the light (stray light) leaking from the light incident section 41 to the outside, so that the quality of the emitted light can be improved. Also, the light leaking from the multiplexing section 42 is more likely to propagate in the positive direction of the first direction (the right direction in FIG. 3) rather than in the direction perpendicular to the first direction (X direction). By exposing the first surface 1a also on the side of the light emitting section 43 downstream of the multiplexing section 42, it is possible to suppress the light leaking from the multiplexing section 42 from becoming stray light, and to improve the quality of the emitted light.

[0030] The cladding layer 2 has an elongated ridge portion 22 along the core 4 at the portion where the first surface 1a is exposed on the side. As shown in FIG. 5, when looking at the cross section perpendicular to the extending direction (X direction) of the light emitting section 43, the ridge portion 22 includes a second surface 22a facing the first surface 1a of the substrate 1, a third surface 22b located on the side opposite to the second surface 22a, a first side surface 22c continuous with the second surface 22a, and a second side surface 22d located on the side opposite to the first side surface 22c. In plan view, the width of the ridge portion 22 may be about 1.5 to 30 times the width of the core 4 (light emitting section 43).

[0031] The first side surface 22c and the second side surface 22d may have a roughened surface. The first side surface 22c and the second side surface 22d may have a larger surface roughness than the third surface 22b. In this case, the light leaking from the core 4 can be diffusely reflected at the boundary between the ridge portion 22 and the outside, and it is possible to suppress the light leaking from the core 4 from re-entering the core 4 and degrading the quality of the emitted light. The first side surface 22c and the second side surface 22d may have an arithmetic mean roughness Ra of about 5 to 100 nm. The third surface 22b may have an arithmetic mean roughness Ra of about 0.1 to 10 nm.

[0032] As shown in FIG. 6, the first side surface 22c and the second side surface 22d may be inclined with respect to the first surface 1a instead of being at an angle of 90 degrees with respect to the first surface 1a. In this case, even if the light leaking from the core 4 is reflected at the boundary between the cladding layer 2 and the outside, it is difficult for the reflected light to be reflected toward the core 4. As a result, it is possible to suppress the light leaking from the core 4 from re-entering the core 4 and degrading the quality of the emitted light. Further, since the protruding portion 22 has a tapered shape upward, the surface on which external light enters becomes smaller, so that it is possible to more effectively suppress the external light from entering the cladding layer 2. As a result, the external light becomes stray light propagating through the optical waveguide 5, and it is possible to effectively suppress the external light from being emitted from the emission end portion 51 of the optical waveguide 5. Further, when the protruding portion 22 has a tapered shape upward, the stress generated between the protruding portion 22 and the substrate is easily dispersed, so that the bonding reliability with the substrate 1 can be improved. The inclination angle θ1 of the first side surface 22c with respect to the first surface 1a and the inclination angle θ2 of the second side surface 22d with respect to the first surface 1a may be 70 degrees or more and less than 90 degrees. In this case, the first side surface 22c and the second side surface 22d can be easily formed using photolithography technology and etching technology. The inclination angle θ1 and the inclination angle θ2 may be the same or different.

[0033] As shown in FIG. 7, the protruding portion 22 may have a third side surface 22e continuous with the first side surface 22c, a fourth side surface 22f connecting the third side surface 22e and the third surface 22b, a fifth side surface 22g continuous with the second side surface 22d, and a sixth side surface 22h connecting the fifth side surface 22g and the third surface 22b. In this case, the number of corners of the protruding portion 22 can be increased, and the angle formed by the side surface of the protruding portion 22 and the first surface 1a can be varied in various ways. As a result, even if the light leaking from the core 4 is reflected at the boundary between the cladding layer 2 and the outside, it is possible to make it difficult for the reflected light to be reflected toward the core 4. Consequently, it is possible to suppress the light leaking from the core 4 from re-entering the core 4 and improve the quality of the emitted light.

[0034] The fourth side surface 22f and the sixth side surface 22h may be inclined with respect to the first surface 1a. The inclination angle θ4 of the fourth side surface 22f with respect to the first surface 1a and the inclination angle θ6 of the sixth side surface 22h with respect to the first surface 1a may be larger than the inclination angle θ1 and the inclination angle θ2. The inclination angles θ4 and θ6 may be 70 degrees or more and less than 90 degrees. In this case, the fourth side surface 22f and the sixth side surface 22h can be easily formed by using photolithography technology and etching technology. The third side surface 22e and the fifth side surface 22g may be substantially parallel to the first surface 1a of the substrate 1. Also, the third side surface 22e and the fifth side surface 22g may have the same height from the first surface 1a, or may have different heights from the first surface 1a.

[0035] The fourth side surface 22f and the sixth side surface 22h may be roughened. The fourth side surface 22f and the sixth side surface 22h may have a larger surface roughness than the third surface 22b. In this case, since the light leaking from the core 4 can be diffusely reflected at the boundary between the fourth side surface 22f and the sixth side surface 22h and the outside, it is possible to suppress the light leaking from the core 4 from being re-incident on the core 4 and degrading the quality of the emitted light. The fourth side surface 22f and the sixth side surface 22h may have an arithmetic mean roughness Ra of about 5 to 100 nm.

[0036] When looking at a cross-section perpendicular to the extending direction (X direction) of the light emitting portion 43, it may be located close to a corner portion in the outer contour shape of the ridge portion 22. In this case, even if the light leaking from the core 4 is reflected at the boundary between the cladding layer 2 and the outside, the reflected light can be made less likely to be reflected toward the core 4. As a result, it is possible to suppress the light leaking from the core 4 from being re-incident on the core 4 and improve the quality of the emitted light.

[0037] In a plan view, the rib portion 22 may have at least one portion (also referred to as an acute-angle surface) 24 that forms an acute angle with the extending direction of the core 4 and whose distance from the core 4 gradually decreases toward the emission end face 43a. In other words, the rib portion 22 may have the acute-angle surface 24 on its side surface. When leakage light is incident on the boundary between the acute-angle surface 24 and the outside, the incident angle of the light can be reduced compared to the case where the leakage light is incident on the boundary between the clad layer 2 other than the acute-angle surface 24 and the outside. In other words, when the side surface of the rib portion 22 extends parallel to the core 4, the incident angle when the leakage light is incident on the boundary between the side surface of the core 4 and the outside can be reduced when the side surface on which the leakage light is incident is the acute-angle surface 24. As a result, it is possible to suppress the reflection of the leakage light at the boundary between the acute-angle surface 24 and the outside, making it easier to release the leakage light to the outside and suppressing the generation of stray light in the optical waveguide 5. Consequently, it becomes possible to improve the quality of the emitted light.

[0038] The inclination angle θ24 of the acute-angle surface 24, that is, the inclination angle θ24 of the acute-angle surface 24 with respect to the extending direction (X direction) of the core 4, may be set according to the emission angle of the leakage light. The inclination angle θ24 may be, for example, 15 degrees to 75 degrees. Since the leakage light is emitted at an acute angle with respect to the extending direction (X direction), by making the inclination angle θ24 an acute angle, the incident angle when the leakage light is incident on the boundary between the acute-angle surface 24 and the outside can be made 0 degrees or an angle close to 0 degrees.

[0039] The acute-angle surface 24 may be located laterally of the core 4 at the same height position as the core 4 from the first surface 1a. Also, the lower end of the acute-angle surface 24 may be located below the lower end of the core 4 and the upper end may be located above the upper end of the core 4. In this case, the generation of stray light in the optical waveguide 5 can be effectively suppressed, and it becomes possible to effectively improve the quality of the emitted light.

[0040] The acute-angle surface 24 may be provided with at least one at a position on the side of the multiplexing portion 42 in the ridge portion 22. In addition, even at other positions, although the strength is weak, stray light is generated. As shown in FIG. 8, a plurality of acute-angle surfaces 24 may be formed over the entire ridge portion 22 in the length direction (X direction) and may be serrated as a whole. As shown in FIG. 8, the acute-angle surfaces 24 may be formed on both sides of the ridge portion 22 in the second direction (Y direction). By forming a plurality of acute-angle surfaces 24 in the ridge portion 22, the generation of stray light in the optical waveguide 5 can be effectively suppressed, and as a result, the quality of the emitted light can be effectively improved.

[0041] The optical waveguide package 100 may further include a lid body 6, a sealing ring 7, and a condenser lens 8.

[0042] The lid body 6 is located on the upper surface 2b of the cladding layer 2 and closes the opening of the recess 21. The lid body 6 may be directly joined to the cladding layer 2, or may be joined to the cladding layer 2 via a sealing ring 7 as shown in FIG. 1. The sealing ring 7 has an annular shape and surrounds the opening of the recess 21 in a plan view. By providing the sealing ring 7, it is possible to enhance the airtightness of the space in which the light-emitting element 10 is accommodated.

[0043] The lid body 6 may be directly joined to the cladding layer 2 by, for example, heat bonding or the like. In that case, due to the stress during bonding, the cladding layer 2 and the core 4 may be distorted, and an optical axis misalignment may occur between the light-emitting element 10 and the core 4. By surrounding the opening of the recess 21 with the sealing ring 7, the mechanical strength of the portion around the recess 21 in the cladding layer 2 can be enhanced. As a result, the distortion of the cladding layer 2 and the core 4 can be reduced, and the optical axis misalignment between the light-emitting element 10 and the core 4 can be suppressed.

[0044] The lid 6 may be made of a glass material such as quartz, borosilicate glass, or sapphire. The lid 6 may be made of a metal material such as Fe, Ni, Co, or an alloy material containing them. The sealing ring 7 may be made of a metal material such as Ti, Ni, Au, Pt, Cr, or an alloy material containing them. The sealing ring 7 may be fixed to the upper surface 2b of the clad layer 2 by, for example, vapor deposition, sputtering, ion plating, plating, etc. The lid 6 may be joined to the sealing ring 7 using a bonding material such as an Au-Sn based, Sn-Ag-Cu based solder, a metal-based nanoparticle paste such as Ag or Cu, or a glass paste.

[0045] The condenser lens 8 is located on the optical path of the light emitted from the emission end face 43a. The condenser lens 8 may be configured to parallelize the light emitted from the emission end face 43a, or may be configured to condense the light emitted from the emission end face 43a. As shown in FIG. 4, the condenser lens 8 may be a plano-convex lens in which the incident surface facing the emission end face 43a is formed as a plane and the emission surface is formed as a convex surface.

[0046] The optical waveguide package 100 may further include a plurality of first wiring conductors and a plurality of second wiring conductors located on the first surface 1a of the substrate 1. One end of each of the plurality of first wiring conductors is connected to each of the plurality of first electrode pads, and the other end is led out outside the recess 21. One end of each of the plurality of second wiring conductors is connected to each of the plurality of second electrode pads, and the other end is led out outside the recess 21. The other ends of the plurality of first wiring conductors and the other ends of the plurality of second wiring conductors are electrically connected to an external power supply circuit.

[0047] Next, a light source module according to an embodiment of the present disclosure will be described. FIG. 9 is an exploded perspective view showing a light source module according to an embodiment of the present disclosure.

[0048] The light source module 200 of this embodiment includes an optical waveguide package 100 and a plurality of light-emitting elements 10. The plurality of light-emitting elements 10 may be a red light-emitting element 10r, a green light-emitting element 10g, and a blue light-emitting element 10b. As shown in FIG. 9, the plurality of light-emitting elements 10 are respectively mounted on a plurality of element mounting regions 3 of the optical waveguide package 100. When the light-emitting element 10 has a structure having a first electrode on the lower surface and a second electrode on the upper surface, the first electrode is electrically connected to the first electrode pad 31 via a conductive bonding material, and the second electrode is electrically connected to the second electrode pad 32 via a connecting member such as a bonding wire.

[0049] FIG. 9 shows an example in which the green light-emitting element 10g, the red light-emitting element 10r, and the blue light-emitting element 10b are arranged in this order in the second direction (Y direction), but the plurality of light-emitting elements 10 may be arbitrarily arranged. Further, FIG. 9 shows an example in which the plurality of light-emitting elements 10 are arranged so as to emit light in directions parallel to each other, but the plurality of light-emitting elements 10 may be arranged so as to emit light in directions non-parallel to each other.

[0050] Since the light source module 200 of this embodiment includes the optical waveguide package 100, high-quality emitted light can be emitted.

[0051] FIG. 10 is a plan view showing a light-emitting device according to another embodiment. Note that the same reference numerals are given to the parts corresponding to the above-described embodiment, and redundant descriptions are omitted. In the above-described embodiment shown in FIG. 3, the core 4 is composed of one integrated path including three split paths 41 and a light-emitting portion 43 in which these three split paths 41 meet at a multiplexing portion 42 to have one emission end face 43a. In contrast, the light-emitting device including the optical waveguide package 100a of the present embodiment has optical paths through which lights with different wavelengths are individually guided. As shown in the example of the plan view of FIG. 10, the light-emitting device of the present embodiment has three cores 4 that individually guide lights with different wavelengths. The three incident end faces 41a are positioned apart from each other according to the positions of the respective light-emitting elements 10 such that the centers of the incident end faces 41a of each core 4 coincide with the optical axes of the respective light-emitting elements 10. In the present embodiment, the exit end faces 43a of each core 4 are positioned close to each other. In the section between each incident end face 41a and each exit end face 43a, the section where the three cores 4 are aggregated to be close to each other and extend in parallel to each exit end face 43a corresponds to the converging section. Each light emitted from each exit end face 43a after passing through this converging section is multiplexed, for example, within the lens 8. The cores 4 do not have to be parallel, and may be arranged such that they are substantially parallel and the interval therebetween becomes smaller toward the exit end. The cores 4 may be greatly bent to be close to each other and extend in parallel to each other toward the exit end. At this time, the interval between adjacent cores 4 may become smaller from the close portion to the exit end. The light multiplexed from the lens 8 is emitted and demultiplexed by a subsequent demultiplexer. Even in the configuration where the three cores 4 are not coupled and the three cores 3 are in parallel contact or adjacent to each other as in the above-described embodiment, a converging phenomenon occurs in which adjacent cores 3 are closely optically coupled, and the configuration is substantially provided with a multiplexing section. The light emitted from each core 4 may be emitted in parallel by, for example, one condenser lens 8. In this case, an image or the like formed by the light emitted from the three exit end faces 43a may be synthesized by, for example, an external device.

[0052] In FIG. 10, the multiplexing section 42 refers to the section where the core 4 curves to approach another adjacent core 4 and becomes parallel. More specifically, in FIG. 10, the multiplexing section 42 refers to the section from the section where the core 4 curves to be parallel to one core 4 on a straight line to the section where the core 4 becomes parallel. The light exit section 43 refers to the section where the core 4 extends in parallel. In the case of the present embodiment, strictly speaking, the lights do not merge in the multiplexing section, but the section where a plurality of cores 4 are aggregated and close to each other is defined as the multiplexing section.

[0053] The optical waveguide package according to the present disclosure can be implemented in the following aspects (1) to (9).

[0054] (1) A substrate having a first surface, a cladding layer located on the first surface and having a concave portion on the surface opposite to the surface facing the first surface, a plurality of element mounting regions located in the concave portion, a core located in the cladding layer and including a plurality of light incident portions each having an incident end face on the inner surface of the concave portion, a multiplexing portion where the plurality of light incident portions converge, and a light emitting portion located at a subsequent stage of the multiplexing portion and having an emission end face on the outer surface of the cladding layer, An optical waveguide package in which the first surface is exposed at least laterally of the multiplexing portion in a plan view.

[0055] (2) The core has a curvature at the plurality of light incident portions, and the first surface is exposed laterally of the location where the curvature of each of the plurality of light incident portions is maximum. The optical waveguide package according to the above configuration (1).

[0056] (3) The first surface is exposed laterally of the multiplexing portion and the light emitting portion. The optical waveguide package according to the above configuration (1) or (2).

[0057] (4) The portion of the cladding layer where the first surface is exposed laterally includes a second surface facing the first surface, a third surface located on the side opposite to the second surface, a first side surface continuous with the second surface, and a second side surface continuous with the second surface and located on the side opposite to the first side surface when viewing a cross section perpendicular to the extending direction of the light emitting portion. The first side surface and the second side surface are inclined with respect to the first surface. The optical waveguide package according to the above configuration (1) or (2).

[0058] (5) The first side surface and the second side surface have a larger surface roughness than the third surface. The optical waveguide package according to the above configuration (4).

[0059] (6) When looking at a cross-section perpendicular to the extending direction of the clad layer, the portion of the clad layer includes a third side surface connected to the first side surface, a fourth side surface connecting the third side surface and the third surface, a fifth side surface connected to the second side surface, and a sixth side surface connecting the fifth side surface and the third surface. The optical waveguide package according to the above configuration (4) or (5).

[0060] (7) The first side surface and the fourth side surface are non-parallel to the third side surface, and the second side surface and the sixth side surface are non-parallel to the fifth side surface. The optical waveguide package according to the above configuration (6).

[0061] (8) The portion of the clad layer has at least one portion where the distance from the core gradually decreases as it approaches the emission end face in a plan view. The optical waveguide package according to any one of the above configurations (4) to (7).

[0062] (9) A lid body for closing the opening of the recess, A condensing lens located on the optical path of the light emitted from the emission end face. The optical waveguide package according to any one of the above configurations (1) to (8).

[0063] The light source module according to the present disclosure can be implemented in the form of the following configuration (10).

[0064] (10) An optical waveguide package according to any one of the above configurations (1) to (9), and A plurality of light emitting elements respectively mounted on the plurality of element mounting regions. A light source module including the same.

[0065] According to the optical waveguide package of the present disclosure, it is possible to suppress stray light from being emitted from the emission end portion of the optical waveguide and improve the quality of the emitted light. Since the light source module of the present disclosure includes the above optical waveguide package, it can emit high-quality emitted light.

[0066] As described above in detail for the embodiments of the present disclosure, the present disclosure is not limited to the above-described embodiments, and various changes, improvements, etc. are possible without departing from the gist of the present disclosure. Needless to say, all or part of each of the above embodiments can be combined as appropriate within a non-contradictory range.

Explanation of Reference Numerals

[0067] 100, 100a Optical waveguide package 200 Light source module 1 Substrate 1a Main surface 1a First surface 1b Side surface 2 Cladding layer 2a Lower surface 2b Upper surface 21 Recess 22 Protrusion 22a Second surface 22b Third surface 22c First side surface 22d Second side surface 22e Third side surface 22f Fourth side surface 22g Fifth side surface 22h Sixth side surface 24 Acute angle surface 3 Element mounting region 31 First electrode pad 32 Second electrode pad 33 First wiring conductor 34 Second wiring conductor 4 Core 41 Light incident portion 41a Incident end face 42 Wavelength multiplexing portion 43 Light emission portion 43a Emission end face 5 Optical waveguide 51 Emission end portion 6 Cover 7 Seal ring 8 Condensing lens 10, 10r, 10g, 10b Light emitting elements

Claims

1. A substrate, a clad layer located on the substrate and having a recess with a gap from the outer side on the surface opposite to the substrate side, an element mounting region located in the recess, a core located in the clad layer and including a plurality of light incident portions, a multiplexing portion where the plurality of light incident portions converge, and one light emitting portion connected to the multiplexing portion, the plurality of light incident portions each have a plurality of incident end faces exposed to the recess, the light emitting portion has an emission end face exposed to the outside of the clad layer, In a plan view, the substrate is continuously exposed from the side of the multiplexing portion to the side of the emission end face, and is covered by the clad layer between the plurality of light incident portions. An optical waveguide package.

2. A substrate, a clad layer located on the substrate and having a recess with a gap from the outer side on the surface opposite to the substrate side, an element mounting region located in the recess, a core located in the clad layer and including a plurality of light incident portions, a converging section where the plurality of light incident portions approach each other, and a plurality of light emitting portions connected to the converging section, the plurality of light incident portions each have a plurality of incident end faces exposed to the recess, the plurality of light emitting portions each have an emission end face exposed to the outside of the clad layer, In a plan view, the substrate is continuously exposed from the outermost side of the converging section to the outermost side of the plurality of emission end faces, and is covered by the clad layer between the plurality of light incident portions. An optical waveguide package.

3. The core has a curvature at the plurality of light incident portions, and the substrate is exposed on the side of the location where the curvature of each of the plurality of light incident portions is maximum. The optical waveguide package according to claim 1 or 2.

4. In a plan view, the substrate is continuously covered by the clad layer from between the plurality of light incident portions to the multiplexing portion. The optical waveguide package according to claim 1.

5. The substrate is continuously covered by the clad layer from between the plurality of light incident portions to the converging section. The optical waveguide package according to claim 2.

6. The core is parallel to each other from the converging section to the plurality of light emitting portions. The optical waveguide package according to claim 2.

7. When the exposed portion of the substrate on the side of the clad layer is defined as an exposed section, The optical waveguide package according to claim 1 or 2, wherein in the exposed section, the width of the clad layer increases as it approaches the substrate when viewed in a cross-section perpendicular to the extending direction of the light emitting portion.

8. In the exposed section, the clad layer has a first side surface and a second side surface connected to the substrate, and a surface located on the core and facing the substrate. The surface roughness of the first side surface and the second side surface is greater than that of the surface. The optical waveguide package according to claim 7.

9. In the exposed section, when viewed in a cross-section perpendicular to the extending direction, the clad layer includes a third side surface continuous with the first side surface, a fourth side surface connecting the third side surface and the surface, a fifth side surface continuous with the second side surface, and a sixth side surface connecting the first side surface and the surface. The optical waveguide package according to claim 8.

10. The first side surface and the fourth side surface are non-parallel to the third side surface, and the second side surface and the sixth side surface are non-parallel to the fifth side surface. The optical waveguide package according to claim 9.

11. In the exposed section, the clad layer has at least one portion in which the distance from the core gradually decreases as it approaches the emission end face in a plan view. The optical waveguide package according to claim 7.

12. A lid covering the recess; The optical waveguide package according to claim 1 or 2, further comprising a condenser lens located on the optical path of the light emitted from the emission end face.

13. An optical waveguide package according to claim 1 or 2; A light source module comprising a plurality of light emitting elements mounted on the element mounting region.

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