Light source module and manufacturing method of light source module

Abstract

To provide a light source module capable of efficiently dissipating heat generated in a semiconductor laser.SOLUTION: A light source module 1 comprises: a base 10 including a first mounting surface 10a and a second mounting surface 10b; a light source 20 mounted on the first mounting surface 10a and including a sub mount 21 and a semiconductor laser 22 mounted on a third mounting surface 21a of the sub mount 21; and a planar light wave circuit element 30 mounted on the second mounting surface 10b and including a light waveguide 31 in which laser light emitted from a light emission plane of the semiconductor laser 22 is wave-guided and a light incidence plane 30i on which laser light is incident to the light waveguide 31. The light source 20 is mounted on the first mounting surface 10a on a fourth mounting surface 21b which is not in parallel with the third mounting surface 21a in surfaces constituting the sub mount 21, and the light incidence plane 30i of the planar light wave circuit element 30 is in parallel with the first mounting surface 10a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a light source module including a semiconductor laser. [Background technology]

[0002] As a light source module equipped with a semiconductor laser, an integrated optical device is known that includes a semiconductor laser (LD: Laser Diode) arranged on the upper surface of a subcarrier and a planar lightwave circuit (PLC: Planar Lightwave Circuit) provided on a substrate (Patent Document 1).

[0003] In the light source module disclosed in Patent Document 1, the incident surface of the optical waveguide is arranged to face the light emission surface of the semiconductor laser so that the laser light emitted from the semiconductor laser is incident on the optical waveguide of the planar lightwave circuit. In addition, the side of the subcarrier and the side of the substrate are joined via multiple metal layers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 196489 Summary of the Invention [Problem to be solved by the invention]

[0005] In the light source module disclosed in Patent Document 1, a silicon substrate made of silicon (Si) is used as a substrate on which a planar lightwave circuit is provided, and the planar lightwave circuit is fabricated on the surface of the substrate by known semiconductor processes including photolithography and etching. In addition, a subcarrier on which an LD is mounted is bonded to the substrate on which the PLC is formed.

[0006] However, since silicon does not have a high thermal conductivity, the light source module disclosed in Patent Document 1 is unable to efficiently dissipate the heat generated by the semiconductor laser during operation through the substrate.

[0007] The present disclosure has been made to solve such problems, and aims to provide a light source module and a method for manufacturing a light source module that can efficiently dissipate heat generated in a semiconductor laser when the semiconductor laser is operated. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, one aspect of a light source module according to the present disclosure comprises a base having a first mounting surface and a second mounting surface, a light source having a submount and a semiconductor laser mounted on a third mounting surface of the submount, and a planar lightwave circuit element mounted on the second mounting surface and having an optical waveguide that guides laser light emitted from a light emission surface of the semiconductor laser and a light incident surface at which the laser light is incident on the optical waveguide, wherein the light source is mounted on the first mounting surface at a fourth mounting surface that is not parallel to the third mounting surface among surfaces constituting the submount, and the light incident surface is parallel to the first mounting surface.

[0009] Moreover, one aspect of a manufacturing method for a light source module according to the present disclosure is a manufacturing method for a light source module including the steps of mounting a semiconductor laser to a third mounting surface of a submount to fabricate a light source, mounting a planar lightwave circuit element having an optical waveguide to a second mounting surface of a base, and mounting the light source to a first mounting surface of the base, in which laser light emitted from the semiconductor laser is incident on the optical waveguide from a light incident surface of the planar lightwave circuit element, and the position of the light source is adjusted in a direction within a plane parallel to the first mounting surface so that the amount of laser light is maximized, and then the light source is fixed to the base via a first bonding layer arranged between a surface not parallel to the third mounting surface and the first mounting surface. Effect of the Invention

[0010] According to the present disclosure, it is possible to realize a light source module capable of efficiently dissipating heat generated in a semiconductor laser when the semiconductor laser is driven. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of a light source module according to the first embodiment. [Diagram 2] FIG. 2 is a diagram for explaining the effect of the light source module according to the first embodiment. [Figure 3A] FIG. 3A is a diagram showing a step of fabricating a light source in a manufacturing method of a light source module according to the first embodiment. [Figure 3B] FIG. 3B is a diagram showing a step of mounting a planar lightwave circuit element on a base in the manufacturing method of the light source module according to the first embodiment. [Figure 3C] FIG. 3C is a diagram showing a step of adjusting the position of the light source in the method for manufacturing the light source module according to the first embodiment. [Figure 3D] FIG. 3D is a diagram showing a step of joining the light source to the base in the manufacturing method of the light source module according to the first embodiment. [Figure 3E] FIG. 3E is a diagram showing a completed light source module in the manufacturing method of the light source module according to the first embodiment. [Figure 4] FIG. 4 is a perspective view illustrating a light source module according to a modified example of the first embodiment. [Diagram 5] FIG. 5 is a cross-sectional view of a light source module according to the second embodiment. [Figure 6] FIG. 6 is a diagram for explaining the effect of the light source module according to the second embodiment. [Figure 7A] FIG. 7A is a diagram showing a step of fabricating a light source in a manufacturing method of a light source module according to the second embodiment. [Figure 7B] FIG. 7B is a diagram showing a step of mounting a planar lightwave circuit element on a base in the method for manufacturing a light source module according to the second embodiment. [Figure 7C]FIG. 7C is a diagram showing a step of adjusting the position of the light source in the manufacturing method of the light source module according to the second embodiment. [Figure 7D] FIG. 7D is a diagram showing a step of joining the light source to the base in the method for manufacturing the light source module according to the second embodiment. [Figure 7E] FIG. 7E is a diagram showing a completed light source module in the manufacturing method of the light source module according to the second embodiment. [Figure 8] FIG. 8 is a diagram showing a configuration of a light source module according to a first modification of the second embodiment. [Figure 9] FIG. 9 is a diagram showing a configuration of a light source module according to Modification 2 of Embodiment 2. In FIG. [Figure 10] FIG. 10 is a perspective view illustrating a light source module according to a third modification of the second embodiment. [Figure 11] FIG. 11 is a cross-sectional view of a light source module according to a third modification of the second embodiment. [Figure 12] FIG. 12 is a diagram showing a configuration of a light source module according to the fourth modification of the second embodiment. In FIG. [Figure 13] FIG. 13 is a cross-sectional view of a light source module according to the third embodiment. [Figure 14] FIG. 14 is a diagram for explaining the effect of the light source module according to the third embodiment. [Figure 15A] FIG. 15A is a diagram showing a substrate etching step in the manufacturing process of a planar lightwave circuit device used in a light source module according to the third embodiment. [Figure 15B] FIG. 15B is a diagram showing an optical waveguide formation step in the manufacturing process of a planar lightwave circuit element used in the light source module according to the third embodiment. [Figure 15C] FIG. 15C is a diagram showing a metal film and anti-reflection film forming step in the manufacturing process of the planar lightwave circuit element used in the light source module according to the third embodiment. [Figure 15D] FIG. 15D is a diagram showing a step of mounting a planar lightwave circuit element on a base in the manufacturing method of the light source module according to the third embodiment. [Figure 15E] FIG. 15E is a diagram showing a step of arranging the light source on the base in the manufacturing method of the light source module according to the third embodiment. [Figure 15F] FIG. 15F is a diagram showing a step of adjusting the position of the light source in the manufacturing method of the light source module according to the third embodiment. [Figure 15G] FIG. 15G is a diagram showing a step of joining the light source to the base in the manufacturing method of the light source module according to the third embodiment. [Figure 15H] FIG. 15H is a diagram showing a completed light source module in the manufacturing method of the light source module according to the third embodiment. [Figure 16] FIG. 16 is a perspective view that illustrates a light source module 3 according to a modified example of the third embodiment. [Figure 17] FIG. 17 is a diagram showing a configuration of a light source module according to a modification of the third embodiment. [Figure 18] FIG. 18 is a cross-sectional view of a light source module according to the fourth embodiment. [Figure 19] FIG. 19 is a diagram for explaining the effect of the light source module according to the fourth embodiment. [Figure 20A] FIG. 20A is a diagram showing a substrate etching step in the manufacturing process of a planar lightwave circuit device used in a light source module according to the fourth embodiment. [Figure 20B] FIG. 20B is a diagram showing an optical waveguide formation step in the manufacturing process of a planar lightwave circuit element used in the light source module according to the fourth embodiment. [Figure 20C] FIG. 20C is a diagram showing a metal film and anti-reflection film forming step in the manufacturing process of the planar lightwave circuit element used in the light source module according to the fourth embodiment. [Figure 20D] FIG. 20D is a diagram showing a step of mounting a planar lightwave circuit element on a base in the manufacturing method of the light source module according to the fourth embodiment. [Figure 20E] FIG. 20E is a diagram showing a step of arranging the light source on the base in the manufacturing method of the light source module according to the fourth embodiment. [Figure 20F]FIG. 20F is a diagram showing a step of adjusting the position of the light source in the manufacturing method of the light source module according to the fourth embodiment. [Figure 20G] FIG. 20G is a diagram showing a step of joining the light source to the base in the manufacturing method of the light source module according to the fourth embodiment. [Figure 20H] FIG. 20H is a diagram showing a completed light source module in the manufacturing method of the light source module according to the third embodiment. [Figure 21] FIG. 21 is a diagram showing a configuration of a light source module according to a first modification of the fourth embodiment. [Figure 22] FIG. 22 is a diagram showing another configuration of the light source module according to the first modification of the fourth embodiment. In FIG. [Diagram 23] FIG. 23 is a perspective view illustrating a light source module according to Modification 2 of the fourth embodiment. [Figure 24] FIG. 24 is a diagram illustrating a part of a light source module according to a second modification of the fourth embodiment. [Diagram 25] FIG. 25 is a diagram showing a configuration of a light source module according to the third modification of the fourth embodiment. [Figure 26] FIG. 26 is a diagram showing a configuration of a light source module according to the fourth modification of the fourth embodiment. In FIG. [Figure 27A] FIG. 27A is a diagram showing a substrate preparation step in a method for fabricating a planar lightwave circuit device used in a light source module according to Modification 4 of Embodiment 4. FIG. [Figure 27B] FIG. 27B is a diagram showing an etching protection mask formation step in the method of manufacturing a planar lightwave circuit device used in a light source module according to Modification 4 of Embodiment 4. As shown in FIG. [Figure 27C] FIG. 27C is a diagram showing a substrate etching step in the method of manufacturing a planar lightwave circuit device used in a light source module according to Modification 4 of Embodiment 4. As shown in FIG. [Figure 27D] FIG. 27D is a diagram showing a first cladding layer formation step in the method of manufacturing a planar lightwave circuit device used in a light source module according to Modification 4 of Embodiment 4. As shown in FIG. [Figure 27E]FIG. 27E is a diagram showing a core layer forming step in a method for producing a planar lightwave circuit device used in a light source module according to Modification 4 of Embodiment 4. As shown in FIG. [Figure 27F] FIG. 27F is a diagram showing a core layer patterning step in the method of manufacturing a planar lightwave circuit device used in a light source module according to Modification 4 of Embodiment 4. As shown in FIG. [Figure 27G] FIG. 27G is a diagram showing a second cladding layer formation step in the method of manufacturing a planar lightwave circuit device used in a light source module according to Modification 4 of Embodiment 4. As shown in FIG. [Fig. 27H] FIG. 27H is a diagram showing a second cladding layer polishing step in the method of manufacturing a planar lightwave circuit device used in a light source module according to Modification 4 of Embodiment 4. [Figure 28A] FIG. 28A is a diagram showing a configuration of a light source module according to a fifth modification of the fourth embodiment. [Figure 28B] FIG. 28B is a diagram showing a configuration of a light source module according to Modification 5' of Embodiment 4. In FIG. [Figure 29] FIG. 29 is a diagram showing a configuration of a light source module according to a sixth modification of the fourth embodiment. In FIG. [Figure 30A] FIG. 30A is a diagram showing a substrate preparation step in a method for fabricating a planar lightwave circuit element in a light source module according to Modification 6 of Embodiment 4. FIG. [Figure 30B] FIG. 30B is a diagram showing a substrate etching step in the method for fabricating a planar lightwave circuit device used in a light source module according to Modification 6 of Embodiment 4. As shown in FIG. [Figure 30C] FIG. 30C is a diagram showing a substrate cleaving step in the method of manufacturing a planar lightwave circuit device used in a light source module according to Modification 6 of Embodiment 4. [Figure 30D] FIG. 30D is a top view of a planar lightwave circuit element fabricated by a method for fabricating a planar lightwave circuit element used in a light source module according to Modification 6 of Embodiment 4. FIG. [Diagram 31] FIG. 31 is a diagram showing a configuration of a light source module according to a seventh modification of the fourth embodiment. In FIG. [Diagram 32]FIG. 32 is a diagram showing a configuration of a light source module according to Modification 8 of the fourth embodiment. In FIG. [Diagram 33] FIG. 33 is a diagram illustrating a configuration of a light source module according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, the arrangement and connection of the components, steps (processes), and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims showing the highest concept of the present disclosure will be described as optional components.

[0013] In addition, each drawing is a schematic diagram and is not necessarily precisely illustrated. Therefore, the scales and the like are not necessarily the same in each drawing. In each drawing, the same reference numerals are given to substantially the same configurations, and duplicated explanations are omitted or simplified.

[0014] In this specification, the terms "above" and "below" do not refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition, but are used as terms defined by a relative positional relationship based on the stacking order in a stacked configuration. The terms "above" and "below" are applied not only to the case where two components are arranged with a gap between them and another component is present between the two components, but also to the case where two components are arranged in contact with each other.

[0015] Furthermore, geometric expressions such as "parallel," "perpendicular," and "orthogonal" do not only mean completely parallel, perpendicular, or orthogonal in mathematical strictness, but also include substantially parallel, perpendicular, or orthogonal. In other words, "parallel," "perpendicular," and "orthogonal" also include an error of about a few percent that is substantially allowed due to manufacturing errors, dimensional tolerances, and the like.

[0016] (Embodiment 1) First, the configuration of a light source module 1 according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of the light source module 1 according to the first embodiment.

[0017] As shown in FIG. 1, the light source module 1 includes a base 10, a light source 20 mounted on the base 10, and a planar lightwave circuit element 30 mounted on the base 10.

[0018] The base 10 functions as a support member for supporting the light source 20 and the planar lightwave circuit element 30. The base 10 has a first mounting surface 10a and a second mounting surface 10b. The first mounting surface 10a of the base 10 is a surface on which the light source 20 is mounted, and the second mounting surface 10b of the base 10 is a surface on which the planar lightwave circuit element 30 is mounted. Specifically, the first mounting surface 10a is a side surface of the base 10, and the second mounting surface 10b is an upper surface of the base 10. In addition, the first mounting surface 10a and the second mounting surface 10b are flat planes. In this embodiment, the first mounting surface 10a and the second mounting surface 10b are orthogonal to each other. Therefore, the side surface of the base 10, which is the first mounting surface 10a, and the upper surface of the base 10, which is the second mounting surface 10b, are orthogonal to each other.

[0019] The base 10 has a base body 11 which is the base material of the base 10, and a metal film 12. The metal film 12 is formed on the side surface of the base body 11. Therefore, a first mounting surface 10a of the base 10 is the outer surface of the metal film 12. Also, a second mounting surface 10b of the base 10 is the upper surface of the base body 11. Note that, as an example, the metal film 12 has a three-layer laminate structure of Ti, Pt, and Au in this order from the side surface, but is not limited thereto.

[0020] The base 10 also functions as a heat dissipation member (heat sink) for dissipating heat generated by the light source 20 and the planar lightwave circuit element 30. Therefore, the base 10 is preferably made of a highly heat-conductive material having high thermal conductivity. The base 10 can be made of metal (including metal alloy), ceramic, or the like.

[0021] In this embodiment, the base 10 is made of at least one selected from Al, Cu, Au, Ag, AlN, and SiC. Specifically, the base body 11 in the base 10 is made of at least one selected from Al, Cu, Au, Ag, AlN, and SiC. The base body 11 may be a metal alloy made of a metal selected from these.

[0022] The thermal conductivity of the base 10 is higher than that of the planar lightwave circuit element 30. Specifically, the thermal conductivity of the base body 11 of the base 10 is higher than that of the planar lightwave circuit element 30.

[0023] Furthermore, when the planar lightwave circuit element 30 is viewed from above, the base 10 is larger than the planar lightwave circuit element 30. Specifically, the area of ​​the base 10 when viewed from above is larger than the area of ​​the planar lightwave circuit element 30 when viewed from above.

[0024] The light source 20 includes a submount 21 and a semiconductor laser 22 mounted on a third mounting surface 21a of the submount 21.

[0025] The submount 21 has a third mounting surface 21a and a fourth mounting surface 21b. The third mounting surface 21a of the submount 21 is a surface on which the semiconductor laser 22 is mounted. In the present embodiment, the third mounting surface 21a is an upper surface of the submount 21. In addition, the third mounting surface 21a is a flat surface and is perpendicular to the side surface of the submount 21.

[0026] The submount 21 functions as a base for mounting the semiconductor laser 22. In this embodiment, the submount 21 has a submount body 25 which is a base material of the submount 21, a first metal film 26, and a second metal film 27. The submount body 25 has a rectangular parallelepiped shape and has a first arrangement surface 25a which is a plane and a second arrangement surface 25b which is a plane perpendicular to the first arrangement surface 25a. The first metal film 26 is formed on the first arrangement surface 25a of the submount body 25. Therefore, in this embodiment, the third mounting surface 21a of the submount 21 is the outer surface of the first metal film 26. Moreover, the second metal film 27 is formed on the second arrangement surface 25b of the submount body 25. Therefore, in this embodiment, the fourth mounting surface 21b of the submount 21 is the outer surface of the second metal film 27. In this embodiment, the second metal film 27 is formed on a part of the second arrangement surface 25b, and is not formed on the surface on the first arrangement surface 25a side. Therefore, the first metal film 26 and the second metal film 27 are not connected. Note that, as an example, the first metal film 26 and the second metal film 27 have a three-layer laminate structure of Ti, Pt, and Au in that order from the submount body 25, but are not limited to this. In addition, in this embodiment, no metal film is formed on the surface of the submount body 25 facing the first arrangement surface 25a and the surface facing the second arrangement surface 25b.

[0027] The submount 21 also functions as a heat dissipation member (heat sink) for dissipating heat generated by the light source 20. Therefore, the submount 21 is preferably made of a highly thermally conductive material having high thermal conductivity. The submount 21 can be made of metal (including metal alloy), ceramic, or a semiconductor material having high thermal conductivity.

[0028] For example, the submount 21 is made of at least one selected from Si, AlN, and SiC. Specifically, in this case, the submount body 25 in the submount 21 is made of at least one selected from Si, AlN, and SiC. By making the submount body 25 of Si, AlN, or SiC in this way, the laser light emitted from the heating laser light source when the submount 21 of the light source 20 is joined to the base 10 can be transmitted through the submount body 25. For example, the submount body 25 made of AlN or SiC transmits at least a part of the laser light having a wavelength in the visible light to infrared light band, and the submount body 25 made of Si transmits the laser light having a wavelength in the infrared light band from 1.2 μm to 15 μm.

[0029] It is preferable that the thermal conductivity of the submount 21 is high. For example, the thermal conductivity of the submount 21 is preferably 100 W / m·K or more. Specifically, it is preferable that the thermal conductivity of the submount body 25 of the submount 21 is 100 W / m·K or more.

[0030] The semiconductor laser 22 is a single-mode transverse semiconductor laser chip that emits laser light with a peak wavelength of 350 nm to 900 nm. The chip size of the semiconductor laser 22 is, for example, a width of 150 μm, a length (resonator length) of 200 μm, and a thickness of 80 μm. A waveguide 22a is formed on one surface of the semiconductor laser 22. In this embodiment, the semiconductor laser 22 has a ridge stripe type waveguide structure, and the width of the waveguide 22a is, for example, 1 μm to 5 μm.

[0031] The semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21. Specifically, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 via a bonding layer 41. The bonding layer 41 is formed on the third mounting surface 21a of the submount 21. Specifically, the bonding layer 41 is formed on the first metal film 26. The bonding layer 41 is made of a conductive bonding material such as solder made of AuSn or the like. The bonding layer 41 can be laminated on the first metal film 26 by, for example, vapor deposition or coating.

[0032] In this embodiment, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 by junction-up mounting so that the light emitting layer is on the opposite side to the third mounting surface 21a. In other words, the surface opposite to the surface on which the waveguide 22a is formed is bonded to the submount. For example, the semiconductor laser 22 can be disposed on a bonding layer 41 formed on the third mounting surface 21a of the submount 21 by junction-up mounting, and the semiconductor laser 22 can be bonded and fixed to the submount 21 by the bonding layer 41.

[0033] Moreover, the front end face 22f, which is the light emitting face of the semiconductor laser 22, does not protrude beyond the second arrangement face 25b, which is the side end face 21f of the submount 21. Among the multiple side faces of the submount 21 (submount body 25), the face in the same direction as the front end face 22f, which is the light emitting face of the semiconductor laser 22, is referred to as the "front face". In this embodiment, the second arrangement face 25b of the submount body 25 is the front face of the submount body 25. In this embodiment, the front end face 22f of the semiconductor laser 22 is located at a position set back from the end face (the outer surface of the second metal film 27) of the submount 21 on the base 10 side. Specifically, the front end face 22f of the semiconductor laser 22 is substantially flush with the second arrangement face 25b, which is the end face of the submount body 25 on the base 10 side.

[0034] The light source 20 is configured by mounting a semiconductor laser 22 on a submount 21. The light source 20 is mounted and fixed on a first mounting surface 10a of the base 10. In the present embodiment, the first mounting surface 10a of the base 10 is a side surface of the base 10. Therefore, the light source 20 is fixed to the side surface of the base 10.

[0035] The light source 20 is mounted on the first mounting surface 10a of the base 10 at a fourth mounting surface 21b, which is orthogonal to the third mounting surface 21a among the surfaces constituting the submount 21. Specifically, the light source 20 is mounted on the first mounting surface 10a of the base 10 at a side surface of the submount 21. That is, the fourth mounting surface 21b of the submount 21 in the light source 20 is bonded to the first mounting surface 10a of the base 10. Specifically, the second metal film 27 of the submount 21 in the light source 20 is bonded to the metal film 12 of the base 10 via a bonding layer 43. The bonding layer 43 is made of a metal alloy having high thermal conductivity, such as solder made of SAC (an alloy of Sn, Ag, and Cu) or AuSn. In this embodiment, the bonding layer 43 that bonds the submount 21 to the base 10 is made of the same material as the bonding layer 41 that bonds the semiconductor laser 22 to the submount 21.

[0036] The planar lightwave circuit element 30 has an optical waveguide 31 through which the laser light emitted from the light emission surface of the semiconductor laser 22 of the light source 20 is guided, and a substrate 32 that holds the optical waveguide 31. The substrate 32 is, for example, a flat plate, and the planar lightwave circuit element 30 has a first surface 30u on the optical waveguide 31 side and a second surface 30b on the substrate 32 side. The planar lightwave circuit element 30 has a third surface 30c, which is a side surface disposed on the light source 20 side, and a fourth surface 30d opposite to the third surface.

[0037] The optical waveguide 31 is provided on a substrate 32. The optical waveguide 31 has a core 31a and a clad 31b having a refractive index lower than that of the core 31a. The clad 31b is present above and below the core 31a in a direction perpendicular to the upper surface of the planar lightwave circuit element 30. Specifically, the clad 31b surrounds the entire core 31a in a cross section perpendicular to the extension direction of the core 31a. With this configuration, light incident on the optical waveguide 31 is propagated and guided through the core 31a while being totally reflected at the interface between the core 31a and the clad 31b.

[0038] The core 31a extends in a plane parallel to the first surface 30u, which is the upper surface of the planar lightwave circuit element 30. The core 31a is formed to extend from the third surface 30c toward the fourth surface 30d. The end surface of the core 31a on the third surface 30c side is the light incident surface 30i, and the end surface of the core 31a on the fourth surface 30d side is the light emitting surface 30e. The core 31a extends, for example, linearly, but is not limited thereto. The core 31a may extend in a curved shape, or may extend to have a curved portion and a linear portion.

[0039] In this embodiment, the substrate 32 is, for example, a flat plate made of a silicon substrate made of silicon or a glass substrate made of glass, but is not limited thereto. As an example, the core 31a is made of silicon nitride (SiN), and the clad 31b is made of silicon dioxide (SiO2).

[0040] In this embodiment, a first antireflection film 33 is formed on the third surface 30c side including the end surface (side surface) of the optical waveguide 31 on the light source 20 side. The first antireflection film 33 prevents the laser light incident on the light incident surface 30i from being reflected by the light incident surface 30i. A second antireflection film 34 is formed on the fourth surface 30d side including the end surface (side surface) of the optical waveguide 31 opposite to the light source 20 side. The second antireflection film 34 prevents the laser light emitted from the optical waveguide 31 to the outside from being reflected on the light emitting surface 30e. The first antireflection film 33 and the second antireflection film 34 are, for example, dielectric multilayer films in which a plurality of dielectric films are laminated. Examples of materials for the dielectric films include titanium oxide (TiO2), tantalum oxide (Ta2O5), silicon oxide (SiO2), and aluminum oxide (Al2O3). It is not essential that the first antireflection film 33 and the second antireflection film 34 are formed, and they may not be formed.

[0041] The planar lightwave circuit element 30 has a light incident surface 30i through which the laser light emitted from the light emitting surface of the semiconductor laser 22 enters the optical waveguide 31, and a light emitting surface 30e through which the laser light guided through the optical waveguide 31 exits from the optical waveguide 31 to the outside.

[0042] In this embodiment, since the first antireflection film 33 is formed on the end face (third face 30c) of the optical waveguide 31 on the light source 20 side, the light incident face 30i of the planar lightwave circuit element 30 is the outer surface of the first antireflection film 33. Furthermore, since the second antireflection film 34 is formed on the end face (fourth face 30d) of the optical waveguide 31 opposite the light source 20 side, the light exit face 30e of the planar lightwave circuit element 30 is the outer surface of the second antireflection film 34. Note that if the first antireflection film 33 and the second antireflection film 34 are not formed, the end face of the optical waveguide 31 on the light source 20 side is the light incident face 30i, and the end face of the optical waveguide 31 opposite the light source 20 side is the light exit face 30e.

[0043] The light incident surface 30i is parallel to the first mounting surface 10a of the base 10. In other words, the light incident surface 30i is parallel to the side surface of the base 10 on the light source 20 side. Specifically, the end portion on the light incident side of the optical waveguide 31 has an optical waveguide end surface which is the side surface of the planar lightwave circuit element 30 on the light source 20 side, and the light incident surface 30i is this optical waveguide end surface.

[0044] In this embodiment, the light incident surface 30i is flush with the first mounting surface 10a of the base 10. In other words, the third surface 30c, which is the side surface of the planar lightwave circuit element 30 on the light source 20 side, which is the light incident surface 30i, is flush with the side surface of the base 10 on the light source 20 side. In this embodiment, the first antireflection film 33 is formed on the end surface of the light guide 31 on the light source 20 side, and the side surface of the planar lightwave circuit element 30 on the light source 20 side is the outer surface of the first antireflection film 33, and the metal film 12 is formed on the side surface of the base body 11 on the light source 20 side, and the side surface of the base 10 on the light source 20 side is the outer surface of the metal film 12, so that the outer surface of the first antireflection film 33 and the outer surface of the metal film 12 are flush with each other.

[0045] Moreover, the light incident surface 30i faces the light emitting surface (front end surface) of the semiconductor laser 22. In this embodiment, the light incident surface 30i is parallel to the light emitting surface of the semiconductor laser 22. Therefore, the light emitting direction of the laser light emitted from the semiconductor laser 22 is perpendicular to the light incident surface 30i. Note that the light emitting direction of the laser light emitted from the semiconductor laser 22 may be inclined at an angle within a range of ±10° with respect to the perpendicular line of the light incident surface 30i.

[0046] The light exit surface 30e of the planar lightwave circuit element 30 is a fourth surface 30d, which is the side surface of the planar lightwave circuit element 30 opposite the light source 20 side, and is parallel to the light entrance surface 30i of the planar lightwave circuit element 30. Therefore, the light exit surface 30e is parallel to the first mounting surface 10a of the base 10. In other words, the light exit surface 30e is parallel to the side surface of the base 10 facing the light source 20. The light exit surface 30e is also parallel to the side surface of the base 10 opposite to the side surface facing the light source 20. Being parallel in this way allows the planar lightwave circuit element 30 to be made smaller.

[0047] The planar lightwave circuit element 30 is fixed on the base 10. In this embodiment, the planar lightwave circuit element 30 is bonded to the second mounting surface 10b of the base 10 and fixed to the base 10. Specifically, the planar lightwave circuit element 30 is bonded to the second mounting surface 10b of the base 10 via a bonding layer 42. The bonding layer 42 is made of a conductive bonding material such as solder made of AuSn or a bonding material made of a metal sintered material. The bonding layer 42 may be made of an insulating material. For example, the bonding layer 42 may be made of an insulating resin adhesive such as an ultraviolet curing resin.

[0048] Next, the effect of the light source module 1 will be described with reference to Fig. 2. Fig. 2 is a diagram for explaining the effect of the light source module 1 according to the embodiment 1. Note that the black arrows in Fig. 2 diagrammatically show the dissipation path of the heat generated in the semiconductor laser 22.

[0049] As shown in FIG. 2, the light source module 1 is placed on, for example, a housing 100. The light source 20 is connected to an external power source by electrical wiring such as a metal wire (not shown). When power is supplied to the light source 20 and the semiconductor laser 22 of the light source 20 is driven, a laser beam is emitted from the front end face 22f of the waveguide 22a of the semiconductor laser 22. The laser beam emitted from the semiconductor laser 22 enters the optical waveguide 31 from the light incident surface 30i of the planar lightwave circuit element 30, is guided through the optical waveguide 31, and is emitted to the outside from the light exit surface 30e of the planar lightwave circuit element 30. Specifically, the laser beam emitted from the semiconductor laser 22 enters the side surface of the planar lightwave circuit element 30 and enters the core 31a of the optical waveguide 31. The laser beam incident on the core 31a of the optical waveguide 31 propagates through the core 31a while repeating total reflection at the interface between the core 31a and the cladding 31b.

[0050] When the semiconductor laser 22 is driven in this manner, the electric power not converted into laser light is generated as Joule heat in the waveguide 22a of the semiconductor laser 22. At this time, in the light source module 1, the light source 20 having the semiconductor laser 22 mounted on the third mounting surface 21a of the submount 21 is mounted on the first mounting surface 10a of the base 10 on a fourth mounting surface 21b that is orthogonal to the third mounting surface 21a among the surfaces constituting the submount 21, and the planar lightwave circuit element 30 is mounted on the second mounting surface 10b of the base 10.

[0051] 2, this configuration allows the heat generated by the semiconductor laser 22 to be conducted to the submount 21, then to the base 10 via the bonding layer 43 between the fourth mounting surface 21b of the submount 21 and the first mounting surface 10a of the base 10, and then to the housing 100 via the heat dissipation surface 10h, which is the lower surface of the base 10. This allows the heat generated by the semiconductor laser 22 when the semiconductor laser 22 is driven to be dissipated efficiently. This allows the temperature rise of the semiconductor laser 22 to be suppressed.

[0052] In this case, the base 10 is preferably made of a material with high thermal conductivity. This allows the heat generated by the semiconductor laser 22 to be quickly conducted and dissipated to the outside. As an example, the submount body 25 of the submount 21 can be made of AlN (thermal conductivity: 170 W / m·K), and the base body 11 of the base 10 can be made of Cu (thermal conductivity: 390 W / m·K) or SiC (thermal conductivity: 300 to 420 W / m·K). The substrate 32 of the planar lightwave circuit element 30 is a silicon substrate made of, for example, Si (thermal conductivity: 150 W / m·K).

[0053] Next, a method for manufacturing the light source module 1 according to the first embodiment will be described with reference to Figures 3A to 3E. Figures 3A to 3E are diagrams for explaining the method for manufacturing the light source module 1 according to the first embodiment.

[0054] First, as shown in FIG. 3A, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 to fabricate the light source 20.

[0055] Specifically, first, the second metal film 27 is formed on a part of the second mounting surface 25b of the submount body 25, and then the first metal film 26 is formed on the first mounting surface 25a. Furthermore, a bonding layer 41 is formed on the first metal film 26. Then, the semiconductor laser 22 is mounted by junction-up mounting on the bonding layer 41 formed in advance on the third mounting surface 21a of the submount 21, and the bonding layer 41 is melted to bond the semiconductor laser 22 to the submount 21. At this time, the front end surface 22f of the semiconductor laser 22 is fixed to the side end surface 21f, which is the second mounting surface 25b, so as not to protrude. This makes it possible to manufacture the light source 20 in which the semiconductor laser 22 is fixed to the submount 21.

[0056] Next, as shown in FIG. 3B, a planar lightwave circuit element 30 having an optical waveguide 31 is mounted on the second mounting surface 10b of the base 10.

[0057] Specifically, first, a first antireflection film 33 and a second antireflection film 34 are formed on both end faces of an optical waveguide 31 formed on a substrate 32 to fabricate a planar lightwave circuit element 30. In addition, a bonding layer 42 is formed on the upper surface of the base 10, for example, by plating. Thereafter, the planar lightwave circuit element 30 and the base 10 are bonded to each other while pressing the side of the planar lightwave circuit element 30 and the side of the base 10 against the same surface of a pressing member (not shown). Specifically, the base 10 on which the bonding layer 42 is formed and the planar lightwave circuit element 30 are both pressed against the pressing member from the lateral direction to melt the bonding layer 42, thereby bonding the planar lightwave circuit element 30 and the base 10. In this way, by bonding the planar lightwave circuit element 30 and the base 10 while pressing the side of the planar lightwave circuit element 30 and the side of the base 10 against the same surface, the planar lightwave circuit element 30 and the base 10 can be easily bonded to each other so that the side surfaces are flush with each other.

[0058] 3C and 3D, the light source 20 is mounted on the first mounting surface 10a of the base 10. In this embodiment, the laser light emitted from the semiconductor laser 22 is made incident on the optical waveguide 31 of the planar lightwave circuit element 30, and the position of the light source 20 is adjusted in a direction within a plane parallel to the first mounting surface 10a of the base 10 so that the amount of laser light from the semiconductor laser 22 is maximized. Then, the light source 20 is fixed to the base 10 via a bonding layer 43 disposed between the fourth mounting surface 21b of the submount 21 and the first mounting surface 10a of the base 10.

[0059] Specifically, as shown in FIG. 3C, the position of the light source 20 is adjusted with respect to the base 10 on which the planar lightwave circuit element 30 is mounted by the laser light emitted from the semiconductor laser 22. That is, active alignment is performed. For example, the light source 20 is first held by a predetermined jig (not shown). At this time, the light source 20 is held by a jig that can supply a predetermined power to the semiconductor laser 22 of the light source 20, for example, a jig having two contact probes. Next, in a state in which the bonding layer 43 is sandwiched between the submount 21 of the light source 20 and the base 10 on which the planar lightwave circuit element 30 is mounted, the semiconductor laser 22 is driven to cause the laser light emitted from the semiconductor laser 22 to enter the optical waveguide 31 of the planar lightwave circuit element 30, and the laser light emitted from the optical waveguide 31 is monitored by the power meter 200. At this time, the position of the light source 20 is moved so that the amount of light of the monitored laser light is maximized. That is, the optical axis of the semiconductor laser 22 and the optical axis of the optical waveguide 31 are adjusted so that the amount of light of the monitored laser light is maximized. This adjustment of the optical axis is performed in a direction within a plane parallel to the first mounting surface 10a of the base 10.

[0060] The bonding layer 43 may be inserted between the base 10 and the submount 21 as a sheet-like solder foil, or may be formed in advance on the first mounting surface 10a of the base 10 by vapor deposition, coating, or the like. When the bonding layer 43 is formed in advance on the first mounting surface 10a of the base 10, the bonding layer 43 may be formed on the base 10 before the planar lightwave circuit element 30 is mounted on the base 10.

[0061] After adjusting the position of the light source 20, as shown in FIG. 3D, a bonding layer 43 is disposed between the side surface of the submount 21 of the light source 20 and the first mounting surface 10a of the base 10, and the laser light emitted from the heating laser light source 300 is transmitted through the submount 21 and irradiated onto the bonding layer 43. Specifically, the heating laser light is partially scattered and absorbed by the submount body 25 of the submount 21, but the transmitted laser light reaches the bonding layer 43. This allows the bonding layer 43 to be directly heated by the laser light. The bonding layer 43 is heated and melted by irradiation with the heating laser light. Then, the temperature of the bonding layer 43 is reduced by stopping the heating laser light, and the bonding layer 43 is solidified. This allows the submount 21 of the light source 20 to be fixed to the base 10 via the bonding layer 43. In this embodiment, the bonding layer 41 that bonds the semiconductor laser 22 to the submount 21 and the bonding layer 43 that bonds the submount 21 to the base 10 are made of the same material.

[0062] In this way, the heating laser light passes through the submount 21, thereby suppressing heat generation in the submount 21. In other words, it is possible to suppress a rise in temperature of the submount 21. This makes it possible to suppress misalignment caused by remelting of the bonding layer 41 located between the semiconductor laser 22 and the submount 21.

[0063] In this embodiment, the step of FIG. 3D (heating laser light irradiation step) is performed after the step of FIG. 3C (active alignment step), but this is not limited thereto. For example, the steps of FIG. 3C and FIG. 3D may be performed simultaneously. Also, the step of FIG. 3D may be performed before the step of FIG. 3C. That is, the step of FIG. 3C may be performed after the step of FIG. 3D. In this case, the heating laser light is transmitted through the submount 21 and irradiated onto the bonding layer 43 to soften the bonding layer 43, and the optical axis of the semiconductor laser 22 of the light source 20 and the optical axis of the optical waveguide 31 of the planar lightwave circuit element 30 are adjusted, and then the irradiation of the heating laser light is stopped to solidify the bonding layer 43.

[0064] In this manner, by fixing the light source 20 to the base 10 on which the planar lightwave circuit element 30 is fixed, the light source module 1 is completed as shown in FIG. 3E.

[0065] In this embodiment, the planar lightwave circuit element 30 and the base 10 are joined using a pressing member so that the side surfaces of the planar lightwave circuit element 30 and the base 10 are flush with each other, but the present invention is not limited to this. For example, after the planar lightwave circuit element 30 and the base 10 are joined, the planar lightwave circuit element 30 and the base 10 may be cut together. This makes it possible to easily make the side surfaces of the planar lightwave circuit element 30 and the base 10 flush with each other.

[0066] As described above, in the light source module 1 according to this embodiment, the light source 20 having the semiconductor laser 22 mounted on the third mounting surface 21a of the submount 21 is mounted on the first mounting surface 10a of the base 10 on a surface constituting the submount 21 that is not parallel to the third mounting surface 21a, and the planar lightwave circuit element 30 is mounted on the second mounting surface 10b of the base 10. The light incident surface 30i of the planar lightwave circuit element 30 is parallel to the first mounting surface 10a of the base 10.

[0067] In this way, since the light source 20 is joined to the base 10 that serves as a heat sink provided separately from the planar lightwave circuit element 30, the heat generated by the semiconductor laser 22 when the semiconductor laser 22 is driven can be efficiently dissipated. This makes it possible to suppress the temperature rise of the semiconductor laser 22, thereby obtaining a highly reliable light source module 1. Furthermore, by efficiently dissipating the heat generated by the semiconductor laser 22, it is possible to suppress the decrease in optical output caused by the heat of the semiconductor laser 22 itself, and high-output operation can be easily performed.

[0068] Moreover, according to the configuration of the light source module 1, when manufacturing the light source module 1, the light source 20 (semiconductor laser 22) can be moved while emitting light within the plane of the first mounting surface 10a of the base 10 to adjust the position of the light source 20 relative to the base 10. That is, the position of the light source 20 can be adjusted by active alignment in the in-plane direction of the first mounting surface 10a, where the light utilization efficiency is greatly affected by installation errors of the light source 20. Therefore, a light source module 1 with higher reliability can be obtained.

[0069] Moreover, in the light source module 1 according to this embodiment, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 by junction-up mounting, and the front end surface 22f, which is the light emission surface of the semiconductor laser 22, does not protrude beyond the side end surface 21f of the submount 21, and the first mounting surface 10a of the base 10 and the light incident surface 30i of the planar lightwave circuit element 30 are flush with each other.

[0070] With this configuration, the front end face 22f of the semiconductor laser 22 and the light incident face 30i are separated by at least the thickness of the bonding layer 43, so that the semiconductor laser 22 does not come into contact with the light incident face 30i of the planar lightwave circuit element 30 during active alignment. Therefore, the position of the light source 20 relative to the base 10 can be easily adjusted, and a highly reliable light source module 1 can be obtained.

[0071] Furthermore, in the light source module 1 according to this embodiment, the light incident end of the optical waveguide 31 of the planar lightwave circuit element 30 has an optical waveguide end face which is a side face of the planar lightwave circuit element 30, the light incident surface 30i of the planar lightwave circuit element 30 is the optical waveguide end face, and the first mounting surface 10a of the base 10 and the light incident surface 30i are parallel to each other.

[0072] With this configuration, the side surface of the planar lightwave circuit element 30 becomes the light incident surface 30i. In this embodiment, the third mounting surface 21a of the submount 21 is parallel to the upper surface of the planar lightwave circuit element 30, but may be perpendicular to the upper surface of the planar lightwave circuit element 30.

[0073] In the light source module 1 according to the present embodiment, the light emission direction of the laser light emitted from the semiconductor laser 22 of the light source 20 is perpendicular to the light incident surface 30i of the planar lightwave circuit element 30.

[0074] This configuration makes it possible to increase the optical coupling rate between the laser light emitted from the semiconductor laser 22 and the optical waveguide 31 of the planar lightwave circuit element 30 .

[0075] In the light source module 1 according to the present embodiment, the thermal conductivity of the base 10 is higher than the thermal conductivity of the planar lightwave circuit element 30. For example, the base 10 may be made of at least one selected from the group consisting of Al, Cu, Au, Ag, AlN, and SiC.

[0076] With this configuration, the heat generated in the semiconductor laser 22 can be efficiently conducted to the outside through the base 10 without passing through the planar lightwave circuit element 30, so that the heat generated in the semiconductor laser 22 can be dissipated even more efficiently.

[0077] In the light source module 1 according to the present embodiment, the thermal conductivity of the base 10 is preferably 170 W / m·K or more.

[0078] This configuration allows the heat generated in the semiconductor laser 22 to be efficiently conducted to the submount 21, and the heat conducted to the submount 21 to be efficiently conducted to the outside through the base 10. This allows the heat generated in the semiconductor laser 22 to be dissipated to the outside even more efficiently.

[0079] (Modification of the first embodiment) Next, a modification of the first embodiment will be described with reference to Fig. 4. Fig. 4 is a perspective view that illustrates a light source module 1A according to a modification of the first embodiment.

[0080] 4, a light source module 1A according to this modification includes a base 10, a plurality of light sources 20, and a planar lightwave circuit element 30. In this modification, the plurality of light sources 20 include a blue light source 20B, a green light source 20G, and a red light source 20R.

[0081] Blue light source 20B (first light source) has an AlInGaN-based first semiconductor laser 22B and a first submount 21B as the semiconductor laser 22 and the submount 21. First semiconductor laser 22B is a blue semiconductor laser chip that emits blue laser light having a peak wavelength in the wavelength range of 400 nm to 480 nm.

[0082] Green light source 20G (second light source) has an AlInGaN-based second semiconductor laser 22G and a second submount 21G as semiconductor laser 22 and submount 21. Second semiconductor laser 22G is a green semiconductor laser chip that emits green laser light with a peak wavelength in the wavelength range of 480 nm to 600 nm.

[0083] The red light source 20R (third light source) has an AlInGaP-based third semiconductor laser 22R and a third submount 21R as the semiconductor laser 22 and the submount 21. The third semiconductor laser 22R is a red semiconductor laser chip that emits red laser light having a peak wavelength in the wavelength range of 600 nm to 700 nm.

[0084] In this modification, the optical waveguide 31 of the planar lightwave circuit element 30 is a lightwave circuit that couples light from a plurality of light sources 20 (blue light source 20B, green light source 20G, red light source 20R). Specifically, the optical waveguide 31 is provided with a plurality of cores 31a corresponding to the plurality of light sources 20. More specifically, the optical waveguide 31 has a first core 31aB into which the laser light emitted from the first semiconductor laser 22B of the blue light source 20B is incident and guided, a second core 31aG into which the laser light emitted from the second semiconductor laser 22G of the green light source 20G is incident and guided, and a third core 31aR into which the laser light emitted from the third semiconductor laser 22R of the red light source 20R is incident and guided. In FIG. 4, the first core 31aB, the second core 31aG, and the third core 31aR are shown as being exposed, but in reality, the first core 31aB, the second core 31aG, and the third core 31aR are covered with cladding.

[0085] The first core 31aB, the second core 31aG, and the third core 31aR extend in a predetermined shape from the third surface 30c, which is the light incident surface 30i of the planar lightwave circuit element 30, toward the fourth surface 30d, which is the light emitting surface 30e, and are joined inside the planar lightwave circuit element 30 (inside the optical waveguide 31) to form one core at the light emitting surface 30e. Specifically, the second core 31aG is located between the first core 31aB and the third core 31aR, and extends linearly from the third surface 30c toward the fourth surface 30d. On the other hand, the first core 31aB extends linearly from the third surface 30c, then bends smoothly toward the second core 31aG, and then extends linearly to be joined to the second core 31aG. The third core 31aR extends linearly from the third surface 30c, then bends smoothly toward the second core 31aG, then extends linearly and couples with the second core 31aG. After the first core 31aB and the second core 31aG are coupled, the third core 31aR is coupled. As a result, the light exit surface 30e of the planar lightwave circuit element 30 emits monochromatic light of blue laser, green laser light, and red laser light, or laser light that is a mixture of at least two of these laser lights. The light entrance surface 30i of the planar lightwave circuit element 30 is common to the first core 31aB, the second core 31aG, and the third core 31aR. Here, the second core 31aG is linear, but the other cores may be linear.

[0086] Moreover, in the light source module 1A of this modification, the base 10 further has a lens fixing portion 13 on the light emission side of the planar lightwave circuit element 30. A condenser lens 50 is fixed to the lens fixing portion 13. As a result, the laser light emitted from the light emission end of the optical waveguide 31 is condensed by the condenser lens 50 and emitted from the light source module 1A.

[0087] The light source module 1A thus configured can be used as a light source for a full-color display. In this modification, the light sources 20 are provided only on the sides of the planar lightwave circuit element 30, but they may be provided both on the sides and above the planar lightwave circuit element 30.

[0088] (Embodiment 2) Next, the configuration of the light source module 2 according to the second embodiment will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view of the light source module 2 according to the second embodiment.

[0089] The light source module 2 of this embodiment differs from the light source module 1 of the above-mentioned embodiment 1 in the mounting form of the semiconductor laser 22, as well as in the position of the semiconductor laser 22 relative to the submount 21 and the position of the planar lightwave circuit element 30 relative to the base 10.

[0090] Specifically, in the above-mentioned first embodiment, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 by junction-up mounting, whereas in the present embodiment, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 by junction-down mounting so that the light emitting layer faces the third mounting surface 21a, as shown in Fig. 5. That is, the waveguide 22a of the semiconductor laser 22 is disposed and fixed on the submount 21 side.

[0091] In addition, in the above-mentioned embodiment 1, the light emission surface of the semiconductor laser 22 did not protrude from the side surface of the submount 21, but in the present embodiment, as shown in FIG. 5, the front end surface 22f, which is the light emission surface of the semiconductor laser 22, protrudes from the front surface, which is the side end surface 21f (second arrangement surface 25b) of the submount 21.

[0092] In addition, in the above-mentioned embodiment 1, the light incident surface 30i of the planar lightwave circuit element 30 was flush with the first mounting surface 10a of the base 10, but in the present embodiment, as shown in FIG. 5, the third surface 30c, which is the light incident surface 30i of the planar lightwave circuit element 30, is located at a position set back from the first mounting surface 10a of the base 10.

[0093] In this case, if the distance between the front end face 22f, which is the light emission surface of the semiconductor laser 22, and the side end face 21f, which is the topmost end of the side face of the submount 21, is ΔZ1, and the distance between the first mounting surface 10a, which is the topmost end of the side face of the base 10, which is the first mounting surface 10a of the base 10, and the third surface 30c, which is the light incidence surface 30i of the planar lightwave circuit element 30, is ΔZ2≧ΔZ1. Specifically, it is preferable that 0≦ΔZ2-ΔZ1≦5 μm.

[0094] Next, the effect of the light source module 2 will be described with reference to Fig. 6. Fig. 6 is a diagram for explaining the effect of the light source module 2 according to the second embodiment. Note that the black arrows in Fig. 6 typically indicate the dissipation path of heat generated in the semiconductor laser 22.

[0095] 6, the light source module 2 is placed, for example, in a housing 100. The light source module 2 operates in the same manner as the light source module 1 of the first embodiment.

[0096] Specifically, when the semiconductor laser 22 of the light source 20 is driven, a laser light is emitted from the semiconductor laser 22. The laser light emitted from the semiconductor laser 22 enters the optical waveguide 31 from the light incident surface 30i of the planar lightwave circuit element 30, is guided through the optical waveguide 31, and is emitted to the outside from the light exit surface 30e of the planar lightwave circuit element 30. Specifically, the laser light emitted from the semiconductor laser 22 enters the side surface of the planar lightwave circuit element 30 and enters the core 31a of the optical waveguide 31. The laser light that has entered the core 31a of the optical waveguide 31 propagates through the core 31a while repeatedly being totally reflected at the interface between the core 31a and the cladding 31b.

[0097] When the semiconductor laser 22 is driven in this manner, Joule heat is generated in the vicinity of the waveguide 22a of the semiconductor laser 22. At this time, in the light source module 2, the waveguide 22a side of the semiconductor laser 22 is joined to the third mounting surface 21a of the submount 21, as shown in Fig. 5. Similarly to the light source module 1 of the above-mentioned first embodiment, the fourth mounting surface 21b of the light source 20, which is perpendicular to the third mounting surface 21a of the submount 21, is mounted on the first mounting surface 10a of the base 10, and the planar lightwave circuit element 30 is mounted on the second mounting surface 10b of the base 10.

[0098] 6, this configuration allows the heat generated in the waveguide 22a of the semiconductor laser 22 to be conducted to the submount 21 over a short distance, then to the base 10 via the bonding layer 43 between the fourth mounting surface 21b of the submount 21 and the first mounting surface 10a of the base 10, and finally to the housing 100. This allows the heat generated in the semiconductor laser 22 when the semiconductor laser 22 is driven to be efficiently dissipated. This allows the temperature rise of the semiconductor laser 22 to be suppressed.

[0099] Next, a method for manufacturing the light source module 2 according to the second embodiment will be described with reference to Figures 7A to 7E. Figures 7A to 7E are diagrams for explaining the method for manufacturing the light source module 2 according to the second embodiment.

[0100] First, as shown in FIG. 7A, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 to fabricate the light source 20.

[0101] Specifically, first, as in the first embodiment, the second metal film 27 is formed on a part of the second arrangement surface 25b of the submount body 25, and the first metal film 26 is formed on the first arrangement surface 25a. Next, the semiconductor laser 22 is arranged on the bonding layer 41 formed in advance on the third mounting surface 21a of the submount 21 so that the waveguide 22a is arranged on the third mounting surface 21a side, that is, by junction-down mounting. At this time, the semiconductor laser 22 is arranged on the bonding layer 41 so that the front end surface 22f, which is the light emission surface of the semiconductor laser 22, protrudes from the second arrangement surface 25b, which is the side end surface 21f of the submount 21. Thereafter, the bonding layer 41 is melted to bond the semiconductor laser 22 to the submount 21. This makes it possible to manufacture the light source 20 in which the semiconductor laser 22 is fixed to the submount 21.

[0102] Next, as shown in FIG. 7B, a planar lightwave circuit element 30 having an optical waveguide 31 is mounted on the second mounting surface 10b of the base 10.

[0103] Specifically, first, a first antireflection film 33 and a second antireflection film 34 are formed on both end faces of an optical waveguide 31 formed on a substrate 32 to fabricate a planar lightwave circuit element 30. In addition, a bonding layer 42 is formed on the upper surface of a base 10 by a plating method. Thereafter, a pressing member 400 having two step faces with different heights, a first step face 400a and a second step face 400b, is disposed on the sides of the third surface 30c of the planar lightwave circuit element 30 and the first mounting surface 10a of the base 10, and the planar lightwave circuit element 30 and the base 10 are bonded to each other while pressing the third surface 30c of the planar lightwave circuit element 30 and the first mounting surface 10a of the base 10 against the first step face 400a and the second step face 400b of the pressing member 400, respectively. Specifically, the base 10 on which the bonding layer 42 is formed and the planar lightwave circuit element 30 are pressed together from the lateral direction by a pressing member 400 having a first step surface 400a and a second step surface 400b higher than the second step surface 400b, thereby melting the bonding layer 42, thereby bonding the planar lightwave circuit element 30 and the base 10. In this manner, the planar lightwave circuit element 30 and the base 10 are bonded while pressing the side surface of the planar lightwave circuit element 30 and the side surface of the base 10 against each other using the pressing member 400 having the first step surface 400a and the second step surface 400b having different heights, whereby the planar lightwave circuit element 30 and the base 10 can be bonded easily and precisely such that the third surface 30c of the planar lightwave circuit element 30 is recessed from the first mounting surface 10a of the base 10.

[0104] Next, as shown in Figures 7C and 7D, the light source 20 is mounted on the first mounting surface 10a of the base 10. Specifically, Figures 7C and 7D can be performed in the same manner as Figures 3C and 3D in the manufacturing method of the light source module 1 of the first embodiment.

[0105] That is, after performing the step of Fig. 7C (active alignment step) as in Fig. 3C, the step of Fig. 7D (heating laser light irradiation step) is performed as in Fig. 3D. Specifically, the laser light emitted from the semiconductor laser 22 is made incident on the optical waveguide 31 of the planar lightwave circuit element 30, and the position of the light source 20 is adjusted in a direction within a plane parallel to the first mounting surface 10a of the base 10 so that the amount of laser light from the semiconductor laser 22 is maximized. Then, the light source 20 is fixed to the base 10 via the bonding layer 43 arranged between the fourth mounting surface 21b of the submount 21 and the first mounting surface 10a of the base 10.

[0106] In this embodiment, the process of Fig. 7C and the process of Fig. 7D may be performed simultaneously, or the process of Fig. 7D may be performed before the process of Fig. 7C. In other words, the process of Fig. 7C may be performed after the process of Fig. 7D.

[0107] In this manner, by fixing the light source 20 to the base 10 on which the planar lightwave circuit element 30 is fixed, the light source module 2 is completed as shown in FIG. 7E.

[0108] The light source module 2 according to the present embodiment configured in this manner provides the same effects as the light source module 1 according to the first embodiment.

[0109] For example, in the light source module 2 according to the present embodiment, the semiconductor laser 22 is mounted on the submount 21 by junction-down mounting. Similarly to the light source module 1 in the above-described first embodiment, the light source 20 is mounted on the first mounting surface 10a of the base 10 at a fourth mounting surface 21b orthogonal to the third mounting surface 21a, and the planar lightwave circuit element 30 is mounted on the second mounting surface 10b of the base 10. The light incident surface 30i of the planar lightwave circuit element 30 is disposed opposite to the front end surface 22f of the semiconductor laser 22.

[0110] This allows heat generated in the waveguide 22a of the semiconductor laser 22 when the semiconductor laser 22 is driven to be efficiently dissipated to the outside through the submount 21 and the base 10, thereby providing a highly reliable light source module 2. Furthermore, due to the configuration of the light source module 2, the positional relationship between the waveguide 22a and the optical waveguide 31 can be adjusted by active alignment when manufacturing the light source module 2. Therefore, a highly reliable light source module 2 can be provided in which the coupling efficiency between the laser light and the optical waveguide 31 is high.

[0111] In addition, the light source module 2 according to the present embodiment has the same effects as the light source module 1 in the first embodiment.

[0112] In the light source module 2 according to this embodiment, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 by junction-down mounting. If the distance between the light emission surface of the semiconductor laser 22 and the side surface of the submount 21 is ΔZ1 and the distance between the side surface of the base 10, which is the first mounting surface 10a of the base 10, and the light incidence surface 30i of the planar lightwave circuit element 30 is ΔZ2, then ΔZ2≧ΔZ1. Specifically, it is preferable that 0≦ΔZ2−ΔZ1≦5 μm.

[0113] With this configuration, during active alignment in manufacturing the light source module 2, the semiconductor laser 22 does not come into contact with the light incident surface 30i of the planar lightwave circuit element 30, and the coupling efficiency between the laser light emitted from the semiconductor laser 22 and the optical waveguide 31 of the planar lightwave circuit element 30 can be maintained high.

[0114] (First modification of the second embodiment) Next, a first modification of the second embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram showing a configuration of a light source module 2A according to the first modification of the second embodiment.

[0115] A light source module 2A according to this modification is different from the light source module 2 according to the second embodiment in that the planar lightwave circuit element 30 is oriented up and down relative to the base 10.

[0116] Specifically, in the light source module 2 in the above-mentioned second embodiment, the planar lightwave circuit element 30 is disposed so that the substrate 32 is closer to the base 10 than the optical waveguide 31 is, but in the light source module 2A in this modification, as shown in Fig. 8, the planar lightwave circuit element 30 is disposed so that the optical waveguide 31 is closer to the base 10 than the substrate 32. In other words, the optical waveguide 31 side of the planar lightwave circuit element 30 is joined to the base 10.

[0117] With this configuration, the position of the optical waveguide 31 through which the laser light emitted from the semiconductor laser 22 is guided can be brought closer to the base 10, improving the installation accuracy of the light source 20 during active alignment in manufacturing the light source module 2A. Even if part of the laser light is absorbed in the optical waveguide 31 and turns into Joule heat when the semiconductor laser 22 is driven, the Joule heat can be conducted to the base 10 and efficiently dissipated. This makes it possible to suppress changes in the characteristics of the optical waveguide 31 caused by changes in the refractive index of the optical waveguide 31 due to a temperature rise in the optical waveguide 31.

[0118] The configuration of this modification may be applied to the above-mentioned first embodiment, or to other embodiments described later.

[0119] (Modification 2 of the second embodiment) Next, a second modification of the second embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram showing a configuration of a light source module 2B according to the second modification of the second embodiment.

[0120] A light source module 2B according to this modification is different from the light source module 2 according to the second embodiment in the configuration of the submount 21.

[0121] Specifically, in the light source module 2 in the above-mentioned embodiment 2, the submount body 25 in the submount 21 was made of only one of ceramic and metal, but as shown in FIG. 9, in the light source module 2B in this modified example, the submount 21 is made of a composite of metal and ceramic.

[0122] The submount 21 in this modification has a first submount body 25F (first member) made of at least one selected from metals Al, Cu, Au, and Ag, and a second submount body 25G (second member) made of at least one selected from ceramics AlN and SiC. The first submount body 25F and the base 10 are joined via a joining layer 43, and the second submount body 25G and the semiconductor laser 22 are joined via a joining layer 41.

[0123] Further, the submount 21 in this modification has a first first metal film 26a formed on the upper surface of the second submount body 25G, and a second first metal film 26b, a third first metal film 26c, and a fourth first metal film 26d laminated between the first submount body 25F and the second submount body 25G. The outer surface of the first first metal film 26a becomes the third mounting surface 21a of the submount 21.

[0124] In this way, by forming the submount 21 from a composite of metal and ceramic, it is possible to improve the dissipation of heat generated by the semiconductor laser 22. In particular, by arranging the second submount body 25G made of ceramic having a linear expansion coefficient close to that of the semiconductor laser 22 on the semiconductor laser 22 side and arranging the first submount body 25F made of metal having high thermal conductivity on the base 10 side, it is possible to efficiently conduct the heat generated by the semiconductor laser 22 to the base 10 and to effectively prevent the semiconductor laser 22 from deteriorating due to stress distortion caused by the difference in linear expansion coefficient between the semiconductor laser 22 and the submount 21. This makes it possible to realize a light source module 2B with even higher reliability.

[0125] The configuration of this modification may be applied to the above-mentioned first embodiment, or to other embodiments described later.

[0126] (Third Modification of the Second Embodiment) Next, a third modification of the second embodiment will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a perspective view that illustrates a light source module 2C according to the third modification of the second embodiment, and Fig. 11 is a cross-sectional view of the light source module 2C.

[0127] As shown in FIG. 10, a light source module 2C according to this modification includes a base 10C, a plurality of light sources 20, and a planar lightwave circuit element 30. In this modification, the plurality of light sources 20 include a blue light source 20B, a green light source 20G, and a red light source 20R. The blue light source 20B, the green light source 20G, and the red light source 20R in this modification are similar to the blue light source 20B, the green light source 20G, and the red light source 20R shown in FIG. 4. Specifically, the blue light source 20B (first light source) has an AlInGaN-based first semiconductor laser 22B and a first submount 21B as the semiconductor laser 22 and the submount 21. The green light source 20G (second light source) has an AlInGaN-based second semiconductor laser 22G and a second submount 21G as the semiconductor laser 22 and the submount 21. The red light source 20R (third light source) has an AlInGaP-based third semiconductor laser 22R and a third submount 21R as the semiconductor laser 22 and the submount 21. However, in this modification, the first semiconductor laser 22B, the second semiconductor laser 22G, and the third semiconductor laser 22R are mounted on the first submount 21B, the second submount 21G, and the third submount 21R by junction-down mounting.

[0128] In this modification, the optical waveguide 31 of the planar lightwave circuit element 30 is a lightwave circuit that couples light from a plurality of light sources 20 (blue light source 20B, green light source 20G, red light source 20R). Specifically, the optical waveguide 31 has, as a plurality of cores 31a corresponding to the plurality of light sources 20, a first core 31aB into which the laser light emitted from the first semiconductor laser 22B of the blue light source 20B is incident and guided, a second core 31aG into which the laser light emitted from the second semiconductor laser 22G of the green light source 20G is incident and guided, and a third core 31aR into which the laser light emitted from the third semiconductor laser 22R of the red light source 20R is incident and guided. In FIG. 10, the first core 31aB, the second core 31aG, and the third core 31aR are shown as being exposed, but in reality, the first core 31aB, the second core 31aG, and the third core 31aR are covered with cladding.

[0129] In this modification, the first core 31aB, the second core 31aG, and the third core 31aR extend in a predetermined shape from the light incident surface 30i of the planar lightwave circuit element 30 toward the light emitting surface 30e, and are joined inside the planar lightwave circuit element 30 (inside the optical waveguide 31) to form one core at the light emitting surface 30e. Specifically, as shown in Fig. 10, the first core 31aB extends linearly from the third surface 30c toward the fourth surface 30d. On the other hand, the second core 31aG extends linearly from the third surface 30c, then smoothly bends toward the first core 31aB, and then extends linearly to be joined to the first core 31aB. The third core 31aR, like the second core 31aG, extends linearly from the third surface 30c, then bends smoothly toward the first core 31aB, and then extends linearly parallel to the second core 31aG and is coupled to the first core 31aB. After the second core 31aG and the first core 31aB are coupled, the third core 31aR is further coupled to the second core 31aR. As a result, the light exit surface 30e of the planar lightwave circuit element 30 emits monochromatic light of blue laser, green laser light, and red laser light, or laser light that is a mixture of at least two of these laser lights. The light entrance surface 30i of the planar lightwave circuit element 30 is common to the first core 31aB, the second core 31aG, and the third core 31aR. Here, the first core 31aB is linear, but the other cores may be linear.

[0130] The light source module 2C configured in this manner can be used as a light source for a full-color display. In this modification, the multiple light sources 20 are provided only on the sides of the planar lightwave circuit element 30, but they may be provided both on the sides and above the planar lightwave circuit element 30.

[0131] 10, in this modification, the outer shape of the base 10C is larger than that of the planar lightwave circuit element 30. Furthermore, as shown in FIG. 10 and FIG. 11, in this modification, the side of the base body 11C of the base 10C closer to the light source has an extension 11C1 extending from the first mounting surface 10a to below the multiple light sources 20. Specifically, the base body 11C extends from the first mounting surface 10a to the rear of the first submount 21B, the second submount 21G, and the third submount 21R, that is, to the rear of the surface opposite to the fourth mounting surface 21b, in top view. Therefore, the distance between the first mounting surface 10a of the extension 11C1 and the surface opposite to it is larger than the distance between the fourth mounting surface 21b of the first submount 21B, the second submount 21G, and the third submount 21R and the surface opposite to it.

[0132] With this configuration, a part of the heat generated by each of the plurality of light sources 20 can be dissipated to the outside through the extension portion 11C1 as shown by the black arrow in Fig. 11. In other words, the area of ​​the heat dissipation surface 10h, which is the lower surface of the base 10C, can be increased, so that the heat can be efficiently dissipated to the outside. In this way, even if the light source module 2C includes the plurality of light sources 20, the light generated by each of the plurality of light sources 20 can be efficiently dissipated to the outside through the base 10C because the light source module 2C includes the base 10, which has high thermal conductivity and can be freely changed in shape, in addition to the planar lightwave circuit.

[0133] (Fourth Modification of the Second Embodiment) Next, a fourth modification of the second embodiment will be described with reference to Fig. 12. Fig. 12 is a diagram showing a configuration of a light source module 2D according to the fourth modification of the second embodiment. In Fig. 12, (a) is a side view of the light source module 2D, (b) is a top view of the light source module 2D, and (c) is a cross-sectional view of the light source module 2D taken along line cc in (b).

[0134] 12, light source module 2D according to this modification includes blue light source 20B, green light source 20G, and red light source 20R as the multiple light sources 20, similar to light source module 2C according to modification 3 of embodiment 2. However, light source module 2D according to this modification is different from light source module 2C according to modification 3 of embodiment 2 in the positional relationship between blue light source 20B, green light source 20G, and red light source 20R. Specifically, in light source module 2D according to this modification, blue light source 20B, green light source 20G, and red light source 20R are arranged so that their polarization directions are aligned in single mode wavelength multiplexing.

[0135] Here, the first and second semiconductor lasers 22B and 22G made of AlGaInN-based semiconductor materials oscillate in the TE mode. That is, the laser light emitted from each of the first and second semiconductor lasers 22B and 22G is polarized in a direction parallel to the chip plane (plane parallel to the active layer) of the first and second semiconductor lasers 22B and 22G.

[0136] The third semiconductor laser 22R made of an AlGaInP-based semiconductor material oscillates in the TM mode. That is, the laser light emitted from the third semiconductor laser 22R is polarized in a direction perpendicular to the chip plane (plane parallel to the active layer) of the third semiconductor laser 22R.

[0137] Therefore, in this modification, the third mounting surface 21aB of the second submount 21G of the green light source 20G and the third mounting surface 21aB of the first submount 21B of the blue light source 20B are oriented perpendicular to the top surface of the planar lightwave circuit element 30. Therefore, the third mounting surface 21aG of the second submount 21G of the green light source 20G and the third mounting surface 21aB of the first submount 21B of the blue light source 20B are parallel to each other. As a result, the laser light emitted from each of the first semiconductor laser 22B mounted on the first submount 21B and the second semiconductor laser 22G mounted on the second submount 21G is polarized in a direction perpendicular to the top surface of the planar lightwave circuit element 30.

[0138] Moreover, the third mounting surface 21aR of the third submount 21R of the red light source 20R is parallel to the upper surface of the planar lightwave circuit element 30. Therefore, the third mounting surface 21aR of the third submount 21R of the red light source 20R and the third mounting surface 21aB of the first submount 21B of the blue light source 20B are perpendicular to each other. As a result, the laser light emitted from the third semiconductor laser 22R is also polarized in a direction perpendicular to the upper surface of the planar lightwave circuit element 30.

[0139] With this configuration, in single mode wavelength multiplexing, the polarization directions of the first semiconductor laser 22B, the second semiconductor laser 22G, and the third semiconductor laser 22R can be made to coincide. That is, the polarization directions of the blue laser light, the green laser light, and the red laser light incident on the planar lightwave circuit element 30 can be made to coincide. That is, since the polarization direction of the mixed laser light output from the planar lightwave circuit element 30 is made to coincide, it is possible to control images using a single liquid crystal. In addition, since the core intervals between the first core 31aB, the second core 31aG, and the third core 31aR can be narrowed, the planar lightwave circuit element 30 can be made smaller. Therefore, the light source module 2D can be made smaller.

[0140] In this modification, the second semiconductor laser 22G in the green light source 20G is located between the first semiconductor laser 22B in the blue light source 20B and the second submount 21G in the green light source 20G. That is, the first semiconductor laser 22B and the second semiconductor laser 22G are arranged so that the first semiconductor laser 22B and the second semiconductor laser 22G face each other.

[0141] With this configuration, the distance between the first semiconductor laser 22B and the second semiconductor laser 22G can be narrowed, and therefore the light source module 2D can be further reduced in size.

[0142] Furthermore, as shown in (c) of Figure 12, if the distance from the optical waveguide in the first semiconductor laser 22B to the chip side surface is ΔW and the distance from the first core 31aB of the optical waveguide 31 of the planar lightwave circuit element 30 to the top surface of the base 10 is ΔD, it is preferable that the relational expression ΔD>ΔW is satisfied.

[0143] With this configuration, even if blue light source 20B in which first semiconductor laser 22B is mounted on first submount 21B is mounted vertically on base 10, it is possible to prevent first semiconductor laser 22B from coming into contact with base 10. This is true not only for blue light source 20B, but also for green light source 20G.

[0144] (Embodiment 3) Next, the configuration of the light source module 3 according to the third embodiment will be described with reference to Fig. 13. Fig. 13 is a cross-sectional view of the light source module 3 according to the third embodiment.

[0145] The light source module 3 of this embodiment differs from the light source module 1 of the above-mentioned embodiment 1 in the shape of the base body 11A of the base 10A, the position of the light incident surface 30i of the planar lightwave circuit element 30A, and the shape of the substrate 32A of the planar lightwave circuit element 30A.

[0146] Specifically, as shown in Fig. 13, in this embodiment, the base body 11A of the base 10A has a first base body portion 11a located to the side of the planar lightwave circuit element 30A and a second base body portion 11b located below the planar lightwave circuit element 30A. For example, the base 10A has an L-shaped cross section. In the base 10A, the metal film 12 is formed on the entire surface of the base body 11A on the side of the planar lightwave circuit element 30A. Specifically, the metal film 12 is formed continuously over the upper surface 11a1 and side surface 11a2 of the first base body portion 11a and the upper surface 11b1 of the second base body portion 11b.

[0147] A first mounting surface 10a (surface on which the light source 20 is mounted) of the base 10A is parallel to a first surface 30u which is the upper surface of the planar lightwave circuit element 30A. A second mounting surface 10b (surface on which the planar lightwave circuit element 30A is mounted) of the base 10A is parallel to a third surface 30c which is a side surface of the planar lightwave circuit element 30A.

[0148] The light source 20 is disposed above the first base body 11a of the base 10A. Specifically, the submount body 25 of the submount 21 of the light source 20 is disposed above the first base body 11a. As in the first embodiment, the submount 21 of the light source 20 has the second metal film 27 formed on a part of the second arrangement surface 25b of the submount body 25 and the first metal film 26 formed on the first arrangement surface 25a. The semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 via a bonding layer 41. In this embodiment, the third mounting surface 21a of the submount 21 is disposed on the side surface. Also, the fourth mounting surface 21b of the submount 21 is disposed on the lower surface. The semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 by so-called junction-up mounting, in which the surface opposite to the surface on which the waveguide 22a is formed is mounted on the third mounting surface 21a of the submount 21. Furthermore, the light source 20 and the base 10A are bonded via a bonding layer 43 between the fourth mounting surface 21b of the submount and the first mounting surface 10a of the base 10A.

[0149] In this embodiment, the front end face 22f, which is the light emitting face of the semiconductor laser 22, does not protrude beyond the second placement face 25b of the submount .

[0150] The planar lightwave circuit element 30A is bonded to a second mounting surface 10b, which is a side surface of the base 10A. Specifically, a metal film 35 is formed on a third surface 30c, which is a side surface of the first base body 11a of the substrate 32A of the planar lightwave circuit element 30A, and the planar lightwave circuit element 30A is bonded to a position corresponding to the side surface of the first base body 11a of the base 10A via a bonding layer 42 formed between the metal film 35 of the planar lightwave circuit element 30A and the metal film 12 of the base 10A.

[0151] A holding member 60 is provided between the second surface 30b of the planar lightwave circuit element 30A opposite to the first base body portion 11a side and the second base body portion 11b. This allows the end of the planar lightwave circuit element 30A on the light source 20 side to be joined to the base 10A, and the end of the planar lightwave circuit element 30A opposite to the side surface on the light source 20 side to be held by the base 10A. Therefore, the planar lightwave circuit element 30A can be stably held on the base 10A. The holding member 60 is made of, for example, an insulating resin material, but is not limited thereto.

[0152] In this modification, the light incident surface 30i of the planar lightwave circuit element 30A is disposed on the first surface 30u, which is the upper surface of the planar lightwave circuit element 30A. Therefore, the laser light emitted from the semiconductor laser 22 is incident on the first surface 30u, which is the upper surface of the planar lightwave circuit element 30A. The first antireflection film 33, whose outer surface is the light incident surface 30i, is formed on the upper surface of the optical waveguide 31.

[0153] An end portion on the light incident side of the optical waveguide 31 of the planar lightwave circuit element 30A has an optical waveguide reflecting surface that is inclined with respect to the upper surface of the planar lightwave circuit element 30A. In this modification, the optical waveguide reflecting surface is an inclined surface 32a formed on the substrate 32A. The inclination angle of the inclined surface 32a (the inclination angle with respect to the upper surface of the planar lightwave circuit element 30A) is, for example, 45°, but is not limited to this.

[0154] The semiconductor laser 22 is disposed so that the laser light is incident from the light incident surface 30i, which is the upper surface of the planar lightwave circuit element 30A, toward the optical waveguide reflecting surface (inclined surface 32a). In this modification, the direction of the laser light emitted from the semiconductor laser 22 is perpendicular to the upper surface of the planar lightwave circuit element 30A. That is, the laser light from the semiconductor laser 22 is perpendicular to the first surface 30u, which is the upper surface of the planar lightwave circuit element 30A. The laser light from the semiconductor laser 22 perpendicularly incident on the planar lightwave circuit element 30A is reflected by the optical waveguide reflecting surface (inclined surface 32a) and propagates in the extension direction of the optical waveguide 31. In this way, the optical waveguide reflecting surface (inclined surface 32a) is a reflecting surface that reflects the laser light from the semiconductor laser 22. The optical waveguide reflecting surface (inclined surface 32a) may be a total reflecting surface that utilizes the refractive index difference at the interface between two members, or may be a metal reflecting surface on which a metal film or the like is formed.

[0155] Next, the effect of the light source module 3 will be described with reference to Fig. 14. Fig. 14 is a diagram for explaining the effect of the light source module 3 according to the third embodiment. Note that the black arrows in Fig. 14 typically indicate the dissipation path of the heat generated in the semiconductor laser 22.

[0156] 14, the light source module 3 is mounted on, for example, a housing 100. When the semiconductor laser 22 of the light source 20 is driven, a laser beam is emitted from the semiconductor laser 22. The laser beam emitted from the semiconductor laser 22 enters the optical waveguide 31 from the light incident surface 30i of the planar lightwave circuit element 30A and is reflected by the optical waveguide reflecting surface (inclined surface 32a). The laser beam reflected by the optical waveguide reflecting surface (inclined surface 32a) enters the core 31a of the optical waveguide 31 and propagates through the core 31a while repeatedly being totally reflected at the interface between the core 31a and the cladding 31b.

[0157] When the semiconductor laser 22 is driven in this manner, heat is generated from the semiconductor laser 22. At this time, in the light source module 3, similarly to the light source module 1 of the above-mentioned first embodiment, the light source 20 having the semiconductor laser 22 mounted on the third mounting surface 21a of the submount 21 is mounted on the first mounting surface 10a of the base 10A on a surface that is not parallel to the third mounting surface 21a among the surfaces that constitute the submount 21, and the planar lightwave circuit element 30A is mounted on the second mounting surface 10b of the base 10A.

[0158] 14, the heat generated by the semiconductor laser 22 is conducted to the submount 21, then to the base 10A via the first mounting surface 10a of the base 10A, and then to the housing 100. This allows the heat generated by the semiconductor laser 22 when the semiconductor laser 22 is driven to be efficiently dissipated. This makes it possible to suppress the temperature rise of the semiconductor laser 22.

[0159] Next, a method for manufacturing the light source module 3 according to the third embodiment will be described with reference to Figs. 15A to 15H. Figs. 15A to 15H are diagrams for explaining the method for manufacturing the light source module 3 according to the third embodiment.

[0160] First, as shown in Fig. 15A to Fig. 15C, a planar lightwave circuit element 30A is fabricated. Specifically, as shown in Fig. 15A, a silicon substrate having a surface with a crystal orientation inclined by 9.7° with respect to the (100) plane is prepared as the substrate 32A, and anisotropic etching is performed on the substrate 32A to form a recess 32b in the substrate 32A and a flat inclined surface 32a based on a crystal plane is formed on the substrate 32A. Here, the surface with a crystal orientation inclined by 9.7° with respect to the (100) plane is a crystal plane having a normal line inclined by 9.7° from the

[0100] direction. Also, a portion 32c of the surface inclined by 9.7° from the (100) plane remains unetched. Next, a light-reflective metal film is formed on the inclined surface. In this embodiment, Ag or Al is used as the metal film. Next, using a mask or the like, cladding 31b, core 31a, and the end of cladding 31b are formed in order while aligning them to an inclined surface, thereby forming planar lightwave circuit element 30A having optical waveguide 31, as shown in Fig. 15B. Next, as shown in Fig. 15C, a first antireflection film 33 is formed on the upper surface of optical waveguide 31 formed on substrate 32A, and a second antireflection film 34 is formed on the end surface of optical waveguide 31 on the light emission surface 30e side. In addition, a metal film 35 serving as a base for bonding by solder or the like is formed on the end surface (side surface) of substrate 32A on the light source 20 side.

[0161] Next, as shown in Fig. 15D, the planar lightwave circuit element 30A having the optical waveguide 31 is mounted on the second mounting surface 10b of the base 10A. Specifically, the side of the planar lightwave circuit element 30A is bonded to the base 10A on which the bonding layer 42 is formed. This makes it possible to fix the base 10A and the planar lightwave circuit element 30A. The bonding layer 42 may be formed on the metal film 35 of the planar lightwave circuit element 30A, instead of the metal film 12 of the base 10A.

[0162] Next, as shown in Fig. 15E, the light source 20 is placed on the base 10A. The light source 20 can be fabricated in the same manner as in Fig. 3A. Specifically, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 by junction-up mounting via the bonding layer 41.

[0163] 15F and 15G, the light source 20 is mounted on the first mounting surface 10a of the base 10A. In the present embodiment as well, the laser light emitted from the semiconductor laser 22 is made incident on the optical waveguide 31 of the planar lightwave circuit element 30A, and the position of the light source 20 is adjusted in a direction in a plane parallel to the first mounting surface 10a of the base 10A so that the amount of laser light from the semiconductor laser 22 is maximized. Then, the light source 20 is fixed to the base 10A via a bonding layer 43 disposed between the fourth mounting surface 21b of the submount 21 and the first mounting surface 10a of the base 10A.

[0164] Specifically, as shown in FIG. 15F, the position of the light source 20 is adjusted with respect to the base 10A on which the planar lightwave circuit element 30A is mounted by the laser light emitted from the semiconductor laser 22. That is, active alignment is performed. For example, in a state where the bonding layer 43 is sandwiched between the submount 21 of the light source 20 and the base 10A on which the planar lightwave circuit element 30A is mounted, the semiconductor laser 22 is driven to make the laser light emitted from the semiconductor laser 22 enter the optical waveguide 31 of the planar lightwave circuit element 30A, and the laser light emitted from the optical waveguide 31 is monitored by the power meter 200. At this time, the position of the light source 20 is moved so that the amount of light of the monitored laser light is maximized. That is, the optical axis of the semiconductor laser 22 and the optical axis of the optical waveguide 31 are adjusted so that the amount of light of the monitored laser light is maximized. This adjustment of the optical axis is performed in a direction in a plane parallel to the first mounting surface 10a of the base 10A.

[0165] The bonding layer 43 may be inserted between the base 10A and the submount 21 as a sheet-like solder foil, or may be formed in advance on the upper surface of the base 10A by deposition, coating, etc. When the bonding layer 43 is formed in advance on the upper surface of the base 10A, the bonding layer 43 may be formed on the base 10A before the planar lightwave circuit element 30A is mounted on the base 10A.

[0166] After adjusting the position of the light source 20, as shown in FIG. 15G, a bonding layer 43 is disposed between the upper surface of the submount 21 of the light source 20 and the first mounting surface 10a of the base 10A, and the laser light emitted from the heating laser light source 300 is transmitted through the submount 21 and irradiated onto the bonding layer 43 to directly heat the bonding layer 43 and heat and melt the bonding layer 43. Then, the temperature of the bonding layer 43 is lowered by stopping the heating laser light, and the bonding layer is solidified. This allows the submount 21 of the light source 20 to be fixed to the base 10A via the bonding layer 43. Note that, in this embodiment as well, the bonding layer 41 that bonds the semiconductor laser 22 to the submount 21 and the bonding layer 43 that bonds the submount 21 to the base 10A are made of the same material.

[0167] In this way, the heating laser light passes through the submount 21, thereby suppressing heat generation in the submount 21. In other words, it is possible to suppress a rise in temperature of the submount 21. This makes it possible to suppress misalignment caused by remelting of the bonding layer 41 located between the semiconductor laser 22 and the submount 21.

[0168] In this embodiment, the step of FIG. 15G (heating laser light irradiation step) is performed after the step of FIG. 15F (active alignment step), but this is not limited thereto. For example, the steps of FIG. 15F and FIG. 15G may be performed simultaneously. Also, the step of FIG. 15G may be performed before the step of FIG. 15F. That is, the step of FIG. 15F may be performed after the step of FIG. 15G. In this case, the heating laser light is transmitted through the submount 21 and irradiated onto the bonding layer 43 to soften the bonding layer 43, and the optical axis of the semiconductor laser 22 of the light source 20 and the optical axis of the optical waveguide 31 of the planar lightwave circuit element 30A are adjusted, and then the irradiation of the heating laser light is stopped to solidify the bonding layer 43.

[0169] 15H, the holding member 60 is inserted between the planar lightwave circuit element 30A and the base 10A, thereby completing the light source module 3.

[0170] The light source module 3 according to the present embodiment configured in this manner provides the same effects as the light source module 1 according to the first embodiment.

[0171] For example, in the light source module 3 according to the present embodiment, similarly to the light source module 1 in the above-mentioned first embodiment, the light source 20 having the semiconductor laser 22 mounted on the third mounting surface 21a of the submount 21 is mounted on the first mounting surface 10a of the base 10A at a fourth mounting surface 21b that is orthogonal to the third mounting surface 21a among the surfaces constituting the submount 21, and the planar lightwave circuit element 30A is mounted on the second mounting surface 10b of the base 10A. The light incident surface 30i of the planar lightwave circuit element 30A is parallel to the first mounting surface 10a of the base 10A.

[0172] This allows efficient dissipation of heat generated by the semiconductor laser 22 when the semiconductor laser 22 is driven, thereby making it possible to obtain a highly reliable light source module 3. Furthermore, due to the configuration of the light source module 3, the position of the light source 20 can be adjusted by active alignment when manufacturing the light source module 3. Therefore, a more reliable light source module 3 can be obtained.

[0173] In addition, the light source module 3 according to this embodiment has the same effects as the light source module 1 in the first embodiment.

[0174] (Modification of the third embodiment) Next, a modified example of the third embodiment will be described with reference to Figs. 16 and 17. Fig. 16 is a perspective view showing a light source module 3A according to a modified example of the third embodiment. Fig. 17 is a diagram showing a configuration of the light source module 3A according to a modified example of the third embodiment. In Fig. 17, (a) is a top view of the light source module 3A, and (b) is a cross-sectional view of the light source module 3A.

[0175] As shown in FIG. 16, a light source module 3A according to this modification includes a base 10A, a plurality of light sources 20, and a planar lightwave circuit element 30A having a substrate 32A on which an inclined surface 32a is formed.

[0176] In this modification, the multiple light sources 20 include a blue light source 20B, a green light source 20G, and a red light source 20R. The blue light source 20B, the green light source 20G, and the red light source 20R in this modification are similar to the blue light source 20B, the green light source 20G, and the red light source 20R shown in FIG. 4. Specifically, the blue light source 20B (first light source) has an AlInGaN-based first semiconductor laser 22B and a first submount 21B as the semiconductor laser 22 and the submount 21. The green light source 20G (second light source) has an AlInGaN-based second semiconductor laser 22G and a second submount 21G as the semiconductor laser 22 and the submount 21. The red light source 20R (third light source) has an AlInGaP-based third semiconductor laser 22R and a third submount 21R as the semiconductor laser 22 and the submount 21. However, in this modification, the first semiconductor laser 22B, the second semiconductor laser 22G, and the third semiconductor laser 22R are mounted on the first submount 21B, the second submount 21G, and the third submount 21R by junction-up mounting.

[0177] In this modification, the optical waveguide 31 of the planar lightwave circuit element 30A is a lightwave circuit that couples light from a plurality of light sources 20 (blue light source 20B, green light source 20G, red light source 20R). Specifically, the optical waveguide 31 has a plurality of cores 31a corresponding to the plurality of light sources 20, including a first core 31aB into which the laser light emitted from the first semiconductor laser 22B of the blue light source 20B is incident and guided, a second core 31aG into which the laser light emitted from the second semiconductor laser 22G of the green light source 20G is incident and guided, and a third core 31aR into which the laser light emitted from the third semiconductor laser 22R of the red light source 20R is incident and guided. As in the third embodiment, the end of the light incident side of the optical waveguide 31 of the planar lightwave circuit element 30A has an optical waveguide reflection surface that is inclined with respect to the upper surface of the planar lightwave circuit element 30A. In FIG. 17(a), the boundary 32d shown by the dashed line indicates the position of the boundary between the inclined surface 32a and the recessed portion 32b, and the boundary 32e shown by the dashed line indicates the position of the boundary between the inclined surface 32a and the portion 32c of the surface that is inclined by 9.7° from the (100) plane and remains unetched. The inclined surface 32a is located between the boundary 32d and the boundary 32e. As shown in FIG. 17(b), the light from the blue light source 20B, the green light source 20G, and the red light source 20R is arranged so as to be incident on the inclined surface 32a. In FIG. 16, the first core 31aB, the second core 31aG, and the third core 31aR are illustrated as being exposed, but in reality, the first core 31aB, the second core 31aG, and the third core 31aR are covered with cladding.

[0178] In this modification, the first core 31aB, the second core 31aG, and the third core 31aR extend in a predetermined shape from the side surface of the planar lightwave circuit element 30A on the light source 20 side toward the light output surface 30e, and are combined inside the planar lightwave circuit element 30A (inside the optical waveguide 31) to form one core at the light output surface 30e. Specifically, as shown in Fig. 16, the third core 31aR extends linearly from the inclined surface 32a near the third surface 30c toward the fourth surface 30d. On the other hand, the second core 31aG extends linearly from the inclined surface 32a near the third surface 30c, then bends smoothly toward the third core 31aR, and then extends linearly to be combined with the third core 31aR. The first core 31aB, like the second core 31aG, extends linearly from the inclined surface 32a near the third surface 30c, then smoothly curves toward the third core 31aR, and then extends linearly parallel to the second core 31aG and couples with the third core 31aR. After the second core 31aG and the third core 31aR couple with each other, the first core 31aB couples with each other. This allows the light emission surface 30e of the planar lightwave circuit element 30A to emit monochromatic light of blue, green, and red laser light, or laser light that is a mixture of at least two of these laser lights.

[0179] The light source module 3A thus configured can be used as a light source for a full-color display.

[0180] 16, in this modification, the outer shape of the base 10A is larger than that of the planar lightwave circuit element 30A. Furthermore, as shown in FIG. 16 and FIG. 17, in this modification, a part of the base body 11A of the base 10A extends from the second mounting surface 10b to below the multiple light sources 20. Specifically, the base body 11A extends from the second mounting surface 10b to the rear of the first submount 21B, the second submount 21G, and the third submount 21R, that is, to the rear of the surface opposite to the third mounting surface 21a, in a top view. Therefore, the distance between the second mounting surface 10b of the first base body part 11a of the base body 11A and the surface opposite to it is longer than the distance between the second mounting surface 10b of the first submount 21B, the second submount 21G, and the third submount 21R and the surface opposite to it.

[0181] With this configuration, even if the light source module 3A is equipped with multiple light sources 20, as shown by the black arrows in Figure 17, when heat generated in each of the multiple light sources 20 is transmitted through the first base main body portion 11a, the heat spreads toward the heat dissipation surface 10h, which is the underside of the first base main body portion 11a, and therefore the heat can be efficiently dissipated to the outside from the heat dissipation surface 10h of the base 10A.

[0182] (Embodiment 4) Next, the configuration of the light source module 4 according to the fourth embodiment will be described with reference to Fig. 18. Fig. 18 is a cross-sectional view of the light source module 4 according to the fourth embodiment.

[0183] As shown in FIG. 18, the light source module 4 of this modified example, like the light source module 3 of the above-mentioned embodiment 3, comprises a base 10A, a light source 20, and a planar lightwave circuit element 30A having a substrate 32A on which an inclined surface 32a is formed.

[0184] The light source module 4 of this embodiment differs from the light source module 3 of the above-mentioned embodiment 3 in the mounting form of the semiconductor laser 22, as well as in the position of the semiconductor laser 22 relative to the submount 21 and the position of the planar lightwave circuit element 30A relative to the base 10A.

[0185] Specifically, in the above-mentioned third embodiment, the semiconductor laser 22 was mounted on the third mounting surface 21a of the submount 21 by junction-up mounting, whereas in the present embodiment, as shown in FIG. 18, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 by junction-down mounting.

[0186] In addition, in the above-mentioned embodiment 3, the front end face 22f, which is the light emission surface of the semiconductor laser 22, does not protrude beyond the second placement surface 25b of the submount 21. However, in the present embodiment, as shown in FIG. 18, the light emission surface of the semiconductor laser 22 protrudes beyond the second placement surface 25b of the submount 21.

[0187] In addition, in the above-mentioned embodiment 3, the first surface 30u on which the light incident surface 30i of the planar lightwave circuit element 30A is formed is flush with the first mounting surface 10a of the base 10A, but in the present embodiment, as shown in FIG. 18, the first surface 30u which is the light incident surface 30i of the planar lightwave circuit element 30A is located below the first mounting surface 10a of the base 10A.

[0188] In this case, if the distance between the front end face 22f, which is the light emission surface of the semiconductor laser 22, and the second arrangement surface 25b of the submount 21 is ΔZ1, and the distance between the upper surface of the base 10A, which is the first mounting surface 10a of the base 10A, and the light incidence surface 30i of the planar lightwave circuit element 30A is ΔZ2, then ΔZ2≧ΔZ1. Specifically, it is preferable that 0≦ΔZ2-ΔZ1≦5 μm.

[0189] Next, the effect of the light source module 4 will be described with reference to Fig. 19. Fig. 19 is a diagram for explaining the effect of the light source module 4 according to the fourth embodiment. Note that the black arrows in Fig. 19 typically indicate the dissipation paths of heat generated in the semiconductor laser 22.

[0190] 19, the light source module 4 is placed, for example, in a housing 100. The light source module 4 operates in the same manner as the light source module 3 of the third embodiment.

[0191] Specifically, when the semiconductor laser 22 of the light source 20 is driven, a laser light is emitted from the semiconductor laser 22. The laser light emitted from the semiconductor laser 22 enters the optical waveguide 31 from the light incident surface 30i of the planar lightwave circuit element 30A, is guided through the optical waveguide 31, and is emitted to the outside from the light exit surface 30e of the planar lightwave circuit element 30A. Specifically, the laser light emitted from the semiconductor laser 22 enters the upper surface of the planar lightwave circuit element 30A and enters the core 31a of the optical waveguide 31. The laser light that has entered the core 31a of the optical waveguide 31 propagates through the core 31a while repeatedly being totally reflected at the interface between the core 31a and the cladding 31b.

[0192] When the semiconductor laser 22 is driven in this manner, heat is generated from the semiconductor laser 22. At this time, in the light source module 4, similarly to the light source module 3 of the above-mentioned third embodiment, the light source 20 having the semiconductor laser 22 mounted on the third mounting surface 21a of the submount 21 is mounted on the first mounting surface 10a of the base 10A at a fourth mounting surface 21b that is orthogonal to the third mounting surface 21a among the surfaces constituting the submount 21, and the planar lightwave circuit element 30A is mounted on the second mounting surface 10b of the base 10A.

[0193] 19, the heat generated by the semiconductor laser 22 is conducted to the submount 21, then to the base 10A via the first mounting surface 10a of the base 10A, and then to the housing 100. This allows the heat generated by the semiconductor laser 22 when the semiconductor laser 22 is driven to be efficiently dissipated. This makes it possible to suppress the temperature rise of the semiconductor laser 22.

[0194] Next, a method for manufacturing light source module 4 according to embodiment 4 will be described with reference to Fig. 20A to Fig. 20H. Fig. 20A to Fig. 20H are diagrams for explaining the method for manufacturing light source module 4 according to embodiment 4.

[0195] First, a planar lightwave circuit element 30A is fabricated as shown in Figures 20A to 20C. Specifically, the planar lightwave circuit element 30A is fabricated in the same manner as in Figures 15A to 15C in the manufacturing method of the light source module 3 according to the third embodiment.

[0196] Next, as shown in FIG. 20D, a planar lightwave circuit element 30A having an optical waveguide 31 is mounted on the second mounting surface 10b of the base 10A.

[0197] Specifically, a pressing member 401 having a first step surface 401a and a second step surface 401b, which are two step surfaces with different heights, is disposed above the planar lightwave circuit element 30A and the base 10A, and the planar lightwave circuit element 30A and the base 10A are joined while the first surface 30u, which is the upper surface of the planar lightwave circuit element 30A, and the first mounting surface 10a, which is the upper surface of the base 10A, are pressed against the first step surface 401a and the second step surface 401b of the pressing member 401, respectively. Specifically, the base 10A on which the bonding layer 42 has been formed and the planar lightwave circuit element 30A are pressed together from above by the pressing member 401 having the first step surface 401a and the second step surface 401b, thereby melting the bonding layer 42, thereby joining the planar lightwave circuit element 30A and the base 10A. In this way, by joining the planar lightwave circuit element 30A and the base 10A while pressing the upper surface of the planar lightwave circuit element 30A against the upper surface of the base 10A using a pressing member 401 having a first step surface 401a and a second step surface 401b whose height is higher than the second step surface 401b, the planar lightwave circuit element 30A and the base 10A can be easily and precisely joined so that the upper surface of the planar lightwave circuit element 30A is located lower than the upper surface of the base 10A. Here, the member is placed above to align the directions of the figures of the light source module, but the pressing member may be placed below.

[0198] Next, as shown in Fig. 20E, the light source 20 is fixed to the base 10A. The light source 20 is fabricated by the same method as in Fig. 20E in the method for manufacturing the light source module 3 according to the third embodiment.

[0199] Next, as shown in Fig. 20F and Fig. 20G, the light source 20 is mounted on the first mounting surface 10a of the base 10A. Specifically, Fig. 20F and Fig. 20G can be performed in the same manner as Fig. 15F and Fig. 15G in the manufacturing method of the light source module 3 of the third embodiment.

[0200] That is, after performing the step of Fig. 20F (active alignment step) as in Fig. 15F, the step of Fig. 20G (heating laser light irradiation step) is performed as in Fig. 15G. Specifically, the laser light emitted from the semiconductor laser 22 is made incident on the optical waveguide 31 of the planar lightwave circuit element 30A, and the position of the light source 20 is adjusted in a direction in a plane parallel to the first mounting surface 10a of the base 10A so that the amount of laser light from the semiconductor laser 22 is maximized, and then the light source 20 is fixed to the base 10A via the bonding layer 43 arranged between the fourth mounting surface 21b of the submount 21 and the first mounting surface 10a of the base 10A.

[0201] In this embodiment, the step of Fig. 20F and the step of Fig. 20G may be performed simultaneously, or the step of Fig. 20G may be performed before the step of Fig. 20F. In other words, the step of Fig. 20F may be performed after the step of Fig. 20G.

[0202] 20H, the holding member 60 is inserted between the planar lightwave circuit element 30A and the base 10A. For example, the holding member 60 can be inserted between the planar lightwave circuit element 30A and the base 10A by applying and curing a liquid holding member 60. In this way, the light source module 4 is completed.

[0203] The light source module 4 according to the present embodiment configured in this manner provides the same effects as the light source modules 1 and 3 in the first and third embodiments described above.

[0204] For example, in the light source module 4 according to the present embodiment, similarly to the light source modules 1 and 3 in the above-mentioned embodiments 1 and 3, the light source 20 having the semiconductor laser 22 mounted on the third mounting surface 21a of the submount 21 is mounted on the first mounting surface 10a of the base 10A at a fourth mounting surface 21b that is orthogonal to the third mounting surface 21a among the surfaces constituting the submount 21, and the planar lightwave circuit element 30A is mounted on the second mounting surface 10b of the base 10A. The light incident surface 30i of the planar lightwave circuit element 30A is parallel to the first mounting surface 10a of the base 10A.

[0205] This allows efficient dissipation of heat generated by the semiconductor laser 22 when the semiconductor laser 22 is driven, thereby making it possible to obtain a highly reliable light source module 4. Furthermore, due to the configuration of the light source module 4, the position of the light source 20 can be adjusted by active alignment when manufacturing the light source module 4. Therefore, a more reliable light source module 4 can be obtained.

[0206] In addition, the light source module 4 according to the present embodiment has the same effects as the light source modules 1 and 3 in the first and third embodiments described above.

[0207] In the light source module 4 according to this embodiment, the semiconductor laser 22 is mounted on the third mounting surface 21a of the submount 21 by junction-down mounting. If the distance between the front end face 22f, which is the light emission surface of the semiconductor laser 22, and the second arrangement surface 25b, which is the front surface of the submount 21, is ΔZ1, and the distance between the first mounting surface 10a of the base 10A and the light incidence surface 30i (first surface 30u) of the planar lightwave circuit element 30A is ΔZ2, then ΔZ2≧ΔZ1. Specifically, it is preferable that 0≦ΔZ2-ΔZ1≦5 μm.

[0208] With this configuration, during active alignment in manufacturing the light source module 4, the semiconductor laser 22 does not come into contact with the light incident surface 30i of the planar lightwave circuit element 30A, and the coupling efficiency between the laser light emitted from the semiconductor laser 22 and the optical waveguide 31 of the planar lightwave circuit element 30A can be maintained high.

[0209] (Variation 1 of the fourth embodiment) Next, a first modification of the fourth embodiment will be described with reference to Fig. 21. Fig. 21 is a diagram showing a configuration of a light source module 4A according to the first modification of the fourth embodiment.

[0210] A light source module 4A according to this modification is different from the light source module 4 according to the fourth embodiment in the configuration of a base 10A.

[0211] Specifically, in the light source module 4 according to the above-mentioned fourth embodiment, the first base body portion 11a and the second base body portion 11b in the base body 11A of the base 10A are integrated, but in the light source module 4A according to this modification, the first base body portion 11a and the second base body portion 11b are separate bodies, and the base body 11A is divided into two. The first base body portion 11a and the second base body portion 11b, which are separate bodies, are joined together.

[0212] 21, the base body 11A is divided into the first base body portion 11a and the second base body portion 11b on the left and right, but is not limited thereto. For example, like the light source module 4B shown in FIG. 22, the base body 11A may be divided into the first base body portion 11a and the second base body portion 11b on the top and bottom.

[0213] (Modification 2 of the fourth embodiment) Next, a second modification of the fourth embodiment will be described with reference to Fig. 23 and Fig. 24. Fig. 23 is a perspective view showing a light source module 4C according to the second modification of the fourth embodiment, and Fig. 24 is a view showing a part of the light source module 4C. In Fig. 24, (a) is a top view of the light source module 4C, and (b) is a cross-sectional view of the light source module 4C.

[0214] As shown in Figs. 23 and 24, a light source module 4C according to this modification includes a base 10A, a plurality of light sources 20, and a planar lightwave circuit element 30A. In this modification, the plurality of light sources 20 include a blue light source 20B, a green light source 20G, and a red light source 20R. The blue light source 20B, the green light source 20G, and the red light source 20R in this modification are similar to the blue light source 20B, the green light source 20G, and the red light source 20R shown in Fig. 4. Specifically, the blue light source 20B (first light source) has an AlInGaN-based first semiconductor laser 22B and a first submount 21B as the semiconductor laser 22 and the submount 21. The green light source 20G (second light source) has an AlInGaN-based second semiconductor laser 22G and a second submount 21G as the semiconductor laser 22 and the submount 21. The red light source 20R (third light source) has an AlInGaP-based third semiconductor laser 22R and a third submount 21R as the semiconductor laser 22 and the submount 21. However, in this modification, the first semiconductor laser 22B, the second semiconductor laser 22G, and the third semiconductor laser 22R are mounted on the first submount 21B, the second submount 21G, and the third submount 21R by junction-down mounting.

[0215] In this modification, the optical waveguide 31 of the planar lightwave circuit element 30A is a lightwave circuit that couples light from a plurality of light sources 20 (blue light source 20B, green light source 20G, red light source 20R). Specifically, the optical waveguide 31 has, as a plurality of cores 31a corresponding to the plurality of light sources 20, a first core 31aB into which the laser light emitted from the first semiconductor laser 22B of the blue light source 20B is incident and guided, a second core 31aG into which the laser light emitted from the second semiconductor laser 22G of the green light source 20G is incident and guided, and a third core 31aR into which the laser light emitted from the third semiconductor laser 22R of the red light source 20R is incident and guided. In FIG. 23, the first core 31aB, the second core 31aG, and the third core 31aR are shown as being exposed, but in reality, the first core 31aB, the second core 31aG, and the third core 31aR are covered with cladding.

[0216] In this modification, the first core 31aB, the second core 31aG, and the third core 31aR extend in a predetermined shape from the optical waveguide 31 below the first semiconductor laser 22B, the second semiconductor laser 22G, and the third semiconductor laser 22R toward the light emitting surface 30e of the planar lightwave circuit element 30A, and are combined within the planar lightwave circuit element 30A (within the optical waveguide 31) to form one core at the light emitting surface 30e. Specifically, the second core 31aG is located between the first core 31aB and the third core 31aR, and extends linearly from the inclined surface 32a near the third surface 30c toward the fourth surface 30d. On the other hand, the first core 31aB extends linearly from the inclined surface 32a near the third surface 30c, then bends smoothly toward the second core 31aG, and then extends linearly to be combined with the second core 31aG. The third core 31aR extends linearly from the inclined surface 32a near the third surface 30c, then smoothly curves toward the second core 31aG, and then extends linearly to couple with the second core 31aG. After the third core 31aR and the second core 31aG are coupled, the third core 31aR is further coupled with the first core 31aB. As a result, monochromatic light of blue, green, and red laser light or a laser light that is a mixture of at least two of these laser lights is emitted from the light emission surface 30e of the planar lightwave circuit element 30A.

[0217] In each of the first core 31aB, the second core 31aG and the third core 31aR, an optical waveguide reflecting surface (inclined surface 32a) that is inclined with respect to the upper surface of the planar lightwave circuit element 30A is formed at the end of the optical waveguide on the light incident side.

[0218] The light source module 4C thus configured can be used as a light source for a full-color display.

[0219] In the light source module 4C of this modification, the outer shape of the base 10A is larger than that of the planar lightwave circuit element 30A. Furthermore, in this modification, a part of the base body 11A of the base 10A extends to below the multiple light sources 20. Specifically, the base body 11A extends to the rear of the first submount 21B, the second submount 21G, and the third submount 21R. A driving component 70 is mounted on the portion of the base 10A that extends rearward.

[0220] In this modification, the base 10A extends to the front of the planar lightwave circuit element 30A. A condensing lens 50 is mounted on the forward extending portion of the base 10A. As a result, the laser light emitted from the light emitting surface 30e of the planar lightwave circuit element 30A is condensed by the condensing lens 50 and emitted from the light source module 4C.

[0221] In this way, by extending the base 10A forward or backward, functional parts such as the driving parts 70 or the condenser lens 50 can be integrated on the base 10A in this extended portion.

[0222] (Third Modification of Fourth Embodiment) Next, Modification 3 of Embodiment 4 will be described with reference to Fig. 25. Fig. 25 is a diagram showing a configuration of a light source module 4D according to Modification 3 of Embodiment 4. In Fig. 25, (a) is a top view of the light source module 4D, (b) is a side view of the light source module 4D, and (c) is a cross-sectional view of the light source module 4D taken along line cc in (a).

[0223] 25, light source module 4D according to this modification includes blue light source 20B, green light source 20G, and red light source 20R as the multiple light sources 20, similar to light source module 4C according to modification 2 of embodiment 4. However, the positional relationship between blue light source 20B, green light source 20G, and red light source 20R is different from that of light source module 4C according to modification 2 of embodiment 4. Specifically, in light source module 4D according to this modification, blue light source 20B, green light source 20G, and red light source 20R are arranged so that their polarization directions coincide in single mode wavelength multiplexing.

[0224] Here, the first and second semiconductor lasers 22B and 22G made of AlGaInN-based semiconductor materials oscillate in the TE mode. That is, the laser light emitted from each of the first and second semiconductor lasers 22B and 22G is polarized in a direction parallel to the chip plane (active layer plane) of the first and second semiconductor lasers 22B and 22G.

[0225] The third semiconductor laser 22R made of an AlGaInP-based semiconductor material oscillates in the TM mode. That is, the laser light emitted from the third semiconductor laser 22R is polarized in a direction perpendicular to the chip plane (active layer plane) of the third semiconductor laser 22R.

[0226] Therefore, in this modification, the third mounting surface 21aG of the second submount 21G of the green light source 20G and the third mounting surface 21aB of the first submount 21B of the blue light source 20B are arranged in a direction perpendicular to the upper surface of the planar lightwave circuit element 30A. Therefore, the third mounting surface 21aG of the second submount 21G of the green light source 20G and the third mounting surface 21aB of the first submount 21B of the blue light source 20B are parallel. In addition, the third mounting surface 21aG of the second submount 21G of the green light source 20G and the third mounting surface 21aB of the first submount 21B of the blue light source 20B are arranged to be parallel to the optical waveguide 31 of the planar lightwave circuit element 30A near the incident surface. As a result, the laser light emitted from each of the first semiconductor laser 22B mounted on the first submount 21B and the second semiconductor laser 22G mounted on the second submount 21G is polarized in a direction perpendicular to the top surface of the planar lightwave circuit element 30A.

[0227] Also, the third mounting surface 21aR of the third submount 21R of the red light source 20R is perpendicular to the upper surface of the planar lightwave circuit element 30. Therefore, the third mounting surface 21aR of the third submount 21R of the red light source 20R and the third mounting surface 21aB of the first submount 21B of the blue light source 20B are perpendicular to each other. Also, the third mounting surface 21aR of the third submount 21R of the red light source 20R is perpendicular to the optical waveguide 31 of the planar lightwave circuit element 30A near the incident surface. As a result, the laser light emitted from the third semiconductor laser 22R is also polarized in a direction perpendicular to the upper surface of the planar lightwave circuit element 30A.

[0228] With this configuration, in single mode wavelength multiplexing, the polarization directions of the first semiconductor laser 22B, the second semiconductor laser 22G, and the third semiconductor laser 22R can be made consistent. That is, the polarization directions of the blue laser light, the green laser light, and the red laser light incident on the planar lightwave circuit element 30A can be made consistent. In addition, the core spacing between the first core 31aB, the second core 31aG, and the third core 31aR can be narrowed, so that the planar lightwave circuit element 30A can be made smaller. Therefore, the light source module 4D can be made smaller.

[0229] In this modification, the second semiconductor laser 22G in the green light source 20G is located between the first semiconductor laser 22B in the blue light source 20B and the second submount 21G in the green light source 20G. That is, the first semiconductor laser 22B and the second semiconductor laser 22G are arranged so that the first semiconductor laser 22B and the second semiconductor laser 22G face each other.

[0230] With this configuration, the distance between the first semiconductor laser 22B and the second semiconductor laser 22G can be narrowed, and therefore the light source module 4D can be further reduced in size.

[0231] Furthermore, by having the first semiconductor laser 22B and the second semiconductor laser 22G face each other, the distance between the first core 31aB through which the blue laser light is guided and the third core 31aR through which the red laser light is guided can be narrowed. This allows the length of the curved portion of the first core 31aB to be shortened. Furthermore, the narrow distance between the first core 31aB and the third core 31aR and the short length of the curved portion of the first core 31aB allow the planar lightwave circuit element 30A to be further miniaturized.

[0232] In addition, in each of the first core 31aB, the second core 31aG, and the third core 31aR of the planar lightwave circuit element 30A, an optical waveguide reflecting surface (inclined surface 32a) that is inclined with respect to the upper surface of the planar lightwave circuit element 30A is formed at the end of the optical waveguide on the light incident side.

[0233] (Fourth Modification of Fourth Embodiment) Next, a fourth modification of the fourth embodiment will be described with reference to Fig. 26. Fig. 26 is a diagram showing a configuration of a light source module 4E according to the fourth modification of the fourth embodiment. In Fig. 26, (a) is a top view of the light source module 4E, (b) is a longitudinal cross-sectional view of the light source module 4E, (c) is a lateral cross-sectional view of the light source module 4E, and (d) is a plan view of a planar lightwave circuit element 30A in the light source module 4E.

[0234] Light source module 4E according to this modification is different from light source module 4D according to modification 3 of embodiment 4 above in the position where red light source 20R is arranged.

[0235] In this modified example, the first mounting surface 10a of the base 10A has, in a planar view of the planar lightwave circuit element 30A, a first sub-mounting surface located outside one side of the planar lightwave circuit element 30A and a second sub-mounting surface located outside another side that is not parallel to the first side, and the blue light source 20B and the green light source 20G are both arranged on one of the first sub-mounting surface and the second sub-mounting surface, and the red light source 20R is arranged on the other of the first sub-mounting surface and the second sub-mounting surface.

[0236] 26, blue light source 20B and green light source 20G are arranged on first mounting surface 10a1 (first sub-mounting surface) located at the rear of base 10A, and red light source 20R is arranged on first mounting surface 10a2 (second sub-mounting surface) located at the side of base 10A, similarly to light source module 4D according to Modification 3 of Embodiment 4. That is, in this modification, multiple light sources 20 are arranged at the rear and side positions of first mounting surface 10a of base 10A. Also, the distance between red light source 20R and light exit surface 30e is shorter than the distance between blue light source 20B and green light source 20G and light exit surface 30e.

[0237] In this way, by arranging the light sources 20 on both the rear and side of the base 10A, the width Y of the light source module 4E can be narrowed. That is, a light source module 4E that is even smaller than the light source module 4D according to the third modification of the fourth embodiment can be realized. Note that, apart from the arrangement of the red light source 20R, the light source module 4E is similar to the light source module 4D according to the third modification of the fourth embodiment.

[0238] In addition, in each of the first core 31aB, the second core 31aG, and the third core 31aR of the planar lightwave circuit element 30A, an optical waveguide reflecting surface (inclined surface 32a) that is inclined with respect to the upper surface of the planar lightwave circuit element 30A is formed at the end of the optical waveguide on the light incident side.

[0239] Here, a method for fabricating the planar lightwave circuit element 30A in the light source module 4E according to this modification will be described with reference to Figs. 27A to 27H. Figs. 27A to 27H are diagrams for explaining a method for fabricating the planar lightwave circuit element 30A in the light source module 4E according to modification 4 of embodiment 4. In Figs. 27A to 27H, the upper figures are top views, the lower figures are cross-sectional views taken along line cc in the upper figures, and the right figures are cross-sectional views taken along line aa in the upper figures.

[0240] First, as shown in Fig. 27A, a substrate 32A is prepared. For example, a silicon substrate having a surface whose crystal orientation is tilted at 9.7° with respect to the (100) plane is prepared as the substrate 32A. Here, the surface whose crystal orientation is tilted at 9.7° with respect to the (100) plane is a crystal plane whose normal is a direction tilted at 9.7° from the

[0100] direction.

[0241] 27B, an etching protection film 500 is formed at a predetermined position (L-shaped) on the surface of the substrate 32A. As the etching protection film 500, for example, an insulating film made of silicon dioxide (SiO2) can be used.

[0242] Next, the substrate 32A is etched using the etching protection film 500 as a mask. Specifically, wet etching is performed on the substrate 32A using an etching solution. For example, anisotropic wet etching is performed using an etching solution made of an alkaline aqueous solution such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH) aqueous solution.

[0243] In this way, by etching the substrate 32A, as shown in FIG. 27C, a recess 32b is formed in the substrate 32A, and two inclined surfaces 32a (inclined surface 32aBG and inclined surface 32aR) are formed in a part of the substrate 32A. The inclined surface 32a is a crystal surface and is therefore flat. For convenience, the inclined surface 32a is shown by dotted hatching in the upper diagram of FIG. 27C. Also, the distance between the inclined surface 32aR and the surface that will become the light exit surface 30e is shorter than the distance between the inclined surface 32aBG and the surface that will become the light exit surface 30e.

[0244] The inclined surface 32a and the recess 32b are etched portions of the substrate 32A. The surface orientation of the inclined surface 32a is the silicon (111) surface, and the inclination angle of the inclined surface 32a is 45°. The inclined surface 32a extends in the [01-1] direction. The surface orientation of the recess 32b after etching is a surface inclined at 9.7° from the (100) surface, which is the same as the surface orientation of the upper surface of the original silicon substrate. The boundary 32d between the inclined surface 32a and the recess 32b, and the boundary 32e between the portion 32c of the surface inclined at 9.7° from the (100) surface that remains unetched and extends in the [01-1] direction. The boundary 32f between the recess 32b and the portion 32c of the surface inclined at 9.7° from the (100) surface that remains unetched is an inclined surface as shown in the right figure, but in the upper figure, it is shown by a line for simplicity.

[0245] Next, as shown in Fig. 27D, a first cladding layer 31b1 made of silicon dioxide (SiO2) to become cladding 31b is formed on the entire surface of substrate 32A. In Fig. 27D to Fig. 27H, the boundary between two of the three portions, namely, inclined surface 32a, recess 32b, and portion 32c of the surface that remains unetched and is inclined at 9.7° from the (100) surface, is shown by a dashed line.

[0246] 27E, a core layer 31a1 made of silicon nitride (SiN) that will become the core 31a is formed on the entire surface of the first cladding layer 31b1. A metal film 36 is formed between the first cladding layer 31b1 and the core layer 31a1 in a portion of the inclined surface 32a of the substrate 32A that contacts the core 31a to be patterned later.

[0247] 27F, the core layer 31a1 is patterned by etching to form a core 31a having a predetermined shape, whereby the first cladding layer 31b1 is exposed in the portion where the core layer 31a1 has been etched away.

[0248] Specifically, the core 31a is composed of a first core 31aB corresponding to the blue light source 20B, a second core 31aG corresponding to the green light source 20G, and a third core 31aR corresponding to the red light source 20R. The third core 31aR extends linearly from the inclined surface 32aR toward the light emitting surface 30e. The second core 31aG extends linearly from the inclined surface 32aBG toward the light emitting surface 30e, then smoothly curves toward the third core 31aR and is coupled to the third core 31aR. The first core 31aB extends linearly from the inclined surface 32aBG toward the light emitting surface 30e, then smoothly curves toward the third core 31aR and is coupled to the third core 31aR. The light source side end of the third core 31aR is located closer to the light emitting surface 30e than the light source side ends of the first core 31aB and the second core 31aG.

[0249] 27G, a second cladding layer 31b2 made of silicon dioxide (SiO2) that will become the cladding 31b is formed on the entire exposed portion of the first cladding layer 31b1 so as to cover the core 31a. As a result, the first cladding layer 31b1 and the second cladding layer 31b2 form the cladding 31b that surrounds the core 31a.

[0250] Next, the surface of the cladding 31b is polished to flatten it, as shown in Fig. 27H. Specifically, the upper portion of the second cladding layer 31b2 is polished to flatten it. With this manufacturing method, the cladding 31b exists above and below the core 31a in a direction perpendicular to the top surface of the planar lightwave circuit element 30A, and the cladding 31b exists outside the core 31a via the reflecting surface (metal film 36) in the direction toward the top surface of the planar lightwave circuit element 30A.

[0251] This makes it possible to fabricate a planar lightwave circuit element 30A having an optical waveguide 31 on which an inclined surface 32a, which is a flat reflecting surface, is formed on a substrate 32A.

[0252] (Fifth Modification of Fourth Embodiment) Next, a fifth modification of the fourth embodiment will be described with reference to Fig. 28A. Fig. 28A is a diagram showing a configuration of a light source module 4F according to the fifth modification of the fourth embodiment. In Fig. 28A, (a) is a top view of the light source module 4F, (b) is a longitudinal cross-sectional view of the light source module 4F, (c) is a lateral cross-sectional view of the light source module 4F, and (d) is a plan view of a planar lightwave circuit element 30A in the light source module 4F.

[0253] A light source module 4F according to this modification and a light source module 4E according to the fourth modification of the fourth embodiment are different in the layout of the first core 31aB, the second core 31aG, and the third core 31aR.

[0254] As shown in FIG. 28A, in a light source module 4F of this modified example, the second core 31aG located between the first core 31aB and the third core 31aR is composed only of straight portions, and the first core 31aB and the third core 31aR are configured to have curved portions.

[0255] Other than the layout of the first core 31aB, the second core 31aG, and the third core 31aR, the light source module 4F according to this modification has the same configuration as the light source module 4E according to modification 4 of the fourth embodiment.

[0256] Therefore, the light source module 4F according to this modification has the same effects as the light source module 4E according to the fourth modification of the fourth embodiment.

[0257] (Modification 5' of the fourth embodiment) Next, a modified example 5' of the fourth embodiment will be described with reference to Fig. 28B. Fig. 28B is a diagram showing a configuration of a light source module 4F' according to the modified example 5' of the fourth embodiment. In Fig. 28B, (a) is a top view of the light source module 4F', (b) is a longitudinal cross-sectional view of the light source module 4F', (c) is a lateral cross-sectional view of the light source module 4F', and (d) is a plan view of the planar lightwave circuit element 30A in the light source module 4F'.

[0258] A light source module 4F' according to this modification and a light source module 4E according to the fourth modification of the fourth embodiment are different in the layout of the first core 31aB, the second core 31aG, and the third core 31aR.

[0259] As shown in Fig. 28B, in the light source module 4F' according to this modification, the first core 31aB is composed of only straight portions, and the second core 31aG, the first core 31aB, and the third core 31aR are configured to have curved portions. Furthermore, the straight portion of the first core 31aB is disposed on a line extending from the straight portion of the second core 31aG toward the light emitting surface 30e. Also, the third semiconductor laser 22R of the red light source 20R is mounted on a line extending from the mounting position of the second semiconductor laser 22G of the green light source 20G toward the light emitting surface 30e.

[0260] In (d) of FIG. 28B, the boundary 32d between the inclined surface 32a and the recessed portion 32b, the boundary 32e between the inclined surface 32a and the portion 32c of the surface that is inclined at 9.7° from the (100) plane and that remains unetched, and the boundary 32f between the recessed portion 32b and the portion 32c of the surface that is inclined at 9.7° from the (100) plane and that remains unetched are indicated by dotted lines. The inclined surface 32aBG and the inclined surface 32aR are formed between the boundary 32d and the boundary 32e. As shown in (d) of FIG. 28, the inclined surface 32aR is formed on the light exit surface 30e side of the inclined surface 32aBG so as to overlap with the inclined surface 32aBG when viewed from the light exit surface 30e.

[0261] Therefore, in the light source module 4F' according to this modified example, the width Y1 of the planar lightwave circuit element 30A can be narrowed.

[0262] (Variation 6 of the Fourth Embodiment) Next, a sixth modification of the fourth embodiment will be described with reference to Fig. 29. Fig. 29 is a diagram showing a configuration of a light source module 4G according to the sixth modification of the fourth embodiment. In Fig. 29, (a) is a top view of the light source module 4G, and (b) is a plan view of a planar lightwave circuit element 30A in the light source module 4G. The dotted line represents the shape of the base 10A hidden by the light source.

[0263] Similar to light source module 4E according to variant 4 of embodiment 4, light source module 4G according to this variant has a blue light source 20B, a green light source 20G and a red light source 20R as the multiple light sources 20. However, the layout of blue light source 20B, green light source 20G and red light source 20R is different from that of light source module 4E according to variant 4 of embodiment 4.

[0264] In this modified example, similar to the light source module 4E relating to modified example 4 of embodiment 4 above, the first mounting surface 10a of the base 10A has, in a planar view of the planar lightwave circuit element 30A, a first sub-mounting surface located outside one side of the planar lightwave circuit element 30A and a second sub-mounting surface located outside another side that is not parallel to the first side, and the blue light source 20B and the green light source 20G are both arranged on one of the first sub-mounting surface and the second sub-mounting surface, and the red light source 20R is arranged on the other of the first sub-mounting surface and the second sub-mounting surface.

[0265] 29, blue light source 20B and green light source 20G are arranged on first mounting surface 10a (second sub-mounting surface 10a2) located on the side of base 10A, and red light source 20R is arranged on first mounting surface 10a (first sub-mounting surface 10a1) located on the rear of base 10A. Note that blue light source 20B and green light source 20G are arranged at an angle, and the incident positions of laser light differ with respect to the extension direction of linear first core 31aB.

[0266] In this way, by arranging the light sources 20 at both the rear and sides of the base 10A, the width of the light source module 4G can be narrowed. Therefore, a small light source module 4G can be realized. In addition, by arranging the multiple light sources 20 diagonally, such as the blue light source 20B and the green light source 20G, the positions of the multiple light sources 20 can be shifted. This makes it easy to lay out the wiring for supplying power to the semiconductor lasers 22 of each of the multiple light sources 20.

[0267] In this modification, the rear end portion of the planar lightwave circuit element 30A is cut so as to be inclined when viewed from above. This allows the blue light source 20B and the green light source 20G to be arranged diagonally along the side that is cut so as to be inclined. This allows the distance between the first core 31aB, the second core 31aG, and the third core 31aR to be narrowed. This allows the light source module 4G to be further miniaturized.

[0268] In addition, in each of the first core 31aB, the second core 31aG, and the third core 31aR of the planar lightwave circuit element 30A, an optical waveguide reflecting surface (inclined surface 32a) that is inclined with respect to the upper surface of the planar lightwave circuit element 30A is formed at the end of the optical waveguide on the light incident side.

[0269] Here, a method for fabricating the planar lightwave circuit element 30A in the light source module 4G according to this modification will be described with reference to Figs. 30A to 30D. Figs. 30A to 30D are diagrams for explaining a method for fabricating the planar lightwave circuit element 30A in the light source module 4G according to modification 6 of embodiment 4. In Figs. 30A to 30D, the upper figures are top views, the lower figures are cross-sectional views taken along line cc in the upper figures, and the right figures are cross-sectional views taken along line aa in the upper figures.

[0270] First, a substrate 32A is prepared as shown in Fig. 30A. For example, a silicon substrate whose surface crystal orientation is inclined at 9.7° with respect to the (100) plane is prepared as the substrate 32A, similarly to Fig. 27A.

[0271] Next, as shown in FIG. 30B, the substrate 32A is etched to form a recess 32b in the substrate 32A and to form three inclined surfaces 32a (inclined surface 32aB, inclined surface 32aG, inclined surface 32aR) in a part of the substrate 32A. The inclined surface 32aB, inclined surface 32aG, and inclined surface 32aR are formed in this order from the side closer to the position that will become the light emission surface 30e. Specifically, wet etching is performed on the substrate 32A in the same manner as in FIG. 27B and FIG. 27B. In the upper diagram of FIG. 30B, the inclined surface 32a is shown by dot-shaped hatching for convenience.

[0272] The inclined surface 32a and the recessed portion 32b are etched portions of the substrate 32A. The surface orientation of the inclined surface 32a is a silicon (111) surface, and the inclination angle of the inclined surface 32a is 45°. Furthermore, the surface orientation of the recessed portion 32b after etching is the same as the surface orientation of the original upper surface of the silicon substrate.

[0273] Next, although not shown, an optical waveguide 31 is formed on the substrate 32A on which the light-reflective inclined surface 32a is formed, using a method similar to that shown in FIGS. 27D to 27G.

[0274] Next, as shown in FIG. 30C, the rear portion of the substrate 32A is cut obliquely along the dashed line, thereby producing a planar lightwave circuit element 30A with a diagonally cut rear portion as shown in FIG. 30D.

[0275] The first core 31aB extends linearly from the inclined surface 32aB toward the light exit surface 30e. The second core 31aG extends linearly from the inclined surface 32aG toward the light exit surface 30e, then bends smoothly toward the first core 31aB and joins with the first core 31aB. The third core 31aR extends linearly from the inclined surface 32aR toward the light exit surface 30e, then bends smoothly toward the first core 31aB and joins with the first core 31aB. From the side closer to the light exit surface 30e, the light source side end of the first core 31aB, the light source side end of the second core 31aG, and the light source side end of the third core 31aR are located in this order.

[0276] (Seventh Modification of Fourth Embodiment) Next, a seventh modification of the fourth embodiment will be described with reference to Fig. 31. Fig. 31 is a diagram showing a configuration of a light source module 4H according to the seventh modification of the fourth embodiment. In Fig. 31, (a) is a top view of the light source module 4H, and (b) is a plan view of a planar lightwave circuit element 30A in the light source module 4H.

[0277] Similar to light source module 4E according to variant 4 of embodiment 4, light source module 4H according to this variant has a blue light source 20B, a green light source 20G and a red light source 20R as the multiple light sources 20. However, the layout of blue light source 20B, green light source 20G and red light source 20R is different from that of light source module 4E according to variant 4 of embodiment 4.

[0278] In this modified example, similar to the light source module 4E relating to modified example 4 of embodiment 4 above, the first mounting surface 10a of the base 10A has, in a planar view of the planar lightwave circuit element 30A, a first sub-mounting surface located outside one side of the planar lightwave circuit element 30A and a second sub-mounting surface located outside another side that is not parallel to the first side, and the blue light source 20B and the green light source 20G are both arranged on one of the first sub-mounting surface and the second sub-mounting surface, and the red light source 20R is arranged on the other of the first sub-mounting surface and the second sub-mounting surface.

[0279] Specifically, as shown in Fig. 31, a first mounting surface 10a1 (first sub-mounting surface) is disposed at the rear of the base 10A, and two first mounting surfaces 10a2 (second sub-mounting surfaces) are disposed on two sides of the base 10A so as to face each other. The blue light source 20B and the green light source 20G are disposed on the first mounting surface 10a2 (second sub-mounting surface) located on the side of the base 10A, and the red light source 20R is disposed on the first mounting surface 10a1 (first sub-mounting surface) located at the rear of the base 10A. The blue light source 20B and the green light source 20G located on the side of the base 10A are disposed at positions facing each other with the third core 31aR in between.

[0280] In this way, by disposing three light sources 20 on each of the rear and two sides of the base 10A, the width of the light source module 4H can be narrowed. Therefore, a compact light source module 4H can be realized. In each of the first core 31aB, the second core 31aG, and the third core 31aR of the planar lightwave circuit element 30A, an optical waveguide reflection surface (inclined surface 32a) that is inclined with respect to the upper surface of the planar lightwave circuit element 30A is formed at the end of the optical waveguide on the light incident side. In addition, the inclined surface 32aB, the inclined surface 32aG, and the inclined surface 32aR are formed in this order from the side closer to the light exit surface 30e.

[0281] The first core 31aB extends linearly from the inclined surface 32aB toward the light exit surface 30e. The second core 31aG extends linearly from the inclined surface 32aG toward the light exit surface 30e, then bends smoothly toward the first core 31aB and joins with the first core 31aB. The third core 31aR extends linearly from the inclined surface 32aR toward the light exit surface 30e, then bends smoothly toward the first core 31aB and joins with the first core 31aB. From the side closer to the light exit surface 30e, the light source side end of the first core 31aB, the light source side end of the second core 31aG, and the light source side end of the third core 31aR are located in this order.

[0282] Furthermore, in this modification, the blue light, green light, and red light are all polarized in a direction perpendicular to the top surface of the planar lightwave circuit element 30A.

[0283] (Eighth Modification of Fourth Embodiment) Next, an eighth modification of the fourth embodiment will be described with reference to Fig. 32. Fig. 32 is a diagram showing a configuration of a light source module 4I according to the eighth modification of the fourth embodiment.

[0284] Similar to light source module 4E according to variant 4 of embodiment 4, light source module 4I according to this variant has a blue light source 20B, a green light source 20G, and a red light source 20R as the multiple light sources 20. However, the layout of blue light source 20B, green light source 20G, and red light source 20R is different from that of light source module 4E according to variant 4 of embodiment 4.

[0285] In this modified example, similar to the light source module 4E relating to modified example 4 of embodiment 4 above, the first mounting surface 10a of the base 10A has, in a planar view of the planar lightwave circuit element 30A, a first sub-mounting surface located outside one side of the planar lightwave circuit element 30A and a second sub-mounting surface located outside another side that is not parallel to the first side, and the blue light source 20B and the green light source 20G are both arranged on one of the first sub-mounting surface and the second sub-mounting surface, and the red light source 20R is arranged on the other of the first sub-mounting surface and the second sub-mounting surface.

[0286] 32, blue light source 20B and green light source 20G are arranged on first mounting surface 10a2 (second sub-mounting surface) located on the side of base 10A, and red light source 20R is arranged on first mounting surface 10a1 (first sub-mounting surface) located on the rear of base 10A. Note that blue light source 20B and green light source 20G located on the side of base 10A are arranged at positions facing each other with third core 31aR in between.

[0287] In this way, by arranging the light sources 20 on both the rear and side of the base 10A, the width of the light source module 4I can be narrowed, and therefore a compact light source module 4I can be realized.

[0288] In this modification, blue light source 20B, green light source 20G, and red light source 20R are arranged so that the entire light is polarized in the TE mode.

[0289] (Embodiment 5) Next, a light source module 5 according to embodiment 5 will be described with reference to Fig. 33. Fig. 33 is a diagram showing a configuration of the light source module 5 according to embodiment 5. In Fig. 33, (a) is a top view of the light source module 5, (b) is a cross-sectional view of the light source module 5, and (c) is a top view of a planar lightwave circuit element 30A in the light source module 5.

[0290] 33, similar to light source modules 3 and 4 according to the above-described embodiments 3 and 4, light source module 5 according to the present embodiment includes base 10A, a plurality of light sources 20, and planar lightwave circuit element 30A having substrate 32A on which inclined surface 32a is formed. Light source module 5 includes, as the plurality of light sources 20, blue light source 20B, green light source 20G, and red light source 20R.

[0291] The light source module 5 in this embodiment is different from the light source modules 3 and 4 according to the above-mentioned embodiments 3 and 4 in that the semiconductor lasers 22 in each of the multiple light sources 20 are mounted in a different manner, and the multiple semiconductor lasers 22 include a lateral incidence type semiconductor laser 22 in which laser light is incident from the side surface of the planar lightwave circuit element 30A, and a vertical incidence type semiconductor laser 22 in which laser light is incident from the top surface of the planar lightwave circuit element 30A. In other words, the light source module 5 in this embodiment has both a lateral incidence type semiconductor laser 22 and a vertical incidence type semiconductor laser 22 mounted thereon.

[0292] Specifically, the first semiconductor laser 22B in the blue light source 20B is of a vertical incidence type and is mounted on the first submount 21B so that the laser light is incident on the top surface of the planar lightwave circuit element 30A. Similarly, the second semiconductor laser 22G in the green light source 20G is of a vertical incidence type and is mounted on the second submount 21G so that the laser light is incident on the top surface of the planar lightwave circuit element 30A.

[0293] On the other hand, the third semiconductor laser 22R in the red light source 20R is of a lateral incidence type, and is mounted on a third submount 21R so that laser light is incident from the side surface of the planar lightwave circuit element 30A.

[0294] In light source module 5 of the present embodiment, light sources 20 are arranged on both the rear and side of base 10A. Specifically, blue light source 20B and green light source 20G are arranged on first mounting surface 10a (first sub-mounting surface) located on the side of base 10A, and red light source 20R is arranged on first mounting surface 10a2 (second sub-mounting surface) located on the rear of base 10A.

[0295] The light source module 5 according to the present embodiment configured in this manner achieves the same effects as the light source modules 1 to 4 in the first to fourth embodiments described above.

[0296] (Other variations) Although the light source module according to the present disclosure has been described based on the first to fifth embodiments, the present disclosure is not limited to the first to fifth embodiments.

[0297] For example, this disclosure also includes forms obtained by applying various modifications that a person skilled in the art would conceive of to each embodiment and variant, and forms realized by arbitrarily combining the components and functions of each embodiment and variant within the scope that does not deviate from the spirit of this disclosure. [Industrial Applicability]

[0298] A light source module according to the present disclosure is useful as a light source for use in, for example, an image display device such as a display or a projector. [Explanation of symbols]

[0299] 1, 1A, 2, 2A, 2B, 2C, 2D, 3, 3A, 4, 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H, 4I, 5 Light source module 10, 10A, 10C base 10a, 10a1, 10a2 First mounting surface 10b Second mounting surface 10h Heat dissipation surface 11, 11A, 11C Base body 11a First base body part 11a1 Top surface 11a2 side 11b Second base body part 11b1 Top surface 11C1 Extension part 12 Metal Film 13 Lens fixing part 20 light source 20B blue light source 20G green light source 20R red light source 21 Submount 21a, 21aB, 21aG, 21aR 3rd mounting surface 21b 4th mounting surface 21f Side end surface 21B 1st submount 21G Second submount 21R 3rd submount 22 Semiconductor laser 22a waveguide 22f Front end surface 22B First semiconductor laser 22G Second semiconductor laser 22R 3rd Semiconductor Laser 25 Submount body 25a 1st placement surface 25b 2nd placement surface 25F 1st submount body 25G Second submount body 26 First metal film 26a First metal film 26b Second first metal film 26c Third first metal film 26d 4th 1st metal film 27 Second metal film 30, 30A Planar lightwave circuit elements 30u 1st page 30b 2nd side 30c 3rd page 30d 4th page 30i light incidence surface 30e Light exit surface 31 Optical waveguide 31a Core 31a1 Core layer 31aB 1st Core 31aG 2nd core 31aR 3rd Core 31b Clad 31b1 First cladding layer 31b2 Second cladding layer 32, 32A board 32a, 32aBG, 32aR, 32aB, 32aG Slope 32b Recess 33 First anti-reflection coating 34 Second anti-reflection coating 35, 36 Metal film 41, 42, 43 Bonding layer 50 Condenser Lens 60 Retaining member 70 Drive parts 100 Case 200 Power Meter 300 Heating laser light source 400, 401 Pressing member 400a, 401a First step surface 400b, 401b 2nd step surface 500 Etching protection film

Claims

1. A base having a first mounting surface and a second mounting surface, A light source having a submount and a semiconductor laser mounted on the third mounting surface of the submount, The second mounting surface is mounted and comprises a planar optical wave circuit element having an optical waveguide for guiding laser light emitted from the optical emission surface of the semiconductor laser and an optical incidence surface into which the laser light enters the optical waveguide, The light source is mounted on the first mounting surface on a fourth mounting surface that is not parallel to the third mounting surface among the surfaces constituting the submount. The light incident surface is parallel to the first mounting surface. Light source module.

2. The semiconductor laser is mounted on the third mounting surface such that the light-emitting layer is on the opposite side from the third mounting surface. The light-emitting surface does not protrude from the front surface of the submount. The first mounting surface and the light incident surface are flush. The light source module according to claim 1.

3. The semiconductor laser is mounted on the third mounting surface such that the light-emitting layer faces the third mounting surface. The light-emitting surface protrudes from the front surface of the submount. Let ΔZ1 be the distance between the light-emitting surface and the front surface, and ΔZ2 be the distance between the first mounting surface and the light-incident surface. Then 0 ≤ ΔZ2 - ΔZ1 ≤ 5 μm. The light source module according to claim 1.

4. The optical waveguide has an optical waveguide end face which is the side surface of the plane light wave circuit element. The light incident surface is the end face of the optical waveguide, The first mounting surface and the light incident surface are parallel. A light source module according to any one of claims 1 to 3.

5. The optical waveguide has an optical waveguide reflecting surface that is inclined with respect to the upper surface of the plane optical circuit element. The semiconductor laser is arranged such that the laser light is incident from the upper surface, which is the light incident surface, toward the optical waveguide reflection surface. The first mounting surface and the upper surface are parallel. A light source module according to any one of claims 1 to 3.

6. The optical waveguide has a core and a cladding with a refractive index lower than that of the core. The cladding is present on the upper and lower sides of the core in a direction perpendicular to the upper surface, and is present on the outside of the core via the optical waveguide reflecting surface in the direction of the upper surface. The light source module according to claim 5.

7. The direction of light emission of the laser beam is perpendicular to the light incident surface. A light source module according to any one of claims 1 to 3.

8. The thermal conductivity of the base is higher than that of the plane light wave circuit element. A light source module according to any one of claims 1 to 3.

9. The base is made of at least one material selected from Al, Cu, Au, Ag, AlN, and SiC. A light source module according to any one of claims 1 to 3.

10. The thermal conductivity of the base is 170 W / m·K or higher. A light source module according to any one of claims 1 to 3.

11. The submount comprises a first member made of at least one selected from Al, Cu, Au, and Ag, and a second member made of at least one selected from AlN and SiC. The first member and the base are joined together. The second member and the semiconductor laser are joined together. The light source module according to claim 10.

12. The aforementioned planar light wave circuit element has the optical waveguide laminated on a substrate, The optical waveguide is positioned closer to the base than the substrate. A light source module according to any one of claims 1 to 3.

13. The optical waveguide is an optical wave circuit that combines light emitted from a plurality of light sources. The aforementioned multiple light sources are The semiconductor laser and the blue light source having an AlInGaN-based first semiconductor laser and a first submount as the submount, A green light source having the semiconductor laser and a second semiconductor laser and a second submount based on AlInGaN as the submount, The system includes the aforementioned semiconductor laser and a red light source having an AlInGaP-based third semiconductor laser and a third submount as the submount, A light source module according to any one of claims 1 to 3.

14. The first mounting surface has a first sub-mounting surface to which the first submount is joined, a second sub-mounting surface to which the second submount is joined, and a third sub-mounting surface to which the third submount is joined. The first sub-mounting surface and the second sub-mounting surface are parallel, The first sub-mounting surface and the third sub-mounting surface are perpendicular to each other. The light source module according to claim 13.

15. The second semiconductor laser is located between the first semiconductor laser and the second submount. The light source module according to claim 14.

16. The aforementioned light source is multiple, Multiple of the aforementioned light sources are The semiconductor laser and the blue light source having an AlInGaN-based first semiconductor laser and a first submount as the submount, A green light source having the semiconductor laser and a second semiconductor laser and a second submount based on AlInGaN as the submount, The system includes the semiconductor laser and a red light source having an AlInGaP-based third semiconductor laser and a third submount as the submount, The first mounting surface is a first sub-mounting surface located outside one side of the plane light wave circuit element in a plan view of the plane light wave circuit element, and a second sub-mounting surface located outside the other side that is not parallel to the aforementioned side. It has a mounting surface, Both the blue light source and the green light source are arranged on one of the first sub-mounting surface and the second sub-mounting surface. The red light source is arranged on the other side of the first sub-mounting surface and the second sub-mounting surface. A light source module according to any one of claims 1 to 3.

17. The process involves mounting a semiconductor laser on the third mounting surface of a submount to create a light source, A process of mounting a planar optical wave circuit element having an optical waveguide on the second mounting surface of a base, A method for manufacturing a light source module, comprising the step of mounting the light source on the first mounting surface of the base, The laser light emitted from the semiconductor laser is incident on the optical waveguide of the planar optical wave circuit element from the optical incident surface, and the position of the light source is adjusted in a direction parallel to the first mounting surface so that the amount of laser light is maximized. Then, the light source is fixed to the base via a first bonding layer positioned between the surface not parallel to the third mounting surface and the first mounting surface. A method for manufacturing a light source module.

18. The semiconductor laser is mounted on the third mounting surface by mounting such that the light-emitting layer faces the third mounting surface. The light-emitting surface of the semiconductor laser protrudes from the front surface of the submount. Let ΔZ1 be the distance between the light-emitting surface and the front surface, and ΔZ2 be the distance between the first mounting surface and the light-incident surface of the planar optical circuit element. Then 0 ≤ ΔZ2 - ΔZ1 ≤ 5 μm. A method for manufacturing a light source module according to claim 17.

19. The semiconductor laser is mounted on the third mounting surface by mounting such that the light-emitting layer is on the opposite side of the third mounting surface. The light-emitting surface of the semiconductor laser does not protrude from the front surface of the submount. The first mounting surface and the light incident surface are flush. A method for manufacturing a light source module according to claim 17.

20. The optical waveguide has an optical waveguide end face which is the side surface of the plane light wave circuit element. The light incident surface is the end face of the optical waveguide, The first mounting surface and the light incident surface are parallel. A method for manufacturing a light source module according to any one of claims 17 to 19.

21. The optical waveguide has an optical waveguide reflecting surface that is inclined with respect to the upper surface of the plane optical circuit element. The semiconductor laser is arranged such that the laser light is incident from the upper surface, which is the light incident surface, toward the optical waveguide reflection surface. The first mounting surface and the upper surface are parallel. A method for manufacturing a light source module according to any one of claims 17 to 19.

22. The semiconductor laser is mounted on the submount via a junction layer. The bonding layer located between the semiconductor laser and the submount and the first bonding layer are made of the same material. In the process of mounting the light source onto the base, the first bonding layer is directly heated by laser light that has passed through the submount. A method for manufacturing a light source module according to any one of claims 17 to 19.

23. After joining the plane light wave circuit element and the base, the plane light wave circuit element and the base Cut both at once. A method for manufacturing a light source module according to any one of claims 17 to 19.

24. In the process of mounting the plane light wave circuit element onto the base, the plane light wave circuit element and the base are joined together while pressing the side surface of the plane light wave circuit element and the side surface of the base against the same surface. A method for manufacturing a light source module according to any one of claims 17 to 19.

25. In the process of mounting the planar light wave circuit element onto the base, a pressing member having two stepped surfaces of different heights is placed on the side or top surface of the planar light wave circuit element, and the planar light wave circuit element and the base are joined together by pressing the side surface of the planar light wave circuit element and the side surface of the base against the two stepped surfaces of the pressing member. A method for manufacturing a light source module according to claim 18.

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