Light source device

Abstract

To provide a light source device suitable for downsizing.SOLUTION: A light source device 100 comprises: a first substrate 10 including a first mounting surface 10a; a second substrate 11 including a second mounting surface 11a opposed to the first mounting surface; a first laser diode 30 supported on the first mounting surface; a first photodetector 40 supported on the second mounting surface; and a frame body 50 defining a space V in which the first laser diode and the first photodetector are accommodated. The frame body 50 includes a window part 50f, and the window part 50f includes an incidence plane 50c to which laser light 14 emitted from the first laser diode is incident, and an emission plane 50d from which the laser light emitted from the first laser diode is emitted. The laser light emitted from the first laser diode is partially transmitted, and the laser light emitted from the first laser diode is partially reflected. The first photodetector 40 detects light reflected by the window part in the laser light emitted from the first laser diode.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a light source device. [Background technology]

[0002] A light source device equipped with a photodetector for monitoring the intensity of a laser beam has been developed. Patent Document 1 discloses a light source device equipped with a photosensor that receives a part of the laser beam emitted from a surface-emitting laser array and detects the intensity of the laser beam. In this light source device, the surface-emitting laser array and the photosensor are arranged in the same space. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-114097 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a light source device suitable for miniaturization. [Means for solving the problem]

[0005] In a non-limiting exemplary embodiment, the light source device of the present disclosure includes a first substrate having a first mounting surface, a second substrate having a second mounting surface opposite the first mounting surface, a first laser diode supported directly or indirectly on the first mounting surface, a first photodetector supported directly or indirectly on the second mounting surface, and a frame body defining a space to accommodate the first laser diode and the first photodetector, wherein the frame body has a window portion, and the window portion has an entrance surface through which laser light emitted from the first laser diode is incident and an exit surface through which the laser light emitted from the first laser diode exits, and transmits a portion of the laser light emitted from the first laser diode and reflects a portion of the laser light emitted from the first laser diode, and the first photodetector detects the light of the laser light emitted from the first laser diode that is reflected by the window portion. Effect of the Invention

[0006] According to an exemplary embodiment of the present disclosure, a light source device suitable for miniaturization is provided. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view parallel to the XY plane of a light source device according to an exemplary embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view parallel to the YZ plane of the light source device according to the exemplary embodiment of the present disclosure. [Diagram 3] FIG. 3 is a perspective view showing a schematic diagram of a laser diode bonded to a submount fixed to one of a pair of substrates. [Figure 4] FIG. 4 is a perspective view that illustrates a photodetector mounted on the other of the pair of substrates. [Diagram 5] FIG. 5 is a cross-sectional view parallel to the YZ plane of another configuration example of a light source device according to an exemplary embodiment of the present disclosure. [Figure 6] FIG. 6 is a cross-sectional view parallel to the YZ plane of still another configuration example of a light source device according to an exemplary embodiment of the present disclosure. [Figure 7]FIG. 7 is a cross-sectional view parallel to the YZ plane of a modified example of a light source device according to an exemplary embodiment of the present disclosure. [Figure 8] FIG. 8 is a cross-sectional view parallel to the YZ plane of a modified example of a light source device according to an exemplary embodiment of the present disclosure. [Figure 9] FIG. 9 is a cross-sectional view parallel to the YZ plane of a modified example of a light source device according to an exemplary embodiment of the present disclosure. [Figure 10] FIG. 10 is a cross-sectional view parallel to the YZ plane of a modified example of a light source device according to an exemplary embodiment of the present disclosure. [Figure 11] FIG. 11 is a cross-sectional view parallel to the XY plane of a light source device including a plurality of laser diodes and a plurality of photodetectors according to an exemplary embodiment of the present disclosure. [Figure 12] FIG. 12 is a perspective view showing a schematic diagram of a plurality of laser diodes bonded to a submount fixed to one of a pair of substrates. [Figure 13A] FIG. 13A is a perspective view showing a schematic diagram of a plurality of photodetectors mounted on the other of the pair of substrates. [Figure 13B] FIG. 13B is a perspective view that illustrates a schematic configuration in which a plurality of photodetectors are integrated together and mounted on the other of the pair of substrates. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. The following embodiments are merely examples, and the light source device according to the present disclosure is not limited to the following embodiments. For example, the numerical values, shapes, materials, steps, and the order of the steps shown in the following embodiments are merely examples, and various modifications are possible as long as no technical contradictions occur. In addition, the various aspects described below are merely examples, and various combinations are possible as long as no technical contradictions occur.

[0009] The dimensions, shapes, etc. of components shown in the drawings may be exaggerated for clarity. In addition, the drawings may not reflect the dimensions, shape, and size relationships between components of an actual light source device. In addition, in order to avoid overly complicating the drawings, some elements may be omitted.

[0010] In the following description, components having substantially the same functions are indicated by common reference symbols, and descriptions thereof may be omitted. Terms indicating a specific direction or position (for example, "upper", "lower", "right", "left" and other terms including these terms) may be used. However, these terms are merely used for the sake of clarity of the relative direction or position in the referenced drawings. As long as the relationship of the relative direction or position by terms such as "upper" and "lower" in the referenced drawings is the same, the drawings other than the present disclosure, the actual product, the manufacturing device, etc. may not be arranged in the same manner as in the referenced drawings.

[0011] In this specification, terms such as "first," "second," and "third" are used as labels to distinguish the objects to which they are added, and are not intended to limit the number, order, sequence, or the like.

[0012] An example of the configuration of a light source device 100 according to this embodiment will be described with reference to FIGS.

[0013] FIG. 1 is a cross-sectional view parallel to the XY plane of the light source device 100 according to this embodiment. In FIG. 1, the emission end surface 30e of the laser diode 30 and the light receiving portion 40r of the photodetector 40 are shown. In the attached drawings, the mutually orthogonal X-axis, Y-axis, and Z-axis are shown for reference. FIG. 2 is a cross-sectional view parallel to the YZ plane of the light source device 100 according to this embodiment. FIG. 3 is a perspective view showing a schematic view of the laser diode 30 bonded to the submount 20 on the substrate 10. In FIG. 3, the frame 50 is shown in a see-through state so that the internal structure of the light source device 100 can be seen, and the central axis of the laser light 14 emitted from the laser diode 30 is shown by a broken line. FIG. 4 is a perspective view showing a schematic view of the photodetector 40 mounted on the substrate 11. It is.

[0014] The light source device 100 in this embodiment includes a first substrate 10, a second substrate 11, a submount 20, at least one laser diode 30, at least one photodetector 40, and a frame 50. In the example of FIG. 1, the light source device 100 includes one laser diode 30 and one photodetector 40. The light source device 100 may include a protective element 60, which will be described later, but the protective element is not shown in FIG. 1 to avoid complicating the drawing. The light source device 100 may further include a temperature sensor (not shown), such as a thermistor, for measuring the internal temperature.

[0015] An example of the shape of the light source device 100 in this embodiment is a substantially rectangular parallelepiped as shown in Fig. 3. For example, the size of the light source device 100 in the X direction is about 1.0 mm to 5.0 mm, the size in the Z direction is about 2.0 mm to 5.0 mm, and the thickness in the Y direction is about 1.0 mm to 3.0 mm. The light source device 100 can be suitably used as a light source for, for example, a head mounted display, a projector, a lighting device, etc.

[0016] The first substrate 10 and the second substrate 11 are a pair of substrates. The first substrate 10 has a first mounting surface 10a that directly or indirectly supports the laser diode 30. The second substrate 11 has a second mounting surface 11a that directly or indirectly supports the photodetector 40. Hereinafter, each of the first substrate and the second substrate will be simply referred to as a "substrate", and each of the first mounting surface and the second mounting surface will be simply referred to as a "mounting surface". The substrate is a plate-shaped member. The pair of substrates 10 and 11 are arranged so that the mounting surface 10a and the mounting surface 11a face each other. The pair of substrates 10 and 11 can be formed with ceramic as the main material. It is to be noted that the substrates are not limited to ceramic and may be formed of metal. For example, ceramics such as aluminum nitride, silicon nitride, aluminum oxide, silicon carbide, etc., metals such as copper, aluminum, iron, and composites such as copper molybdenum, copper-diamond composite material, and copper tungsten, as well as silicon, resin, etc. can be used as the main material of the substrate. However, when a metal is used, mounting surfaces 10a and 11a need to be insulated in order to provide a conductor wiring layer on the board.

[0017] The substrate 10 has a conductor wiring layer electrically connected to the laser diode 30. As shown in FIG. 3, a pair of electrode pads pd for mounting the protection element 60 is provided on the mounting surface 10a of the substrate 10 as a part of the conductor wiring layer. The substrate 11 has a conductor wiring layer electrically connected to the photodetector 40. As shown in FIG. 4, a pair of electrode pads pd for mounting the photodetector 40 is provided on the mounting surface 11a of the substrate 11 as a part of the conductor wiring layer. The laser diode 30 is electrically connected to one of the conductor wiring layers of the pair of substrates 10 and 11, and the photodetector 40 is electrically connected to the other conductor wiring layer, thereby facilitating wiring of the laser diode 30 and the photodetector 40. In addition, since the wiring can be provided separately on each of the substrates 10 and 11, the light source device 100 can be made smaller in size.

[0018] The conductor wiring layer may be formed from a metal material such as tungsten, molybdenum, nickel, gold, silver, platinum, titanium, copper, aluminum, ruthenium, etc. The conductor wiring layer may have a multi-layer structure in which each layer is electrically connected through a via.

[0019] The submount 20 is a heat dissipation member, and typically has a rectangular parallelepiped shape, but is not limited thereto. The submount 20 plays a role in dissipating heat generated from the laser diode 30. From the viewpoint of further improving heat dissipation, it is preferable that the submount 20 is formed from a material having a higher thermal conductivity than the laser diode 30. Examples of such materials include ceramic materials such as aluminum nitride, silicon nitride, aluminum oxide, and silicon carbide, as well as copper, aluminum, silver, iron, nickel, molybdenum, tungsten, and copper molybdenum. and the like. A metal containing at least one selected from the group consisting of

[0020] The submount 20 is bonded to the mounting surface 10a of the substrate 10. Such bonding can be achieved through a layer of an inorganic material such as a metal, or an organic material. However, when using a laser diode that emits blue or green light, it is preferable to avoid using an organic material, taking into account the effect of dust collection by the laser light.

[0021] The submount 20 has a mounting surface 20a on which the laser diode 30 is disposed. In the example of FIG. 3, an electrode pad pd electrically connected to the laser diode 30 is formed on the mounting surface 20a of the submount 20. The laser diode 30 is indirectly mounted on the mounting surface 10a of the substrate 10 while being bonded to the submount 20. However, the laser diode 30 may be directly bonded to the mounting surface 10a of the substrate 10 without the submount 20. Therefore, although the submount 20 is not an essential member in this embodiment, the use of the submount 20 can improve heat dissipation. In addition, the position of the light emitting point of the laser diode 30 in the height direction can be easily adjusted.

[0022] The laser diode 30 has a p-side electrode, an n-side electrode, and a semiconductor laminate structure (not shown) including a p-side semiconductor layer, an n-side semiconductor layer, and an active layer located between these layers. By applying a voltage to the p-side electrode and the n-side electrode to pass a current inside, the laser diode 30 emits laser light 14 from an emission end face 30e. In this embodiment, the laser diode 30 is an edge-emitting type having an end face that emits laser light, but may be a vertical cavity surface-emitting laser (VCSEL).

[0023] For example, a laser diode that emits blue light, a laser diode that emits green light, or a laser diode that emits red light can be used as the laser diode 30. Also, a laser diode that emits other light, such as near-infrared light or ultraviolet light, may be used.

[0024] In this specification, blue light is light having a peak emission wavelength in the range of 420 nm to 494 nm, green light is light having a peak emission wavelength in the range of 495 nm to 570 nm, and red light is light having a peak emission wavelength in the range of 605 nm to 750 nm.

[0025] Examples of laser diodes that emit blue light or laser diodes that emit green light include laser diodes that include nitride semiconductors. Examples of nitride semiconductors that can be used include GaN, InGaN, and AlGaN. Examples of laser diodes that emit red light include those that include InAlGaP, GaInP, GaAs, and AlGaAs semiconductors.

[0026] The laser light emitted from a laser diode has a spreading property and forms an elliptical far-field pattern (hereinafter referred to as "FFP") on a plane parallel to the output facet of the laser light. The FFP is defined by the light intensity distribution of the laser light at a position away from the output facet. In this light intensity distribution, the 1 / e 2 The portion having the above intensity may be called the beam cross section.

[0027] 2, the actual laser light 14 diverges and spreads after being emitted from the emission end surface 30e of the laser diode 30. Therefore, the laser light 14 can be collimated or converged by an optical system including a lens (not shown). Such an optical system can be provided inside or outside the light source device 100.

[0028] The photodetector 40 monitors the intensity of the laser light 14 emitted from the laser diode 30. To explain in more detail, the photodetector 40 has a light receiving section 40r, and receives at least a part of the total area of ​​the beam cross section of the laser light 14 emitted from the laser diode 30 or at least a part of the total laser output of the laser light 14 emitted from the laser diode 30 at the light receiving section 40r to monitor the intensity of the laser light 14. An example of the light receiving section 40r is a photoelectric conversion element such as a photodiode, and is preferably provided at a position facing an incident surface 50c of a window section 50f provided in the frame body 50, which will be described later. The intensity of the laser light can also be called optical power.

[0029] The photodetector 40 detects, as monitor light, light reflected by at least one of an entrance surface 50c and an exit surface 50d of a window portion 50f of the frame body 50, which will be described later. The photodetector 40 requires monitor light of, for example, about 5 mW in order to monitor the intensity of the laser light 14 emitted from the laser diode 30. In this embodiment, for example, about 5% of the laser light 14 emitted from the laser diode 30 is used as monitor light, and the remaining about 95% is extracted to the outside.

[0030] The photodetector 40 is directly or indirectly supported on the mounting surface 11a of the substrate 11. In the example of FIG. 4, the photodetector 40 is electrically connected to a pair of electrode pads pd formed on the mounting surface 11a. The photodetector 40 may be indirectly supported on the substrate 11 via a submount, similar to the laser diode 30. In that case, the height adjustment of the photodetector 40 in the Y direction is easy. In this embodiment, in the example of FIG. 1, the thickness of the laser diode 30 in the Y direction may be, for example, about 0.1 mm, and the thickness of the photodetector 40 in the Y direction may be, for example, about 0.4 mm. In addition, the laser diode 30 and the photodetector 40 may be disposed closely to each other with an interval of, for example, about 0.05 mm in the Y direction.

[0031] As shown in FIG. 1 or FIG. 2, when viewed from a direction perpendicular to the mounting surface 10a (i.e., the Y-axis direction), the photodetector 40 at least partially overlaps the laser diode 30. In the example of FIG. 1, the photodetector 40 is disposed directly above the laser diode 30. This arrangement can prevent the laser light 14 emitted from the laser diode 30 from directly entering the light receiving section 40r of the photodetector 40, and the intensity of the laser light 14 can be monitored with high accuracy. In addition, as described later, a part of the laser light 14 reflected by the window section 50f of the frame body 50 is easily received by the light receiving section 40r of the photodetector 40. However, the relative positional relationship or size relationship of the photodetector 40 to the laser diode 30 in the example of FIG. 1 is merely an example and is not limited thereto. For example, the width of the laser diode 30 may be longer than the width of the photodetector 40 in the X-direction. Alternatively, the first line segment that approximately bisects the emission end face 30e of the laser diode 30 does not have to coincide with the second line segment that approximately bisects the light receiving portion 40r of the photodetector 40. Furthermore, in the example of Fig. 2, the end face of the light receiving portion 40r is disposed at the same position as the emission end face 30e in the Z direction, but this is not limited thereto. The photodetector 40 can be disposed at a position farther away from the window portion 50f than the emission end face 30e of the laser diode 30 as long as a level of reflected light required for monitoring is obtained (see Fig. 5).

[0032] 3, the frame 50 is bonded to the edge of the mounting surface 10a of the substrate 10 so as to surround the laser diode 30. A lower end surface 50b of the frame 50 is bonded to the mounting surface 10a of the substrate 10. Such bonding can be achieved via an inorganic material such as a metal, or a layer of an organic material. However, when using a laser diode that emits blue or green light, it is preferable to avoid using an organic material in consideration of the effect of dust collection by the laser light.

[0033] An upper end surface 50a of the frame 50 is joined to the mounting surface 11a of the substrate 11, similar to the substrate 10. The frame 50 defines a space V for accommodating the laser diode 30 and the photodetector 40. The substrate 11 functions as a cap, and the laser diode 30 and the photodetector 40 are mounted on the frame 50. is airtightly sealed in the space V. By airtightly sealing, the influence of dust collection by the laser light can be suppressed. However, airtight sealing is not essential.

[0034] In this way, by mounting the laser diode 30 and the photodetector 40 on different mounting surfaces 10a, 11a of a pair of substrates 10, 11, respectively, and by disposing the laser diode 30 and the photodetector 40 inside the same space V, the wiring can be divided and provided on each of the substrates 10, 11, making it possible to miniaturize the light source device 100.

[0035] As shown in FIG. 2, the frame 50 has a window 50f that transmits a part of the laser light 14 emitted from the laser diode 30 and reflects a part of the laser light 14 emitted from the laser diode 30. The window 50f is disposed at a position on the substrate 10 that crosses the laser light 14. The window 50f has an entrance surface 50c on which the laser light 14 emitted from the laser diode 30 enters, and an exit surface 50d from which the laser light 14 emitted from the laser diode 30 exits. The window 50f may be formed of a material that transmits light, such as glass, sapphire, or a transparent ceramic material, and may contain a phosphor. The portion of the frame 50 other than the window 50f may be formed of, for example, silicon, glass, ceramic, or the same material as the substrate described above.

[0036] In this embodiment, a protective element 60 is provided on the substrate 10. An example of the protective element 60 is a Zener diode. The protective element 60 is electrically connected in parallel to the laser diode 30 and functions as a protective circuit that suppresses the reverse voltage that can be applied to the laser diode 30 to a predetermined level or less. The protective element 60 is mounted on a pair of electrode pads pd formed on the mounting surface 10a of the substrate 10. In the example of FIG. 3, the p-side electrode of the laser diode 30 is electrically connected to the electrode pad pd on the mounting surface 20a. The anode side of the pair of electrode pads pd on the mounting surface 10a of the substrate 10 is electrically connected to the electrode pad pd on the mounting surface 20a via a conductive wire w. The cathode side of the pair of electrode pads pd is electrically connected to the n-side electrode of the laser diode 30 via a conductive wire w. In this manner, the protective element 60 can be electrically connected in parallel to the laser diode 30.

[0037] The laser light 14 reflected by the window 50f will be described in detail with reference to Fig. 2. Fig. 2 shows how the monitor light enters the photodetector 40. The laser light 14 reflected by each of the entrance surface 50c and the exit surface 50d of the window 50f is shown diagrammatically by a representative light beam. Although the actual light beam is refracted at the interface between the window 50f and the air, for simplicity, the refraction is not shown in the attached drawings including Fig. 2.

[0038] When the laser light 14 emitted from the laser diode 30 enters the incident surface 50c of the window portion 50f, it passes through a first interface between the gas and the solid. The first interface corresponds to the incident surface 50c. The "gas" is air or an inert gas present inside the space V. The "solid" is, for example, glass constituting the window portion 50f. The refractive index of a gas such as air is about 1.0, whereas the refractive index of glass is, for example, 1.4 or more. Therefore, the first interface is an interface between a dielectric material (air) with a relatively low refractive index and a dielectric material (glass) with a relatively high refractive index. As a result, a so-called "fixed end reflection" occurs, and a part of the laser light 14 is reflected.

[0039] When the laser light 14 passes through the inside of the window portion 50f and is emitted from the emission surface 50d, the laser light 14 passes through a second interface that exists between a solid and a gas. The second interface corresponds to the emission surface 50d. The second interface is an interface between a dielectric material with a relatively high refractive index (e.g., glass) and a dielectric material with a relatively low refractive index (e.g., air). The so-called "free-end reflection" also occurs at the second interface, and a part of the laser light 14 is reflected.

[0040] In this way, the proportion of the laser light 14 emitted from the laser diode 30 that is reflected by the window portion 50f is determined by the reflectance of the entrance surface 50c and the exit surface 50d of the window portion 50f. The reflectance of the entrance surface 50c and the exit surface 50d, i.e., the reflectance at the first and second interfaces, can be adjusted by an optical film composed of, for example, one dielectric layer or multiple laminated dielectric layers, as described later. Note that the reflectance depends on the wavelength of light, so the "reflectance" in this disclosure means the reflectance at the peak wavelength of the laser light 14 emitted from the laser diode 30.

[0041] As described above, the laser light 14 emitted from the laser diode 30 has a spreading shape, and forms an elliptical FFP on a plane parallel to the emitting end surface 30e of the laser light 14. The long axis of the ellipse is parallel to the lamination direction of the laser diode 30, and in the example of FIG. 2, the long axis of the ellipse faces the Y-axis direction. Therefore, a part of the laser light emitted from the laser diode 30 and spreading upward (positive direction of the Y-axis) with respect to the central axis of the laser light is reflected by the incident surface 50c of the window portion 50f, and a part of the reflected light reaches the photodetector 40 without being blocked by the submount 20 and the laser diode 30. Similarly, a part of the laser light emitted from the laser diode 30 and spreading upward with respect to the central axis of the laser light is transmitted through the window portion 50f and reflected by the emitting surface 50d, and a part of the reflected light reaches the photodetector 40 without being blocked by the submount 20 and the laser diode 30. A part of the laser light 14 emitted from the laser diode 30 passes through the window portion 50f and is emitted to the outside. In this embodiment, by disposing the photodetector 40 directly above the laser diode 30, it is possible to prevent the laser light 14 emitted from the laser diode 30 from being directly incident on the light receiving portion 40r. Instead, the reflected light reflected by the window portion 50f can be incident on the light receiving portion 40r.

[0042] The higher the reflectance of the entrance surface 50c and the exit surface 50d of the window portion 50f, the higher the intensity of the laser light incident on the light receiving portion 40r of the photodetector 40. However, the lower the reflectance of the entrance surface 50c and the exit surface 50d of the window portion 50f, the higher the light intensity of the laser light extracted from the light source device 100 and used. Therefore, the reflectances of the entrance surface 50c and the exit surface 50d of the window portion 50f can be adjusted so as to enable monitoring of a required level while realizing a sufficiently high light intensity of the laser light 14.

[0043] The reflectance of each of the entrance surface 50c and the exit surface 50d of the window portion 50f is preferably, for example, 1% to 10% with respect to the peak wavelength of the light to be reflected. In other words, the light transmittance of each of the entrance surface 50c and the exit surface 50d is preferably, for example, 90% to 99%.

[0044] With reference to Fig. 5, a configuration example of the light source device 100 in which the reflectance of the entrance surface 50c and the exit surface 50d of the window portion 50f are adjusted will be described. Fig. 5 is a cross-sectional view parallel to the YZ plane of another configuration example of the light source device 100 according to this embodiment. A reflectance adjustment portion may be formed on at least one of the entrance surface 50c and the exit surface 50d of the window portion 50f. The reflectance adjustment portion makes it possible to adjust the amount of laser light 14 emitted from the laser diode 30 and the amount of light required for monitoring the photodetector 40.

[0045] In the example of FIG. 5, a reflectance adjusting section 55a is formed on the incident surface 50c, and a reflectance adjusting section 55b is formed on the exit surface 50d. Each of the reflectance adjusting sections 55a and 55b may be, for example, a dielectric multilayer film composed of one dielectric layer or a plurality of laminated dielectric layers. Each of the reflectance adjusting sections 55a and 55b has a configuration similar to that of an optical film called an "anti-reflection film". However, a general anti-reflection film has an extremely low reflectance, for example, a reflectance of 0.5% or less, so as to suppress reflection as much as possible. In contrast, in the embodiment of the present disclosure, it is necessary to obtain a level of reflected light required for monitoring from at least one of the first and second interfaces. This Therefore, the reflectance of the reflectance adjuster 55a and the reflectance adjuster 55b as a whole including both of them is determined to be within a range of, for example, 1% to 10%.

[0046] By changing the film thickness and material of the reflectance adjusting portion, it is possible to control the reflectance of the reflecting surface. This means that the amount of monitor light can be controlled. For example, when a laser diode with an average output of 500 mW is used, by setting the reflectance of the reflectance adjusting portion to 1%, a monitor light of 5 mW or less can be obtained. Or, when a laser diode with an average output of 100 mW is used, by setting the reflectance of the reflectance adjusting portion to 5%, a monitor light of 5 mW or less can be obtained. In this way, by adjusting the reflectance of the reflectance adjusting portion, it is possible to obtain a monitor light of a desired intensity for a laser light of any intensity. In addition, by suppressing the amount of light reflected by the window portion 50f, it is possible to suppress a decrease in the amount of light output to the outside. As a result, it is possible to detect the monitor light with high accuracy while maintaining a high output.

[0047] In one embodiment, the reflectance of the reflectance-adjusting portion 55a is higher than the reflectance of the reflectance-adjusting portion 55b. In this case, as long as the laser light 14s reflected by the reflectance-adjusting portion 55a can provide the light detector 40 with the amount of light required for monitoring, the reflectance of the reflectance-adjusting portion 55b may have a reflectance of 0.5% or less, like a general anti-reflection film. Therefore, the reflectance-adjusting portion 55b having such a low reflectance can be formed in the same manner as a general "anti-reflection film."

[0048] In another embodiment, the reflectance of the reflectance adjustment unit 55b is higher than that of the reflectance adjustment unit 55a. In that case, if the laser light 14t reflected by the reflectance adjustment unit 55b can provide the light detector 40 with the amount of light required for monitoring, the reflectance adjustment unit 55a may have a reflectance of 0.5% or less, like a general anti-reflection film. Therefore, the reflectance adjustment unit 55a with such a low reflectance can be formed in the same manner as a normal "anti-reflection film". By adjusting the reflectance of the incident surface 50c out of the incident surface 50c and the exit surface 50d to a low reflectance, an advantage is obtained that the return light to the laser diode can be reduced. In addition, the distance from the exit surface 50d to the light detector 40 is longer by the width of the window portion 50f than the distance from the incident surface 50c to the light detector 40. Therefore, the laser light 14t reflected by the reflectance adjustment unit 55b with a relatively high reflectance is more likely to reach the light detector 40.

[0049] In this way, one of the reflectance adjusting section 55a and the reflectance adjusting section 55b may have an extremely low reflectance, similar to a conventional anti-reflection film. Also, when the sensitivity of the photodetector 40 is high, or when the reflected light is efficiently incident on the light receiving section 40r of the photodetector 40, both the reflectance adjusting section 55a and the reflectance adjusting section 55b may have an extremely low reflectance, similar to a conventional anti-reflection film.

[0050] Moreover, the reflectance adjusting portion 55a and the reflectance adjusting portion 55b do not have to have the form of a film. A fine uneven structure having a size shorter than the wavelength, such as a powder layer of nanoparticles or a moth-eye structure, may be formed on the incident surface 50c and / or the exit surface 50d. Alternatively, the reflectance can be adjusted by forming a region on the glass surface having a lower refractive index than the inside by modifying the surface of the incident surface 50c and / or the exit surface 50d. The reflectance adjusting portion 55a and the reflectance adjusting portion 55b can also be realized by the modified region thus formed on the glass surface. In addition, various configurations capable of adjusting the reflectance described above may be combined. The reflectance adjusting portion 55a and the reflectance adjusting portion 55b may be selectively formed in the region through which the laser light 14 passes, or may be formed to extend to other regions depending on the manufacturing process.

[0051] Hereinafter, a configuration example for reducing noise in monitoring by the photodetector 40 will be described with reference to FIG.

[0052] FIG. 6 is a cross-sectional view parallel to the YZ plane of yet another configuration example of the light source device 100 according to this embodiment. The light source device 100 may further include a polarizer 70. The polarizer 70 may be disposed on the optical path between the window portion 50f and the photodetector 40. In the example of FIG. 6, the polarizer 70 is disposed in front of the light receiving portion 40r of the photodetector 40. Since the relatively weak non-laser light emitted in all directions from the laser diode 30 is non-polarized, the intensity can be halved using the polarizer 70. As a result, the amount of non-laser light incident on the light receiving portion 40r can be reduced, and the noise of the monitor by the photodetector 40 can be reduced. The polarization transmission axis of the polarizer 70 is aligned with the polarization direction of the laser light 14 emitted from the laser diode 30. The reflected light of the laser light 14 emitted from the laser diode 30 and reflected by the window portion 50f enters the polarizer 70 while maintaining its polarization state. Therefore, such reflected light passes through the polarizer 70 and is appropriately detected by the photodetector 40.

[0053] Some representative modifications of the light source device 100 according to this embodiment will be described with reference to FIGS.

[0054] 7 to 10 are cross-sectional views parallel to the YZ plane of modified examples of the light source device 100 according to this embodiment. Each of the drawings shows a schematic central axis of the laser light emitted from the laser diode 30. In these modified examples, at least one of the entrance surface 50c and the exit surface 50d of the window portion 50f intersects with the optical axis (i.e., the central axis) of the laser light 14 emitted from the laser diode 30 at an angle other than 90°.

[0055] In the example of FIG. 7, the window portion 50f is inclined from the normal direction (direction parallel to the Y-axis) of the mounting surface 10a of the substrate 10. The rear surface portion 50h of the frame body 50, which is located on the opposite side of the window portion 50f with respect to the laser diode 30, is not inclined. As shown in FIG. 7, the inclination angles of the incident surface 50c and the exit surface 50d are defined as θ1 and θ2, respectively. θ1 and θ2 may be equal or different. In the example of FIG. 7, both θ1 and θ2 are smaller than 90°. Therefore, the incident surface 50c and the exit surface 50d are not perpendicular to the optical axis of the laser light 14 emitted from the laser diode 30, that is, they intersect at an angle other than 90°.

[0056] Since the entrance surface 50c and the exit surface 50d are inclined, it is easy to direct the light reflected by the inclined surfaces toward the photodetector 40. As a result, the return light to the laser diode 30 can be appropriately reduced.

[0057] The central axis of the reflected light by the window portion 50f may also change depending on the inclination angles of the incident surface 50c and the exit surface 50d. By adjusting the inclination angles of the incident surface 50c and / or the exit surface 50d of the window portion 50f so that more light reflected by the incident surface 50c and / or the exit surface 50d reaches the photodetector 40, a sufficient amount of light required for monitoring can be obtained. As a result, the detection accuracy of the photodetector 40 can be improved. At this time, the decrease in the amount of received light can also be suppressed by adjusting the position and angle of the light receiving portion 40r of the photodetector 40 as necessary.

[0058] As shown in the example of FIG. 2, when the window portion 50f is not tilted, the light passing through the central axis of the laser light 14 passes through the window portion 50f and is emitted to the outside. In contrast, as shown in the example of FIG. 7, by tilting at least one of the entrance surface 50c and the exit surface 50d of the window portion 50f, a portion of the light passing through the central axis of the laser light 14 can be reflected by the window portion 50f and reach the photodetector 40. Compared to the light passing through the central axis of the laser light 14, the output of the light passing through the periphery of the beam cross section tends to change more easily depending on the laser output, etc., especially the closer to the base. Therefore, by tilting the window portion 50f, the amount of light passing through the central axis of the laser light 14 can be reduced. A part of the light can be directed to the photodetector 40. This is very advantageous in terms of improving the detection accuracy of the monitor light.

[0059] In the example of FIG. 8, the rear surface 50h is also inclined from the normal direction of the mounting surface 10a of the substrate 10, like the window 50f. In the example of FIG. 9, only the exit surface 50d of the entrance surface 50c and the exit surface 50d of the window 50f is inclined at a predetermined inclination angle. In the example of FIG. 10, only the entrance surface 50c of the entrance surface 50c and the exit surface 50d of the window 50f is inclined at a predetermined inclination angle. In either configuration, a sufficient amount of light required for the monitor can be obtained by adjusting the inclination angle of the entrance surface 50c or the exit surface 50d. Furthermore, by combining the adjustment of the inclination angle of the entrance surface 50c and / or the exit surface 50d with the reflectance adjustment unit described above, a desired level of reflected light can be obtained.

[0060] The light source device 100 in the embodiment of the present disclosure may include a plurality of laser diodes 30 and a plurality of photodetectors 40 .

[0061] A configuration example of a light source device 100 including a plurality of laser diodes 30 and a plurality of photodetectors 40 will be described with reference to Fig. 11 to Fig. 13A. Fig. 11 is a cross-sectional view parallel to the XY plane of a light source device 100 including a plurality of laser diodes 30 and a plurality of photodetectors 40 according to this embodiment. Fig. 12 is a perspective view showing a schematic view of a plurality of laser diodes 30 fixed to a submount 20 on a substrate 10. Fig. 13A is a perspective view showing a schematic view of a plurality of photodetectors 40 mounted on a substrate 11. Below, differences from the configuration of the light source device already described will be mainly described.

[0062] In the example of FIG. 11, the light source device 100 includes a plurality of laser diodes 30 and a plurality of photodetectors 40. The plurality of laser diodes 30 include a first laser diode 30a, a second laser diode 30b, and a third laser diode 30c. The plurality of photodetectors 40 include a first photodetector 40a, a second photodetector 40b, and a third photodetector 40c. Hereinafter, the first laser diode, the second laser diode, and the third laser diode will each be simply referred to as a "laser diode", and the first photodetector, the second photodetector, and the third photodetector will each be simply referred to as a "photodetector". The three laser diodes 30a, 30b, and 30c, and the three photodetectors 40a, 40b, and 40c can be hermetically sealed inside the space V.

[0063] The three laser diodes 30a, 30b, and 30c are mounted on the mounting surface 10a of the substrate 10 in a state where they are bonded to the submount 20. The interval between two adjacent laser diodes in the example of FIG. 11 can be, for example, 50 μm or more and 2000 μm or less. The laser beams 14a, 14b, and 14c emitted from the laser diodes 30a, 30b, and 30c, respectively, enter the incident surface 50c of the window portion 50f, a part of the laser beams passes through the window portion 50f and exits from the exit surface 50d, and a part of the laser beams is reflected by the window portion 50f. The emission peak wavelengths of the laser beams 14a, 14b, and 14c emitted from the laser diodes 30a, 30b, and 30c, respectively, are different from each other. In this embodiment, the laser diode 30a emits red light, the laser diode 30b emits green light, and the laser diode 30c emits blue light. However, the present invention is not limited to this. According to this configuration example, a light source device is realized in which laser diodes of the three primary colors, RGB, are mounted in one package.

[0064] The substrate 10 has a conductor wiring layer electrically connected to the three laser diodes 30a, 30b, and 30c. A plurality of protection elements 60 are provided on the mounting surface 10a of the substrate 10. The plurality of protection elements 60 include three protection elements 60a, 60b, and 60c. Each of the three protection elements 60a, 60b, and 60c is electrically connected to a pair of electrode pads pd formed on the mounting surface 10a. The protection element 60a is electrically connected to the laser diode 30a. 3, the protection element 60b is electrically connected in parallel to the laser diode 30b, and the protection element 60c is electrically connected in parallel to the laser diode 30c.

[0065] The substrate 11 has a conductor wiring layer electrically connected to the three photodetectors 40a, 40b, and 40c. As shown in Fig. 13A, the three photodetectors 40a, 40b, and 40c are directly or indirectly supported on the mounting surface 11a of the substrate 11. Each of the three photodetectors 40a, 40b, and 40c is electrically bonded to a pair of electrode pads pd on the mounting surface 11a.

[0066] In the example of FIG. 11, the photodetector 40a is located directly above the laser diode 30a. The photodetector 40a has a light receiving section 40ar, and monitors the intensity of the laser light 14a by receiving the light reflected by the window section 50f of the laser light 14a emitted from the laser diode 30a at the light receiving section 40ar. The photodetector 40b is located directly above the laser diode 30b. The photodetector 40b has a light receiving section 40br, and monitors the intensity of the laser light 14b by receiving the light reflected by the window section 50f of the laser light 14b emitted from the laser diode 30b at the light receiving section 40br. The photodetector 40c is located directly above the laser diode 30c. The photodetector 40c has a light receiving section 40cr, and monitors the intensity of the laser light 14c by receiving the light reflected by the window section 50f of the laser light 14c emitted from the laser diode 30c at the light receiving section 40cr. The photodetectors 40a, 40b, and 40c are located directly above the laser diodes 30a, 30b, and 30c, respectively, and therefore prevent the laser beams 14a, 14b, and 14c from directly entering the photodetectors. Also, each photodetector can monitor the intensity of the corresponding laser beam, improving the monitoring accuracy.

[0067] FIG. 13B is a perspective view showing a schematic configuration in which a plurality of photodetectors are integrated and mounted on the substrate 11. As shown in the figure, instead of the three independent photodetectors 40a, 40b, and 40c, a photodetector 41 in which the functions of these detectors are mounted on one chip can be used. The photodetector 41 has light receiving sections 40ar, 40br, and 40cr that receive the laser beams 14a, 14b, and 14c, respectively. Compared to mounting individual photodetectors, using the photodetector 41 makes it possible to reduce the mounting space of the entire photodetector. This is advantageous for miniaturizing the light source device. [Industrial Applicability]

[0068] The light source device of the present disclosure can be suitably used as a light source for head mounted displays, projectors, lighting devices, and the like. [Explanation of symbols]

[0069] 10: first substrate, 10a: first mounting surface, 11: second substrate, 11a: second mounting surface, 14a, 14b, 14c: laser light, 20: submount, 30, 30a: first laser diode, 30b: second laser diode, 30c: third laser diode, 40, 40a: first photodetector, 40b: second photodetector, 40c: third photodetector, 40ar, 40br, 40cr: light receiving section, 41: photodetector, 50: frame, 50c: incident surface, 50d: exit surface, 50f: window section, 55a, 55b: reflectance adjustment section, 60, 60a, 60b, 60c: protection element, 70: polarizer, 100: light source device, pd: electrode pad, w: conductive wire

Claims

1. a first substrate having a first mounting surface; a second substrate having a second mounting surface facing the first mounting surface; a first laser diode supported directly or indirectly on the first mounting surface; a first photodetector supported directly or indirectly on the second mounting surface; a frame defining a space for accommodating the first laser diode and the first photodetector; the frame has a window portion and is joined to the first substrate and the second substrate; The window portion is inclined from a normal direction of the first mounting surface of the first substrate, a first laser diode having an incident surface on which the laser light emitted from the first laser diode is incident and an exit surface from which the laser light emitted from the first laser diode is exited, the first laser diode transmitting a portion of the laser light emitted from the first laser diode and reflecting a portion of the laser light emitted from the first laser diode; The first photodetector detects light reflected by the window portion out of the laser light emitted from the first laser diode.

2. The light source device according to claim 1 , wherein the first laser diode and the first photodetector are hermetically sealed within the space.

3. the first substrate has a wiring layer electrically connected to the first laser diode; The light source device according to claim 1 , wherein the second substrate has a wiring layer electrically connected to the first photodetector.

4. 4 . The light source device according to claim 1 , wherein the first photodetector at least partially overlaps the first laser diode when viewed in a direction perpendicular to the first mounting surface of the first substrate.

5. The light source device according to claim 1 , further comprising a submount bonded to the first mounting surface, the submount having the first laser diode disposed thereon.

6. The light source device according to claim 1 , wherein a reflectance adjusting portion is formed on at least one of the entrance surface and the exit surface of the window portion.

7. The light source device according to claim 1 , further comprising a polarizer disposed on an optical path between the window portion and the first photodetector.

8. The light source device according to claim 7 , wherein a polarization transmission axis of the polarizer is aligned with a polarization direction of the laser light emitted from the first laser diode.

9. 9. The light source device according to claim 1, wherein at least one of the entrance surface and the exit surface of the window portion intersects with an optical axis of the laser light emitted from the first laser diode at an angle other than 90°.

10. a second laser diode supported directly or indirectly on the first mounting surface; a third laser diode supported directly or indirectly on the first mounting surface; a second photodetector supported directly or indirectly on the second mounting surface; a third photodetector supported directly or indirectly on the second mounting surface; Further equipped with The laser light emitted from each of the second laser diode and the third laser diode is incident on the incident surface, a part of the laser light passes through the window portion and is emitted from the exit surface, and a part of the laser light is reflected by the window portion, the second photodetector detects light reflected by the window portion out of the laser light emitted from the second laser diode; The light source device according to claim 1 , wherein the third photodetector detects light reflected by the window portion out of the laser light emitted from the third laser diode.

11. The light source device according to claim 10 , wherein the first laser diode, the second laser diode, the third laser diode, the first photodetector, the second photodetector and the third photodetector are hermetically sealed within the space.

12. the first substrate has a wiring layer electrically connected to the first laser diode, the second laser diode, and the third laser diode; 12. The light source device according to claim 10, wherein the second substrate has a wiring layer electrically connected to the first photodetector, the second photodetector, and the third photodetector.

13. 13. The light source device according to claim 11, further comprising a submount bonded to the first mounting surface, on which the first laser diode, the second laser diode and the third laser diode are arranged.

14. 14. The light source device according to claim 10, wherein the first laser diode, the second laser diode, and the third laser diode each have a different emission peak wavelength from one another.

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