Light source device

Abstract

A light source device (100) is provided with: a first board (10) having a first mounting surface (10a); a second board (11) having a second mounting surface (11a) facing the first mounting surface; a first laser diode (30a) supported directly or indirectly on the first mounting surface; a second laser diode (30b) supported directly or indirectly on the first mounting surface; and a third laser diode (30c) supported directly or indirectly on the second mounting surface. The light emitting point of the third laser diode is positioned between the light emitting point of the first laser diode and the light emitting point of the second laser diode, in the width direction, and in a plan view as seen from a direction perpendicular to the first mounting surface, at least one of the first laser diode and the second laser diode overlaps the third laser diode at least partially.

Description

[Technical field]

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

[0002] Light source devices equipped with multiple laser diodes have been developed for various applications. Patent Document 1 discloses a configuration in which multiple light-emitting elements are arranged between a pair of substrates so that the light-emitting points of each light-emitting element are located at the same height. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-27149 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a light source device with excellent light collecting properties. [Means for solving the problem]

[0005] In a non-limiting exemplary embodiment, a light source device according to the present disclosure includes a first substrate having a first mounting surface, a second substrate having a second mounting surface opposite to the first mounting surface, a first laser diode supported directly or indirectly on the first mounting surface, a second laser diode supported directly or indirectly on the first mounting surface, and a third laser diode supported directly or indirectly on the second mounting surface. An emission point of the third laser diode is located between an emission point of the first laser diode and an emission point of the second laser diode in a width direction, and at least one of the first laser diode and the second laser diode at least partially overlaps the third laser diode in a plan view seen from a direction perpendicular to the first mounting surface. Effect of the Invention

[0006] According to the embodiments of the present disclosure, a light source device with excellent light collecting properties is provided. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view parallel to the XY plane of an illustrative light source device according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view parallel to the YZ plane of the illustrative light source device according to the first embodiment. [Diagram 3] FIG. 3 is a schematic diagram of the light source device, showing a pair of substrates separated from each other. [Figure 4A] FIG. 4A is a plan view of the pair of boards as viewed from a direction perpendicular to the mounting surface of one of the boards. [Figure 4B] FIG. 4B is a plan view of the boards when viewed from a direction perpendicular to the mounting surface of the other of the pair of boards. [Diagram 5] FIG. 5 is a cross-sectional view parallel to the XY plane of a modified example of the illustrative light source device according to the first embodiment. [Figure 6] FIG. 6 is a schematic diagram showing a typical structural example of a laser diode. [Figure 7] FIG. 7 is a cross-sectional view parallel to the YZ plane of another configuration example of the illustrative light source device according to the first embodiment. [Figure 8] FIG. 8 is a cross-sectional view parallel to the XY plane of yet another configuration example of the illustrative light source device according to the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view parallel to the YZ plane of still another configuration example of the illustrative light source device according to the first embodiment. [Figure 10] FIG. 10 is a cross-sectional view parallel to the XY plane of still another configuration example of the illustrative light source device according to the first embodiment. [Figure 11] FIG. 11 is a cross-sectional view parallel to the XY plane of still another configuration example of the illustrative light source device according to the first embodiment. [Figure 12] FIG. 12 is a cross-sectional view parallel to the XY plane of an illustrative light source device according to the second embodiment. [Figure 13]FIG. 13 is a cross-sectional view parallel to the YZ plane of an illustrative light source device according to the second embodiment. [Figure 14] FIG. 14 is a cross-sectional view parallel to the XY plane of another configuration example of an illustrative light source device according to the second embodiment. 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 the components shown in the drawings may be exaggerated for ease of understanding, and may not reflect the dimensions, shapes, and size relationships between the components in the actual light source device. Also, in order to avoid the drawings becoming overly complicated, some elements may be omitted from the illustration.

[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] (First embodiment) A configuration example of the light source device 100 according to this embodiment will be described with reference to Fig. 1 to Fig. 4B. 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, three light-emitting points e1, e2, and e3 located on the emission end faces of three laser diodes 30a, 30b, and 30c are shown in a circular pattern. In the drawing, for reference, an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other are shown. Fig. 2 is a cross-sectional view parallel to the YZ plane of the light source device 100 according to this embodiment.

[0012] Fig. 3 is a schematic diagram of the light source device 100, showing the pair of substrates 10 and 11 in a separated state. Fig. 4A is a plan view of the substrate 10 (the lower portion shown in Fig. 3) when viewed from a direction perpendicular to the mounting surface 10a of the substrate 10. Fig. 4B is a plan view of the substrate 11 (the upper portion shown in Fig. 3) when viewed from a direction perpendicular to the mounting surface 11a of the substrate 11. Fig. 4A illustrates two laser diodes 30a and 30b mounted on the mounting surface 10a when viewed from the positive direction of the Y axis, and Fig. 4B illustrates a laser diode 30c mounted on the mounting surface 11a when viewed from the negative direction of the Y axis.

[0013] The light source device 100 includes a first substrate 10, a second substrate 11, a first submount 20, a second submount 21, a plurality of laser diodes 30, and a frame 50. The plurality of laser diodes 30 in this embodiment include a first laser diode 30a, a second laser diode 30b, and a third laser diode 30c. Hereinafter, the first laser diode, the second laser diode, and the third laser diode will be simply referred to as "laser diodes", respectively. As described later, the light source device 100 may include a plurality of protective elements 40, but the protective elements are not shown in FIG. 1 and FIG. 2 to avoid cluttering the drawings. The light source device 100 may further include a temperature sensor (not shown) for measuring the internal temperature, such as a thermistor.

[0014] An example of the shape of the light source device 100 in this embodiment is a substantially rectangular parallelepiped as shown in Fig. 4A. For example, the size of the light source device 100 in the X direction may be about 1.0 mm to 10.0 mm, the size in the Z direction may be about 2.0 mm to 5.0 mm, and the thickness in the Y direction may be about 1.0 mm to 3.0 mm. The light source device 100 may be suitably used as a light source for, for example, a head mounted display, a projector, a lighting device, etc.

[0015] 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, and the second substrate 11 has a second mounting surface 11a that directly or indirectly supports the laser diode 30. 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.

[0016] In this embodiment, the pair of substrates 10 and 11 each have a conductor wiring layer (not shown) electrically connected to the laser diode 30 and the protection element 40. As shown in FIG. 4A or FIG. 4B, a pair of electrode pads pd for mounting the protection element 40 is provided on the mounting surface of each substrate as a part of the conductor wiring layer. The conductor wiring layer may be formed from a metal material such as tungsten, molybdenum, nickel, gold, silver, platinum, titanium, copper, aluminum, or ruthenium. The conductor wiring layer may have a multi-layer structure in which each layer is electrically connected through a via.

[0017] Each of the first submount 20 and the second submount 21 is a heat dissipation member, and typically has a rectangular parallelepiped shape, but is not limited thereto. Each submount plays a role of dissipating heat generated from the laser diode 30. From the viewpoint of further improving heat dissipation, each submount is preferably formed from a material having a higher thermal conductivity than the laser diode 30. For example, a ceramic material such as AlN, SiC, or SiN, or a metal containing at least one selected from the group consisting of Cu, Al, Ag, Fe, Ni, Mo, Cu, W, and CuMo is used as the material. Hereinafter, each of the first submount and the second submount will be simply referred to as a "submount."

[0018] The submount 20 is bonded to the mounting surface 10a of the substrate 10, and the submount 21 is bonded to the mounting surface 11a of the substrate 11. Such bonding can be achieved through a layer of inorganic material such as metal, or an organic material. However, when using a laser diode that emits blue or green light, it is preferable to avoid using organic materials in consideration of the effect of dust collection by the laser light. The thickness of the submount 20 may be the same as or different from the thickness of the submount 21. By adjusting the thickness of the submount, the height of the light emitting point of the laser diode from the mounting surface can be adjusted. The light emitting point in this specification generally refers to the emitter region of the laser diode. The light emitting point will be described in detail later.

[0019] The submount 20 has a mounting surface 20a on which the laser diode 30a and the laser diode 30b are disposed. The laser diode 30a and the laser diode 30b are mounted on the mounting surface 10a of the substrate 10 while being fixed to the submount 20. By bonding the laser diode 30a and the laser diode 30b to a common submount 20, the number of submounts used can be reduced, which is advantageous in that the number of components is reduced. The submount 21 has a mounting surface 21a on which the laser diode 30c is disposed. The laser diode 30c is mounted on the mounting surface 11a of the substrate 11 while being fixed to the submount 21.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] In this embodiment, the laser diode 30 is an end-emitting type having an end face for emitting laser light, but may be a surface-emitting type (VCSEL). The emission peak wavelengths of the laser light emitted from the laser diode 30a, the laser diode 30b, and the laser diode 30c are different from each other. The laser diode 30a emits blue light, the laser diode 30b emits green light, and the laser diode 30c emits red light. According to this embodiment, a light source device is realized in which laser diodes 30 of three primary colors, for example, RGB, are mounted in one package. However, in this disclosure, it is preferable that the multiple laser diodes 30 include at least two types of laser diodes having different emission peak wavelengths.

[0025] In order to collimate the multiple laser beams emitted from the multiple laser diodes, multiple collimating lenses that collimate each laser beam separately may be used. In order to miniaturize the light source device, it is effective to collimate the multiple laser beams with a single collimating lens. However, when multiple laser diodes are arranged on a substrate and laser beams are emitted from the light emitting points of the individual laser diodes, it is not possible to make all the laser beams enter the same position of the collimating lens in parallel. According to the light source device of the present disclosure, if the light emitting points of the multiple laser diodes are brought close to each other by devising the arrangement of the multiple laser diodes, it is possible to form approximately collimated light with excellent light collection ability with a single collimating lens.

[0026] As shown in FIG. 4A and FIG. 4B, the light source device 100 in this embodiment includes a single collimating lens 200 provided outside the frame body 50. The laser light 14a emitted from the laser diode 30a, the laser light 14b emitted from the laser diode 30b, and the laser light 14c emitted from the laser diode 30c are collimated by the collimating lens 200. In FIG. 4A, the collimated laser light 14a, 14b is shown separately from the viewpoint of clarity, but in reality, the two light emitting points e1, e2 may be arranged close to each other to such an extent that the laser light 14a, 14b overlap each other. The collimating lens 200 is not limited to the example shown in the figure, and may be provided in the space inside the frame body 50.

[0027] FIG. 5 is a cross-sectional view parallel to the XY plane of a modified example of the light source device 100 according to the present embodiment. Each laser diode 30 can be bonded to the mounting surface of the substrate without a submount. Therefore, the submount is not an essential component in the present disclosure. In the example of FIG. 5, the two laser diodes 30a and 30b are bonded to the mounting surface 10a, and the laser diode 30c is mounted on the mounting surface 11a. This example is not limited to the above, and for example, the two laser diodes 30a and 30b may be bonded to the mounting surface 10a via the submount 20, and the laser diode 30c may be mounted on the mounting surface 11a, or conversely, the two laser diodes 30a and 30b may be bonded to the mounting surface 10a, and the laser diode 30c may be mounted on the mounting surface 11a via the submount 21. However, in consideration of improving heat dissipation and adjusting the position of the light emitting point in the height direction, it is preferable that the laser diode 30 is mounted on a submount. The adjustment of the height of the light emitting point will be described in detail later.

[0028] An electrode pad electrically connected to the laser diode 30 is formed on the mounting surface of the submount. In this embodiment, as shown in Fig. 4A, two electrode pads pd electrically connected to the laser diode 30a and the laser diode 30b are formed on the mounting surface 20a of the submount 20. As shown in Fig. 4B, an electrode pad pd electrically connected to the laser diode 30c is formed on the mounting surface 21a of the submount 21.

[0029] FIG. 6 is a schematic diagram showing a typical structural example of a laser diode 30. In FIG. 6, the optical axis of the laser light 14 is shown. The laser diode 30 has a p-side electrode 31, an n-side electrode 32, a semiconductor laminated structure 33 including a p-side semiconductor layer 33a, an n-side semiconductor layer 33b, and an active layer 33c located between the p-side semiconductor layer 33a and the n-side semiconductor layer 33b, and a substrate 33d supporting the semiconductor laminated structure 33. One end face of the active layer 33c is an emission end face (or emitter region) 33e that emits the laser light 14. By applying a voltage to the p-side electrode 31 and the n-side electrode 32 to pass a current therethrough, the laser light 14 is emitted from the emitter region 33e of the laser diode 30. In this embodiment, the size of the laser diode 30 in plan view can be, for example, about 50 μm to 500 μm in the short direction, about 100 μm to 2000 μm in the long direction, and about 50 μm to 200 μm in thickness.

[0030] The laser diode 30 is directly or indirectly mounted face-down or face-up on the mounting surface of the substrate. Face-down mounting refers to mounting in which the laser diode 30 is disposed on the mounting surface so that the active layer 33c is closer to the submount than the substrate 33d. In contrast, face-up mounting refers to mounting in which the laser diode 30 is disposed on the mounting surface so that the active layer 33c is farther from the submount than the substrate 33d.

[0031] In this embodiment, the n-side electrode of each laser diode 30 is electrically connected to an electrode pad on the mounting surface of the submount. As shown in FIG. 1, the laser diodes 30a and 30b are indirectly mounted face-up on the mounting surface 10a of the substrate 10, more specifically, on the mounting surface 20a of the submount 20. The laser diode 30c is indirectly mounted face-up on the mounting surface 11a of the substrate 11, more specifically, on the mounting surface 21a of the submount 21. The laser diode 30c is disposed opposite the laser diodes 30a and 30b. By supporting the three laser diodes 30a, 30b, and 30c on the mounting surface in a face-up state, it is possible to bring the two light-emitting points e1 and e3 or the two light-emitting points e2 and e3 closer to each other in the direction perpendicular to the mounting surface 10a, i.e., in the height direction.

[0032] An example of the protection element 40 is a Zener diode. The protection element 40 is electrically connected in parallel to the laser diode 30, and functions as a protection circuit that suppresses the reverse voltage that can be applied to the laser diode 30 to a predetermined level or less. In the example of Figures 4A and 4B, a protection element 40a is provided as a protection circuit for the laser diode 30a, a protection element 40b is provided as a protection circuit for the laser diode 30b, and a protection element 40c is provided as a protection circuit for the laser diode 30c.

[0033] As shown in FIG. 4A, the protection elements 40a and 40b are mounted on a pair of electrode pads pd formed on the mounting surface 10a of the substrate 10. The cathode sides of the pair of electrode pads pd on the mounting surface 10a are electrically connected to the electrode pad pd on the mounting surface 20a, which is joined to the n-side electrode of the laser diode 30a, via a conductive wire w. The anode sides of the pair of electrode pads pd are electrically connected to the p-side electrode of the laser diode 30a via a conductive wire w. In this way, the protection element 40a is electrically connected in parallel to the laser diode 30a. Similar to the protection element 40a, the protection element 40b is electrically connected in parallel to the laser diode 30b.

[0034] 4B, the protection element 40c is mounted on a pair of electrode pads pd formed on the mounting surface 11a of the substrate 11. The cathode sides of the pair of electrode pads pd on the mounting surface 11a are electrically connected via a conductive wire w to an electrode pad pd on the mounting surface 21a, which is joined to an n-side electrode of the laser diode 30c. The anode sides of the pair of electrode pads pd are electrically connected via a conductive wire w to a p-side electrode of the laser diode 30c. In this manner, the protection element 40c is electrically connected in parallel to the laser diode 30c.

[0035] The frame 50 is fixed to the edge of the mounting surface 10a of the substrate 10 so as to surround the multiple laser diodes 30. In the example of FIG. 1, the 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.

[0036] The substrate 11 is fixed to an upper end surface 50a of a frame 50. The frame 50 defines a space for accommodating a plurality of laser diodes 30. The 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 substrate 11 functions as a cap, and hermetically seals the plurality of laser diodes 30 within the space. By hermetically sealing, the effect of dust collection by the laser light can be suppressed. However, hermetically sealing is not essential.

[0037] As shown in FIG. 2, the frame 50 has a light-transmitting portion 50F that transmits the laser light 14 emitted from each of the laser diodes 30. The light-transmitting portion 50F is disposed at a position on the substrate 10 that crosses the laser light 14a, 14c. The light-transmitting portion 50F may be made of a material that transmits light, such as glass or a transparent ceramic material. The glass may contain sapphire or the like. The portions of the frame 50 other than the light-transmitting portion 50F may be made of, for example, silicon, glass, ceramic, or the same material as the substrate described above.

[0038] Referring again to FIG. 1, the arrangement of the three light-emitting points e1, e2, and e3 in this embodiment will be described in detail.

[0039] The light emitting point e3 of the laser diode 30c bonded to the submount 21 is located between the light emitting point e1 of the laser diode 30a and the light emitting point e2 of the laser diode 30b bonded to the submount 20 in the width direction of the laser diode 30 parallel to the X direction.

[0040] In a plan view from a direction perpendicular to the mounting surface 10a of the substrate 10, at least one of the laser diode 30a and the laser diode 30b at least partially overlaps the laser diode 30c. In the example of FIG. 1, both the laser diode 30a and the laser diode 30b at least partially overlap the laser diode 30c. According to such an arrangement of the laser diodes 30, it is possible to set the interval between the two laser diodes 30a and 30b to be equal to or less than the width of the laser diode 30c. By doing so, the light emitting points of the laser diodes 30 can be brought closer to each other, making it easier to collect light. As a result, it is possible to miniaturize the collimator lens 200. However, it is not limited to the example of FIG. 1, and in a plan view, the laser diode 30a may entirely overlap the laser diode 30c, or the laser diode 30b may entirely overlap the laser diode 30c.

[0041] The distance in the width direction from the light emitting point e1 of the laser diode 30a to the laser diode 30b is shorter than the distance in the width direction from the center of the laser diode 30a to the laser diode 30b. In other words, the light emitting point e1 of the laser diode 30a that emits blue light may be closer to the side where the laser diode 30b is located with the center of the laser diode 30a as a reference. Or, the distance in the width direction from the light emitting point e2 of the laser diode 30b to the laser diode 30a is shorter than the distance in the width direction from the center of the laser diode 30b to the laser diode 30a. In other words, the light emitting point e2 of the laser diode 30b that emits green light may be closer to the side where the laser diode 30a is located with the center of the laser diode 30b as a reference. Here, the center of the laser diode means a line that approximately bisects the end face of the laser diode where the light emitting point is located, or a point on that line.

[0042] In this embodiment, as shown in FIG. 1, the light emitting point e1 is closer to the side where the laser diode 30b is located, and the light emitting point e2 is closer to the side where the laser diode 30a is located. With such an arrangement of the light emitting points, the distance between the two light emitting points e1 and e2 can be made smaller, and the two light emitting points e1 and e2 can be brought closer to each other. Furthermore, the width of the gap formed between the laser diode 30a and the laser diode 30b is equal to or smaller than the width of the laser diode 30c. Consider a case where the three laser diodes 30a, 30c, and 30b are arranged in this order on the same mounting surface. In this case, the distance between the light emitting point e1 and the light emitting point e2 is larger than the width of the laser diode 30c, but according to this embodiment, the distance between the light emitting point e1 and the light emitting point e2 can be made smaller than the width of the laser diode 30c.

[0043] The optical axis of the laser beam 14a emitted from the laser diode 30a, the optical axis of the laser beam 14b emitted from the laser diode 30b, and the optical axis of the laser beam 14c emitted from the laser diode 30c can be located within a range of a circle having a diameter equal to the narrowest width among the widths of the three laser diodes 30a, 30b, and 30c. For example, the light emitting points e1, e2, and e3 of the three laser diodes 30a, 30b, and 30c can be brought close to each other to a distance of 0.15 mm or less.

[0044] 7 is a cross-sectional view parallel to the YZ plane in another configuration example of the light source device 100 according to this embodiment. The light-transmitting portion 50F of the frame body 50 has an entrance surface 50c on which the laser light emitted from each laser diode 30 enters, and an exit surface 50d from which the laser light emitted from each laser diode 30 exits.

[0045] A part of each end face of the submount 20 and the submount 21 may be in contact with the incident surface 50c. To explain in more detail, the submount 20 has an end face 20e including an inclined surface 20s on the side where the incident surface 50c of the light-transmitting portion 50F is located. The submount 21 has an end face 21e including an inclined surface 21s on the side where the incident surface 50c of the light-transmitting portion 50F is located. A part of the end face 20e other than the inclined surface 20s is in contact with the incident surface 50c, and a part of the end face 21e other than the inclined surface 21s is in contact with the incident surface 50c.

[0046] Since the refractive index of the lens changes according to the wavelength of the light emitted from the laser diode 30a, the focal length of the lens differs according to the wavelength of the light. This can cause chromatic aberration, so it is necessary to adjust the position of the light emitting point of the laser diode 30 in the Z direction parallel to the optical axis of the laser light of the laser diode 30. According to this embodiment, by pressing the end face of the submount against the incident surface of the light transmitting section, it is possible to obtain an advantage that it is easy to adjust the position of the light emitting point of the laser diode 30 in the Z direction.

[0047] A part of the end face 20e of the submount 20 and the incident face 50c come into contact with each other to form a first contact face fcs. The first contact face fcs is spaced apart from the mounting face 10a. A part of the end face 21e of the submount 21 and the incident face 50c come into contact with each other to form a second contact face scs. The second contact face scs is spaced apart from the mounting face 11a. A metal such as AuSn is used as a bonding material for bonding the substrate and the submount. By separating the first contact face fcs and the second contact face scs from the mounting faces 10a and 11a, respectively, a space is secured for the bonding material to escape. By allowing the bonding material to escape into the space, the bonding material is prevented from adhering to the first contact face fcs and the second contact face scs. As a result, the position of the light emitting point of the laser diode 30 in the Z direction can be adjusted with high accuracy.

[0048] FIG. 8 is a cross-sectional view parallel to the XY plane of yet another configuration example of the light source device 100. FIG. 9 is a cross-sectional view parallel to the YZ plane of yet another configuration example of the light source device 100. In this configuration example, a first wiring layer 90 is disposed between the submount 20 and the substrate 10 and between the frame body 50 and the substrate 10, and a groove 90c formed in the first wiring layer 90 separates the first contact surface fcs from the mounting surface 10a. Similarly, a second wiring layer 91 is disposed between the submount 21 and the substrate 11 and between the frame body 50 and the substrate 11, and a groove 91c formed in the second wiring layer 91 separates the second contact surface scs from the mounting surface 11a. The wiring layer may be formed of a metal material such as tungsten, molybdenum, nickel, gold, silver, platinum, titanium, copper, aluminum, or ruthenium. A space is ensured for allowing the bonding material to escape when bonding the frame 50 and the submounts 20, 21 to the substrates 10, 11 via the wiring layer, which makes it easy to adjust the position of the light emitting point of the laser diode 30 in the Z direction.

[0049] FIG. 10 is a cross-sectional view parallel to the XY plane in yet another configuration example of the light source device 100 according to this embodiment. As shown in the figure, the light source device 100 can further include a heat sink 60. The heat sink 60 is disposed on the substrate 11 supporting the laser diode 30c emitting red light. The temperature characteristics of the laser diode 30c emitting red light are more susceptible to heat than the temperature characteristics of the laser diode 30a emitting blue light and the laser diode 30b emitting green light. Therefore, the optical output or wavelength of the laser diode 30c may change due to the influence of heat emitted from the laser diode 30a and / or the laser diode 30b. By disposing the heat sink 60 on the substrate 11, it is possible to efficiently dissipate heat that may adversely affect the temperature characteristics of the laser diode 30c to the outside.

[0050] 11 is a cross-sectional view parallel to the XY plane of yet another configuration example of the light source device 100 according to this embodiment. As shown in the figure, the light source device 100 can further include a Peltier element 70 in addition to the heat sink 60. The Peltier element 70 can be disposed between the substrate 11 and the heat sink 60. By passing a direct current through the Peltier element 70, the substrate 11 can be efficiently cooled, and the heat dissipation properties of the light source device 100 can be further improved.

[0051] Second embodiment Next, a light source device 101 according to a second embodiment will be described with reference to Fig. 12 to Fig. 14. The light source device 101 according to this embodiment differs from the light source device 100 according to the first embodiment in that the laser diode 30c is disposed opposite the laser diode 30a. Below, a description of the structure and function of the members common to the light source device 100 according to the first embodiment will be omitted, and differences will be mainly described.

[0052] 12 is a cross-sectional view parallel to the XY plane of a light source device 101 according to this embodiment. The cross section includes the emission end faces of three laser diodes 30a, 30b, and 30c.

[0053] In this embodiment, the laser diode 30a emits green light. The laser diode 30a is mounted face-up on the mounting surface 20a of the submount 20 while being fixed to the submount 20. The laser diode 30c emits blue light. The laser diode 30c is mounted face-up on the mounting surface 21a of the submount 21 while being fixed to the submount 21. The laser diode 30c is disposed opposite the laser diode 30a. For example, the laser diode 30c and the laser diode 30a may be disposed such that the two light emitting points e1 and e3 overlap in a plan view. The thickness of the submount 20 may be the same as or different from the thickness of the submount 21.

[0054] By mounting the two laser diodes 30a and 30c face-up on the two submounts 20 and 21, respectively, it becomes easy to adjust the height of each submount and bring the two light emitting points e1 and e3 closer to each other in the direction perpendicular to the mounting surface 10a. The distance between the two light emitting points e1 and e3 can be adjusted to, for example, 0.01 mm or more and 0.2 mm or less.

[0055] The light source device 101 in this embodiment further includes a third submount 22 bonded to the mounting surface 10a and having a laser diode 30b disposed thereon. Hereinafter, the third submount will be simply referred to as a "submount" like the first and second submounts. As shown in the figure, the submount 22 can be disposed on the mounting surface 10a adjacent to the submount 20. The submount 22 is thicker than the submount 20. The laser diode 30b in this embodiment emits red light. The laser diode 30b is mounted face-down on the mounting surface 22a of the submount 22 while being fixed to the submount 22.

[0056] Consider a case where a laser diode that emits red light is used as the laser diode 30b as in this embodiment. In this case, by mounting the laser diode 30b face-down on the mounting surface 22a of the submount 22, the two light emitting points e1 and e3 are brought closer to each other, and the heat generated by the laser diode 30b and the heat received from the laser diodes 30a and 30c can be efficiently dissipated to the submount 22. This can reduce changes in the temperature characteristics of the laser diode 30b due to the influence of heat.

[0057] In this embodiment, the height distance from the mounting surface 10a to the light emitting point e2 of the laser diode 30b is longer than the height distance from the mounting surface 10a to the light emitting point e1 of the laser diode 30a, and is shorter than the height distance from the mounting surface 10a to the light emitting point e3 of the laser diode 30c. Alternatively, the height distance from the mounting surface 10a to the light emitting point e1 may be the same as the height distance from the mounting surface 10a to the light emitting point e2.

[0058] In the example of FIG. 12, the light emitting point e2 of the laser diode 30b that emits red light is closer to the side where the laser diode 30a or 30c is located with respect to the center of the laser diode 30b. Furthermore, the light emitting point e1 of the laser diode 30a that emits green light is closer to the side where the laser diode 30b is located with respect to the center of the laser diode 30a, and the light emitting point e3 of the laser diode 30c that emits blue light is closer to the side where the laser diode 30b is located with respect to the center of the laser diode 30c. As in the first embodiment, the width of the gap formed between the laser diode 30b and the laser diode 30a or 30c is equal to or smaller than the width of the laser diode 30c. With this arrangement, the three light emitting points e1, e2, and e3 can be brought closer to each other.

[0059] By arranging the laser diode 30c facing the laser diode 30a, it is possible to arrange the light emitting point e3 of the laser diode 30c directly above the light emitting point e1 of the laser diode 30a, and the two light emitting points e1 and e3 can be brought closer to each other. Furthermore, by arranging the light emitting point e2 between the two light emitting points e1 and e3 in the height direction, the two light emitting points e1 and e2 can be brought closer to each other, and the two light emitting points e2 and e3 can be brought closer to each other. As a result, the three light emitting points e1, e2, and e3 can be arranged in a triangular shape close to each other. For example, the three light emitting points e1, e2, and e3 can be located within the range of a circle whose diameter is the narrowest width among the widths of the three laser diodes 30a, 30b, and 30c. The diameter of the circle can be, for example, 0.05 mm or more and 0.4 mm or less. The three light emitting points e1, e2, and e3 can be brought closer to each other to a distance of 0.15 mm or less.

[0060] FIG. 13 is a cross-sectional view parallel to the YZ plane of the light source device 101 according to this embodiment. As in the first embodiment, a part of each end face of the submounts 20, 21, and 22 may be in contact with the incident surface 50c. Specifically, the submount 22 has an end face 22e including an inclined surface 22s on the side where the incident surface 50c of the light-transmitting portion 50F is located. A part of the end face 20e other than the inclined surface 20s is in contact with the incident surface 50c, and a part of the end face 21e other than the inclined surface 21s is in contact with the incident surface 50c. Furthermore, a part of the end face 22e other than the inclined surface 22s may be in contact with the incident surface 50c. This provides an advantage that the position of the light-emitting point of the laser diode 30 mounted on each submount in the Z direction can be easily adjusted.

[0061] Due to mounting space restrictions, it may be difficult to bring all of the end faces of the submounts bonded to the mounting surface of the same substrate into contact with the incident surface of the light-transmitting portion. In such a case, it is sufficient to bring at least one end face of the submounts into contact with the incident surface preferentially. The remaining submounts can be mounted based on the submount that has a part of its end face in contact with the incident surface, thereby adjusting the position of the light-emitting point of the laser diode in the Z direction.

[0062] A first contact surface fcs is formed by a portion of the end surface 20e of the submount 20 being in contact with the incident surface 50c. The first contact surface fcs is spaced apart from the mounting surface 10a. A second contact surface scs is formed by a portion of the end surface 21e of the submount 21 being in contact with the incident surface 50c. The second contact surface scs is spaced apart from the mounting surface 11a. Furthermore, a third contact surface tcs may be formed by a portion of the end surface 22e of the submount 22 being in contact with the incident surface 50c. The third contact surface tcs is spaced apart from the mounting surface 10a. By spaced apart the first contact surface fcs, the second contact surface scs and the third contact surface tcs from the mounting surfaces 10a and 11a, respectively, a space is provided for the bonding material to escape.

[0063] 14 is a cross-sectional view parallel to the XY plane of another configuration example of the light source device 101 according to this embodiment. The cross section includes the emission end faces of the four laser diodes 30a, 30b, 30c, and 30d.

[0064] The light source device 101 may further include a fourth submount 23 and a fourth laser diode 30d. Hereinafter, the fourth submount will be simply referred to as a "submount" like the first to third submounts, and the fourth laser diode will be simply referred to as a "laser diode" like the first to third laser diodes. The laser diode 30d may be directly or indirectly supported on the mounting surface 11a. The laser diode 30d in this embodiment emits infrared light. This realizes a light source device in which four laser diodes 30 that emit the three primary colors of RGB and infrared light are mounted in one package. The laser diode 30d that emits infrared light may be used, for example, as a laser diode for distance measurement.

[0065] The submount 23 is bonded to the mounting surface 11a. The laser diode 30d is mounted face-down on the mounting surface 23a of the submount 23 while being fixed to the submount 23. As shown in Fig. 14, the submount 23 may be disposed on the mounting surface 11a adjacent to the submount 21. The submount 23 is thicker than the submount 21. The thicknesses of the four submounts 20, 21, 22 and 23 may differ from one another.

[0066] The height distance from the mounting surface 10a to the light emitting point e4 of the laser diode 30d is equal to or greater than the height distance from the mounting surface 10a to the light emitting point e1 of the laser diode 30a, and is shorter than the height distance from the mounting surface 10a to the light emitting point e3 of the laser diode 30c. The laser diodes 30b and 30d are preferably arranged such that the heights of the two light emitting points e2 and e4 from the mounting surface 10a are aligned.

[0067] In the example of FIG. 14, the light emitting point e4 of the laser diode 30d that emits infrared rays is closer to the side where the laser diodes 30a, 30b, or 30c are located, with the center of the laser diode 30d as the reference. By adjusting the thickness of the submount 23, the positioning of the light emitting point e4 of the laser diode 30d becomes easier, and the four light emitting points e1, e2, e3, and e4 can be brought closer to each other. The four light emitting points e1, e2, e3, and e4 can be located within a circle whose diameter is the narrowest width among the widths of the four laser diodes 30a, 30b, 30c, and 30d. For example, the diameter of the circle can be 0.05 mm or more and 0.4 mm or less. The four light emitting points e1, e2, e3, and e4 can be brought closer to each other to a distance of 0.15 mm or less. [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: first submount, 21: second submount, 22: third submount, 23: fourth submount, 30a: first laser diode, 30b: second laser diode, 30c: third laser diode, 30d: fourth laser diode, 40a, 40b, 40c: protective element, 50: frame, 50F: light transmitting portion, 60: heat sink, 70: Peltier element, 100: light source device, 101: light source device, 200: collimating lens, e1, e2, e3: light emitting point, 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 second laser diode supported directly or indirectly on the first mounting surface; a third laser diode supported directly or indirectly on the second mounting surface; a frame that defines a space for accommodating the first laser diode, the second laser diode, and the third laser diode and is in contact with the first mounting surface and the second mounting surface; Equipped with an emission point of the third laser diode is located between an emission point of the first laser diode and an emission point of the second laser diode in a width direction; In a plan view seen from a direction perpendicular to the first mounting surface, at least one of the first laser diode and the second laser diode at least partially overlaps the third laser diode.

2. 2. The light source device of claim 1, wherein the widthwise distance from the light emitting point of the first laser diode to the second laser diode is shorter than the widthwise distance from the center of the first laser diode to the second laser diode, or the widthwise distance from the light emitting point of the second laser diode to the first laser diode is shorter than the widthwise distance from the center of the second laser diode to the first laser diode.

3. 3. The light source device according to claim 1, wherein a width of a gap formed between said first laser diode and said second laser diode is equal to or smaller than a width of said third laser diode.

4. the third laser diode is disposed opposite the first laser diode, 4. The light source device according to claim 3, wherein a height distance from the first mounting surface to the light emitting point of the second laser diode is equal to or greater than a height distance from the first mounting surface to the light emitting point of the first laser diode, and is shorter than a height distance from the first mounting surface to the light emitting point of the third laser diode.

5. the first laser diode is directly or indirectly mounted face-up on the first mounting surface, The light source device according to claim 4 , wherein the third laser diode is mounted face-up directly or indirectly on the second mounting surface.

6. a first submount bonded to the first mounting surface and having the first laser diode disposed thereon; a second submount bonded to the second mounting surface and having the third laser diode disposed thereon; Equipped with the first laser diode is mounted face-up on a mounting surface of the first submount; 6. The light source device according to claim 5, wherein the third laser diode is mounted face-up on a mounting surface of the second submount.

7. The light source device according to claim 6 , wherein the second laser diode is bonded to a mounting surface of the first submount.

8. a third submount bonded to the first mounting surface and on which the second laser diode is disposed; The second laser diode is mounted face-down on the mounting surface of the third submount. And, The light source device of claim 6 , wherein the third submount is thicker than the first submount.

9. 9. The light source device according to claim 1, wherein the first laser diode, the second laser diode, and the third laser diode each have a different emission peak wavelength from one another.

10. 9. The light source device according to claim 8, wherein the second laser diode emits red light.

11. 11. The light source device according to claim 10, wherein the first laser diode emits green light and the third laser diode emits blue light.

12. 12. The light source device according to claim 1, wherein the optical axis of the laser light emitted from the first laser diode, the optical axis of the laser light emitted from the second laser diode, and the optical axis of the laser light emitted from the third laser diode are located within a circular range having a diameter equal to the narrowest width among the widths of the first laser diode, the second laser diode, and the third laser diode.

13. a fourth laser diode supported directly or indirectly on the second mounting surface; 12. The light source device according to claim 10, wherein a height distance from the first mounting surface to the light emitting point of the fourth laser diode is equal to or greater than a height distance from the first mounting surface to the light emitting point of the first laser diode, and is shorter than a height distance from the first mounting surface to the light emitting point of the third laser diode.

14. The light source device according to claim 13 , wherein the fourth laser diode emits infrared light.

15. 15. The light source device according to claim 13, further comprising a fourth submount bonded to the second mounting surface, the fourth submount having the fourth laser diode disposed thereon.

16. The frame body includes a light-transmitting portion that transmits laser light emitted from each laser diode, the light transmitting portion has an incident surface onto which the laser light emitted from each laser diode is incident and an exit surface from which the laser light emitted from each laser diode exits, The light source device according to claim 6 , wherein a portion of each end surface of the first submount and the second submount is in contact with the incident surface.

17. a first contact surface is formed by a portion of an end surface of the first submount being in contact with the incidence surface, the first contact surface being spaced from the first mounting surface; The light source device according to claim 16 , wherein a part of an end surface of the second submount and the incident surface are in contact with each other to form a second contact surface, the second contact surface being spaced apart from the second mounting surface.

18. a first wiring layer is disposed between the first submount and the first substrate and between the frame and the first substrate, and a groove formed in the first wiring layer separates the first contact surface from the first mounting surface; 18. The light source device of claim 17, wherein a second wiring layer is disposed between the second submount and the second substrate, and between the frame and the second substrate, and a groove formed in the second wiring layer separates the second contact surface from the second mounting surface.

19. 19. The light source device according to claim 1, comprising a single lens that collimates the laser light emitted from the first laser diode, the laser light emitted from the second laser diode, and the laser light emitted from the third laser diode.

20. A light source device as described in any one of claims 1 to 19, wherein the first laser diode, the second laser diode and the third laser diode are hermetically sealed in the space by the first substrate, the second substrate and the frame body.

Images