Semiconductor laser device

Abstract

To provide a semiconductor laser device with higher reliability which is suitable for space beam coupling.SOLUTION: A semiconductor laser device comprises: a support substrate which has a plurality of mounting surfaces, and in which the heights of the plurality of mounting surfaces from a reference plane gradually or continuously reduce along a first direction; a first semiconductor laser element which is directly or indirectly fixed to a first mounting surface, and which emits a first laser beam in a second direction intersecting the first direction in plan view from the normal direction of the reference plane; a second semiconductor laser element which is directly or indirectly fixed to a second mounting surface, and which emits a second laser beam in the second direction in plan view; and a first sealing cover which has a lateral wall surrounding the first semiconductor laser element and the second semiconductor laser element, and in which the lower end of the lateral wall is bonded to the support substrate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a semiconductor laser device. [Background technology]

[0002] In recent years, with the increasing power output of semiconductor laser elements (also called "laser diodes"), technology is being developed that uses semiconductor laser elements not as excitation light sources but as light sources of laser beams that directly irradiate materials for processing. This technology is called direct diode laser (DDL) technology.

[0003] Patent Document 1 discloses an example of a laser light source that combines multiple laser beams emitted from multiple semiconductor laser elements to increase the optical output. The combination of multiple laser beams is called "spatial beam combining" and can be used to increase the optical output of, for example, a pumping light source of a fiber laser device and a DDL device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent No. 7,733,932 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for a semiconductor laser device that can reduce the volume of the region for sealing a plurality of semiconductor laser elements. [Means for solving the problem]

[0006] In an embodiment, a semiconductor laser device according to the present disclosure includes a support base having a plurality of mounting surfaces arranged in a first direction, the heights of the plurality of mounting surfaces from a reference plane parallel to the first direction decreasing stepwise or continuously along the first direction; a first semiconductor laser element fixed directly or indirectly to a first mounting surface of the plurality of mounting surfaces, the first semiconductor laser element emitting a first laser light in a second direction intersecting the first direction in a plan view from a normal direction to the reference plane; and a second semiconductor laser element fixed directly or indirectly to a second mounting surface of the plurality of mounting surfaces, the second semiconductor laser element emitting a second laser light in the second direction in the plan view. a first slow-axis collimating lens fixed directly or indirectly to the first mounting surface and provided at a position where the first laser light is incident, a second slow-axis collimating lens fixed directly or indirectly to the second mounting surface and provided at a position where the second laser light is incident, and a first sealing cover having a sidewall surrounding the first semiconductor laser element and the second semiconductor laser element, a lower end of the sidewall being joined to the support base, defining an interior that accommodates the first semiconductor laser element and the second semiconductor laser element, and having a light-transmitting region that transmits the first laser light and the second laser light. Each of the multiple mounting surfaces has a first region covered by the first sealing cover and a second region located outside the first sealing cover. Effect of the Invention

[0007] According to the embodiments of the present disclosure, a semiconductor laser device capable of reducing the volume of a region for sealing a plurality of semiconductor laser elements can be provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a top view showing an example of a basic configuration of a semiconductor laser device according to a first embodiment of the present disclosure. [Diagram 2]FIG. 2 is a schematic cross-sectional view of the semiconductor laser device taken along line II-II in FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view of the semiconductor laser device taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic cross-sectional view of the semiconductor laser device taken along line IV-IV in FIG. [Figure 5A] FIG. 5A is a perspective view that illustrates a schematic configuration example of a light source within a sealing cover in an embodiment of the present disclosure. [Figure 5B] FIG. 5B is a top view that illustrates the light source of FIG. 5A. [Figure 5C] FIG. 5C is a cross-sectional view of the light source shown in FIG. 5B taken along line VC-VC parallel to the YZ plane. [Figure 5D] FIG. 5D is a rear view that illustrates the light source of FIG. 5A. [Figure 6] FIG. 6 is a top view diagrammatically illustrating a configuration example of a semiconductor laser device according to the second embodiment of the present disclosure. [Figure 7] FIG. 7 is a perspective view of a semiconductor laser device according to the third embodiment of the present disclosure. [Figure 8] FIG. 8 is a perspective view showing a state in which the top surfaces of the first sealing cover and the second sealing cover have been removed from the semiconductor laser device of FIG. [Figure 9] FIG. 9 is a top view of the semiconductor laser device of FIG. [Figure 10] FIG. 10 is a side view of the semiconductor laser device of FIG. 7 as viewed from the negative direction of the Z axis. [Figure 11] FIG. 11 is a side view of the semiconductor laser device of FIG. 7 as viewed from the negative direction of the X-axis. [Figure 12] FIG. 12 is a diagram illustrating a step on the mounting surface of the support base provided in the semiconductor laser device of FIG. [Figure 13] FIG. 13 is a top view of the semiconductor laser device in the state shown in FIG. [Figure 14] FIG. 14 is a diagram showing a configuration example of a direct diode laser (DDL) device including a semiconductor laser device according to the present disclosure. [Figure 15]FIG. 15 is a diagram illustrating a configuration example of a fiber laser device including a semiconductor laser device according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Embodiment 1> FIG. 1 is a diagram showing a basic configuration example of a semiconductor laser device 100 in this embodiment, and is a schematic top view of the semiconductor laser device 100 as viewed from a normal direction of the XZ plane. However, FIG. 1 is a top view showing a state in which an upper surface portion 33 of a first sealing cover 30 described later is removed. FIG. 2 is a schematic cross-sectional view of the semiconductor laser device 100 taken along line II-II in FIG. 1. FIG. 3 is a schematic cross-sectional view of the semiconductor laser device 100 taken along line III-III in FIG. 1. FIG. 4 is a schematic cross-sectional view of the semiconductor laser device 100 taken along line IV-IV in FIG. 1.

[0010] In the illustrated example, the semiconductor laser device 100 includes a support base 10, a first semiconductor laser element LD1, a second semiconductor laser element LD2, a first slow-axis collimating lens SAC1, a second slow-axis collimating lens SAC2, a first fast-axis collimating lens FAC1, a second fast-axis collimating lens FAC2, and a first sealing cover 30. In the present disclosure, when a reference symbol "Z" is used to collectively refer to a plurality of members, parts, or elements, reference symbols such as "Z1", "Z2", ... are used to distinguish individual parts or elements. For example, "LD" may be used as a reference symbol for a group including a plurality of semiconductor laser elements. Reference symbols such as "LD1", "LD2", ... are used to distinguish individual semiconductor laser elements. The same applies to other members.

[0011] The beam cross-sectional shape of the laser light emitted from the end face of the semiconductor laser element LD is asymmetric with respect to the beam central axis. In the beam cross-sectional shape (far-field pattern) at a position away from the end face of the semiconductor laser element LD, the size in the semiconductor lamination direction of the semiconductor laser element LD is larger than the size in the direction perpendicular thereto. For this reason, the semiconductor lamination direction is called the "fast axis direction" and the direction perpendicular to the fast axis direction is called the "slow axis direction". However, since the laser beam may be reflected by a mirror and change its propagation direction, the terms "fast axis direction" and "slow axis direction" in this disclosure are not necessarily parallel to the "Y axis direction" and "X axis direction" in the global XYZ coordinate system, respectively, and are determined depending on the asymmetry of the beam quality of each laser beam.

[0012] The fast axis collimating lens FAC is a lens that collimates the laser light emitted from the end face of the semiconductor laser element LD in the fast axis direction. In contrast, the slow axis collimating lens SAC is a lens that collimates the laser light emitted from the end face of the semiconductor laser element LD in the slow axis direction. Both the fast axis collimating lens FAC and the slow axis collimating lens SAC are cylindrical lenses (e.g., cylindrical surface plano-convex lenses). A cylindrical lens has a curved surface that converges a parallel bundle of rays onto a straight line (focal point). The curved surface has a shape equivalent to a part of the outer peripheral surface of a cylinder, and the curvature in the axial direction of the cylinder is zero. In this specification, the beam cross-sectional size is expressed as 1 / e with respect to the peak power of the light intensity at the center of the beam. 2 It is defined by the size of the region with a light intensity equal to or greater than e, where e is Napier's constant (approximately 2.71).

[0013] The support base 10 has a plurality of mounting surfaces T arranged in a first direction (X-axis + direction). In the illustrated example of the support base 10, the number of mounting surfaces T is two, but the number may be three or more. In the present disclosure, one of the plurality of mounting surfaces T is referred to as a "first mounting surface T1" and the other is referred to as a "second mounting surface T2". In the illustrated example of the support base 10, the height of the plurality of mounting surfaces T, specifically, the height from a reference plane Ref (see FIG. 2) parallel to the first direction, decreases stepwise along the first direction. In other words, there is a step between adjacent mounting surfaces T. The reference plane Ref is a virtual plane parallel to the XZ plane. In the illustrated example, each of the plurality of mounting surfaces T is parallel to the reference plane Ref. As long as the plurality of mounting surfaces T are parallel to each other, they do not need to be strictly parallel to the reference plane Ref. In this specification, "multiple placement surfaces T are parallel to each other" also includes a case where one placement surface is inclined to the other placement surface by ±0.1 degrees with respect to the rotation direction around the X axis with respect to one placement surface. Note that it is preferable that the inclination of the other placement surface with respect to the rotation direction around the X axis is ±0.02 degrees or less with respect to one placement surface. Also, "multiple placement surfaces T are parallel to each other" also includes a case where the other placement surface is inclined to the one placement surface by ±0.5 degrees with respect to the rotation direction around the Z axis with respect to one placement surface. Note that it is preferable that the inclination of the other placement surface with respect to the rotation direction around the Z axis is ±0.1 degrees or less with respect to one placement surface. In another embodiment, the height of the multiple placement surfaces T may be continuously decreased along the first direction. In that case, the entire multiple placement surfaces T may be configured by a slope that is not parallel to the reference plane Ref.

[0014] The first semiconductor laser element LD1 is fixed directly or indirectly to a first mounting surface T1 of the multiple mounting surfaces T. The first semiconductor laser element LD1 is arranged to emit the first laser light B1 in a second direction (Z-axis + direction) intersecting the first direction (X-axis + direction) in a plan view from the normal direction (Y-axis + direction) of the reference plane Ref. In this example, the first direction and the second direction are perpendicular to each other, but they do not have to be perpendicular to each other. The second semiconductor laser element LD2 is fixed directly or indirectly to a second mounting surface T2 of the multiple mounting surfaces T. The second semiconductor laser element LD2 is arranged to emit the second laser light B2 in the second direction in the above plan view. In this disclosure, the phrase "directly or indirectly fixed" to "any of the multiple mounting surfaces T" means that "at least one other member Y" may or may not be present between the "member X" and "any of the multiple mounting surfaces T". In this plan view, each mounting surface T has a rectangular shape extending parallel to the second direction. However, the shape of each mounting surface T is not limited to this example, and may be a parallelogram or a trapezoid with one interior angle other than 90 degrees.

[0015] A wiring structure for supplying current for driving the first semiconductor laser element LD1 and the second semiconductor laser element LD2 from an external circuit may be provided on the mounting surface T of the support base 10. The wiring structure may include wiring elements such as a wiring layer provided inside the support base 10 or on the mounting surface T, wires supported directly or indirectly by the support base 10, terminal electrodes, and conductor leads. A part or the whole of the wiring structure may be provided on the first sealing cover 30. The first semiconductor laser element LD1 and the second semiconductor laser element LD2 are connected in series or in parallel to an external drive circuit.

[0016] The support base 10 may be formed of ceramics such as aluminum nitride, silicon nitride, aluminum oxide, silicon carbide, or metal materials such as copper, aluminum, or silver, which have better heat dissipation than ceramics. The support base 10 may also be formed of a metal matrix composite material in which diamond particles are dispersed in a metal material such as copper, aluminum, or silver. The support base 10 may be an assembly of multiple parts. Each part may be formed of a different material. The support base 10 is preferably formed of a metal material such as copper, aluminum, or silver, and is preferably made of a single member. Metal materials have higher heat dissipation than ceramics, and are soft, making them easy to process. One or more flow paths for water cooling may be provided inside the support base 10, and a fin structure for air cooling may be provided on the surface of the support base 10. In this manner, the supporting base 10 in this embodiment functions as a support base on which the multiple semiconductor laser elements LD are placed, and can also function as a heat spreader or a heat sink that dissipates heat generated by the multiple semiconductor laser elements LD to suppress an excessive rise in temperature of the semiconductor laser elements LD.

[0017] The first slow axis collimating lens SAC1 is fixed directly or indirectly to the first mounting surface T1 and is provided at a position where the first laser light B1 is incident. The second slow axis collimating lens SAC2 is fixed directly or indirectly to the second mounting surface T2 and is provided at a position where the second laser light B2 is incident. The first slow axis collimating lens SAC1 can be fixed to the first mounting surface T1 via an adhesive, for example. The second slow axis collimating lens SAC2 can also be fixed to the second mounting surface T2 via an adhesive. As the adhesive, for example, Au paste, Ag paste, Cu paste, AuSn solder, resin, Ag nanoparticles, solder foil, etc. can be used.

[0018] The first sealing cover 30 has a side wall 32 and an upper surface portion 33 surrounding the first semiconductor laser element LD1 and the second semiconductor laser element LD2. Specifically, the shape of the first sealing cover 30 may have a side wall 32 having four sides and an upper surface portion 33 connecting the upper ends of the side walls 32. The upper surface portion 33 may be processed from the same material as the side walls 32 and integrally connected, or each may be manufactured as a separate part and assembled. When the upper surface portion 33 and the side walls 32 are separate parts, the upper surface portion 33 may be called a "lid". The first sealing cover 30 may be formed from, for example, a ceramic or metal material. The side walls 32 and the upper surface portion 33 may be formed from the same material, or may be formed from different materials.

[0019] The lower end of the side wall 32 of the first sealing cover 30 is bonded to the support base 10. The first sealing cover 30 defines an interior for accommodating the first semiconductor laser element LD1 and the second semiconductor laser element LD2, and has a light-transmitting region 34 that transmits the first laser light B1 and the second laser light B2. The light-transmitting region 34 is provided between the first semiconductor laser element LD1 and the second semiconductor laser element LD2 and the first slow-axis collimating lens SAC1 and the second slow-axis collimating lens SAC2. In this way, the first semiconductor laser element LD1 and the second semiconductor laser element LD2 can be hermetically sealed by the first sealing cover 30. In the embodiment of the present disclosure, the first sealing cover 30 is bonded to the support base 10, and has a configuration for sealing a plurality of semiconductor laser elements. According to a certain manufacturing method, the first semiconductor laser element LD1 and the second semiconductor laser element LD2 are mounted on the mounting surface T, and then covered by the first sealing cover 30. The first semiconductor laser element LD1 and the second semiconductor laser element LD2 may be mounted on the mounting surface T before the first sealing cover 30 is provided, or may be mounted on the mounting surface T during the provision of the first sealing cover 30. For this reason, the optical axes can be more easily aligned than when the individual semiconductor laser elements are sealed in the semiconductor laser package and then the semiconductor laser packages are mounted on the support base. In addition, it is possible to narrow the center interval between adjacent semiconductor laser elements compared to the case where the individual semiconductor laser elements are accommodated in separate semiconductor laser packages one by one. This makes it possible to arrange a large number of semiconductor laser elements without considering physical interference between the semiconductor laser packages. In addition, since there are no semiconductor laser packages around each semiconductor laser element, it is also possible to obtain a sufficient space around each semiconductor laser element in which an optical member or an electronic element such as a photodiode can be arranged. Furthermore, since the sealing effect can be ensured, it is possible to suppress the decrease in optical output due to the light dust collection effect and improve the reliability of the semiconductor laser device.

[0020] The first sealing cover 30 may be fabricated by joining the lower end of the side wall 32 of the first sealing cover 30 to the first groove 16 of the mounting surface T, and then fixing the upper surface portion 33 of the first sealing cover 30 to the side wall 32. In this case, a step of mounting the first semiconductor laser element LD1 and the second semiconductor laser element LD2 on the mounting surface T may be provided between the step of joining the lower end of the side wall 32 of the first sealing cover 30 to the first groove 16 of the mounting surface T and the step of fabricating the first sealing cover 30 by fixing the upper surface portion 33 of the first sealing cover 30 to the side wall 32. This allows the upper surface portion 33 to be fixed to the side wall 32 and sealed after the optical axis of the laser light emitted by the first semiconductor laser element LD1 and the optical axis of the first slow axis collimating lens SAC1 and the optical axis of the laser light emitted by the second semiconductor laser element LD2 and the optical axis of the second slow axis collimating lens are aligned. That is, the optical axes can be easily aligned and the semiconductor laser element LD can be sealed.

[0021] As shown in FIG. 3 and FIG. 4, each of the multiple mounting surfaces T has a first region 11 covered by the first sealing cover 30 and a second region 12 located outside the first sealing cover 30. In this embodiment, in each of the multiple mounting surfaces T, the height of the first region 11 from the reference plane Ref is equal to the height of the second region 12 from the reference plane Ref. In this specification, "in each of the multiple mounting surfaces T, the height of the first region 11 from the reference plane Ref is equal to the height of the second region 12 from the reference plane Ref" also includes the case where "the height of the first region 11 from the reference plane Ref in each of the multiple mounting surfaces T is within ±1% of the height of the second region 12 from the reference plane Ref in each of the multiple mounting surfaces T". The first semiconductor laser element LD1 and the second semiconductor laser element LD2 are present on the first region 11. In contrast, the first slow axis collimator lens SAC1 and the second slow axis collimator lens SAC2 are present on the second region 12. For example, in the first mounting surface T1, the height of the first region 11 to which the first semiconductor laser element LD1 is fixed is equal to the height of the second region 12, so that the optical axis of the first semiconductor laser element LD1 can be easily aligned with respect to the optical member fixed to the second region 12. This is also true for the second mounting surface T2. In this embodiment, the first region 11 and the second region 12 are configured to be parallel to each other and to be located on the same plane in each mounting surface T. As a result, the optical axes of the components mounted in the first region 11 and the second region 12 can be easily aligned. In this specification, "the first region and the second region are parallel" also includes the case where the second region forms an angle of ±0.1 degrees with respect to the first region.

[0022] The first fast axis collimator lens FAC1 is provided between the first semiconductor laser element LD1 and the first slow axis collimator lens SAC1 at a position where the first laser light B1 emitted from the first semiconductor laser element LD1 is incident. The second fast axis collimator lens FAC2 is provided between the second semiconductor laser element LD2 and the second slow axis collimator lens SAC2 at a position where the second laser light B2 emitted from the second semiconductor laser element LD2 is incident. In the example shown in FIG. 3 and FIG. 4, the side wall 32 of the first sealing cover 30 surrounds the first fast axis collimator lens FAC1 and the second fast axis collimator lens FAC2. In other words, the first sealing cover 30 also seals the first fast axis collimator lens FAC1 and the second fast axis collimator lens FAC2. This allows the first fast axis collimating lens FAC1 to be mounted close to the light-emitting end face of the first semiconductor laser element LD1 without being interfered with by the first sealing cover 30. Similarly, the second fast axis collimating lens FAC2 can be mounted close to the light-emitting end face of the second semiconductor laser element LD2. By shortening the distance between the fast axis collimating lens FAC and the light-emitting end face of the corresponding semiconductor laser element LD, the focal length and size of the fast axis collimating lens FAC can be reduced, and the size of the collimated light in the fast axis direction can be reduced.

[0023] Thus, in this embodiment, the first fast axis collimator lens FAC1 and the second fast axis collimator lens FAC2 are located inside the first sealing cover 30, and the first slow axis collimator lens SAC1 and the second slow axis collimator lens SAC2 are located outside the first sealing cover 30. This allows the semiconductor laser elements to be sealed together while reducing the size of the collimated light in the fast axis direction. By arranging each slow axis collimator lens SAC outside the first sealing cover 30, the volume of the area to be hermetically sealed can be reduced, making hermetically sealing easier. In addition, by arranging the SAC lens outside the first sealing cover 30, the options for adhesives for fixing the SAC lens can be expanded. For example, it is possible to select a resin as the material of the adhesive. Resin can align the optical axis more easily than other adhesives. In addition, resin can fix the SAC lens easily.

[0024] In this embodiment, the support base 10 has a first groove 16 that receives at least a part of the side wall 32 of the first sealing cover 30. A part or the whole of the lower end of the side wall 32 of the first sealing cover 30 is joined to the bottom surface of the first groove 16. It is preferable that the height of the bottom surface of the first groove 16 from the reference plane Ref is constant along the first direction (X-axis + direction). As shown in FIG. 3 and FIG. 4, the depth of the first groove 16 is different for each of the multiple mounting surfaces T, but the height of the bottom surface of the first groove 16 from the reference plane Ref is equal. By providing such a first groove 16 in the support base 10, it is no longer necessary to provide a step corresponding to the step between the mounting surfaces T in the side wall 32 of the first sealing cover 30, and it is possible to make the side wall 32 have a simple shape, such as a roughly rectangular shape. This makes it easier to manufacture the first sealing cover 30, and it is possible to suppress a decrease in sealing strength caused by dimensional deviation of the sealing portion, thereby improving the reliability of sealing. Furthermore, the width of the first groove 16 in the z direction can be, for example, from 2 to 50 times, preferably from 2 to 10 times, the thickness in the z direction of the sidewall 32 of the first sealing cover 30. This allows the width of the first groove 16 to be sufficiently large relative to the thickness of the sidewall 32 of the first sealing cover 30, so that the first sealing cover 30 can be easily joined to the supporting base 10.

[0025] As shown in FIG. 1, FIG. 2, FIG. 3, and FIG. 4, the semiconductor laser device 100 further includes a first submount SB1 supporting the first semiconductor laser element LD1 and a second submount SB2 supporting the second semiconductor laser element LD2. The submounts SB1 and SB2 may each be configured in the shape of a rectangular parallelepiped, for example. The submounts SB1 and SB2 may be formed of, for example, aluminum nitride, silicon carbide, a metal matrix composite material in which diamond particles are dispersed, or graphite. A metal film for bonding to the semiconductor laser element LD or the support base 10 may be provided on the upper and lower surfaces of each of the submounts SB1 and SB2. The submounts SB1 and SB2 and the semiconductor laser, or the submounts and the support base 10 may be bonded by a bonding material. For example, AuSn solder, Ag paste, Cu paste, Au paste, or the like may be used as the bonding material.

[0026] The first submount SB1 has a first lens support member that supports the first fast axis collimating lens FAC1, and the second submount SB2 has a second lens support member that supports the second fast axis collimating lens FAC2. An example of such a configuration will be described in detail below using the first semiconductor laser element LD1 as an example.

[0027] FIG. 5A is an exploded perspective view of the first semiconductor laser element LD1, the first submount SB1, and the first fast axis collimating lens FAC1 sealed by the first sealing cover 30. In this example, the first semiconductor laser element LD1 is bonded to the upper surface of the first submount SB1, the lens support member 52 is bonded to the upper surface of the first submount SB1, and the first fast axis collimating lens FAC1 is fixed to the lens support member 52. The first fast axis collimating lens is fixed to the lens support member 52 via an adhesive. For example, Au paste, Ag paste, Cu paste, AuSn solder, or the like can be used as the adhesive. FIG. 5B is a top view diagrammatically illustrating the configuration of FIG. 5A. FIG. 5C is a VC-VC line cross-sectional view parallel to the YZ plane of the configuration of FIG. 5B. FIG. 5D is a rear view diagrammatically illustrating the configuration of FIG. 5A.

[0028] As shown in FIG. 5A, the first submount SB1 has a principal plane 50T, a back surface 50B, and a front end surface 50F. The first semiconductor laser element LD1 is mounted face-down on the principal plane 50T of the first submount SB1. The emission end surface F of the first semiconductor laser element LD1 is disposed so as to protrude from the first submount SB1. This makes it possible to suppress a part of the laser light emitted from the emission end surface F from being reflected by the first submount. A lens support member 52 supporting the first fast axis collimator lens FAC1 is bonded to the principal plane 50T of the first submount SB1. The lens support member 52 has a pair of fixing portions 52S bonded to the principal plane 50T and a connecting portion 52L connecting the pair of fixing portions 52S. The connecting portion 52L has a shape that straddles the first semiconductor laser element LD1 so as not to impede the propagation of the laser light emitted from the emission end surface F of the first semiconductor laser element LD1.

[0029] In FIG. 5A, the first submount SB1, the lens support member 52, and the first fast axis collimating lens FAC1 are illustrated in a separated state, but in reality, these are joined together.

[0030] The connecting portion 52L overlaps with the emission end face F of the first semiconductor laser element LD1 in the top view of FIG. 5B. As shown in FIG. 5D, the lens support member 52 is disposed on the main plane 50T of the first submount SB1 so as to straddle the first semiconductor laser element LD1. The size of the lens support member 52 in the X direction may be larger or smaller than the size of the first submount SB1 in the X direction. For example, the size of the lens support member 52 in the X direction can be larger than the size of the submount SB1 in the X direction. This increases the area of ​​the end face 52F of the lens support member 52, and the area for bonding the FAC lens 1 to the lens support member 52 can be increased. As a result, the first fast axis collimating lens FAC1 can be easily bonded to the end face 52F of the lens support member 52. The size of the lens support member 52 in the Y direction can be approximately the same as the size of the first fast axis collimating lens FAC1 in the Y direction. The size of the lens support member 52 in the Y direction may be larger than, equal to, or smaller than the size of the fast axis collimator lens FAC1 in the Y direction. The size of the lens support member 52 in the X direction is, for example, 1 mm or more and 2 mm or less, the maximum size in the Y direction is, for example, 0.3 mm or more and 2 mm or less, and the size in the Z direction is, for example, 0.2 mm or more and 1 mm or less.

[0031] A method for fabricating the illustrated configuration may include, for example, a step of bonding the first semiconductor laser element LD1 to the main plane 50T of the first submount SB1, a step of bonding a lens support member 52 to the main plane 50T of the first submount SB1 so as to straddle the first semiconductor laser element LD1, and a step of bonding the first fast axis collimator lens FAC1 to an end face 52F of the lens support member 52, and these steps may be performed in this order. Alternatively, the lens support member 52 to which the first fast axis collimator lens FAC1 is bonded may be bonded to the first submount SB1 to which the first semiconductor laser element LD1 is bonded to the main plane 50T.

[0032] In this example, the first semiconductor laser element LD1 and the lens support member 52 are bonded to the main plane 50T of the first submount SB1, and the first fast axis collimator lens FAC1 is bonded to the end face 52F of the lens support member 52. This makes it possible to narrow the distance between the first semiconductor laser element LD1 and the first fast axis collimator lens FAC1. This makes it possible to reduce the size of the first fast axis collimator lens FAC1. It also makes it possible to reduce the size in the fast axis direction of the laser light B1 collimated in the first fast axis direction.

[0033] The above configuration can be similarly realized for the second semiconductor laser element LD2. Note that the configurations shown in Figures 5A, 5B, 5C, and 5D are merely examples, and the method of fixing the fast axis collimator lens FAC to the submount SB is not limited to the above examples.

[0034] According to this embodiment, the submount SB supporting both the semiconductor laser element LD and the fast axis collimating lens FAC is fixed to the first region 11 of the support base 10, and the slow axis collimating lens SAC and the mirror M are fixed to the second region 12 of the support base 10. In this embodiment, the lower end of the side wall 32 of the first sealing cover 30 is bonded to the first groove 16 of the mounting surface T, and then the submount SB supporting both the semiconductor laser element LD and the fast axis collimating lens FAC is bonded to the support base 10. After that, after the optical axis is aligned, the upper surface portion 33 of the first sealing cover 30 is fixed to the side wall 32, and the semiconductor laser element LD can be sealed in the space defined by the first sealing cover 30. This makes it easy to align the optical axis. In addition, the semiconductor laser element LD can be hermetically sealed to reduce light dust collection.

[0035] As shown in FIG. 1, the semiconductor laser device 100 further includes a beam combining unit 20 that combines the first laser light B1 emitted from the first slow-axis collimating lens SAC1 and the second laser light B2 emitted from the second slow-axis collimating lens SAC2. The beam combining unit 20 includes a first mirror M1 provided in the second region 12 of the first mounting surface T1 and a second mirror M2 provided in the second region 12 of the second mounting surface T2. The first mirror M1 reflects the first laser light B1 in a first direction. The second mirror M2 reflects the second laser light B2 in the first direction. The beam combining unit 20 further includes a condenser lens 42 that combines the first laser light B1 and the second laser light B2 reflected in the first direction into the optical fiber 40. In the illustrated example, the condenser lens 42 includes a fast-axis condenser lens 42a and a slow-axis condenser lens 42b. In this example, the focal length of the fast axis condenser lens 42a is longer than the focal length of the slow axis condenser lens 42b. Therefore, the slow axis condenser lens 42b is disposed closer to the light incident end of the optical fiber 40 than the fast axis condenser lens 42a.

[0036] The first laser light B1 incident on the first mirror M1 is collimated by the first fast axis collimator lens FAC1 and the first slow axis collimator lens SAC1. Similarly, the second laser light B2 incident on the second mirror M2 is collimated by the second fast axis collimator lens FAC2 and the second slow axis collimator lens SAC2. As shown in FIG. 3 and FIG. 4, the height of the first mirror M1 and the height of the second mirror M2 from the reference plane Ref are different from each other. Therefore, the height of the position where the first laser light B1 reflected by the first mirror M1 enters the fast axis condenser lens 42a is different from the height of the position where the second laser light B2 reflected by the second mirror M2 enters the fast axis condenser lens 42a. The difference between these heights is approximately equal to the size of the step between the mounting surface T1 and the mounting surface T2. "Almost equal" means that, for example, the difference between the thickness of the adhesive placed between the first mirror M1 and the support base 10 and the thickness of the adhesive material placed between the second mirror M2 and the support base 10 can be ignored. The mirror M can be fixed to the mounting surface T via an adhesive. For example, AuSn solder, Ag paste, Cu paste, Au paste, resin, etc. can be used as the adhesive. The mirror M may be fixed to the mounting surface T of the support base 10 via a part capable of adjusting the position and orientation of each mirror M. It is desirable that the reflecting surface of the mirror M is formed from a multilayer film having a selectively high reflectance at the wavelength of the incident laser light. An optical part other than the mirror M, for example, a filter having wavelength selectivity, may be arranged on the mounting surface T. The slow axis collimating lens SAC may be fixed to the mounting surface T of the support base 10 via a part capable of adjusting the position and orientation of each mirror M.

[0037] The first semiconductor laser element LD1 and the second semiconductor laser element LD2 may be, for example, a semiconductor laser element that emits purple light, a semiconductor laser element that emits blue light, a semiconductor laser element that emits green light, or a semiconductor laser element that emits red light. Here, the purple light is light whose oscillation wavelength is in the range of 360 nm or more and 420 nm or less. The blue light is light whose emission peak wavelength is in the range of 420 nm or more and 495 nm or less. The green light is light whose emission peak wavelength is in the range of 495 nm or more and 570 nm or less. The red light is light whose emission peak wavelength is in the range of 605 nm or more and 750 nm or less. The semiconductor laser element that emits purple light, the semiconductor laser element that emits blue light, or the semiconductor laser element that emits green light may be a semiconductor laser element containing a nitride semiconductor. For example, GaN, InGaN, and AlGaN may be used as the nitride semiconductor. Examples of semiconductor laser elements that emit red light include InAlGaP-based, GaInP-based, GaAs-based, and AlGaAs-based semiconductors.

[0038] According to the semiconductor laser device 100 of this embodiment, it is possible to reduce the volume of the region in which a plurality of semiconductor laser elements are sealed.

[0039] Furthermore, according to the semiconductor laser device 100 of this embodiment, the reliability is improved by the sealing structure that makes it easy to align the optical axis of the semiconductor laser element and the optical axis of the slow axis collimating lens, and it becomes possible to optically couple laser light emitted from multiple semiconductor laser elements to one optical fiber.

[0040] <Embodiment 2> Next, another embodiment of the semiconductor laser element of the present disclosure will be described. Fig. 6 is a top view that shows a schematic configuration example of a semiconductor laser device 200 in this embodiment. However, Fig. 6 is a top view showing a state in which a top surface portion 63 of a second sealing cover 60 described later is removed.

[0041] 1, the semiconductor laser device 200 further includes a third semiconductor laser element LD3, a fourth semiconductor laser element LD4, a third slow axis collimating lens SAC3, a fourth slow axis collimating lens SAC4, and a second sealing cover 60. The semiconductor laser device 200 in this example also includes a third fast axis collimating lens FAC3 and a fourth fast axis collimating lens FAC4.

[0042] The third semiconductor laser element LD3 and the fourth semiconductor laser element LD4 may have the same structure and shape as the first semiconductor laser element LD1 and the second semiconductor laser element LD2 described above. Also, the third slow axis collimator lens SAC3, the fourth slow axis collimator lens SAC4, the third fast axis collimator lens FAC3, the fourth fast axis collimator lens FAC4, and the second sealing cover 60 may have the same structure and shape as the first slow axis collimator lens SAC1, the second slow axis collimator lens SAC2, the first fast axis collimator lens FAC1, the second fast axis collimator lens FAC2, and the first sealing cover 30 in the semiconductor laser device 100, respectively.

[0043] The third semiconductor laser element LD3 is fixed directly or indirectly to a first mounting surface T1 of the multiple mounting surfaces T. The third semiconductor laser element LD3 is arranged so as to emit the third laser light B3 in the opposite direction (Z axis − direction) to the second direction (Z axis + direction) in a plan view from the normal direction (Y axis + direction) of the reference plane Ref. The fourth semiconductor laser element LD4 is fixed directly or indirectly to a second mounting surface T2 of the multiple mounting surfaces T. The fourth semiconductor laser element LD4 is arranged so as to emit the fourth laser light B4 in the opposite direction (Z axis − direction) to the second direction (Z axis + direction) in the above plan view.

[0044] The third slow-axis collimating lens SAC3 is directly or indirectly fixed to the first mounting surface T1 and is provided at a position where the third laser light B3 is incident. The fourth slow-axis collimating lens SAC4 is directly or indirectly fixed to the second mounting surface T2 and is provided at a position where the fourth laser light B4 is incident.

[0045] The second sealing cover 60 has a side wall 62 surrounding the third semiconductor laser element LD3 and the fourth semiconductor laser element LD4. The lower end of the side wall 62 is joined to the support base 10. The second sealing cover 60 defines an interior that accommodates the third semiconductor laser element LD3 and the fourth semiconductor laser element LD4, and has a light-transmitting region 64 that transmits the third laser light B3 and the fourth laser light B4. In this way, the third semiconductor laser element LD3 and the fourth semiconductor laser element LD4 can be hermetically sealed by the second sealing cover 60. In the embodiment of the present disclosure, the first sealing cover 30 and the second sealing cover 60 are each joined to the support base 10, and have a configuration that seals a plurality of semiconductor laser elements. According to a certain manufacturing method, the third semiconductor laser element LD3 and the fourth semiconductor laser element LD4 are each mounted on the mounting surface T and then covered by the second sealing cover 60. The third semiconductor laser element LD3 and the fourth semiconductor laser element LD4 may be mounted on the mounting surface T before the second sealing cover 60 is provided, or may be mounted on the mounting surface T during the process of providing the second sealing cover 60.

[0046] Each of the multiple placement surfaces T has a third region 13 covered by a second sealing cover 60, and the second region 12 is located between the first region 11 and the third region 13.

[0047] In this embodiment, the height of the third region 13 from the reference plane Ref on each of the multiple mounting surfaces T is equal to the height of the second region 12 from the reference plane Ref on each of the multiple mounting surfaces T. The third semiconductor laser element LD3 and the fourth semiconductor laser element LD4 are present on the third region 13. In contrast, the third slow axis collimating lens SAC3 and the fourth slow axis collimating lens SAC4 are present on the second region 12.

[0048] The third fast axis collimator lens FAC3 is provided between the third semiconductor laser element LD3 and the third slow axis collimator lens SAC3 at a position where the third laser light B3 emitted from the third semiconductor laser element LD3 is incident. The fourth fast axis collimator lens FAC4 is provided between the fourth semiconductor laser element LD4 and the fourth slow axis collimator lens SAC4 at a position where the fourth laser light B4 emitted from the fourth semiconductor laser element LD4 is incident. In the example shown in FIG. 6, the side wall 62 of the second sealing cover 60 surrounds the third fast axis collimator lens FAC3 and the fourth fast axis collimator lens FAC4. In other words, the second sealing cover 60 also seals the third fast axis collimator lens FAC3 and the fourth fast axis collimator lens FAC4. This allows the third fast axis collimating lens FAC3 to be mounted close to the light emitting end surface of the third semiconductor laser element LD3 without being interfered with by the second sealing cover 60. Similarly, the fourth fast axis collimating lens FAC4 can be mounted close to the light emitting end surface of the fourth semiconductor laser element LD4.

[0049] Thus, in this embodiment, the third fast axis collimator lens FAC3 and the fourth fast axis collimator lens FAC4 are located inside the second sealing cover 60, and the third slow axis collimator lens SAC3 and the fourth slow axis collimator lens SAC4 are located outside the second sealing cover 60. This makes it possible to seal each semiconductor laser element collectively while reducing the size of the collimated light in the fast axis direction. By arranging each slow axis collimator lens SAC outside the second sealing cover 60, the volume of the area to be hermetically sealed can be reduced, making it easier to hermetically seal.

[0050] In this embodiment, the supporting base 10 has a second groove 18 that receives at least a part of the side wall 62 of the second sealing cover 60. A part or the whole of the lower end of the side wall 62 of the second sealing cover 60 is joined to the bottom surface of the second groove 18. Similarly to the first groove 16, the height of the bottom surface of the second groove 18 from the reference plane Ref is also preferably constant along the first direction (X-axis + direction).

[0051] 6, the semiconductor laser device 200 in this embodiment further includes a third submount SB3 supporting the third semiconductor laser element LD3 and a fourth submount SB4 supporting the fourth semiconductor laser element LD4. The third submount SB3 and the fourth submount SB4 have the same configuration as the first submount SB1 and the second submount SB2, respectively, and may be made of the same material.

[0052] By utilizing the above-mentioned lens support members, the third submount SB3 can support the third fast axis collimating lens FAC3, and the fourth submount SB4 can support the fourth fast axis collimating lens FAC4.

[0053] The beam combining unit 20 in this embodiment includes a third mirror M3 provided in the second region 12 of the first mounting surface T1 and a fourth mirror M4 provided in the second region 12 of the second mounting surface T2. The third mirror M3 reflects the third laser light B3 in a first direction. The fourth mirror M4 reflects the fourth laser light B4 in the first direction. The beam combining unit 20 further includes a mirror 44 that guides the third laser light B3 reflected by the third mirror M3 and the fourth laser light B4 reflected by the fourth mirror M4 to the condenser lens 42 (fast axis condenser lens 42a, slow axis condenser lens 42b), a 1 / 2 wavelength plate 46, and a beam combining element 48. The 1 / 2 wavelength plate 46 is disposed between the mirror 44 and the beam combining element 48.

[0054] The mirror 44 has a reflecting surface of a shape and size for receiving the third laser light B3 reflected by the third mirror M3 and the fourth laser light B4 reflected by the fourth mirror M4. The mirror 44 reflects the third laser light B3 reflected by the third mirror M3 and the fourth laser light B4 reflected by the fourth mirror M4 toward the beam combining element 48.

[0055] The half-wave plate 46 rotates the polarization direction of the third laser light B3 and the fourth laser light B4 by 90 degrees around an axis parallel to the Z axis when passing through the half-wave plate 46. The optical axis of the half-wave plate 46 is inclined at 45 degrees with respect to the polarization direction of the laser light reflected by the mirror 44. In this embodiment, the polarization direction of the laser light reflected by the mirror 44 is parallel to the X axis. The optical axis of the half-wave plate 46 is parallel to the XY plane and faces a direction intersecting the XZ plane at 45 degrees. Therefore, the polarization direction of the laser light reflected by the mirror 44 rotates by 90 degrees around an axis parallel to the Z axis when passing through the half-wave plate 46. As a result, the polarization direction of the laser light reflected by the mirror 44 when it enters the beam combining element 48 is parallel to the Y axis.

[0056] The beam combining element 48 has a configuration similar to that of a polarizing beam splitter. Specifically, the laser light whose polarization direction is parallel to the Y axis is reflected, but the laser light whose polarization direction is parallel to the Z axis is transmitted. Therefore, the laser light from the semiconductor laser element LD sealed by the first sealing cover 30 and the laser light from the semiconductor laser element LD sealed by the second sealing cover 60 are both incident on the condenser lens 42. Therefore, the beam combining element 48 reflects the third laser light B3 and the fourth laser light B4 reflected by the mirror 44 in the first direction and directs them to the condenser lens 42, and the beam combining element 48 transmits the first laser light B1 reflected by the first mirror M1 and the second laser light B2 reflected by the second mirror M2 and directs them to the condenser lens 42. In this way, these laser lights are optically coupled to the optical fiber 40 by the condenser lens 42.

[0057] As is clear from the above description, the multiple mounting surfaces T of the semiconductor laser device 200 and the multiple electronic and optical components arranged on the multiple mounting surfaces T have a roughly symmetrical arrangement with respect to the XY plane of FIG. 6.

[0058] In this embodiment, the first semiconductor laser element LD1, the second semiconductor laser element LD2, the third semiconductor laser element LD3, and the fourth semiconductor laser element LD4 oscillate laser light of any one of green light, blue light, and violet light. Moreover, it is preferable that each semiconductor laser element LD oscillates laser light of the same color among green light, blue light, and violet light. By oscillating light of the same color, the optical design of each lens or beam combining element 48, etc. becomes easier, and the laser light can be efficiently focused on the optical fiber 40.

[0059] According to the semiconductor laser device 200 of this embodiment, in addition to the effects described for the semiconductor laser device 100, the following effects can be obtained.

[0060] By increasing the number of semiconductor laser elements arranged in the first direction (X-axis + direction) to two rows, it is possible to increase the number of semiconductor laser elements mounted on the support base 10 without increasing the size of the support base in the first direction. By increasing the number of semiconductor laser elements, the intensity of the laser light coupled to the optical fiber can be increased.

[0061] Instead of covering all the semiconductor laser elements on the support base with one sealing cover, groups of semiconductor laser elements arranged in different regions are covered with two different sealing covers, so that the sealing space can be divided into relatively narrow portions, which can improve the reliability of sealing.

[0062] All the semiconductor laser elements on the support base are not integrated in one area, but are arranged in two areas on opposite sides of the support base, so the heat generated by the semiconductor laser elements during operation is easily dissipated. This makes it possible to suppress excessive temperature rise in the semiconductor laser elements, improve operational reliability, and extend the element life.

[0063] <Embodiment 3> Next, still another embodiment of the semiconductor laser device according to the present disclosure will be described with reference to Figs. 7 to 13. Fig. 7 is a perspective view of the semiconductor laser device 300 in this embodiment. Fig. 8 is a perspective view showing a state in which the upper surface portion 33 of the first sealing cover 30 and the upper surface portion 63 of the second sealing cover 60 are removed from the semiconductor laser device 300. Fig. 9 is a top view of the semiconductor laser device 300. Fig. 10 is a side view of the semiconductor laser device 300 seen from the negative direction of the Z axis. Fig. 11 is a side view of the semiconductor laser device 300 seen from the negative direction of the X axis. Fig. 12 is a diagram showing a schematic diagram of a step on the mounting surface T of the support base 10. Fig. 13 is a top view of the semiconductor laser device 300 in the state shown in Fig. 8.

[0064] The semiconductor laser device 300 basically has the same configuration as the semiconductor laser device 200. The first difference is in the number of the semiconductor laser elements LD, the fast axis collimating lenses FAC, the slow axis collimating lenses SAC, and the mirrors M. For example, the number of the semiconductor laser elements LD in the semiconductor laser device 300 is 11×2=22, which is more than the number of the semiconductor laser elements LD in the semiconductor laser device 200. The peak wavelengths of the laser light emitted by the semiconductor laser elements LD are all almost the same (for example, about 465 nm±10 nm). The second difference is that the support base 10 has a first portion 10A, a second portion 10B, a third portion 10C, and a fourth portion 10D, as shown in FIG. 11. This will be described later.

[0065] In the semiconductor laser device 300, eleven semiconductor laser elements LD are accommodated and sealed inside the first sealing cover 30. The upper surface portion 33 of the first sealing cover 30 has, for example, a rectangular shape with a short side length of 6 mm to 12 mm and a long side length of 20 mm to 40 mm. The height of the side wall 32 is, for example, 5 mm to 12 mm. The length of the long side is determined according to the number of semiconductor laser elements LD sealed by the first sealing cover 30. Therefore, the length of the long side is not limited to the above-mentioned length. The side wall 32 and the upper surface portion 33 of the first sealing cover 30 in this embodiment are formed of, for example, a metal material such as Kovar or a general ceramic material. The thickness of the side wall 32 and the upper surface portion 33 of the first sealing cover is, for example, 0.1 mm to 1 mm. On one surface of the side wall 32 of the first sealing cover 30, there is a thick portion 36 with a thickness of, for example, 0.2 mm to 2 mm. In the example shown in FIG. 7, the thick portion 36 is provided with eleven holes arranged along the first direction (X-axis + direction), and eleven conductive leads 35 penetrate these holes. The center-to-center distance of the holes in the first direction is 1 mm or more and 4 mm or less. The center-to-center distance of the holes may coincide with the center-to-center distance of the semiconductor laser elements LD in the first direction. One of the p-side electrode and the n-side electrode of each semiconductor laser element LD may be electrically connected to a corresponding one conductive lead 35 via a wire. The other of the p-side electrode and the n-side electrode may be electrically connected to a common wiring provided on the mounting surface T, for example. With this configuration, each of the semiconductor laser elements LD sealed by the first sealing cover 30 can be independently driven by an external circuit. The semiconductor laser elements LD sealed by the first sealing cover 30 may be connected in series. In that case, two conductive leads 35 are sufficient.

[0066] Similarly, eleven semiconductor laser elements LD are accommodated inside the second sealing cover 60. The number of semiconductor laser elements LD accommodated inside the second sealing cover 60 may be different from the number of semiconductor laser elements LD accommodated inside the first sealing cover 30. A thick portion 66 is present on one surface of the side wall 62 of the second sealing cover. The thick portion 66 is provided with eleven holes arranged along the first direction (X-axis + direction), and eleven conductive leads 65 penetrate these holes. In this embodiment, the shapes of the first sealing cover 30 and the second sealing cover 60 are symmetrical with respect to the XY plane. The material and dimensions of the second sealing cover 60 may be the same as the material and dimensions of the first sealing cover 30. One of the p-side electrode and the n-side electrode of each semiconductor laser element LD may be electrically connected to a corresponding conductive lead 65 via a wire. The other of the p-side electrode and the n-side electrode may be electrically connected to a common wiring provided on the mounting surface T, for example. With this configuration, each of the semiconductor laser elements LD sealed by the second sealing cover 60 can be driven independently by an external circuit. The semiconductor laser elements LD sealed by the second sealing cover 60 may be connected in series. In this case, two conductive leads 65 are sufficient.

[0067] As described above, the support base 10 in this embodiment has the first portion 10A, the second portion 10B, the third portion 10C, and the fourth portion 10D (see FIG. 11). The first portion 10A is located in a space sealed by the first sealing cover 30. The second portion 10B is located in a space sealed by the second sealing cover 60. The third portion 10C is located between the first portion 10A and the second portion 10B. A first groove 16 is present between the third portion 10C and the first portion 10A. A second groove 18 is present between the third portion 10C and the second portion 10B. The first groove 16 and the second groove 18 each reach from the mounting surface T to the upper surface of the fourth portion 10D. The width of each of the first groove 16 and the second groove 18 in the z direction is, for example, in the range of 0.2 mm to 5 mm.

[0068] According to this embodiment, the first sealing cover 30 and the second sealing cover 60, which are two sealing covers, separately seal the first portion 10A and the second portion 10B of the support base 10, so that the sealed volume can be reduced compared to sealing them in a single space, and airtightness can be easily maintained. Therefore, the light dust collection effect can be suppressed.

[0069] The fourth portion 10D of the support base 10 is a base plate that supports the first portion 10A, the second portion 10B, and the third portion 10C. The fourth portion 10D can function as a heat sink. The fourth portion 10D has a pair of flow paths 72 that extend along the first direction (X-axis + direction) below the first portion 10A and the second portion 10B. Cooling water flows through the inside of the flow paths 72, thereby enhancing the function of the support base 10 as a heat sink.

[0070] As shown in FIG. 12, the first portion 10A has a stepped upper surface (first region 11 of the mounting surface T). Similarly, the second portion 10B has a stepped upper surface (third region 13 of the mounting surface T). The third portion 10C has a stepped upper surface (second region 12 of the mounting surface T). The fourth portion 10D has a flat upper surface on which the first portion 10A, the second portion 10B, and the third portion 10C are placed. The upper surface of the fourth portion 10D is joined to the lower end of the side wall 32 of the first sealing cover 30 and the lower end of the side wall 62 of the second sealing cover 60. The size of the step of the mounting surface T (i.e., the difference in height between adjacent mounting surfaces T) can be, for example, in the range of 0.2 mm to 1 mm.

[0071] The first portion 10A, the second portion 10B, the third portion 10C, and the fourth portion 10D are preferably each formed from a material having a high thermal conductivity. These portions may all be formed from the same material. Also, only the fourth portion 10D may be formed from a material different from the other portions 10A, 10B, and 10C. It is preferable that the first portion 10A, the second portion 10B, the third portion 10C, and the fourth portion 10D are all formed from the same material. This can reduce peeling between the portions caused by differences in thermal expansion coefficient.

[0072] In this embodiment, the first portion 10A, the second portion 10B, and the third portion 10C are joined to the fourth portion 10D. This joining may be realized through a joining material such as an alloy, or may be realized by welding. The support base 10 including these portions 10A, 10B, 10C, and 10D may be an integrated part produced by processing one material. For example, the support base 10 may be an integrated part produced by processing one block-shaped material. It is preferable that the first portion 10A, the second portion 10B, the third portion 10C, and the fourth portion 10D are integrated parts. This reduces the thermal resistance compared to the case where each portion is joined, and allows the heat generated during the operation of the semiconductor laser element LD to be efficiently released.

[0073] The semiconductor laser device 300 includes a base 80 to which an optical fiber 40, a condenser lens 42 (fast axis condenser lens 42a and slow axis condenser lens 42b), a mirror 44, a half-wave plate 46, and a beam combining element 48 are fixed. The optical fiber 40 is fixed to a support portion 40S fixed to the base 80. The base 80 is fixed to a fourth portion 10D of the support base 10. The half-wave plate 46 is disposed on the base 80 between the mirror 44 and the beam combining element 48.

[0074] <Direct diode laser device> Next, a configuration example of a direct diode laser (DDL) apparatus including the semiconductor laser apparatus 300 according to the third embodiment will be described with reference to Fig. 14. Fig. 14 is a diagram showing a configuration example of a DDL apparatus 1000.

[0075] The illustrated DDL apparatus 1000 includes four semiconductor laser devices 300, a processing head 400, and an optical transmission fiber 350 that connects the semiconductor laser devices 300 to the processing head 400. The number of semiconductor laser devices 300 may be one or more and is not limited to four.

[0076] Each semiconductor laser device 300 has a configuration similar to that described above. The number of semiconductor laser elements mounted on each semiconductor laser device 300 is not particularly limited, and is determined according to the required optical output or irradiance. The wavelength of the laser light emitted from each semiconductor laser element can also be selected according to the material to be processed. For example, when processing copper, brass, aluminum, etc., a semiconductor laser element having a central wavelength in the range of 350 nm to 550 nm can be suitably adopted. The wavelength of the laser light emitted from each semiconductor laser element does not need to be the same, and laser lights with different central wavelengths may be superimposed. In addition, the effect of the present invention can be obtained even when using a laser light having a central wavelength outside the range of 350 nm to 550 nm.

[0077] In the illustrated example, the optical fibers 320 extending from each of the semiconductor laser devices 300 are coupled to the optical transmission fiber 350 by the optical multiplexer 330. The optical multiplexer 330 may be, for example, a TFB (Tapered Fiber Bundle). The processing head 400 converges and irradiates the laser beam emitted from the tip of the optical fiber 320 on the object 500. In a case where one DDL device 1000 includes M semiconductor laser devices 300, and each semiconductor laser device 300 includes N semiconductor laser elements, if the optical output of one semiconductor laser element is P watts, a laser beam having an optical output of P×N×M watts at maximum can be converged on the object 500. Here, N is an integer of 2 or more, and M is a positive integer. For example, if P=10 watts, N=22, and M=12, an optical output exceeding 2.5 kilowatts is realized.

[0078] According to this embodiment, since the semiconductor laser element in the semiconductor laser device is sealed by a sealing cover, the decrease in optical output caused by the optical dust collection effect is suppressed, and the reliability is improved. In addition, since a large number of collimated beams with small beam diameters can be packed into a limited space, a high optical output can be achieved with a small device, and it is easy to couple to an optical fiber.

[0079] <Fiber laser device> Next, a configuration example of a fiber laser device including the semiconductor laser device 300 according to the third embodiment will be described with reference to Fig. 15. Fig. 15 is a diagram showing a configuration example of a fiber laser device 2000.

[0080] The illustrated fiber laser device 2000 includes a semiconductor laser device 300 functioning as an excitation light source, and a rare-earth doped optical fiber 600 excited by excitation light emitted from the semiconductor laser device 300. In the illustrated example, an optical fiber 320 extending from each of the semiconductor laser devices 300 is coupled to the rare-earth doped optical fiber 600 by an optical multiplexer 330. The rare-earth doped optical fiber 600 is sandwiched between a pair of fiber Bragg gratings that define a resonator. When the rare-earth doped optical fiber 600 is doped with ytterbium (Yb) ions, a semiconductor laser device 300 that generates excitation light with a wavelength of, for example, 915 nm is used. In addition, when a rare-earth doped optical fiber 600 formed of fluoride glass doped with praseodymium (Pr), for example, is used, it is possible to realize visible laser oscillation by blue excitation light. The semiconductor laser device 300 according to the embodiment of the present disclosure is useful as such an excitation light source. In the semiconductor laser device 300 according to the embodiment of the present disclosure, a plurality of semiconductor laser elements are housed in a space hermetically sealed by a sealing cover, and therefore, as described above, particularly excellent effects can be exhibited when semiconductor laser elements that emit blue or green laser light are employed.

[0081] The processing head 400 converges a laser beam emitted from the tip of a rare earth doped optical fiber 600 onto an object 500 and irradiates the object 500 with the laser beam. [Industrial Applicability]

[0082] The semiconductor laser device of the present disclosure may be used to realize a high-power laser beam by combining multiple laser beams. The semiconductor laser device of the present disclosure may also be used in industrial fields requiring a high-power laser light source, such as cutting, drilling, local heat treatment, surface treatment, metal welding, 3D printing, and the like. Furthermore, the semiconductor laser device of the present disclosure may also be used for applications other than DDL devices, such as a pumping light source for a fiber laser device. [Explanation of symbols]

[0083] 10···Support base, 16···First groove, 18···Second groove, 20···Beam combining portion, 30···First sealing cover, 40···Optical fiber, 42···Condenser lens, 60···Second sealing cover, 100···Semiconductor laser device, 200···Semiconductor laser device, 300···Semiconductor laser device, 320···Optical fiber, 330···Optical multiplexer, 350···Optical transmission fiber, 400···Processing head, 500···Object, 1000···Direct diode laser (DDL) device, 2000···Fiber laser device, B···Laser light, M···Mirror, FAC···Fast axis collimating lens, SAC···Slow axis collimating lens

Claims

1. A support base having a plurality of mounting surfaces arranged in a first direction, wherein heights of the plurality of mounting surfaces from a reference plane parallel to the first direction decrease stepwise or continuously along the first direction; a first semiconductor laser element fixed directly or indirectly to a first mounting surface among the plurality of mounting surfaces, the first semiconductor laser element emitting a first laser light in a second direction intersecting the first direction in a plan view from a normal direction to the reference plane; a second semiconductor laser element fixed directly or indirectly to a second mounting surface among the plurality of mounting surfaces, the second semiconductor laser element emitting a second laser light in the second direction in the plan view; a first slow axis collimator lens fixed directly or indirectly to the first mounting surface, the first slow axis collimator lens being provided at a position where the first laser light is incident; a second slow axis collimator lens fixed directly or indirectly to the second mounting surface, the second slow axis collimator lens being provided at a position where the second laser light is incident; a first sealing cover having a side wall surrounding the first semiconductor laser element and the second semiconductor laser element, a lower end of the side wall being joined to the support base, defining an interior for accommodating the first semiconductor laser element and the second semiconductor laser element, and having a light-transmitting region for transmitting the first laser light and the second laser light; Equipped with Each of the plurality of mounting surfaces has a first region covered by the first sealing cover and a second region located outside the first sealing cover, the supporting base has a first groove that receives at least a portion of the side wall of the first sealing cover; a part or the whole of the lower end of the side wall of the first sealing cover is joined to a bottom surface of the first groove.

2. 2. The semiconductor laser device according to claim 1, wherein, on each of said plurality of mounting surfaces, a height of said first region from said reference plane is equal to a height of said second region from said reference plane.

3. a first fast axis collimating lens provided between the first semiconductor laser element and the first slow axis collimating lens at a position where the first laser light emitted from the first semiconductor laser element is incident; a second fast axis collimating lens provided between the second semiconductor laser element and the second slow axis collimating lens at a position where the second laser light emitted from the second semiconductor laser element is incident; 3. The semiconductor laser device according to claim 1, further comprising:

4. the first fast axis collimating lens and the second fast axis collimating lens are located inside the first sealing cover, and 4. The semiconductor laser device according to claim 3, wherein the first slow axis collimating lens and the second slow axis collimating lens are located outside the first sealing cover.

5. a first submount supporting the first semiconductor laser element; a second submount supporting the second semiconductor laser element; Equipped with the first submount has a first lens support member that supports the first fast axis collimating lens, 5. The semiconductor laser device according to claim 4, wherein the second submount has a second lens support member that supports the second fast axis collimating lens.

6. a beam combining unit that combines the first laser light emitted from the first slow axis collimating lens and the second laser light emitted from the second slow axis collimating lens, The beam combining unit includes: a first mirror provided in the second region of the first mounting surface and configured to reflect the first laser light in the first direction; a second mirror provided in the second region of the second mounting surface and configured to reflect the second laser light in the first direction; a condenser lens for coupling the first laser light reflected by the first mirror and the second laser light reflected by the second mirror to an optical fiber; 6. The semiconductor laser device according to claim 1, further comprising:

7. a third semiconductor laser element fixed directly or indirectly to the first mounting surface, the third semiconductor laser element emitting a third laser light in a direction opposite to the second direction in the plan view; a fourth semiconductor laser element directly or indirectly fixed to the second mounting surface, the fourth semiconductor laser element emitting a fourth laser light in the opposite direction to the second direction in the plan view; a third slow axis collimator lens fixed directly or indirectly to the first mounting surface, the third slow axis collimator lens being provided at a position where the third laser light is incident; a fourth slow axis collimator lens fixed directly or indirectly to the second mounting surface, the fourth slow axis collimator lens being provided at a position where the fourth laser light is incident; a second sealing cover having a side wall surrounding the third semiconductor laser element and the fourth semiconductor laser element, a lower end of the side wall being joined to the support base, defining an interior for accommodating the third semiconductor laser element and the fourth semiconductor laser element, and having a light-transmitting region for transmitting the third laser light and the fourth laser light; Equipped with 7. The semiconductor laser device according to claim 6, wherein each of the plurality of mounting surfaces has a third region covered by the second sealing cover, and the second region is located between the first region and the third region.

8. 8. The semiconductor laser device according to claim 7, wherein, on each of said plurality of mounting surfaces, a height of said third region from said reference plane is equal to a height of said second region from said reference plane.

9. the beam combining unit combines the first laser light emitted from the first slow axis collimating lens, the second laser light emitted from the second slow axis collimating lens, the third laser light emitted from the third slow axis collimating lens, and the fourth laser light emitted from the fourth slow axis collimating lens; The beam combining unit includes: a third mirror provided in the second region of the first mounting surface and configured to reflect the third laser light in the first direction; a fourth mirror provided in the second region of the second mounting surface and configured to reflect the fourth laser light in the first direction; having 9. The semiconductor laser device according to claim 7, wherein the condenser lens couples the third laser light reflected by the third mirror and the fourth laser light reflected by the fourth mirror into the optical fiber.

10. a third fast axis collimating lens provided between the third semiconductor laser element and the third slow axis collimating lens at a position where the third laser light emitted from the third semiconductor laser element is incident; a fourth fast axis collimating lens provided between the fourth semiconductor laser element and the fourth slow axis collimating lens at a position where the fourth laser light emitted from the fourth semiconductor laser element is incident; 10. The semiconductor laser device according to claim 7, further comprising:

11. the third fast axis collimating lens and the fourth fast axis collimating lens are located inside the second sealing cover, and The semiconductor laser device according to claim 10 , wherein the third slow axis collimating lens and the fourth slow axis collimating lens are located outside the second sealing cover.

12. a third submount supporting the third semiconductor laser element; a fourth submount supporting the fourth semiconductor laser element; Equipped with the third submount has a third lens support member that supports the third fast axis collimating lens, the fourth submount has a fourth lens support member that supports the fourth fast axis collimating lens; 12. The semiconductor laser device according to claim 10.

13. the supporting base has a second groove that receives at least a portion of the side wall of the second sealing cover; 13. The semiconductor laser device according to claim 7, wherein a part or all of the lower end of the side wall of the second sealing cover is joined to a bottom surface of the second groove.

14. 14. The semiconductor laser device according to claim 7, wherein the first semiconductor laser element, the second semiconductor laser element, the third semiconductor laser element, and the fourth semiconductor laser element oscillate to emit any one of green light, blue light, and violet light laser light.

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