Semiconductor laser element and light source device using the same

Abstract

To provide a semiconductor laser element capable of individually controlling on / off of a secondary beam.SOLUTION: A semiconductor laser element includes a semiconductor stacked body including a first semiconductor layer on a first conductive side, a second semiconductor layer on a conductive side opposite to the first conductive side, and an active layer, a first electrode and a second electrode connected to the second semiconductor layer, and a third electrode connected to the first semiconductor layer. One or both of the first semiconductor layer and the second semiconductor layer have a two-dimensional photonic crystal region and a non-two-dimensional photonic crystal region. The two-dimensional photonic crystal region has a two-dimensional periodic structure in which a second medium having a second refractive index different from a first refractive index is disposed in a two-dimensional periodic manner inside a first medium having the first refractive index. The non-two-dimensional photonic crystal region does not have a periodic structure and is disposed outside the two-dimensional photonic crystal region. The first electrode is located inside the two-dimensional photonic crystal region in plan view, and the second electrode overlaps a boundary region orthogonal to the diffraction direction determined by the two-dimensional periodic structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor laser element and a light source device using the same. [Background technology]

[0002] Photonic Crystal Surface Emitting Lasers (PCSELs) using two-dimensional photonic crystals have been proposed (see, for example, Patent Document 1). In PCSELs, a resonance mode determined by the two-dimensional periodicity of the photonic crystal is formed, enabling high-power, single-mode oscillation. High-power PCSELs that operate in single modes in both longitudinal and transverse modes have high beam quality and are expected to be used in a variety of fields, including remote sensing, laser processing, and optical communications. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 031966 Summary of the Invention [Problem to be solved by the invention]

[0004] In some cases, it may be desirable to use secondary beams depending on the application of the semiconductor laser element. One aspect of the present disclosure provides a semiconductor laser element capable of individually controlling the on / off of the secondary beams. [Means for solving the problem]

[0005] In one embodiment, the semiconductor laser device comprises: a semiconductor laminate including a first semiconductor layer on a first conductive side, a second semiconductor layer on a conductive side opposite to the first conductive side, and an active layer disposed between the first semiconductor layer and the second semiconductor layer; a first electrode and a second electrode separated from each other and electrically connected to the second semiconductor layer; a third electrode electrically connected to the first semiconductor layer; and One or both of the first semiconductor layer and the second semiconductor layer has a two-dimensional photonic crystal region and a non-two-dimensional photonic crystal region. the two-dimensional photonic crystal region has a two-dimensional periodic structure in which a second medium having a second refractive index different from a first refractive index is arranged in a two-dimensional period inside a first medium having a first refractive index, the second medium being arranged in a two-dimensional period; the non-two-dimensional photonic crystal region does not have a periodic structure and is disposed outside the two-dimensional photonic crystal region; the first electrode is located inside the two-dimensional photonic crystal region in a plan view, The second electrode overlaps at least a boundary region between the two-dimensional photonic crystal region and the non-two-dimensional photonic crystal region that is perpendicular to the diffraction direction determined by the two-dimensional periodic structure. [Effects of the Invention]

[0006] A semiconductor laser element is realized that can individually control the on / off of the secondary beams. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of a semiconductor laser element according to an embodiment. [Figure 2] FIG. 2 is a diagram showing an example of a two-dimensional periodic structure of a two-dimensional photonic crystal region. [Figure 3] FIG. 10 is a diagram showing another example of a two-dimensional periodic structure of a two-dimensional photonic crystal region. [Figure 4] FIG. 10 is a diagram showing an example of electrode arrangement when a two-dimensional periodic structure of a triangular lattice is used. [Figure 5] FIG. 10 is a diagram showing an example of electrode arrangement when a two-dimensional periodic structure of a square lattice is used. [Figure 6] Schematic diagram of an excitation spot on a square two-dimensional photonic crystal region. [Figure 7]These are the far-field pattern (FFP) and near-field pattern (NFP) when the spot diameter of the excitation light is 300 μm. [Figure 8] These are FFP and NFP when the spot diameter of the excitation light is 1000 μm. [Figure 9] Schematic diagram of an excitation spot on a circular two-dimensional photonic crystal region. [Figure 10] These are FFP and NFP when the spot diameter of the excitation light is 300 μm. [Figure 11] These are FFP and NFP when the spot diameter of the excitation light is 1000 μm. [Figure 12] FIG. 2 is a schematic diagram showing excitation positions on a two-dimensional photonic crystal region. [Figure 13] These are the FFP and NFP when excited at position P1. [Figure 14] These are the FFP and NFP when excited at position P2. [Figure 15] These are the FFP and NFP when excited at position P3. [Figure 16] These are the FFP and NFP when excited at position P4. [Figure 17] These are the FFP and NFP when excited at position P5. [Figure 18] FIG. 10 is a diagram showing an example of the arrangement of electrodes for current injection. [Figure 19] FIG. 10 is a diagram showing another example of the arrangement of electrodes for current injection. [Figure 20] FIG. 10 is a diagram showing yet another example of electrode arrangement for current injection. [Figure 21] 1 is a schematic cross-sectional view of a light source device using a semiconductor laser element according to an embodiment. [Figure 22A] 1A to 1C are diagrams illustrating the manufacturing process of a semiconductor laser element. [Figure 22B] 1A to 1C are diagrams illustrating the manufacturing process of a semiconductor laser element. [Figure 22C] 1A to 1C are diagrams illustrating the manufacturing process of a semiconductor laser element. [Figure 22D] 1A to 1C are diagrams illustrating the manufacturing process of a semiconductor laser element. [Figure 22E] 1A to 1C are diagrams illustrating the manufacturing process of a semiconductor laser element. DETAILED DESCRIPTION OF THE INVENTION

[0008] In this embodiment, a semiconductor layer of a semiconductor laser element is provided with a two-dimensional photonic crystal region having a two-dimensional periodic structure, and a non-two-dimensional photonic crystal region without a periodic structure is disposed outside the two-dimensional photonic crystal region. A first electrode is disposed inside the two-dimensional photonic crystal region in a planar view, and a second electrode is disposed in the same plane as the first electrode, overlapping at least a portion of the boundary between the two-dimensional photonic crystal region and the non-two-dimensional photonic crystal. The first electrode and the second electrode are separated from each other and electrically connected to the same semiconductor layer. The second electrode overlaps at least a boundary region between the two-dimensional photonic crystal region and the non-two-dimensional photonic crystal region that is perpendicular to the diffraction direction determined by the two-dimensional periodic structure. The secondary beams are individually turned on and off by controlling the current flow to the first electrode and the second electrode.

[0009] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. The following description is intended to embody the technical concept of the present disclosure, and unless otherwise specified, the present disclosure is not limited to the following description. In each drawing, components having the same function may be assigned the same reference numerals. For convenience, the embodiments may be shown separately in consideration of ease of explanation or understanding of the main points, but partial substitution or combination of configurations shown in different embodiments or examples is possible. In the embodiments shown later, differences from the previously shown embodiments will be mainly described, and redundant description of matters common to the previously shown embodiments may be omitted. The size and positional relationship of components shown in each drawing may be exaggerated for clarity.

[0010] <Configuration of semiconductor laser element> FIG. 1 is a schematic cross-sectional view of a semiconductor laser device 10 according to an embodiment. The semiconductor laser device 10 includes a semiconductor stack 14 including a first semiconductor layer 11 on a first conductive side, a second semiconductor layer 12 on a conductive side opposite to the first conductive side, and an active layer 13 disposed between the first semiconductor layer 11 and the second semiconductor layer 12. The semiconductor laser device 10 also includes a first electrode 171 and a second electrode 172 that are separated from each other and electrically connected to the second semiconductor layer 12, and a third electrode 173 that is electrically connected to the first semiconductor layer 11. One or both of the first semiconductor layer 11 and the second semiconductor layer 12 includes a two-dimensional photonic crystal region 151 and a non-two-dimensional photonic crystal region 152. The two-dimensional photonic crystal region 151 has a two-dimensional periodic structure in which a second medium having a second refractive index different from the first refractive index is arranged two-dimensionally inside a first medium having a first refractive index. Non-two-dimensional photonic crystal region 152 does not have a periodic structure and is disposed outside two-dimensional photonic crystal region 151. First electrode 171 is located inside two-dimensional photonic crystal region 151 in a planar view, and second electrode 172 overlaps at least a boundary region between two-dimensional photonic crystal region 151 and non-two-dimensional photonic crystal region 152 that is orthogonal to the diffraction direction determined by the two-dimensional periodic structure. The arrangement of first electrode 171 and second electrode 172 will be described later with reference to FIGS. 4 and 5.

[0011] In the configuration example of FIG. 1 , the first semiconductor layer 11 is, for example, an n-side semiconductor layer, and the second semiconductor layer 12 is a p-side semiconductor layer. The first electrode 171 is a first positive electrode, the second electrode 172 is a second positive electrode, and the third electrode 173 is a negative electrode. The second semiconductor layer 12, which is a p-side semiconductor layer, has a two-dimensional photonic crystal region 151 and a non-two-dimensional photonic crystal region 152. This allows the two-dimensional photonic crystal region 151 to be provided in the second semiconductor layer (i.e., the p-side semiconductor layer) after the semiconductor stack 14 is formed. Compared to when the two-dimensional photonic crystal region 151 is formed during the formation of the semiconductor stack 14, misalignment is less likely to occur between the active layer 13 directly above the two-dimensional photonic crystal region 151 and the active layer 13 directly above the non-two-dimensional photonic crystal region 152. Furthermore, the period of the two-dimensional photonic crystal region 151 can be adjusted to match the gain of the semiconductor stack 14. One or more electrodes are provided as the second electrode 172. For example, the second electrode 172 may include two or more second electrodes 172 spaced apart from each other, each of which overlaps with a boundary region perpendicular to the diffraction direction, thereby effectively extracting the secondary beams.

[0012] The semiconductor stack 14 including the first semiconductor layer 11, the active layer 13, and the second semiconductor layer 12 is provided on the substrate 101, but the substrate 101 may be polished or removed after growing the semiconductor stack 14 and before forming the third electrode 173. The first semiconductor layer 11, the active layer 13, and the second semiconductor layer 12 are nitride semiconductor layers. In the example of FIG. 1, an n-side GaN layer as the first semiconductor layer 11 and a p-side GaN layer as the second semiconductor layer 12 are disposed on a GaN substrate containing n-type impurities. The active layer 13 between the first semiconductor layer 11 and the second semiconductor layer 12 is formed of, for example, In y Ga 1-y The first semiconductor layer 11 and the second semiconductor layer 12 are formed of a multi-quantum well of N (0≦y≦1). Each of the first semiconductor layer 11 and the second semiconductor layer 12 may include a plurality of types of layers such as a cladding layer and a contact layer. Each of the first semiconductor layer 11 and the second semiconductor layer 12 is made of, for example, Al x Ga 1-x N (0≦x≦1).

[0013] In FIG. 1 , the second semiconductor layer 12, which is a p-side semiconductor layer, includes a two-dimensional photonic crystal region 151 and a non-two-dimensional photonic crystal region 152. However, depending on the device design, the two-dimensional photonic crystal region 151 and the non-two-dimensional photonic crystal region 152 may be provided in the n-side semiconductor layer. The surface of the non-two-dimensional photonic crystal region 152 may be protected by an insulating layer 16. Light generated in the active layer 13 by carrier recombination is affected by various diffraction effects due to the two-dimensional periodic structure of the two-dimensional photonic crystal region 151, resulting in a resonant mode. For example, the two-dimensional photonic crystal region 151 is formed near the active layer 13 by forming a two-dimensional periodic pattern of a second medium having a refractive index different from that of the nitride semiconductor in a first medium made of a nitride semiconductor. In the example of FIG. 1 , recesses 181 are provided at a predetermined period in the in-plane direction of the second semiconductor layer 12, and air is used as the second medium. However, the recesses 181 may be filled with a medium other than air having a refractive index different from that of the second semiconductor layer 12. The second medium may be, in addition to air, for example, SiO2, TiO2, Al2O3, Nb2O5, Ta2O5, SiN, SiON, or the like.

[0014] Among the light propagating in the in-plane direction through the two-dimensional photonic crystal region 151, light having a wavelength that matches the period of the two-dimensional periodic structure resonates, and the phase is synchronized throughout the two-dimensional photonic crystal region 151, generating a standing wave. The two-dimensional periodic structure of the two-dimensional photonic crystal region 151 is, for example, a square lattice structure or a triangular lattice structure. The light that constitutes the standing wave that matches the two-dimensional period of the two-dimensional photonic crystal region 151 is also diffracted in a direction perpendicular to the crystal plane, and the semiconductor laser device 10 operates as a surface-emitting laser. In the configuration of FIG. 1, laser light is generated in both directions, from the active layer 13 toward the first semiconductor layer 11 and from the active layer 13 toward the second semiconductor layer 12. The laser light is reflected by the first electrode 171 and the second electrode 172 and is emitted from the back surface of the substrate 101 on which the third electrode 173 is provided. In the stacking direction of the semiconductor laser element 10, the first semiconductor layer 11 and the second semiconductor layer 12 confine light by utilizing the refractive index difference with respect to the active layer 13, and in the in-plane direction, the two-dimensional periodic structure of the two-dimensional photonic crystal region 151 is responsible for light confinement.

[0015] 2 and 3 are diagrams illustrating an example of the two-dimensional periodic structure of the two-dimensional photonic crystal region 151 (see FIG. 1). The two-dimensional periodic structure 150A in FIG. 2 has a second medium 154 arranged in a triangular lattice inside a first medium 153. The second medium 154 forms the vertices of the triangles, and the triangles, sharing their sides, extend within a two-dimensional plane. The spacing between the lattice planes is the lattice constant a, i.e., the period, of the triangular lattice photonic crystal. The lattice constant a of the triangular lattice is determined according to the wavelength of the laser light to be generated and is, for example, 0.1 μm to 2.0 μm. The diameter of the second medium 154 is, for example, 0.1 to 1.15 times the lattice constant a, preferably 0.1 to 0.5 times. This balances the proportion of light sensed by the two-dimensional photonic crystal and the coupling coefficient, resulting in efficient surface emission. When the triangular lattice is a regular triangular lattice, it is also called a hexagonal lattice. The diffraction direction Ddif of the triangular lattice is directed in six directions, which divide all directions equally from a certain lattice point, as shown by the thick arrows.

[0016] The two-dimensional periodic structure 150B in FIG. 3 has a second medium 154 arranged in a square lattice inside a first medium 153. The second medium 154 forms the vertices of a square, and the square, sharing its sides, extends in a two-dimensional plane. The spacing between the lattice planes is the lattice constant a, i.e., the period, of the square lattice photonic crystal. The lattice constant a of the square lattice is determined according to the wavelength of the laser light to be generated and is, for example, 0.1 μm to 2.0 μm. The diameter of the second medium 154 is, for example, 0.1 to 0.7 times the lattice constant a. The diffraction directions Ddif of the square lattice are four mutually orthogonal directions extending from one lattice point to four adjacent lattice points, as indicated by the bold arrows.

[0017] In the examples shown in FIGS. 2 and 3 , the second medium 154 has a circular planar shape, and cylindrical air holes are formed as the recesses 181 in FIG. 1 , but this is not limiting. Holes or protrusions having a planar shape such as a triangle, square, hexagon, or ellipse may also be formed in the second medium 154. The two-dimensional periodic structure 150A or 150B is not limited to a triangular or square lattice, and may have a rectangular or diamond lattice pattern depending on the application. A non-two-dimensional photonic crystal region 152 without a periodic structure is disposed outside the two-dimensional photonic crystal region 151 having such a two-dimensional periodic structure. In a planar view, the boundary between the two-dimensional photonic crystal region 151 and the non-two-dimensional photonic crystal region 152 is, for example, a line connecting the outermost periphery of the second medium 154 forming the two-dimensional periodic structure. In a three-dimensional lattice structure, when the second medium 154 has a circular planar shape, the surface circumscribing the outermost cylindrical holes is the boundary where standing waves are felt.

[0018] The planar shape of the two-dimensional photonic crystal region 151 having a two-dimensional periodic structure is a circle with a circumference perpendicular to the diffraction direction Ddif, or a polygon with sides perpendicular to the diffraction direction Ddif. When the two-dimensional periodic structure is a triangular lattice, the planar shape of the two-dimensional photonic crystal region 151 may be a circle with a circumference along which a tangent can be drawn perpendicular to the diffraction direction Ddif determined by the triangular lattice, or a polygon with sides perpendicular to the diffraction direction Ddif determined by the triangular lattice. This allows for efficient generation of secondary beams. When the two-dimensional periodic structure is a square lattice structure, the planar shape of the two-dimensional photonic crystal region 151 is a circle with a circumference along which a tangent can be drawn perpendicular to the diffraction direction Ddif determined by the square lattice, or a polygon with sides perpendicular to the diffraction direction Ddif determined by the square lattice. This allows for efficient generation of secondary beams. The secondary beams are extracted by utilizing the boundary surface between second medium 154, which is provided near the outermost periphery of two-dimensional photonic crystal region 151 having such a planar shape, and the semiconductor layer formed of first medium 153. For this reason, second electrode 172 is provided so as to overlap, in plan view, at least the boundary between two-dimensional photonic crystal region 151 and non-two-dimensional photonic crystal region 152 that is perpendicular to the diffraction direction.

[0019] FIG. 4 shows an example of an electrode arrangement when a two-dimensional periodic structure of a triangular lattice is used, and FIG. 5 shows an example of an electrode arrangement when a two-dimensional periodic structure of a square lattice is used. The first electrode 171 and the second electrode 172 are separated from each other and electrically connected to the second semiconductor layer 12 (see FIG. 1) in which the two-dimensional photonic crystal region 151 is formed. In FIG. 4, the non-two-dimensional photonic crystal region 152 is disposed outside the two-dimensional photonic crystal region 151, which is hexagonal in plan view. The first electrode 171 is provided inside the two-dimensional photonic crystal region 151 in plan view. The second electrode 172 overlaps with at least one of boundary regions 155a to 155f, which are orthogonal to the diffraction direction determined by the two-dimensional periodic structure, among the boundaries 155 between the two-dimensional photonic crystal region 151 and the non-two-dimensional photonic crystal region 152. The diffraction directions determined by the triangular lattice in FIG. 4 are six directions obtained by equally dividing all directions from a certain lattice point into six equal parts, as shown in FIG. 2. The second electrode 172 is arranged so as to overlap with at least one side of the hexagonal two-dimensional photonic crystal region 151 formed by sides perpendicular to the six diffraction directions.

[0020] In the configuration example of Fig. 4, the second electrode 172 includes six second electrodes 172 separated from one another, and each of the six second electrodes 172 overlaps with boundary regions 155a to 155f orthogonal to the diffraction direction. This allows secondary beams to be generated efficiently by current excitation. The second electrodes 172 may overlap with the two-dimensional photonic crystal region 151 outside the first electrode 171 when viewed from the center of the two-dimensional photonic crystal region 151. This allows secondary beams to be generated by exciting the two-dimensional photonic crystal region 151 with current excitation of the second electrodes alone.

[0021] 5, non-two-dimensional photonic crystal region 152 is disposed outside two-dimensional photonic crystal region 151, which is square in plan view. First electrode 171 is located inside two-dimensional photonic crystal region 151 in plan view. Second electrode 172 overlaps with at least one of boundary regions 155g to 155j, which are part of boundary 155 between two-dimensional photonic crystal region 151 and non-two-dimensional photonic crystal region 152 and are orthogonal to the diffraction direction determined by the two-dimensional periodic structure. In the case of a square lattice, the diffraction directions determined by this square lattice are four directions that are perpendicular to each other from a certain lattice point, as shown in FIG. 3. Second electrode 172 is disposed so as to overlap with at least one side of square two-dimensional photonic crystal region 151 formed by sides that are orthogonal to the four diffraction directions.

[0022] 5, the second electrode 172 includes four second electrodes 172 separated from one another, and each of the four second electrodes 172 overlaps with boundary regions 155g to 155j perpendicular to the diffraction direction. This allows secondary beams to be generated efficiently by current excitation. The second electrodes 172 may overlap with the two-dimensional photonic crystal region 151 outside the first electrode 171 when viewed from the center of the two-dimensional photonic crystal region 151. This allows secondary beams to be generated by exciting the two-dimensional photonic crystal region 151 with current excitation of the second electrodes alone.

[0023] The number of divided second electrodes 172 is not limited to four or six, and may include two or more second electrodes 172. Depending on the application of the semiconductor laser device 10, one first electrode 171 and one second electrode 172 may be arranged, or one first electrode 171 and two or more second electrodes 172 may be arranged. The two or more second electrodes 172 do not necessarily have to be arranged in all directions outside the first electrode 171, but may be arranged only at positions from which secondary beams are desired to be emitted.

[0024] The second electrode 172 overlaps the non-two-dimensional photonic crystal region 152 by a predetermined width from the boundary region. The predetermined width is, for example, 0.1% to 50% of the length of a perpendicular line drawn from the center of the two-dimensional photonic crystal region 151 to the boundary regions 155a to 155f or 155g to 155j in a planar view. Alternatively, the second electrode 172 may overlap the non-two-dimensional photonic crystal region 152 by a width that is 2 to 10 times the lattice constant a of the two-dimensional photonic crystal region 151. This is because, as will be described later, the circumscribing surface of the second medium 154 located near the outermost periphery of the two-dimensional photonic crystal region 151 is used to extract diffracted light of the secondary beam. If the second electrode 172 extends excessively outside the boundary region, current injection loss occurs. Therefore, it is desirable for the second electrode 172 to cover the boundary region by a width of approximately 2 to 10 periods of the two-dimensional photonic crystal lattice. However, the end of second electrode 172 may be located inside two-dimensional photonic crystal region 151 within the range of manufacturing error.

[0025] By individually controlling the first electrode 171 and the second electrode 172, or individually controlling the plurality of second electrodes 172, it is possible to emit light only in a desired direction.

[0026] <Diffraction light patterns generated by optical excitation> The semiconductor laser device 10 emits light by current excitation using the first electrode 171, the second electrode 172, and the third electrode 173. In particular, light is emitted at a desired position by individually controlling the current flow to the first electrode 171 and the second electrode 172, or the current flow to each of the divided second electrodes. This driving principle of the semiconductor laser device 10 will be explained using the diffracted light pattern obtained by optically exciting the two-dimensional photonic crystal region 151.

[0027] <Square two-dimensional photonic crystal region> Figure 6 is a schematic diagram of an excitation spot 103 on a rectangular two-dimensional photonic crystal region 151A. First, a sample of a semiconductor laser device 10 with a two-dimensional periodic structure is fabricated. This sample has a two-dimensional photonic crystal region 151A with a triangular lattice arrangement within a rectangular region. The diffraction directions of the triangular lattice arrangement are six directions obtained by dividing all directions equally. The area outside the two-dimensional photonic crystal region 151A is a non-two-dimensional photonic crystal region without a periodic structure. The length L of one side of the two-dimensional photonic crystal region 151A is 1000 μm. This two-dimensional photonic crystal region 151A is irradiated with excitation light with a circular cross section to generate laser oscillation. Ultraviolet light with a wavelength of 355 nm is used as the excitation light. The spot diameter φexc of the excitation light on the two-dimensional photonic crystal region 151A is changed, and the FFP and NFP of the generated diffracted light are observed. The excitation spot 103 corresponds to the current injection region, i.e., the electrode region, in the case of current excitation.

[0028] FIG. 7 shows the FFP and NFP when the spot diameter φexc of the excitation light is 300 μm. NFP is the beam pattern near the emission surface, and FFP is the beam pattern at a position approximately 30 cm away from the emission surface. The rectangular region 160 surrounded by the dotted line in the FFP corresponds to the two-dimensional photonic crystal region 151A. Diffracted light emitted from the excitation spot 103 (see FIG. 6) is observed in the center of region 160. In the NFP, diffracted light corresponding to the excitation spot 103 is observed on the emission surface, i.e., the surface of the two-dimensional photonic crystal region 151. The beam pattern in FIG. 7 corresponds to the beam pattern obtained by applying a current to a first electrode 171 arranged in the center of the two-dimensional photonic crystal region 151A.

[0029] Figure 8 shows the FFP and NFP when the spot diameter φexc of the excitation light is 1000 μm. The excitation spot 103 is inscribed on each side of the two-dimensional photonic crystal region 151A. Diffracted light is generated in the center of the FFP, and secondary beams 21 are observed in the 12 o'clock and 6 o'clock directions. The secondary beams 21 appear near the four sides of the rectangular two-dimensional photonic crystal region 151A that are perpendicular to the diffraction direction Ddif (see Figure 2) determined by the triangular lattice. No secondary beams are observed in the 3 o'clock and 9 o'clock directions, which are sides that are not perpendicular to the diffraction direction of the triangular lattice.

[0030] In the NFP, it can be seen that light 22 senses the boundary of two-dimensional photonic crystal region 151A perpendicular to the diffraction direction Ddif, i.e., the interface of second medium 154 located on the outermost periphery of the triangular lattice arrangement. When the excited region overlaps with the outer periphery of square two-dimensional photonic crystal region 151A in the diffraction direction, secondary beams 21 are output in addition to the central diffracted light.

[0031] <Circular two-dimensional photonic crystal region> Figure 9 is a schematic diagram of the excitation spot 103 on a circular two-dimensional photonic crystal region 151B. Another sample of the semiconductor laser device 10 with a two-dimensional periodic structure was fabricated. The two-dimensional photonic crystal region 151B of this sample had a triangular lattice arrangement within a circular region. The diffraction directions of the triangular lattice arrangement were six directions obtained by dividing all directions equally into six. The area outside the circular two-dimensional photonic crystal region 151B was a non-two-dimensional photonic crystal region without a periodic structure. The diameter L of the two-dimensional photonic crystal region 151B was 1000 μm. Laser oscillation was generated by irradiating this two-dimensional photonic crystal region 151B with excitation light having a circular cross section. Ultraviolet light with a wavelength of 300 nm was used as the excitation light. The spot diameter φexc of the excitation light on the two-dimensional photonic crystal region 151B was changed, and the FFP and NFP of the diffracted light were observed. The excitation spot 103 corresponds to the current injection region, i.e., the electrode region, in the case of current excitation.

[0032] Figure 10 shows the FFP and NFP when the spot diameter φexc of the excitation light is 300 μm. In the NFP, diffracted light is observed at a position corresponding to the excitation spot 103. In the FFP, in addition to the central diffracted light, weak diffracted light is observed at positions corresponding to the vertices of the hexagon. This is light that is generated by optical excitation and propagates through the two-dimensional photonic crystal region 151B in the diffraction direction, and is diffracted in a direction perpendicular to the plane that forms the two-dimensional period.

[0033] Figure 11 shows the FFP and NFP when the spot diameter φexc of the excitation light is 1000 μm. The excitation spot 103 covers the entire two-dimensional photonic crystal region 151B. In the NFP, the light 22 spreads over the entire circular two-dimensional photonic crystal region 151B. In the FFP, six sub-beams 21 are clearly observed in the six diffraction directions determined by the triangular lattice of the two-dimensional photonic crystal region 151B. In the case of the circular two-dimensional photonic crystal region 151B, the diffraction directions determined by the triangular lattice are perpendicular to the tangent at the position of the sub-beams 21.

[0034] 6 to 11 lead to the theory that secondary beams are emitted at desired positions by passing current through electrodes that overlap with boundary regions perpendicular to the diffraction direction determined by the two-dimensional periodic structure, among the boundaries of the two-dimensional photonic crystal region 151 of the semiconductor laser device 10. To verify this theory, multiple positions within the triangular lattice two-dimensional photonic crystal region are partially optically excited, and the diffracted light that is generated is observed.

[0035] <Evaluation of two-dimensional photonic crystal regions by optical excitation> 12 is a schematic diagram showing excitation positions on two-dimensional photonic crystal region 151. A two-dimensional periodic structure of a triangular lattice is formed inside two-dimensional photonic crystal region 151, which is rectangular in plan view. A non-two-dimensional photonic crystal region 152, which does not have a periodic structure, is disposed outside two-dimensional photonic crystal region 151. Boundary 155 between two-dimensional photonic crystal region 151 and non-two-dimensional photonic crystal region 152 circumscribes the outermost periphery of the two-dimensional periodic structure. In other words, the line circumscribing the outermost second medium 154 and surrounding second medium 154 is boundary 155 between two-dimensional photonic crystal region 151 and non-two-dimensional photonic crystal region 152.

[0036] Excitation positions P1 to P5 are set on the two-dimensional photonic crystal region 151. Each of points P1 to P5 is excited by irradiating it with ultraviolet light having a circular beam cross section. Figure 13 shows the FFP and NFP when excited at position P1. P1 is located near the center of the two-dimensional photonic crystal region 151. In the FFP, diffracted light is observed only at the center of the two-dimensional photonic crystal region 151. In the NFP, nearly circular diffracted light is observed near the center of the two-dimensional photonic crystal region 151, diffracted in a direction perpendicular to the plane that forms the two-dimensional period.

[0037] Figure 14 shows the FFP and NFP when excited at position P2. Position P2 is located inside two-dimensional photonic crystal region 151 in the diffraction direction determined by the triangular lattice. Striped diffracted light is observed in NFP, indicating that the light is experiencing the interface of second medium 154 (see Figure 2), which forms a triangular lattice, near P2. In this case, as observed in FFP, secondary beam 21 is generated at a position corresponding to excitation position P2.

[0038] Figure 15 shows the FFP and NFP when excited at position P3. P3 is located on the boundary 155 between the two-dimensional photonic crystal region 151 and the non-two-dimensional photonic crystal region 152. In the NFP, the light senses the interface of the second medium 154 at the outermost periphery of the triangular lattice near the boundary 155, but no secondary beams are generated in the FFP. Instead, an X-shaped line pattern appears. This is thought to be because the periodicity of the triangular lattice is insufficient near the boundary 155 of the two-dimensional photonic crystal region 151, making it difficult for secondary beams to be generated.

[0039] 16 shows the FFP and NFP when excited at position P4. In the NFP, the light senses the interface of the second medium 154, which forms a triangular lattice inside the two-dimensional photonic crystal region 151, but no secondary beam is generated at position P4. This is thought to be because P4 is outside the diffraction direction determined by the triangular lattice.

[0040] Figure 17 shows the FFP and NFP when excited at position P5. P5 is located on the boundary 155 between the two-dimensional photonic crystal region 151 and the non-two-dimensional photonic crystal region 152. In the NFP, the light senses the interface of the second medium 154 at the outermost periphery of the triangular lattice near boundary 155, but no secondary beams are generated in the FFP. Instead, a horizontal line pattern appears. This is thought to be due to a lack of periodicity near boundary 155 of the two-dimensional photonic crystal region 151.

[0041] 13 to 17, it was found that secondary beams can be generated by individually exciting specific positions or regions in the diffraction direction determined by the two-dimensional periodic structure of the two-dimensional photonic crystal region 151. Based on this finding, the semiconductor laser device of this embodiment was developed to utilize this phenomenon by current excitation rather than optical excitation. That is, the region to which current is injected is divided by the first electrode 171 and the second electrode 172, making it possible to individually excite the areas near P1 and P2 in FIG. 12.

[0042] <Behavior during current injection predicted from photoexcitation evaluation> Instead of photoexcitation, a current is injected by passing electricity through an electrode electrically connected to the second semiconductor layer 12 (see FIG. 1). As in the photoexcitation evaluation, a two-dimensional periodic structure of a triangular lattice is provided in a rectangular two-dimensional photonic crystal region 151.

[0043] Fig. 18 is a diagram showing an example of an electrode arrangement for current injection. In Fig. 18, a rectangular first electrode 171 is provided inside two-dimensional photonic crystal region 151. This is a typical electrode arrangement. When current is applied to first electrode 171, light is output from the center of two-dimensional photonic crystal region 151, as shown in Fig. 13.

[0044] FIG. 19 shows another example of the arrangement of electrodes for current injection. A rectangular first electrode 171 is disposed in the center of the two-dimensional photonic crystal region 151. The diffraction direction Ddif, determined by the triangular lattice that forms the two-dimensional photonic crystal region 151, is indicated by a black arrow for convenience. A second electrode 172, separated from the first electrode 171, covers a portion of the two-dimensional photonic crystal region 151. The second electrode 172 overlaps one of the four sides of the two-dimensional photonic crystal region 151, i.e., one side perpendicular to the diffraction direction Ddif, of the boundary 155 with the non-two-dimensional photonic crystal region 152, with a predetermined width between the edge of the second electrode 172 on the non-two-dimensional photonic crystal region 152 side and the boundary 155. The predetermined width is between two and ten times the period of the triangular lattice. This is to extract the diffracted light of the secondary beams by utilizing the outermost surface of the second medium 154 located near the outermost periphery of the two-dimensional photonic crystal region 151. If second electrode 172 protrudes excessively outside the boundary region, it will result in a loss of current injection, so it is desirable for the boundary region to be covered with a width of about 2 to 10 periods of the two-dimensional photonic crystal lattice.

[0045] In the electrode arrangement of FIG. 19, when the current to the first electrode 171 is turned off and the current to the second electrode 172 is turned on, a secondary beam 21 is generated in the diffraction direction Ddif as shown in the FFP of FIG.

[0046] FIG. 20 shows another example of the electrode arrangement for current injection. A rectangular first electrode 171 is arranged in the center of a rectangular two-dimensional photonic crystal region 151. The diffraction direction Ddif determined by the triangular lattice that forms the two-dimensional photonic crystal region 151 is indicated by a black arrow for convenience. Four second electrodes 172 separated from the first electrode 171 cover the area of ​​the two-dimensional photonic crystal region 151 except for the central portion. The four second electrodes 172, each having a trapezoidal planar shape, overlap each of the four sides of the two-dimensional photonic crystal region 151 by a predetermined width. Almost the entire boundary 155 between the two-dimensional photonic crystal region 151 and the non-two-dimensional photonic crystal region 152 is covered by the bottom edges of the four second electrodes 172.

[0047] In the electrode arrangement shown in Fig. 20, the first electrode 171 and all four second electrodes 172 are energized. As shown in the FFP of Fig. 8, in addition to the diffracted light in the center, secondary beams 21 are generated in the vicinity of the sides of the boundary 155 that are perpendicular to the diffraction direction Ddif determined by the triangular lattice.

[0048] In this way, by individually controlling the energization of multiple electrodes electrically connected to the semiconductor layer having the two-dimensional photonic crystal region 151 of the semiconductor laser device 10, it is possible to emit laser light at desired positions. When the two-dimensional periodic structure is a square lattice with the electrode arrangement shown in FIG. 20, in addition to the central diffracted light, secondary beams are generated in four directions determined by the square lattice, i.e., at positions corresponding to the four sides of the rectangular two-dimensional photonic crystal region 151. The greater the number of beams emitted, the higher the overall power of the emitted light. By selectively emitting specific secondary beams, it is possible to individually irradiate minute targets.

[0049] <Light source device using semiconductor laser element> FIG. 21 is a schematic cross-sectional view of a light source device 40 using the semiconductor laser element 10 of the embodiment. The light source device 40 includes the semiconductor laser element 10 described above and a circuit board 30 connected to the semiconductor laser element 10. The circuit board 30 has a first terminal 31 connected to the first electrode 171 of the semiconductor laser element 10 and a second terminal 32 connected to the second electrode 172. This allows the main beam and secondary beams to be generated separately. When the semiconductor laser element 10 has two or more second electrodes 172 spaced apart from each other as shown in FIG. 20, the circuit board 30 has the first terminal 31 connected to the first electrode 171 and multiple second terminals 32 connected to the two or more second electrodes 172, each of which is independent from the other. This allows the generation of secondary beams to be independently controlled. Each of the multiple second terminals 32 may be connected to two or more second electrodes 172 in a one-to-one correspondence. This allows the generation of secondary beams to be independently controlled. The first terminal 31 is connected to the first electrode 171 via a conductive bonding material 131. The second terminal 32 is connected to the second electrode 172 via a conductive bonding material 132.

[0050] A third electrode 173 provided on the surface opposite to the first electrode 171 and the second electrode 172 may be connected to a third terminal 33 of the circuit board 30 via a wiring 174. The third terminal 33 is connected to the wiring 174 via a conductive bonding material 133. The wiring 174 may be formed along the outer surface of the semiconductor laser element 10, or may be formed as a through-via that penetrates the semiconductor laser element 10 in the stacking direction. An insulating layer is provided between the semiconductor laser element 10 and the wiring 174. Alternatively, only the third electrode 173 may be connected to the third terminal 33 via a wire.

[0051] The circuit board 30 includes a current injection control circuit, which individually controls the supply of electricity to the first electrode 171 and the second electrode 172, or the on / off of electricity to each of the plurality of second electrodes 172, via the first terminal 31, the second terminal 32, and the third terminal 33. The current injection control circuit may be realized by a part of an LSI mounted on the circuit board 30, or may be realized by a logic device such as a field programmable gate array (FPGA). This realizes a light source device 40 that can output light in a desired direction with a desired power.

[0052] <Fabrication process of semiconductor laser element> 22A to 22E show an example of a manufacturing process for a semiconductor laser device. In FIG. 22A, a first semiconductor layer 11, an active layer 13, and a second semiconductor layer 12 are grown in this order on a substrate 101 to form a semiconductor laminate 14. The substrate 101 is, for example, a GaN substrate, which may contain n-type impurities such as Si and Ge. The first semiconductor layer 11 is an n-side nitride semiconductor layer, and Al x Ga 1-x N (0≦x≦1). The first semiconductor layer 11 includes at least one n-type semiconductor layer. The first semiconductor layer 11 may have an n-side cladding layer on the side closer to the substrate 101, and an n-side optical guide layer on the side closer to the active layer 13. The active layer 13 has, for example, a single quantum well layer having one well layer and multiple barrier layers, or a multiple quantum well structure having multiple well layers and multiple barrier layers. The well layer is made of, for example, GaN, InGaN, or AlGaN, and the barrier layer is made of, for example, AlGaN or GaN. The period of the multiple quantum well and the film thicknesses of the well layer and barrier layer are appropriately designed according to the target wavelength.

[0053] After the active layer 13 is formed, the second semiconductor layer 12 is grown. The second semiconductor layer 12 is a p-side semiconductor layer. The refractive indexes of the first semiconductor layer 11 and the second semiconductor layer 12 are lower than the refractive index of the active layer 13. When the first semiconductor layer 11, the active layer 13, and the second semiconductor layer 12 are formed of AlGaN-based materials, the Al composition ratios of the first semiconductor layer 11 and the second semiconductor layer 12 are set higher than the Al composition ratio of the active layer 13. When the second semiconductor layer 12 is formed of multiple layers, a layer farther from the active layer 13 may be doped with a p-type impurity such as Mg. The second semiconductor layer 12 may have, in order from the side closest to the active layer 13, a p-side optical guide layer, an electron blocking layer, and a p-side cladding layer.

[0054] A conductive layer 18 is formed on the semiconductor stack 14. As the conductive layer 18, a transparent conductive layer such as ITO, IZO, or IGZO may be formed by sputtering or the like. As the conductive layer 18, a nitride semiconductor layer containing a high concentration of p-type impurities may be grown continuously from the semiconductor stack 14.

[0055] 22B, recesses 181 are formed with a two-dimensional periodicity in predetermined regions of conductive layer 18 and second semiconductor layer 12 by electron beam (EB) lithography and reactive ion etching (RIE). Recesses 181 are cylindrical or polygonal prism-shaped holes, and their depths may reach the vicinity of active layer 13. The region containing the periodic arrangement of recesses 181 is two-dimensional photonic crystal region 151. The region outside two-dimensional photonic crystal region 151 that does not have a periodic structure is non-two-dimensional photonic crystal region 152.

[0056] 22C, the conductive layer 18 is removed from the area other than the current injection area. The conductive layer 18 remaining in the current injection area including the two-dimensional photonic crystal area 151 may be used as a contact layer.

[0057] In FIG. 22D, an insulating layer 16 is formed on the exposed surface of the second semiconductor layer 12. The insulating layer 16 may be used as a protective layer. The insulating layer 16 may cover the side surfaces of the substrate 101 and the semiconductor stack 14. In FIG. 22E, a first electrode 171 and a second electrode 172 are formed on the conductive layer 18 by a lift-off method or the like. In addition, a third electrode 173 is formed on the back surface of the substrate 101, i.e., the surface of the substrate 101 opposite to the semiconductor stack 14. This completes the semiconductor laser device 10A.

[0058] According to the semiconductor laser elements 10 and 10A of the embodiments, it is possible to individually control the flow of current to multiple electrodes, making it possible to irradiate beams in multiple directions with a single chip. A light source device using the semiconductor laser element 10 or 10A individually controls the output of secondary beams at different positions, making it possible to irradiate beams in multiple directions with a single semiconductor laser element 10 or 10A. The semiconductor laser elements and light source devices of the embodiments are applicable to sensing such as LiDAR (Light Detection and Ranging) and displays.

[0059] Although the above description has been based on specific configuration examples, the present disclosure is not limited to the above configuration examples. The planar shape of the two-dimensional photonic crystal region 151 is not limited to a rectangle or a circle, but may be a polygon such as a triangle or a hexagon. The two-dimensional periodic structure formed in the two-dimensional photonic crystal region 151 is not limited to a square lattice or a triangular lattice, but may be a rectangular lattice, an oblique (parallelogram) lattice, a rhombic lattice, a hexagonal lattice, or the like. The planar shape of the second medium 154 arranged with two-dimensional periodicity within the first medium 153 is not limited to a circle, but may be a polygon such as a triangle, a rectangle, or a hexagon, or an ellipse. The planar shapes of the first electrode 171 and the second electrode 172 can be appropriately designed depending on the desired position from which diffracted light is to be emitted.

[0060] An embodiment of the present disclosure may include, for example, the following configuration. (Section 1) a semiconductor laminate including a first semiconductor layer on a first conductive side, a second semiconductor layer on a conductive side opposite to the first conductive side, and an active layer disposed between the first semiconductor layer and the second semiconductor layer; a first electrode and a second electrode separated from each other and electrically connected to the second semiconductor layer; a third electrode electrically connected to the first semiconductor layer; and one or both of the first semiconductor layer and the second semiconductor layer has a two-dimensional photonic crystal region and a non-two-dimensional photonic crystal region; the two-dimensional photonic crystal region has a two-dimensional periodic structure in which a second medium having a second refractive index different from a first refractive index is arranged in a two-dimensional period inside a first medium having a first refractive index, the second medium being arranged in a two-dimensional period; the non-two-dimensional photonic crystal region does not have a periodic structure and is disposed outside the two-dimensional photonic crystal region; the first electrode is located inside the two-dimensional photonic crystal region in a plan view, the second electrode overlaps at least a boundary region between the two-dimensional photonic crystal region and the non-two-dimensional photonic crystal region that is orthogonal to the diffraction direction determined by the two-dimensional periodic structure; Semiconductor laser element. (Section 2) the first semiconductor layer is an n-side semiconductor layer, the second semiconductor layer is a p-side semiconductor layer, the first electrode is a first positive electrode; the second electrode is a second positive electrode; the third electrode is a negative electrode; the p-side semiconductor layer has the two-dimensional photonic crystal region and the non-two-dimensional photonic crystal region; Item 1. The semiconductor laser device according to item 1. (Section 3) the second electrode includes two or more second electrodes spaced apart from each other; Each of the two or more second electrodes overlaps the boundary region perpendicular to the diffraction direction. Item 1 or 2. The semiconductor laser device according to item 1 or 2. (Section 4) the second electrode overlaps with the two-dimensional photonic crystal region outside the first electrode when viewed from the center of the two-dimensional photonic crystal region; Item 4. The semiconductor laser device according to any one of items 1 to 3. (Section 5) the second electrode overlaps the non-two-dimensional photonic crystal region by a predetermined width from the boundary region; The predetermined width is equal to or greater than 2 times and equal to or less than 10 times the period. Item 5. The semiconductor laser device according to any one of items 1 to 4. (Section 6) the two-dimensional periodic structure of the two-dimensional photonic crystal region is a square lattice structure or a triangular lattice structure; Item 6. The semiconductor laser device according to any one of items 1 to 5. (Section 7) the two-dimensional periodic structure is a triangular lattice structure, the two-dimensional photonic crystal region is a circle having a circumference along which a tangent line perpendicular to the diffraction direction determined by the triangular lattice can be drawn, or a polygon having sides perpendicular to the diffraction direction determined by the triangular lattice. Item 7. The semiconductor laser device according to item 6. (Section 8) the two-dimensional periodic structure is a square lattice structure, the two-dimensional photonic crystal region is a circle having a circumference along which a tangent line perpendicular to the diffraction direction determined by the square lattice can be drawn, or a polygon having sides perpendicular to the diffraction direction determined by the square lattice. Item 7. The semiconductor laser device according to item 6. (Section 9) the first semiconductor layer, the active layer, and the second semiconductor layer are nitride semiconductor layers; Item 9. The semiconductor laser device according to any one of items 1 to 8. (Section 10) The semiconductor laser element according to any one of items 1 to 9, a circuit board connected to the semiconductor laser element; Including, the circuit board has a first terminal connected to the first electrode and a second terminal connected to the second electrode; Light source device. (Section 11) the semiconductor laser element according to claim 3; a circuit board connected to the semiconductor laser element; and the circuit board has a first terminal connected to the first electrode and a plurality of second terminals connected to two or more of the second electrodes; The plurality of second terminals are independent of each other. Light source device. (Section 12) each of the plurality of second terminals is connected to two or more of the second electrodes in one-to-one correspondence; Item 12. The light source device according to item 11. [Explanation of symbols]

[0061] 10, 10A semiconductor laser element 11 First semiconductor layer 12 Second semiconductor layer 13 Active layer 14 Semiconductor laminate 16 Insulating layer 18 Conductive layer 21 Secondary Beam 22 light 30 Circuit Board 31 1st terminal 32 2nd terminal 33 3rd terminal 40 Light source device 101 Substrate 103 Excitation Spot 150A, 150B 2D periodic structure 151, 151A, 151B Two-dimensional photonic crystal region 152 Non-two-dimensional photonic crystal region 153 First Medium 154 Second Medium 155 Boundary 155a to 155j Boundary area 171 1st electrode 172 2nd electrode 173 3rd electrode 181 recess Ddif diffraction direction

Claims

1. a semiconductor laminate including a first semiconductor layer on a first conductive side, a second semiconductor layer on a conductive side opposite to the first conductive side, and an active layer disposed between the first semiconductor layer and the second semiconductor layer; a first electrode and a second electrode separated from each other and electrically connected to the second semiconductor layer; a third electrode electrically connected to the first semiconductor layer; and one or both of the first semiconductor layer and the second semiconductor layer has a two-dimensional photonic crystal region and a non-two-dimensional photonic crystal region; the two-dimensional photonic crystal region has a two-dimensional periodic structure in which a second medium having a second refractive index different from a first refractive index is arranged in a two-dimensional period inside a first medium having a first refractive index, the second medium being arranged in a two-dimensional period; the non-two-dimensional photonic crystal region does not have a periodic structure and is disposed outside the two-dimensional photonic crystal region; the first electrode is located inside the two-dimensional photonic crystal region in a plan view, the second electrode overlaps at least a boundary region between the two-dimensional photonic crystal region and the non-two-dimensional photonic crystal region that is orthogonal to a diffraction direction determined by the two-dimensional periodic structure; Semiconductor laser element.

2. the first semiconductor layer is an n-side semiconductor layer, the second semiconductor layer is a p-side semiconductor layer, the first electrode is a first positive electrode; the second electrode is a second positive electrode; the third electrode is a negative electrode; the p-side semiconductor layer has the two-dimensional photonic crystal region and the non-two-dimensional photonic crystal region; 2. The semiconductor laser device according to claim 1.

3. the second electrodes include two or more second electrodes spaced apart from each other; each of the two or more second electrodes overlaps with the boundary region perpendicular to the diffraction direction; 2. The semiconductor laser device according to claim 1.

4. the second electrode overlaps with the two-dimensional photonic crystal region outside the first electrode when viewed from the center of the two-dimensional photonic crystal region; 2. The semiconductor laser device according to claim 1.

5. the second electrode overlaps the non-two-dimensional photonic crystal region by a predetermined width from the boundary region; The predetermined width is equal to or greater than 2 times and equal to or less than 10 times the period.

2. The semiconductor laser device according to claim 1.

6. the two-dimensional periodic structure of the two-dimensional photonic crystal region is a square lattice structure or a triangular lattice structure; 2. The semiconductor laser device according to claim 1.

7. the two-dimensional periodic structure is a triangular lattice structure, the two-dimensional photonic crystal region is a circle having a circumference along which a tangent line perpendicular to the diffraction direction determined by a triangular lattice can be drawn, or a polygon having sides perpendicular to the diffraction direction determined by the triangular lattice.

7. The semiconductor laser device according to claim 6.

8. the two-dimensional periodic structure is a square lattice structure, the two-dimensional photonic crystal region is a circle having a circumference along which a tangent perpendicular to the diffraction direction determined by a square lattice can be drawn, or a polygon having sides perpendicular to the diffraction direction determined by the square lattice.

7. The semiconductor laser device according to claim 6.

9. the first semiconductor layer, the active layer, and the second semiconductor layer are nitride semiconductor layers; 2. The semiconductor laser device according to claim 1.

10. The semiconductor laser device according to any one of claims 1 to 9, a circuit board connected to the semiconductor laser element; Including, the circuit board has a first terminal connected to the first electrode and a second terminal connected to the second electrode; Light source device.

11. The semiconductor laser element according to claim 3 ; a circuit board connected to the semiconductor laser element; and the circuit board has a first terminal connected to the first electrode and a plurality of second terminals connected to two or more of the second electrodes; The plurality of second terminals are independent of each other. Light source device.

12. each of the plurality of second terminals is connected to two or more of the second electrodes in one-to-one correspondence; The light source device according to claim 11.

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