Laser element, laser element array, and method for manufacturing a laser element

Abstract

[Problem] To provide: a laser element which has a concave mirror structure and which exhibits excellent optical characteristics; a laser element array; and a laser element manufacturing method. [Solution] The laser element according to the present technology is equipped with a first light reflection layer, a second light reflection layer, and a laminate. The laminate comprises an active layer, and has a lens provided on a first surface on the first light reflection layer side. In the lens, the longitudinal direction is defined as a first direction and the short direction is defined as a second direction. The lens has a lens shape protruding toward the first light reflection layer. A central part of the lens in the first direction has a first width which is the shortest width along the second direction, and a non-central part of the lens in the first direction has a second width which is the largest width along the second direction. The height of the lens is constant, or larger at the central part than at an end part. The lens top part has a constant radius of curvature in the second direction. The first light reflection layer is laminated on the first surface, and forms on the lens a concave mirror having a concave shape.

Description

[Technical Field]

[0001] This technology relates to a laser element that emits a laser in a direction perpendicular to the layer surface, a laser element array, and a method for manufacturing the laser element. [Background technology]

[0002] One type of laser element is the VCSEL (Vertical Cavity Surface Emitting Laser). A VCSEL has a structure in which an emitting layer is sandwiched between a pair of mirrors. A current-constricting structure is provided near the emitting layer, and the current is concentrated in a part of the emitting layer by this structure, producing spontaneous emission light. The pair of mirrors form a resonator, and by reflecting light of a predetermined wavelength from the spontaneous emission light towards the emitting layer, laser oscillation is generated.

[0003] In VCSEL elements, as the resonator length, which is the distance between the pair of mirrors, increases, diffraction loss due to optical field confinement in the lateral direction (layer plane direction) increases. As a method to neutralize this diffraction loss, a structure has been proposed in which a spherical concave mirror is provided on one of the pair of mirrors (see Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2018 / 083877 [Overview of the project] [Problems that the invention aims to solve]

[0005] The proposal described in Patent Document 1 above involves applying heat treatment to a fluid material patterned on a substrate to form a convex spherical shape, and then using that convex spherical shape to form a concave mirror. However, this method has the problem that, due to the tension between the substrate surface and the fluid material, as well as gravity, the shape of the fluid material does not become a convex spherical shape, but rather flat or concave.

[0006] For example, if the diameter of the patterned fluid material is large, capillary action is hindered by gravity, resulting in a flat or concave shape. Also, when the fluid material is made into a thin film, the contact angle between the substrate surface and the fluid material cannot be made smaller than a certain value due to the tension between them, resulting in a flat or concave shape for the fluid material. When the fluid material is flat or concave, the desired optical properties cannot be obtained with a concave mirror.

[0007] In light of the above circumstances, the objective of this technology is to provide a laser element having a concave mirror structure and excellent optical properties, a laser element array, and a method for manufacturing a laser element. [Means for solving the problem]

[0008] To achieve the above objective, the laser element relating to this technology comprises a first light-reflecting layer, a second light-reflecting layer, and a laminate. The first light-reflecting layer described above reflects light of a specific wavelength. The second light-reflecting layer described above reflects light of the above wavelength. The laminate comprises a first semiconductor layer made of a semiconductor material having a first conduction type, a second semiconductor layer made of a semiconductor material having a second conduction type, and an active layer disposed between the first semiconductor layer and the second semiconductor layer, which generates light emission by carrier recombination. The active layer is disposed between the first light-reflecting layer and the second light-reflecting layer, and has a first surface on the side of the first light-reflecting layer and a second surface on the side of the second light-reflecting layer, with a lens provided on the first surface. The above-described lens has a longitudinal direction in which a first direction parallel to a plane perpendicular to the optical axis direction of the emitted light is parallel, and a short direction in which a second direction parallel to the above plane and perpendicular to the above first direction is parallel, and has a lens shape that protrudes toward the first light reflection layer side, has a first width in which the central part in the first direction is the minimum width along the second direction, has a second width in which the non-central part in the first direction is the maximum width along the second direction, has a shape in which the height from the above plane is uniform or the central part is higher than the ends, and has a uniform radius of curvature in the second direction of the lens top. The first light-reflecting layer described above is laminated onto the first surface to form a concave mirror having a concave shape on the lens. In this specification, "uniform" height and radius of curvature means that the value does not exceed ±20% from the average value at the top of a predetermined concave mirror in approximately all parts.

[0009] The above laminate has a current-constricting structure that narrows the current and forms a current injection region where the current is concentrated. The current injection region may have a shape in which the planar figure viewed from the optical axis direction has the first direction as the longitudinal direction and the second direction as the short direction, and overlaps with the lens when viewed from the optical axis direction.

[0010] The length of the lens along the first direction may be greater than the second width.

[0011] The length of the lens along the first direction may be 40 μm or more.

[0012] The second width of the above lens may be 10 μm or more.

[0013] The resonator length of the above laser element is the distance between the concave mirror and the second light-reflecting layer. The radius of curvature mentioned above may be greater than or equal to the resonator length mentioned above.

[0014] The surface precision of the above lens may be such that the RMS (Root Mean Square) is 1.0 nm or less.

[0015] The first semiconductor layer and the second semiconductor layer may be made of GaN. Laser element.

[0016] The first semiconductor layer and the second semiconductor layer may be made of GaAs.

[0017] The first semiconductor layer and the second semiconductor layer may be made of InP.

[0018] The laser element may further comprise a wavelength conversion layer made of a wavelength conversion material, provided on the side of the second light reflection layer opposite to the laminate.

[0019] The first light-reflecting layer and the second reflective layer described above may be a DBR (Distributed Bragg Reflector) made of a multilayer light-reflecting film.

[0020] To achieve the above objective, the laser element array relating to this technology is a laser element array in which a plurality of individually drivable laser elements are arranged, The above laser element is A first light-reflecting layer that reflects light of a specific wavelength, A second light-reflecting layer that reflects light of the above wavelength, A laminate comprising: a first semiconductor layer made of a semiconductor material having a first conduction type; a second semiconductor layer made of a semiconductor material having a second conduction type; and an active layer disposed between the first and second semiconductor layers and generating light emission by carrier recombination; and disposed between the first and second light reflection layers, having a first surface on the first light reflection layer side and a second surface on the second light reflection layer side, with a lens provided on the first surface. It is equipped with, The above lens has a longitudinal direction in a first direction parallel to a plane perpendicular to the optical axis direction of the emitted light, a short direction in a second direction parallel to the plane and perpendicular to the first direction, a lens shape that protrudes toward the first light reflection layer, a first width in the central part in the first direction which is the minimum width along the second direction, a second width in the non-central part in the first direction which is the maximum width along the second direction, a shape in which the height from the plane is uniform or the central part is higher than the ends, and the radius of curvature of the lens top in the second direction is uniform. The first light-reflecting layer described above is laminated onto the first surface, forming a concave mirror having a concave shape on the lens.

[0021] To achieve the above objective, the manufacturing method of the laser element according to this technology comprises a first semiconductor layer made of a semiconductor material having a first conduction type, a second semiconductor layer made of a semiconductor material having a second conduction type, and an active layer disposed between the first semiconductor layer and the second semiconductor layer and generating light emission by carrier recombination, and a laminate having a first surface and a second surface is fabricated. If we define a first direction as one direction parallel to a plane perpendicular to the optical axis of the emitted light, and a second direction as one direction parallel to the plane and perpendicular to the first direction, then a structure is formed on the first surface that is made of a fluid material, has a constant thickness, has the first direction as the longitudinal direction, the second direction as the short direction, has a first width in the central part in the first direction which is the minimum width along the second direction, and has a second width in the non-central part in the first direction which is the maximum width along the second direction. The above structure is heated, the above fluid material is allowed to flow and deform the structure, and the shape of the structure is used to form a lens in which the height from the plane is uniform on the first surface or the center is higher than the edges, and the radius of curvature in the second direction of the lens top is uniform. A first light-reflecting layer that reflects light of a specific wavelength is laminated on the first surface, and a concave mirror having a concave shape is formed on the lens. A second light-reflecting layer that reflects light of the above wavelength is formed on the second surface side of the laminate.

[0022] In the process of forming the lens described above, the structure may be deformed to have a lens shape that protrudes toward the first light-reflecting layer, with the first direction being the longitudinal direction and the second direction being the short direction, the central part having the first width, the non-central part having the second width, the height from the plane being uniform or the central part being higher than the ends, and the radius of curvature of the apex in the second direction being uniform.

[0023] In the process of forming the lens described above, the laminate may be etched using the structure deformed into the above shape as an etching mask to form the lens on the first surface.

[0024] In the process of forming the above lens, the structure deformed into the above shape may be used as the lens.

[0025] The length of the above structure along the first direction may be greater than the second width.

[0026] The length of the above structure along the first direction may be 40 μm or more.

[0027] The etching described above may be dry etching or wet etching. [Brief explanation of the drawing]

[0028] [Figure 1] This is a cross-sectional view of a laser element according to the first embodiment of this technology. [Figure 2] This is an exploded cross-sectional view of a part of the above-mentioned laser element. [Figure 3] This is a schematic diagram showing the current injection region of the laser element described above. [Figure 4] This is a schematic diagram showing the current injection region of the laser element described above. [Figure 5] This is a plan view of the lens provided by the laser element described above. [Figure 6] This is a perspective view of the lens provided by the laser element described above. [Figure 7]This is a plan view of the lens provided by the laser element described above. [Figure 8] This is a schematic diagram showing the shape of the lens provided by the laser element described above. [Figure 9] This is a schematic diagram showing the cross-sectional shapes of the central and non-central parts of the lens of the laser element described above. [Figure 10] This is a schematic diagram showing the resonator length of the laser element described above. [Figure 11] This is a schematic diagram showing the positional relationship between the current injection region of the laser element and the concave mirror. [Figure 12] This is a cross-sectional view of a laser element in which the lens is made of a separate component, according to the first embodiment of this technology. [Figure 13] This is a schematic diagram showing the operation of a laser element according to the first embodiment of this technology. [Figure 14] This is a schematic diagram showing the shape of the lens for comparison. [Figure 15] This is a schematic diagram showing a method for manufacturing a laser element according to the first embodiment of this technology. [Figure 16] This is a schematic diagram showing the manufacturing method of the laser element described above. [Figure 17] This is a perspective view of the structure in the manufacturing method of the laser element described above. [Figure 18] This is a plan view of the structure in the manufacturing method of the laser element described above. [Figure 19] This is a schematic diagram showing the shape of the structure in the manufacturing method of the laser element described above. [Figure 20] This is a perspective view of the deformed structure in the above-described method for manufacturing the laser element. [Figure 21] This is a schematic diagram showing the etching process in the manufacturing method of the laser element described above. [Figure 22] This is a perspective view of the structure in the manufacturing method of the laser element described above. [Figure 23] This is a plan view of a differently shaped lens provided by the laser element described above. [Figure 24] Figure 23 is a perspective view of the structure used in the lens formation process. [Figure 25]This is a plan view of a differently shaped lens provided by the laser element described above. [Figure 26] Figure 25 is a perspective view of the structure used in the lens formation process. [Figure 27] This is a cross-sectional view of a laser element equipped with a wavelength conversion layer according to a first embodiment of this technology. [Figure 28] This is a cross-sectional view of a laser element array according to the first embodiment of this technology. [Figure 29] This is a plan view of the laser element array shown above. [Figure 30] This is a cross-sectional view of a laser element array equipped with a wavelength conversion layer according to a first embodiment of this technology. [Figure 31] This is a cross-sectional view of a laser element according to a second embodiment of this technology. [Figure 32] This is a cross-sectional view showing a disassembled portion of the above-mentioned laser element. [Figure 33] This is a schematic diagram showing the current constriction structure of the laser element described above. [Figure 34] This is a cross-sectional view of a laser element having a different configuration according to a second embodiment of the present technology. [Figure 35] This is a cross-sectional view of a laser element according to a third embodiment of this technology. [Figure 36] This is a cross-sectional view showing a disassembled portion of the above-mentioned laser element. [Figure 37] This is a schematic diagram showing the current constriction structure of the laser element described above. [Modes for carrying out the invention]

[0029] (First Embodiment) A laser element according to the first embodiment of this technology will now be described. In each figure of this disclosure, the optical axis direction of the light emitted from the laser element is defined as the Z direction, the direction perpendicular to the Z direction is defined as the X direction, and the direction perpendicular to both the Z and X directions is defined as the Y direction. The laser element according to this embodiment has a structure similar to a VCSEL (Vertical Cavity Surface Emitting Laser) element, but while a VCSEL element has a structure in which optical resonance occurs in the Z direction, the laser element according to this embodiment differs from a VCSEL element in that resonance occurs in the Z direction as well as in another direction (Y direction).

[0030] [Structure of laser element] Figure 1 is a cross-sectional view of the laser element 100 according to this embodiment, and Figure 2 is a schematic diagram showing the laser element 100 in disassembled form. As shown in these figures, the laser element 100 comprises a first semiconductor layer 101, a second semiconductor layer 102, an active layer 103, a first light reflection layer 104, a second light reflection layer 105, a first electrode 106, and a second electrode 107. Of these, the first semiconductor layer 101, the second semiconductor layer 102, and the active layer 103 together form a laminate 150.

[0031] Each of these layers has a layer plane direction along the XY plane, and they are stacked in the order of first electrode 106, first light reflection layer 104, first semiconductor layer 101, active layer 103, second semiconductor layer 102, second electrode 107, and second light reflection layer 105. Therefore, the laminate 150 is positioned between the first light reflection layer 104 and the second light reflection layer 105.

[0032] The first semiconductor layer 101 is made of a semiconductor having a first conduction type and is a layer that transports carriers to the active layer 103. The first conduction type can be n-type, and the first semiconductor layer 101 can be, for example, an n-GaN substrate. A lens 160 is provided on the first semiconductor layer 101. This lens 160 will be described later. The second semiconductor layer 102 is made of a semiconductor having a second conduction type and is a layer that transports carriers to the active layer 103. The second conduction type can be p-type, and the second semiconductor layer 102 can be, for example, made of p-GaN.

[0033] The active layer 103 is positioned between the first semiconductor layer 101 and the second semiconductor layer 102, and is a layer that generates light emission due to carrier recombination. The active layer 103 has a multiple quantum well structure in which multiple layers of quantum well layers and barrier layers are alternately stacked, and the quantum well layers can be made of, for example, InGaN, and the barrier layers can be made of, for example, GaN. In addition to the multiple quantum well structure, the active layer 103 may be any layer that generates light emission due to carrier recombination.

[0034] As shown in Figure 2, of the surfaces of the laminate 150, the surface on the side of the first light-reflecting layer 104 is designated as the first surface 151, and the surface on the side of the second light-reflecting layer 105 is designated as the second surface 152. The lens 160 is provided on the first surface 151. Thus, the first surface 151 has a main surface 151a and a lens surface 151b. The main surface 151a is a plane (X-Y plane) perpendicular to the optical axis direction (Z direction) of the emitted light. The lens surface 151b is the surface of the lens 160 and is a surface that protrudes from the main surface 151a.

[0035] The first light-reflecting layer 104 reflects light of a specific wavelength (hereinafter referred to as wavelength λ) and transmits light of other wavelengths. The wavelength λ is, for example, 445 nm. As shown in Figure 1, the first light-reflecting layer 104 can be a DBR (Distributed Bragg Reflector) consisting of a multilayer light-reflecting film in which multiple layers of high refractive index layers 104a and low refractive index layers 104b, each having an optical film thickness λ / 4, are alternately stacked. The first light-reflecting layer 104 can have a multilayer structure such as Ta2O5 / SiO2, SiO2 / SiN, or SiO2 / Nb2O5.

[0036] The first light-reflecting layer 104 has a concave mirror 104c. The first light-reflecting layer 104 is laminated on the first surface 151 of the laminate 150 with a constant thickness, and as shown in Figure 2, according to the shape of the lens 160, the surface on the laminate 150 side forms a concave surface 104d, and the surface on the opposite side of the laminate 150 forms a convex surface 104e. In this way, a concave mirror 104c is formed on the first light-reflecting layer 104.

[0037] The second light-reflecting layer 105 reflects light of wavelength λ and transmits light of other wavelengths. As shown in Figure 1, the second light-reflecting layer 105 can be a DBR (Distributed Bragg Reflector) consisting of a multilayer light-reflecting film in which multiple layers of high refractive index layers 105a and low refractive index layers 105b, each having an optical film thickness of λ / 4, are alternately stacked. The second light-reflecting layer 105 can have a multilayer structure such as Ta2O5 / SiO2, SiO2 / SiN, or SiO2 / Nb2O5.

[0038] The first electrode 106 is provided on the first light reflection layer 104 around the concave mirror 104c and functions as one electrode of the laser element 100. The first electrode 106 can be a single-layer metal film made of, for example, Au, Ni, or Ti, or a multilayer metal film made of Ti / Au, Ag / Pd, or Ni / Au / Pt.

[0039] The second electrode 107 is positioned between the second semiconductor layer 102 and the second light-reflecting layer 105 and functions as the other electrode of the laser element 100. The second electrode 107 can be made of a transparent conductive material such as ITO (Indium Tin Oxide), ITiO (Indium Titanium Oxide), TiO, AZO (Aluminum doped zinc oxide), ZnO, SnO, ZSnO, SnO2, SnO3, TiO, TiO2, or graphene.

[0040] In the laser element 100, a current-constricting structure is formed in the laminate 150. Figures 3 and 4 are schematic diagrams showing the current-constricting structure. Figures 3(a) and 4(a) are plan views of the current-constricting structure as seen from the optical axis direction (Z direction). Figure 3(b) is a cross-sectional view of the XZ section showing the current-constricting structure, and Figure 4(b) is a cross-sectional view of the YZ section showing the current-constricting structure. As shown in Figures 3(b) and 4(b), the current-constricting structure has a current-injection region 121 and an insulating region 122 (a region with dots). The current-injection region 121 is a region where ions have not been implanted (non-ion-implanted region) and is a conductive region.

[0041] The insulating region 122 is the region surrounding the current injection region 121 in the layer plane direction (XY direction), and is an insulating region (ion-implanted region) in which ions are implanted into the semiconductor material constituting the laminate 150. The ions implanted into the insulating region 122 can be boron ions. In addition to boron ions, other ions capable of insulating semiconductor materials, such as oxygen ions or hydrogen ions, may also be used.

[0042] As shown in Figures 3(a) and 4(a), the current injection region 121 has an elongated planar shape with one direction (Y direction) as the longitudinal direction and the direction perpendicular to the longitudinal direction (X direction) as the short direction. Hereinafter, the longitudinal direction (Y direction) of the current injection region 121 will be referred to as the first direction A1, and the short direction (X direction) of the current injection region 121 will be referred to as the second direction A2. Both the first direction A1 and the second direction A2 are perpendicular to the optical axis direction (Z direction) and are also perpendicular to each other.

[0043] As shown in Figures 3(a) and 4(a), the length of the current injection region 121 along the first direction A1 is length L. e The width along the second direction A2 is width d. e Therefore, length L e is width d e A ratio of 3 times or more is preferable, and 20 times or more is even preferable. Specifically, the length L e A thickness of 40 μm or more is preferable.

[0044] The current flowing through the laser element 100 cannot pass through the insulating region 122 and is concentrated in the current injection region 121. That is, a current-constricting structure is formed by the current injection region 121 and the insulating region 122. Note that the insulating region 122 does not need to be provided in all of the first semiconductor layer 101, the active layer 103, and the second semiconductor layer 102; it is sufficient if it is provided in at least one of these layers.

[0045] Furthermore, the planar shape of the current injection region 121 as viewed from the optical axis direction (Z direction), as shown in Figures 3(a) and 4(a), is the planar shape of the part of the current injection region 121 with the smallest diameter in the layer plane direction (XY direction), as shown in Figures 3(b) and 4(b). Since the diameter of the current injection region 121 increases as it moves away from the interface between the second semiconductor layer 102 and the second electrode 106, the planar shape of the current injection region 121 is the shape of the current injection region 121 at that interface.

[0046] [Regarding lens shape] The shape of the lens 160 will now be described. Figures 5 to 7 are schematic diagrams showing the shape of the lens 160. Figure 5(a) is a top view of the first semiconductor layer 101 as seen from the optical axis direction (Z direction), and Figure 5(b) is a cross-sectional view of the first semiconductor layer 101. Figure 6 is a perspective view of the lens 160. Figure 7(a) is a plan view of the lens 160 as seen from the X direction, and Figure 7(b) is a plan view of the lens 160 as seen from the Y direction. As shown in Figures 5 to 7, the lens 160 is provided projecting toward the first light reflection layer 104 from a main surface 151a parallel to the XY plane. Hereafter, the main surface 151a will be referred to as the "plane" for defining the shape of the lens 160.

[0047] As shown in Figure 5, the lens 160 has an elongated lens shape with one direction parallel to the main surface 151a (Y direction) as its longitudinal direction and the direction perpendicular to the longitudinal direction (X direction) as its short direction. The longitudinal direction (Y direction) of the lens 160 coincides with the first direction A1, which is the longitudinal direction of the current injection region 121 (see Figure 3), and the short direction (X direction) of the lens 160 coincides with the second direction A2, which is the short direction of the current injection region 121. That is, the lens 160 has the first direction A1 as its longitudinal direction and the second direction A2 as its short direction.

[0048] Figure 8 is a schematic diagram showing the shape of the lens 160 as viewed from the optical axis direction (Z direction). As shown in the figure, the lens 160 has a central portion 160a and a non-central portion 160b. The central portion 160a is the part of the lens 160 located in the center in the first direction A1. The width of the central portion 160a along the second direction A2 is the first width d. s If we set it to 1, then the first width d s1 is the minimum width along the second direction A2 of the lens 160. The first width d s 1 can be, for example, 36 μm.

[0049] Also, the non-central part 160b is a part of the lens 160 that is located at a position separated from the central part 160a in the first direction A1, and is a part near both ends of the lens 160. The width along the second direction A2 of the non-central part 160b is the second width d s 2. Then, the second width d s 2 is the maximum width along the second direction A2 of the lens 160. The second width d s 2 is preferably 10 μm or more and can be, for example, 40 μm.

[0050] In the lens 160, the part between the central part 160a and the non-central part 160b can have a shape in which the width along the second direction A2 gradually decreases from the non-central part 160b toward the central part 160a, as shown in FIG. 8. The angle θ formed by the peripheral edge of the lens 160 and the first direction A1 as viewed from the optical axis direction (Z direction) can be, for example, 3.8°. Also, as shown in FIG. 8, the length along the first direction A1 of the lens 160 is the length L s Then, the length L s is preferably larger than the second width d s 2, and preferably 40 μm or more. The length L s can be, for example, 100 μm.

[0051] FIG. 9 is a schematic diagram showing the shapes of the central part 160a and the non-central part 160b. FIG. 9(a) shows the cross-sectional shape of the central part 160a in the X-Z plane, and FIG. 9(b) shows the cross-sectional shape of the non-central part 160b in the X-Z plane. As shown in FIGS. 9(a) and (b), the central part 160a and the non-central part 160b can have a shape in which the peripheral edge in the X-Z cross-section draws a curve, and the curve shapes are different between the central part 160a and the non-central part 160b. The part between the central part 160a and the non-central part 160b has a shape in which the curve drawn by the peripheral edge in the X-Z cross-section is intermediate between FIGS. 9(a) and 9(b).

[0052] As shown in Figures 7 and 9, the height (in the Z direction) of the lens 160 from the main surface 151a is defined as height H. s As shown in Figures 9(a) and (b), the central part 160a and the non-central part 160b are both at height H s It has the following characteristics. Also, the portion between the central part 160a and the non-central part 160b is also at height H s As shown in Figure 7, the lens 160 has a uniform height H s It has a height H. s A thickness of 10 nm or more is preferable. Furthermore, the lens 160 may have a shape where the height of the central portion 160a from the main surface 151a is greater than the height of the end portion from the main surface 151a. The end portion is the part located near both ends of the lens 160a in the first direction A1, for example, the non-central portion 160b.

[0053] Furthermore, the lens 160 has a radius of curvature (ROC) R at the top of the lens surface 152b (hereinafter referred to as the lens top) in the second direction A2. s It has the following characteristics. In Figures 9(a) and (b), the lens apex is shown by a dashed line, and the radius of curvature R in the second direction A2 of the lens apex is... s This is shown. As shown in Figures 9(a) and (b), the central part 160a and the non-central part 160b both have the same radius of curvature R at the top of the lens. s It also has a radius of curvature R between the central part 160a and the non-central part 160b. s The lens 160 has a uniform radius of curvature R at the top of the lens in the second direction A2. s It has.

[0054] This radius of curvature R s The radius of curvature R is preferably greater than or equal to the resonator length of the laser element 100. Figure 10 is a schematic diagram showing the resonator length K of the laser element 100. As shown in the figure, the resonator length K of the laser element 100 is the distance between the concave mirror 104c and the second light reflective layer 105. s The resonator length is preferably K or greater, and may be the same as the resonator length K, or may be longer than the resonator length K. This is because the radius of curvature R sThis is because if the resonator length K is less than the specified radius R, laser oscillation, as described later, may not occur. For example, the resonator length K is 25 μm, and the radius of curvature R is 25 μm. s For example, it can be set to 44 μm.

[0055] Furthermore, the lens 160 preferably has a surface accuracy (RMS: Root Mean Square) of the lens surface 152b of 1.0 nm or less. This is because if the surface accuracy (RMS) of the lens surface 152b exceeds 1.0 nm, optical loss occurs at the lens surface 152b. The surface accuracy (RMS) can be, for example, 0.6 nm.

[0056] Figure 11 is a schematic diagram showing the positional relationship between the lens 160 and the current injection region 121 (see Figure 3), and is a view of the lens 160 and the current injection region 121 from the optical axis direction (Z direction). As shown in the figure, the lens 160 is positioned and shaped such that the current injection region 121 overlaps with the lens 160 when viewed from the same direction.

[0057] The lens 160 may be formed from a part of the first semiconductor layer 101, as shown in Figure 2, but it may also be made of a different material from the first semiconductor layer 101. Figure 12 is a cross-sectional view showing the lens 160 bonded to the first semiconductor layer 101. As shown in the same figure, the lens 160 may be a material bonded to the first semiconductor layer 101.

[0058] Furthermore, in the above explanation, the principal surface 151a parallel to the XY plane was defined as the "plane" for defining the shape of the lens 160. However, the principal surface 151a is not limited to a flat surface parallel to the XY plane, but may be a curved surface or the like. In this case, a virtual plane parallel to the XY plane can be defined as the "plane" for defining the shape of the lens 160.

[0059] Furthermore, as described above, the lens 160 can have a curved edge in the X-Z cross-section. The shape of the edge of the lens 160 in the X-Z cross-section can be a part of a circle, a part of a parabola, a part of a sine curve, a part of an ellipse, or a part of a catenary curve. This shape may not be strictly a part of a circle, a part of a parabola, a part of a sine curve, a part of an ellipse, or a part of a catenary curve. In other words, even if it is roughly a part of a circle, a part of a parabola, a part of a sine curve, a part of an ellipse, or a part of a catenary curve, it is still encompassed by the statement, "The shape is a part of a circle, a part of a parabola, a part of a sine curve, a part of an ellipse, or a part of a catenary curve." Parts of these curves may be replaced by line segments. The shape traced by the periphery of lens 160 in the X-Z cross-section can be determined by measuring the shape of the lens surface 152b with a measuring instrument and analyzing the obtained data based on the least squares method.

[0060] [Laser element operation] The operation of the laser element 100 will now be explained. Figure 13 is a schematic diagram showing the operation of the laser element 100. When a voltage is applied between the first electrode 106 and the second electrode 107, a current flows between the first electrode 106 and the second electrode 107. The current is narrowed by the current constriction structure and injected into the current injection region 121, as shown by arrow C in Figure 13.

[0061] This injected current generates spontaneous emission light F near the current injection region 121 of the active layer 103. The spontaneous emission light F propagates in the stacking direction (Z direction) of the laser element 100 and is reflected by the first light reflection layer 104 and the second light reflection layer 105.

[0062] The first light-reflecting layer 104 and the second light-reflecting layer 105 are configured to reflect light having an oscillation wavelength λ. Therefore, the component of spontaneously emitted light with an oscillation wavelength λ forms a standing wave between the first light-reflecting layer 104 and the second light-reflecting layer 105, which is amplified by the active layer 103. When the injected current exceeds a threshold, the light forming the standing wave generates laser oscillation. The resulting laser light E passes through the second light-reflecting layer 105 and is emitted from the laser element 100 with the Z direction as the optical axis.

[0063] Here, in the laser element 100, the current injection region 121 has an elongated planar shape extending along the first direction A1 (Y direction), and the lens 160 also has an elongated lens shape extending along the first direction A1 (see Figure 11). By making the current injection region 121 and the lens 160 elongated along the first direction A1, it is possible to expand the optical confinement region by the current injection region 121 in the first direction A1 while limiting the optical confinement region by the current injection region 121 in the second direction A2. As a result, the width of the laser beam E emitted from the laser element along the first direction A1 is increased, and the emission angle of the laser beam E along the Y direction is reduced.

[0064] Furthermore, the lens 160 causes optical resonance not only in the stacking direction (Z direction) but also in the first direction A1 (Y direction). This improves the coherence of the laser light E. Thus, because the current injection region 121 and the lens 160 have an elongated shape aligned with the first direction A1, the laser element 100 is capable of emitting laser light E with a large beam diameter and a narrow emission angle, and operates as a line light source emitting a linear beam.

[0065] [Effects of laser elements] As described above, the laser element 100 is at a height H from the main surface 151a. s The radius of curvature R in the second direction A2 at the top of the lens is uniform. sThe lens 160 has a uniform radius. Figure 14 is a schematic diagram of lens 560 as seen from various directions for comparison. Lens 560 has an elongated lens shape with the first direction A1 as the longitudinal direction and the second direction A2 as the short direction. Lens 560 has an uneven height from the plane 551a, with a lower height in the center. In addition, the radius of curvature of the lens apex in the second direction A2 is also uneven.

[0066] If the lens has a shape that is elongated in one direction (especially 40 μm or more), the central part may become concave due to the effects of surface tension and gravity during the manufacturing process, as shown in Figure 14, and the height from the plane 551a and the radius of curvature of the lens top may become uneven. If the laser element 100 were to have lens 560 instead of lens 160, the height of lens 560 would be uneven, especially higher at the edges than in the center, so the resonator length K (see Figure 10) would differ depending on which part of lens 560 the light reaches. As a result, different longitudinal modes (states that repeatedly appear in the Z direction) would occur at different locations in the laser element 100.

[0067] Furthermore, because the radius of curvature of the lens 560 is also non-uniform at the top of the lens, different transverse modes (states that repeatedly appear in the XY direction) are established within the laser element 100. Due to these reasons, when the laser element 100 has the lens 560, brightness unevenness of the laser light E occurs within the laser element 100, the light field within the laser element 100 is not coherent, and it is not possible to emit laser light E with a narrow emission angle.

[0068] In contrast, the laser element 100 has a height H s and the radius of curvature R at the top of the lens s The lens 160 has a uniform radius. Therefore, by forming a current injection region 121 on the lens 160, a mode is formed that has both resonance in the optical axis direction (Z direction) and resonance in the longitudinal direction (Y direction) of the lens 160, and a laser element 100 that emits highly linear light can be realized. In addition, the laser element 100 has a radius of curvature R s Because it is uniform, the horizontal mode can be unified, and the height H sBecause the beam is uniform, it may be possible to unify the vertical modes. As a result, the laser element 100 can emit laser light E without brightness unevenness, making it possible to achieve a good line light source.

[0069] In addition, with shapes like lens 560, where the height is uneven, especially where the edges are higher than the center, stress concentrates in the center, which can lead to damage due to heating or physical contact. In contrast, with lens 160, where the height is uniform, stress is distributed, thus improving durability.

[0070] [Manufacturing method for laser elements] A method for manufacturing the laser element 100 will now be described. Figures 15 to 21 are schematic diagrams showing the manufacturing method of the laser element 100. First, a laminate 150 is fabricated as shown in Figure 15. The laminate 150 can be fabricated by stacking an active layer 103 and a second semiconductor layer 102 on a first semiconductor layer 101 (substrate). The active layer 103 and the second semiconductor layer 102 can be stacked by methods such as metal-organic-chemical vapor deposition (MOCVD).

[0071] Next, as shown in Figure 16, an insulating region 122 is formed. The insulating region 122 can be formed by implanting ions into the laminate 150 from the second semiconductor layer 102 side. At this time, by covering a part of the second semiconductor layer 102 with a mask, a current-injection region 121, which is a region where ions are not implanted, can be formed.

[0072] Next, as shown in Figure 17, a structure 170 is formed on the first surface 151 of the laminate 150. The structure 170 has a constant thickness from the first surface 151 and is patterned into a predetermined shape. Figure 18 is a plan view showing the shape of the structure 170, viewed from the optical axis direction (Z direction). As shown in the figure, the structure 170 has an elongated shape with one direction (Y direction) as the longitudinal direction and the direction perpendicular to the longitudinal direction (X direction) as the short direction. The longitudinal direction (Y direction) of the structure 170 coincides with the first direction A1, which is the longitudinal direction of the current injection region 121 (see Figure 3), and the short direction (X direction) of the structure 170 coincides with the second direction A2, which is the short direction of the current injection region 121. That is, the structure 170 has the first direction A1 as the longitudinal direction and the second direction A2 as the short direction.

[0073] Figure 19 is a schematic diagram showing the shape of the structure 170 as viewed from the optical axis direction (Z direction). As shown in the figure, the structure 170 has a central part 170a and a non-central part 170b. The central part 170a is the part of the structure 170 located in the center in the first direction A1. The width of the central part 170a along the second direction A2 is the first width d. p If we set it to 1, then the first width d p 1 is the minimum width of the structure 170 along the second direction A2. First width d p 1 can be, for example, 36 μm.

[0074] Furthermore, the non-central portion 170b is the part of the structure 170 that is spaced apart from the central portion 170a in the first direction A1, and is the part near both ends of the structure 170. The width of the non-central portion 170b along the second direction A2 is the second width d. p If we set it to 2, then the second width d p 2 is the maximum width of the structure 170 along the second direction A2. Second width d p 2 is preferably 10 μm or larger, and can be, for example, 40 μm.

[0075] In the structure 170, the portion between the central portion 170a and the non-central portion 170b can have a shape in which the width along the second direction A2 gradually decreases from the non-central portion 170b toward the central portion 170a, as shown in Figure 19. The angle θ between the periphery of the structure 170 and the first direction A1, as viewed from the optical axis direction (Z direction), can be, for example, 3.8°. Also, as shown in Figure 19, the length of the structure 170 along the first direction A1 can be defined as length L. p Therefore, length L p is the second width d p A value greater than 2 is preferred, and 40 μm or larger is preferred. Length L p This can be, for example, 100 μm.

[0076] The structure 170 is made of a fluid material that is fluid at room temperature or in a heating process described later. The fluid material can be an organic material or SOG (silicon on glass), or it may be a commercially available photoresist. The structure 170 can be formed by coating the fluid material to the first surface 151 with a certain thickness and then patterning it.

[0077] The fluid material can be applied by spin coating, with a spin coating rotation speed of 10 rpm or more, for example, 3000 rpm. Patterning can be performed by forming a mask having the planar shape of the structure 170 described above on the fluid material, and then etching using the mask. Etching may be wet etching or dry etching. Reactive ion etching (RIE) may also be used. The mask can be formed by photolithography, and the exposure apparatus can be an aligner, stepper, or electron beam lithography apparatus. The light source can be a g-line, i-line, KrF laser, or ArF laser.

[0078] Next, the structure 170 is subjected to a heat treatment (reflow) that heats it to a temperature above the melting point of the fluid material. The heating temperature can be, for example, 160°. This heating changes the viscosity of the fluid material and alters the shape of the structure 170. Figure 20 is a schematic diagram showing the structure 175, which is the result of the heat treatment that deformed the structure 170. The shape of the structure 175 is identical to the shape of the lens 160. That is, the width of the central part of the structure 175 is the same as the first width d of the lens 160. s Equal to 1 (see Figure 8), the width of the non-central part of the structure 175 is the second width d of the lens 160. s It is equal to 2. Also, the height of the structure 175 is uniform and the height H of the lens 160. s This becomes equal to the radius of curvature of the top of structure 175 in the second direction A2, and the radius of curvature of the top of lens 160 in the second direction A2 R s This is equal to:

[0079] Next, the first semiconductor layer 101 is etched using the structure 175 as an etching mask. Figure 21 is a schematic diagram illustrating this etching process. As indicated by the arrows in the figure, etchant is supplied to the first semiconductor layer 101 from the first surface 151 side. This etches the first semiconductor layer 101 from the first surface 151 side, forming the lens 160. By making the etching rates of the first semiconductor layer 101 and the structure 175 the same, a lens 160 with the same shape as the structure 175 can be formed. The etching can be wet etching or dry etching, but anisotropic etching is preferable, and reactive ion etching may also be used.

[0080] In addition to using structure 175 as an etching mask, structure 175 may also be used as a lens 160. When structure 175 is used as a lens 160, a lens 160 made of a different material from the first semiconductor layer 101 is formed, as shown in Figure 12. By forming structure 170 from a material that is transparent to light of the oscillation wavelength λ, structure 175 can be used as a lens 160.

[0081] As described above, the lens 160 can be formed on the first surface 151 (see Figure 6). After this, the first light-reflecting layer 104, the second light-reflecting layer 105, the first electrode 106, and the second electrode 107 can be formed to create the laser element 100 shown in Figure 1. Each of these layers can be formed by sputtering, vacuum deposition, or the like. When the first light-reflecting layer 104 is laminated onto the first semiconductor layer 101, a concave mirror 104c is formed on the first surface 151 because the lens 160 is provided therein. Note that the second light-reflecting layer 105 and the second electrode 107 can also be formed before the lens 160 is formed.

[0082] In this manufacturing method, by making the structure 170 have a narrow width in the central part 170a (see Figure 19) as described above, the height and radius of curvature of the top of the structure 175 can be made uniform, thereby making the height and radius of curvature of the top of the lens 160 uniform. If the structure 170 has a uniform width when viewed from the Z direction, when the structure 175 is deformed, the central part will become concave due to the effects of surface tension and weight (see Figure 14), and the radius of curvature of the central part will become larger. In contrast, if the structure 170 has a narrow width in the central part 170a, the radius of curvature will decrease due to surface tension, making it possible to make the height and radius of curvature of the top of the structure 175 uniform.

[0083] Furthermore, in the etching process of the first semiconductor layer 101, by etching under conditions where the surface accuracy (RMS: Root Mean Square) of the structure 175 is lower than the surface accuracy (RMS) of the first semiconductor layer 101, the surface accuracy (RMS) of the lens 160 surface after etching can be lowered compared to before etching. This suppresses scattering loss on the surface of the lens 160 and improves the performance of the resonator. Consequently, threshold reduction and power consumption reduction of the laser element 100 can be achieved, and improvements in output structure, efficiency, and reliability can be made.

[0084] The laser element 100 can be manufactured as described above. However, the manufacturing method of the laser element 100 is not limited to that shown herein, and it is also possible to manufacture the laser element 100 by other manufacturing methods.

[0085] Figure 22 is a schematic diagram showing another manufacturing method for the laser element 100. After forming the structure 170 (see Figure 17) on the first surface 151, the first surface 151 is oriented vertically downward as shown in the figure, and heat treatment (reflow) is performed. This prevents the height of the central part of the structure 175 from decreasing due to gravity, making it possible to make the height of the structure 175 uniform or to make the central part higher than the edges.

[0086] [Other lens configurations] The lens 160 of the laser element 100 may have the following configurations in addition to the above configuration. Figures 23 and 25 are plan views of the lens 160 having other configurations, and show the lens 160 as viewed from the optical axis direction (Z direction).

[0087] As shown in Figure 23, the lens 160 can also have a shape in which the width along the second direction A2 decreases in a stepped manner from the non-center portion 160b to the center portion 160a. Height H of lens 160 s and the radius of curvature R in the second direction A2 at the top of the lens. s (See Figure 9) is uniform, and height H s For example, 3.6 μm, radius of curvature R s This length can be longer than the resonator length K (see Figure 10), for example, 44 μm.

[0088] The first width d along the second direction A2 of the central part 160a s 1 is, for example, 36 μm, and the second width d is along the second direction A2 of the non-central part 160b. s 2 can be, for example, 40 μm. Also, the length L along the first direction A1 of the lens 160. s For example, 100 μm, first width d s Length M of the portion having 1 along the first direction A1 s 1 is, for example, 10 μm, and the second width d sThe length M of the portion having 2 along the first direction A1 s 2 can be, for example, 30 μm.

[0089] The shape of the lens 160 shown in Figure 23 can be manufactured using the following structure 170. Figure 24 is a plan view of the structure 170 capable of forming the shape of this lens 160. The structure 170 has a constant thickness from the first surface 151 (see Figure 17), and as shown in the same figure, the width along the second direction A2 can be made to decrease in a stepped manner from the non-center part 160b towards the center part 160a.

[0090] The first width d along the second direction A2 of the central part 170a p 1 is, for example, 36 μm, and the second width d is along the second direction A2 of the non-central part 170b. p 2 can be, for example, 40 μm. Also, the length L along the first direction A1 of the structure 170. p For example, 100 μm, first width d p Length M of the portion having 1 along the first direction A1 p 1 is, for example, 10 μm, and the second width d p The length M of the portion having 2 along the first direction A1 p 2 can be, for example, 30 μm.

[0091] Furthermore, as shown in Figure 25, the lens 160 can also have a shape consisting of a series of rectangular blocks (B1 to B5) whose width narrows from the non-center portion 160b towards the center portion 160a. The number of blocks is not particularly limited and can be, for example, five. Height H of lens 160 s and the radius of curvature R in the second direction A2 at the top of the lens. s (See Figure 9) is uniform, and height H s For example, 3.6 μm, radius of curvature R s This length can be longer than the resonator length K (see Figure 10), for example, 44 μm.

[0092] The first width d along the second direction A2 of the central part 160a s 1 is, for example, 36 μm, and the second width d is along the second direction A2 of the non-central part 160b.s 2 can be, for example, 40 μm. The portion between the central part 160a and the non - central part 160b has a width that narrows along the second direction A2 from the non - central part 160b towards the central part 160a, and the second width d s 2 > the third width d s 3 > the fourth width d s 4 > the first width d s 1 satisfies the relationship.

[0093] Specifically, for example, the second width d s 2 is 40 μm, the third width d s 3 is 39 μm, the fourth width d s 4 is 38 μm, and the first width d s 1 can be 36 μm. Also, the length L of the lens 160 along the first direction A1 s can be, for example, 100 μm, and the lengths M s 1 to M s 4 of each part, the length M s 2 is 10 μm, the length M s 3 is 10 μm, the length M s 4 is 5 μm, and the length M s 1 can be 10 μm.

[0094] The shape of the lens 160 shown in FIG. 25 can be fabricated using the following structure 170. FIG. 26 is a plan view of the structure 170 capable of forming the shape of this lens 160. The structure 170 has a certain thickness from the first surface 151 (see FIG. 17), and as shown in the figure, it can be in the shape of a series of rectangular blocks (B1 to B5) whose width narrows from the non - central part 170b towards the central part 170a. The first width d p 1 along the second direction A2 of the central part 170a can be, for example, 36 μm, and the second width d p 2 along the second direction A2 of the non - central part 170b can be, for example, 40 μm.

[0095] The portion between the central part 170a and the non - central part 170b has a width that narrows along the second direction A2 from the non - central part 170b towards the central part 170a, and the second width d p 2 > the third width d p 3 > the fourth width d p4 > the first width d p satisfies the relationship of 1. Specifically, for example, the second width d p 2 is 40 μm, the third width d p 3 is 39 μm, the fourth width d p 4 is 38 μm, and the first width d p 1 can be 36 μm. Also, the length L of the lens 160 along the first direction A1 p is, for example, 100 μm, and the lengths M of each part along the first direction A1 p 1 to M p 4 are such that the length M p 2 is 10 μm, the length M p 3 is 10 μm, the length M p 4 is 5 μm, and the length M p 1 can be 10 μm

[0096] Even when the lens 160 has a configuration as shown in FIGS. 23 and 25, since the height H s and the radius of curvature R of the lens top s are uniform, it is possible to realize a good line light source that emits laser light E without luminance unevenness. Also, the shape of the lens 160 can be other than that shown here, having a central portion 160a and a non - central portion 160b, and the height H s and the radius of curvature R of the lens top s can be made into a uniform shape.

[0097] [Other configurations of the laser element] The configuration of the laser element 100 is not limited to the above, and it is also possible to have a wavelength conversion layer. FIG. 27 is a cross - sectional view of the laser element 100 provided with a wavelength conversion layer 181. The wavelength conversion layer 181 is made of a wavelength conversion material, is provided on the side opposite to the laminate 150 of the second light reflection layer 105, and converts the wavelength of the laser light E (see FIG. 13) incident from the second light reflection layer 105.

[0098] The wavelength conversion material constituting the wavelength conversion layer 181 can be a wavelength conversion material that is excited by blue light and emits red light. Specifically, red light-emitting phosphor particles, more specifically, (ME:Eu)S [wherein "ME" means at least one atom selected from the group consisting of Ca, Sr, and Ba, and the same applies hereinafter], (M:Sm)x(Si,Al) 12 (O,N) 16 [However, "M" means at least one atom selected from the group consisting of Li, Mg, and Ca, and the same applies below], ME2Si5N8:Eu, (Ca:Eu)SiN2, and (Ca:Eu)AlSiN3 are examples.

[0099] Furthermore, the wavelength conversion material constituting the wavelength conversion layer 181 can be a wavelength conversion material that is excited by blue light and emits green light. Specifically, green light-emitting phosphor particles, more specifically (ME:Eu)Ga2S4, (M:RE) X (Si, Al) 12 (O,N) 16 [However, "RE" means Tb and Yb], (M:Tb) X (Si,Al) 12 (O,N) 16 , (M:Yb) X (Si,Al) 12 (O,N) 16 Si 6-Z Al Z O Z N 8-Z :Eu can be cited.

[0100] Furthermore, the wavelength conversion material constituting the wavelength conversion layer 181 can be a wavelength conversion material that is excited by blue light and emits yellow light. Specifically, this can be a yellow-emitting phosphor particle, or more specifically, a YAG (yttrium aluminum garnet) phosphor particle. The wavelength conversion material may be one type or a mixture of two or more types.

[0101] Furthermore, by mixing two or more types of wavelength conversion materials that constitute the wavelength conversion layer 181, it is possible to create a configuration in which light of a color other than yellow, green, and red is emitted from the wavelength conversion material mixture. Specifically, for example, a configuration that emits cyan light may be used, in which case green light-emitting phosphor particles (e.g., LaPO4:Ce,Tb,BaMgAl) may be used. 10 O 17 :Eu,Mn,Zn2SiO4:Mn,MgAl 11 O 19 :Ce,Tb,Y2SiO5:Ce,Tb,MgAl 11 O 19 :CE,Tb,Mn) and blue-emitting phosphor particles (e.g., BaMgAl 10 O 17 :Eu,BaMg2Al 16 O 27 A mixture of :Eu, Sr2P2O7:Eu, Sr5(PO4)3Cl:Eu, (Sr,Ca,Ba,Mg)5(PO4)3Cl:Eu, CaWO4, and CaWO4:Pb should be used.

[0102] Furthermore, the wavelength conversion material constituting the wavelength conversion layer 181 can be a wavelength conversion material that is excited by ultraviolet light and emits red light. Specifically, red light-emitting phosphor particles, more specifically, Y2O3:Eu, YVO4:Eu, Y(P,V)O4:Eu, 3.5MgO·0.5MgF2·Ge2:Mn, CaSiO3:Pb,Mn, Mg6AsO 11 Examples of suitable molecules include Mn, (Sr,Mg)3(PO4)3:Sn, La2O2S:Eu, and Y2O2S:Eu.

[0103] Furthermore, the wavelength conversion material constituting the wavelength conversion layer 181 can be a wavelength conversion material that is excited by ultraviolet light and emits green light. Specifically, green light-emitting phosphor particles, more specifically, LaPO4:Ce,Tb,BaMgAl 10 O 17 :Eu,Mn,Zn2SiO4:Mn,MgAl 11 O 19 :Ce,Tb,Y2SiO5:Ce,Tb,MgAl 11 O 19 :CE,Tb,Mn,Si6-Z Al Z O Z N 8-Z :Eu can be cited.

[0104] Furthermore, the wavelength conversion material constituting the wavelength conversion layer 181 can be a wavelength conversion material that is excited by ultraviolet light and emits blue light. Specifically, blue light-emitting phosphor particles, more specifically, BaMgAl 10 O 17 :Eu,BaMg2Al 16 O 27 Examples of suitable oviducts include Eu, Sr2P2O7:Eu, Sr5(PO4)3Cl:Eu, (Sr,Ca,Ba,Mg)5(PO4)3Cl:Eu, CaWO4, and CaWO4:Pb.

[0105] Furthermore, the wavelength conversion material constituting the wavelength conversion layer 181 can be a wavelength conversion material that is excited by ultraviolet light and emits yellow light. Specifically, yellow light-emitting phosphor particles, and more specifically, YAG-based phosphor particles, can be used. Note that the wavelength conversion material may be one type or a mixture of two or more types may be used. Furthermore, by using a mixture of two or more wavelength conversion materials, it is possible to create a configuration in which light of a color other than yellow, green, or red is emitted from the wavelength conversion material mixture. Specifically, a configuration that emits cyan light may be used, in which case a mixture of the above-mentioned green light-emitting phosphor particles and blue light-emitting phosphor particles may be used.

[0106] However, wavelength conversion materials (color conversion materials) are not limited to phosphor particles. For example, in indirect transition silicon-based materials, in order to efficiently convert carriers into light, similar to direct transition types, we can also cite luminescent particles that utilize quantum well structures such as 2D quantum well structures, 1D quantum well structures (quantum nanowires), and 0D quantum well structures (quantum dots), which localize the wave function of carriers and use quantum effects. Furthermore, rare earth atoms added to semiconductor materials are known to emit light sharply due to intrashell transitions, and we can also cite luminescent particles that utilize such techniques.

[0107] As mentioned above, quantum dots can be used as the wavelength conversion material (color conversion material) constituting the wavelength conversion layer 181. As the size (diameter) of the quantum dot decreases, the band gap energy increases, and the wavelength of the light emitted from the quantum dot becomes shorter. That is, the smaller the quantum dot, the shorter the wavelength of light it emits (light on the blue side), and the larger the quantum dot, the longer the wavelength of light it emits (light on the red side). Therefore, by using the same material to constitute the quantum dot and adjusting the size of the quantum dot, it is possible to obtain a quantum dot that emits light with a desired wavelength (converts to a desired color).

[0108] Specifically, quantum dots preferably have a core-shell structure. Examples of materials constituting quantum dots include, but are not limited to, Si;Se;chalcopalite compounds such as CIGS(CuInGaSe), CIS(CuInSe2), CuInS2, CuAlS2, CuAlSe2, CuGaS2, CuGaSe2, AgAlS2, AgAlSe2, AgInS2, AgInSe2;perovskite materials;group III-V compounds such as GaAs, GaP, InP, InAs, InGaAs, AlGaAs, InGaP, AlGaInP, InGaAsP, GaN;CdSe, CdSeS, CdS, CdTe, In2Se3, In2S3, Bi2Se3, Bi2S3, ZnSe, ZnTe, ZnS, HgTe, HgS, PbSe, PbS, and TiO2.

[0109] Furthermore, although the first semiconductor layer 101 is made of an n-type semiconductor material and the second semiconductor layer 102 is made of a p-type semiconductor material in the above description, the first semiconductor layer 101 may be made of a p-type semiconductor material and the second semiconductor layer 102 may be made of an n-type semiconductor material. In addition to this, the laser element 100 may have other configurations that enable the operation of the laser element 100.

[0110] [About laser element arrays] A laser element array can be constructed using the laser element 100. Figure 28 is a cross-sectional view of the laser element array 10 according to this embodiment, and Figure 29 is a schematic plan view of the laser element array 10.

[0111] As shown in Figures 28 and 29, the laser element array 10 is composed of a plurality of arranged laser elements 100. The number of laser elements 100 constituting the laser element array 10 is not particularly specified, but can be, for example, 10. As shown in Figure 29, the laser elements 100 can be arranged so that the first direction A1 (longitudinal direction of the lens 160) of each laser element 100 coincides. The array pitch R (distance between the centers of the lenses 160) can be, for example, 20 μm. The arrangement direction of the laser elements 100 is not limited to this, and the lenses 160 may be arranged in a hexagonal close-packed arrangement.

[0112] The first electrode 106 of each laser element 100 is separated from the first electrode 106 of adjacent laser elements 100. Therefore, by independently controlling the voltage between the first electrode 106 and the second electrode 107 of each laser element 100, it is possible to make each laser element 100 emit light independently. The laser element array 10 is a good line light source in which each laser element 100 emits laser light E without brightness uniformity, and the array configuration allows for high output, for example, an output of more than 1W.

[0113] In the laser element array 10, it is also possible for the laser elements 100 to be equipped with a wavelength conversion layer 181. Figure 30 is a cross-sectional view showing a laser element array 10 equipped with a wavelength conversion layer 181. The wavelength conversion layer 181 may be provided by each laser element 100, or it may be a single continuous layer between multiple laser elements 100.

[0114] (Second embodiment) A laser element according to a second embodiment of this technology will now be described. The laser element according to this embodiment differs from the laser element according to the first embodiment mainly in its current constriction structure. The laser element according to this embodiment has a structure similar to a VCSEL element, but it differs from a VCSEL element in that it generates resonance in another direction (Y direction) in addition to the Z direction.

[0115] [Structure of laser element] Figure 31 is a cross-sectional view of the laser element 200 according to this embodiment, and Figure 32 is a cross-sectional view showing a partially exploded view of the laser element 200. As shown in these figures, the laser element 200 comprises a substrate 201, a first semiconductor layer 202, a second semiconductor layer 203, a third semiconductor layer 204, an active layer 205, a tunnel junction layer 206, a first light reflection layer 207, a second light reflection layer 208, a first electrode 209, a second electrode 210, and an insulating film 211. Of these, the substrate 201, the first semiconductor layer 202, the second semiconductor layer 203, the third semiconductor layer 204, the active layer 205, and the tunnel junction layer 206 together form a laminate 250.

[0116] Each of these layers has a layer plane direction along the XY plane, and they are stacked in the following order: first light-reflecting layer 207, substrate 201, first semiconductor layer 202, active layer 205, second semiconductor layer 203, third semiconductor layer 204, and second light-reflecting layer 208. Therefore, the laminate 250 is positioned between the first light-reflecting layer 207 and the second light-reflecting layer 208.

[0117] The substrate 201 supports each layer of the laser element 200. The substrate 201 can be, for example, a semi-insulating InP substrate. As shown in Figure 32, a lens 260 is provided on the substrate 201. This lens 260 will be described later.

[0118] The first semiconductor layer 202 is made of a semiconductor having a first conduction type and is a layer that transports carriers to the active layer 205. The first conduction type can be n-type, and the first semiconductor layer 202 can be, for example, a layer made of n-InP. The second semiconductor layer 203 is made of a semiconductor having a second conduction type and is a layer that transports carriers to the active layer 205. The second conduction type can be p-type, and the second semiconductor layer 203 can be, for example, a layer made of p-InP. The third semiconductor layer 204 is made of a semiconductor having a first conduction type and is a layer that transports carriers to the tunnel junction layer 206. The third semiconductor layer 204 can be, for example, a layer made of n-InP.

[0119] The active layer 205 is positioned between the first semiconductor layer 202 and the second semiconductor layer 203 and is a layer that generates light emission due to carrier recombination. The active layer 205 has a multiple quantum well structure in which multiple layers of quantum well layers and barrier layers are stacked alternately. The quantum well layers can be made of, for example, InGaAsP, and the barrier layers can be made of, for example, InGaAsP with a different composition from the quantum well layers. In addition to the multiple quantum well structure, the active layer 205 can be any layer that generates light emission due to carrier recombination.

[0120] The tunnel junction layer 206 forms a buried tunnel junction. The tunnel junction layer 206 is located between the central part of the second semiconductor layer 203 and the central part of the third semiconductor layer 204. The tunnel junction layer 206 has a first layer 206a on the second semiconductor layer 203 side and a second layer 206b on the third semiconductor layer 204 side. The first layer 206a is a second conduction type layer with a high impurity concentration, for example p + -The layer can be made of AlInGaAs. The second layer 206b is a first conduction type layer with a high impurity concentration, for example n + -The layer can consist of InP.

[0121] As shown in Figure 31, the outer periphery of the active layer 205, the second semiconductor layer 203, and the third semiconductor layer 204 is removed to form a mesa (plateau-like structure) M. The tunnel junction layer 206 is positioned in the central part of the mesa M when viewed from the Z direction.

[0122] As shown in Figure 31, of the surfaces of the laminate 250, the surface on the side of the first light-reflecting layer 207 is designated as the first surface 251, and the surface on the side of the second light-reflecting layer 208 is designated as the second surface 252. The lens 260 is provided on the first surface 251. As a result, as shown in Figure 32, the first surface 251 has a main surface 251a and a lens surface 251b. The main surface 251a is a plane (X-Y plane) perpendicular to the optical axis direction (Z direction) of the emitted light. The lens surface 251b is the surface of the lens 260 and is a surface that protrudes from the main surface 251a.

[0123] The first light-reflecting layer 207 reflects light of a specific wavelength (hereinafter referred to as wavelength λ) and transmits light of other wavelengths. Wavelength λ is, for example, a specific wavelength within the range of 1300 to 1600 nm. As shown in Figure 31, the first light-reflecting layer 207 can be a DBR (Distributed Bragg Reflector) consisting of a multilayer light-reflecting film in which multiple layers of high refractive index layers 207a and low refractive index layers 207b, each having an optical film thickness of λ / 4, are alternately stacked. For example, the first light-reflecting layer 207 can have a multilayer structure such as Ta2O5 / SiO2, SiO2 / SiN, or SiO2 / Nb2O5.

[0124] The first light-reflecting layer 207 has a concave mirror 207c. The first light-reflecting layer 207 is laminated on the second surface 201b of the substrate 201 with a constant thickness, and according to the shape of the lens 260 provided on the first surface 251, the surface on the laminate 250 side forms a concave surface 207d, and the surface on the opposite side of the laminate 250 forms a convex surface 207e. As a result, a concave mirror 207c is formed in the first light-reflecting layer 207.

[0125] The second light-reflecting layer 208 reflects light of wavelength λ and transmits light of other wavelengths. As shown in Figure 31, the second light-reflecting layer 208 can be a DBR (Distributed Bragg Reflector) consisting of a multilayer light-reflecting film in which multiple layers of high refractive index layers 208a and low refractive index layers 208b, each having an optical film thickness of λ / 4, are alternately stacked. For example, the second light-reflecting layer 208 can have a multilayer structure such as Ta2O5 / SiO2, SiO2 / SiN, or SiO2 / Nb2O5.

[0126] The first electrode 209 is provided on the first semiconductor layer 202 around the mesa M and functions as one electrode of the laser element 200. The first electrode 209 can be a single-layer metal film made of, for example, Au, Ni, or Ti, or a multilayer metal film made of Ti / Au, Ag / Pd, or Ni / Au / Pt.

[0127] The second electrode 210 is provided on the third semiconductor layer 204 around the second light-reflecting layer 208 and functions as the other electrode of the laser element 200. The second electrode 210 can be a single-layer metal film made of, for example, Au, Ni, or Ti, or a multilayer metal film made of Ti / Au, Ag / Pd, or Ni / Au / Pt. The insulating film 211 is provided around the second electrode 210 on the side surface and top surface of the mesa M and insulates the outer periphery of the mesa M. The insulating film 211 is made of any insulating material.

[0128] In the laser element 200, a current-constricting structure is formed in the laminate 250 by the tunnel junction layer 206. Figure 33 is a schematic diagram showing the current-constricting structure. As shown in the figure, the current-constricting structure has a current injection region 221 and an insulating region 222. The current injection region 221 is a region where a tunnel junction is formed by the tunnel junction layer 206 (tunnel junction region), and current passes through the tunnel junction. The insulating region 222 surrounds the current injection region 221 in the layer plane direction (XY direction) and is a region where no tunnel junction is formed and therefore current does not pass through (non-tunnel junction region). The current flowing through the laser element 200 cannot pass through the insulating region 222 and therefore concentrates in the current injection region 221. That is, a current-constricting structure is formed by the current injection region 221 and the insulating region 222.

[0129] [Regarding the current injection area and lens shape] The shape of the current injection region 221 in the laser element 200 is the same as that of the current injection region 121 in the first embodiment. That is, the current injection region 221 has an elongated planar shape with the first direction A1 as the longitudinal direction and the second direction A2 as the short direction (see Figures 3 and 4). Both the first direction A1 and the second direction A2 are perpendicular to the optical axis direction (Z direction) and are also perpendicular to each other.

[0130] Furthermore, the shape of the lens 260 in the laser element 200 is the same as that of the lens 160 in the first embodiment. That is, the lens 260 has an elongated lens shape with the first direction A1 as the longitudinal direction and the second direction A2 as the short direction. The length, width, height, radius of curvature of the lens apex, and surface accuracy (RMS) of the lens 260 are also the same as those of the lens 160.

[0131] The lens 260 may be formed from a part of the substrate 201 as shown in Figure 32, but it may also be made from a separate material and bonded to the substrate 201 (see Figure 12).

[0132] [Laser element operation] The laser element 200 operates similarly to the laser element 100 according to the first embodiment. That is, when a voltage is applied between the first electrode 209 and the second electrode 210, a current flows between the first electrode 209 and the second electrode 210. The current is narrowed by the current constriction structure and injected into the current injection region 221. The spontaneously emitted light generated by this injected current is reflected by the first light reflection layer 207 and the second light reflection layer 208, causing laser oscillation. The resulting laser light passes through the second light reflection layer 208 and is emitted from the laser element 200 with the Z direction as the optical axis. Due to the shape of the current injection region 221 and the lens 260, the laser element 200 is capable of emitting laser light E with a large beam diameter and a narrow emission angle, and operates as a line light source emitting a linear beam.

[0133] [Effects of laser elements] In the laser element 200, the height H from the main surface 251a is also s and the radius of curvature R in the second direction A2 at the top of the lens. s (See Figure 9) The lens 260 has a uniform radius of curvature R. Therefore, by forming a current injection region 221 on the lens 260, a mode is formed that has both resonance in the optical axis direction (Z direction) and resonance in the longitudinal direction of the lens 260 (Y direction), and a laser element 200 that emits highly linear light can be realized. In addition, the laser element 200 has a radius of curvature R s Because it is uniform, the horizontal mode can be unified, and the height H s Because the surface is uniform, it may be possible to unify the vertical modes. As a result, the laser element 200 can emit laser light E without brightness unevenness, enabling it to achieve a good line light source. Furthermore, the lens 260 has a more uniform height and the stress is distributed, which improves durability.

[0134] [Manufacturing method for laser elements] In the manufacturing method of the laser element 200, each layer up to the second layer 206b is laminated on the substrate 201 by a method such as metal-organic chemical vapor deposition. Then, unnecessary portions of the first layer 206a and the second layer 206b are removed by photolithography and etching to form a tunnel junction layer 206. The shape of the tunnel junction layer 206 can be freely controlled by photolithography.

[0135] Next, a third semiconductor layer 204 is laminated on the tunnel junction layer 206, and a mesa M is formed by photolithography and etching. This forms a laminate 250 on the substrate 201. Furthermore, a lens 260 is provided on the substrate 201 using the same method as in the first embodiment, and a laser element 200 can be manufactured by laminating the first light reflection layer 207 and the second light reflection layer 208, etc. The laser element 200 can also be manufactured by other manufacturing methods.

[0136] [Regarding current constriction structures induced by ion implantation] As described above, the laser element 200 is provided with a current-constricting structure by an embedded tunnel junction using a tunnel junction layer 206. However, it is also possible to provide a current-constricting structure by ion implantation into the tunnel junction layer 206, as described below.

[0137] Figure 34 is a cross-sectional view of a laser element 200 having an insulating region 223 formed by ion implantation. In this configuration, the tunnel junction layer 206 is arranged across the entire space between the second semiconductor layer 203 and the third semiconductor layer 204, and the insulating region 223 (the region with dots) is provided in the outer peripheral region of the tunnel junction layer 206.

[0138] As shown in Figure 34, the current-constricted structure is composed of a current-injection region 221 and an insulating region 223. The current-injection region 221 is formed by a tunnel junction layer 206 into which ions have not been implanted. On the other hand, the insulating region 223 surrounds the current-injection region 221 in the layer plane direction (XY direction) and is an insulating region in which ions have been implanted into the tunnel junction layer 206. The ions implanted in the ion-implantation region can be boron ions (B). In addition to boron ions, other ions capable of insulating semiconductor materials, such as oxygen ions (O) and hydrogen ions (H), may also be used.

[0139] In this configuration as well, the current flowing through the laser element 200 cannot pass through the insulating region 223 and is therefore concentrated in the current injection region 221. In other words, a current-constricting structure is formed by the current injection region 221 and the insulating region 223.

[0140] [Other configurations of laser elements] In the above description, the laminate 250 is fabricated by stacking each layer on the substrate 201. However, it is also possible to form the laminate 250 by stacking each layer on another support substrate, removing the support substrate, and bonding it to the substrate 201. Furthermore, similar to the first embodiment, the laser element 200 may also be equipped with a wavelength conversion layer (see Figure 27) on the opposite side of the second light reflection layer 208 from the laminate 250, which changes the wavelength of the emitted light.

[0141] Furthermore, although the first semiconductor layer 202 and the third semiconductor layer 204 are made of n-type semiconductor material and the second semiconductor layer 203 is made of p-type semiconductor material, the first semiconductor layer 202 and the third semiconductor layer 204 may be made of p-type semiconductor material and the second semiconductor layer 203 may be made of n-type semiconductor material. In this case, the first layer 206a of the tunnel junction layer 206 can be an n-type layer with a high impurity concentration, and the second layer 206b can be a p-type layer with a high impurity concentration. In addition to the above-described configurations, the laser element 200 may also have other configurations that enable the operation of the laser element 200.

[0142] [About laser element arrays] The laser elements 200 can be arranged in an array, similar to the first embodiment. A laser element array consisting of laser elements 200 is a good line light source in which each laser element 200 emits laser light E without brightness uniformity, and high output power can be achieved by arraying, for example, by exceeding 1W. The laser element array consisting of laser elements 200 may also include a wavelength conversion layer (see Figure 28).

[0143] (Third embodiment) A laser element according to a third embodiment of this technology will now be described. The laser element according to this embodiment differs from the laser element according to the first embodiment mainly in its current constriction structure. The laser element according to this embodiment has a structure similar to a VCSEL element, but it differs from a VCSEL element in that it generates resonance in another direction (Y direction) in addition to the Z direction.

[0144] [Structure of laser element] Figure 35 is a cross-sectional view of the laser element 300 according to this embodiment, and Figure 36 is a cross-sectional view showing a partially exploded view of the laser element 300. As shown in these figures, the laser element 300 comprises a substrate 301, a first semiconductor layer 302, a second semiconductor layer 303, an active layer 304, an oxide constriction layer 305, a first light reflection layer 306, a second light reflection layer 307, a first electrode 308, a second electrode 309, and an insulating film 310. Of these, the substrate 301, the first semiconductor layer 302, the second semiconductor layer 303, the active layer 304, and the oxide constriction layer 305 together form a laminate 350.

[0145] Each of these layers has a layer plane direction along the XY plane, and they are stacked in the following order: first light-reflecting layer 306, substrate 301, first semiconductor layer 302, active layer 304, second semiconductor layer 303, oxide constriction layer 305, and second light-reflecting layer 307. Therefore, the laminate 350 is positioned between the first light-reflecting layer 306 and the second light-reflecting layer 307.

[0146] The substrate 301 supports each layer of the laser element 300. The substrate 301 can be, for example, a semi-insulating GaAs substrate. As shown in Figure 36, a lens 360 is provided on the substrate 301. This lens 360 will be described later.

[0147] The first semiconductor layer 302 is made of a semiconductor having a first conduction type and is a layer that transports carriers to the active layer 304. The first conduction type can be n-type, and the first semiconductor layer 302 can be, for example, a layer made of n-GaAs. The second semiconductor layer 303 is made of a semiconductor having a second conduction type and is a layer that transports carriers to the active layer 304. The second conduction type can be p-type, and the second semiconductor layer 303 can be, for example, a layer made of p-GaAs.

[0148] The active layer 304 is positioned between the first semiconductor layer 302 and the second semiconductor layer 303 and is a layer that generates light emission due to carrier recombination. The active layer 304 has a multiple quantum well structure in which multiple layers of quantum well layers and barrier layers are stacked alternately, and the quantum well layers can be made of, for example, GaAs, and the barrier layers can be made of, for example, AlGaAs. In addition to the multiple quantum well structure, the active layer 304 may be any layer that generates light emission due to carrier recombination.

[0149] The oxidation-constricted layer 305 forms a current-constricted structure. The oxidation-constricted layer 305 has a non-oxidized region 305a in which the semiconductor material is not oxidized and an oxidized region 305b in which the semiconductor material is oxidized. The non-oxidized region 305a consists of a material with a high impurity concentration in the second conduction type, for example, p + -It can consist of AlAs. The oxidized region 305b consists of a material from which the constituent material of the non-oxidized region 305a has been oxidized, and can consist of, for example, AlAs oxide.

[0150] As shown in Figure 35, of the surfaces of the laminate 350, the surface on the side of the first light-reflecting layer 306 is designated as the first surface 351, and the surface on the side of the second light-reflecting layer 307 is designated as the second surface 352. The lens 360 is provided on the first surface 351. As a result, as shown in Figure 36, the first surface 351 has a main surface 351a and a lens surface 351b. The main surface 351a is a plane (X-Y plane) perpendicular to the optical axis direction (Z direction) of the emitted light. The lens surface 351b is the surface of the lens 360 and is a surface that protrudes from the main surface 351a.

[0151] The first light-reflecting layer 306 reflects light of a specific wavelength (hereinafter referred to as wavelength λ) and transmits light of other wavelengths. Wavelength λ is, for example, a specific wavelength within the range of 850 to 1400 nm. As shown in Figure 35, the first light-reflecting layer 306 can be a DBR (Distributed Bragg Reflector) consisting of a multilayer light-reflecting film in which multiple layers of high-refractive-index layers 306a and low-refractive-index layers 306b, each having an optical film thickness of λ / 4, are alternately stacked. For example, the first light-reflecting layer 306 can have a multilayer structure such as Ta2O5 / SiO2, SiO2 / SiN, or SiO2 / Nb2O5.

[0152] The first light-reflecting layer 306 has a concave mirror 306c. The first light-reflecting layer 306 is laminated on the second surface 301b of the substrate 301 with a constant thickness, and according to the shape of the lens 360 provided on the first surface 351, the surface on the laminate side 350 forms a concave surface 306d, and the surface opposite to the laminate 350 forms a convex surface 306e. As a result, a concave mirror 306c is formed in the first light-reflecting layer 306.

[0153] The second light-reflecting layer 307 reflects light of wavelength λ and transmits light of other wavelengths. As shown in Figure 35, the second light-reflecting layer 307 can be a DBR (Distributed Bragg Reflector) consisting of multiple layers of high refractive index layers 307a and low refractive index layers 307b, each having an optical film thickness of λ / 4, stacked alternately. The second light-reflecting layer 307 can be a semiconductor DBR made of a semiconductor material.

[0154] As shown in Figure 35, the outer periphery of the active layer 304, the second semiconductor layer 303, the oxidized constriction layer 305, and the second light-reflecting layer 307 is removed to form a mesa (plateau-like structure) M.

[0155] The first electrode 308 is provided on the first semiconductor layer 302 around the mesa M and functions as one electrode of the laser element 300. The first electrode 308 can be a single-layer metal film made of, for example, Au, Ni, or Ti, or a multilayer metal film made of Ti / Au, Ag / Pd, or Ni / Au / Pt.

[0156] The second electrode 309 is provided on the second light reflection layer 307 and functions as the other electrode of the laser element 300. The second electrode 309 can be a single-layer metal film made of, for example, Au, Ni, or Ti, or a multilayer metal film made of Ti / Au, Ag / Pd, or Ni / Au / Pt. The insulating film 310 is provided around the second electrode 309 on the side and top surface of the mesa M and insulates the outer circumference of the mesa M. The insulating film 310 is made of any insulating material.

[0157] In the laser element 300, a current-constricting structure is formed in the laminate 350 by the oxidation-constricting layer 305. Figure 37 is a schematic diagram showing the current-constricting structure. As shown in the figure, the current-constricting structure has a current injection region 321 and an insulating region 322. The current injection region 321 is a conductive region due to the non-oxidized region 305a. The insulating region 322 surrounds the current injection region 321 in the layer plane direction (XY direction) and is a non-conductive region due to the oxidized region 305b which is insulated by oxidation. The current flowing through the laser element 300 cannot pass through the insulating region 322 and therefore concentrates in the current injection region 321. In other words, a current-constricting structure is formed in the laser element 300 by the oxidation-constricting layer 305.

[0158] [Regarding the current injection area and lens shape] The shape of the current injection region 321 in the laser element 300 is the same as that of the current injection region 321 in the first embodiment. That is, the current injection region 321 has an elongated planar shape with the first direction A1 as the longitudinal direction and the second direction A2 as the short direction (see Figures 3 and 4). Both the first direction A1 and the second direction A2 are perpendicular to the optical axis direction (Z direction) and are also perpendicular to each other.

[0159] Furthermore, the shape of the lens 360 in the laser element 300 is the same as that of the lens 160 in the first embodiment. That is, the lens 360 has an elongated lens shape with the first direction A1 as the longitudinal direction and the second direction A2 as the short direction. The length, width, height, radius of curvature of the lens apex, and surface accuracy (RMS) of the lens 360 are also the same as those of the lens 160.

[0160] The lens 360 may be formed from a part of the substrate 301 as shown in Figure 36, but it may also be made from a separate material and bonded to the substrate 301 (see Figure 12).

[0161] [Laser element operation] The laser element 300 operates similarly to the laser element 100 according to the first embodiment. That is, when a voltage is applied between the first electrode 308 and the second electrode 309, a current flows between the first electrode 308 and the second electrode 309. The current is narrowed by the current constriction structure and injected into the current injection region 321. The spontaneously emitted light generated by this injected current is reflected by the first light reflection layer 306 and the second light reflection layer 307, causing laser oscillation. The resulting laser light passes through the second light reflection layer 307 and is emitted from the laser element 300 with the Z direction as the optical axis. Due to the shape of the current injection region 321 and the lens 360, the laser element 300 is capable of emitting laser light E with a large beam diameter and a narrow emission angle, and operates as a line light source emitting a linear beam.

[0162] [Effects of laser elements] In the laser element 300, the height H from the main surface 351a is also s and the radius of curvature R in the second direction A2 at the top of the lens.s (See Figure 9) The lens 360 has a uniform radius. Therefore, by forming a current injection region 321 on the lens 360, a mode is formed that has both resonance in the optical axis direction (Z direction) and resonance in the longitudinal direction of the lens 360 (Y direction), and a laser element 300 that emits highly linear light can be realized. In addition, the laser element 300 has a radius of curvature R at the top of the lens. s Because it is uniform, the horizontal mode can be unified, and the height H s Because the vertical modes are uniform, it is sometimes possible to unify them. As a result, the laser element 300 can emit laser light E without brightness unevenness, enabling it to achieve a good line light source. Furthermore, the lens 360 has a more uniform height and the stress is distributed, which improves durability.

[0163] [Manufacturing method for laser elements] In the manufacturing method of the laser element 300, each layer up to the second light-reflecting layer 307 is laminated on the substrate 301 by a method such as metal-organic chemical vapor deposition, and then a mesa M is formed by photolithography and etching. Subsequently, the laminate 350 is heated in a water vapor atmosphere or the material of the oxidation constriction layer 305 is oxidized from the outer periphery to form an oxidation region 305b. At this time, the shape of the mesa M as viewed from the Z direction can be controlled to control the shape of the non-oxidized region 305a as viewed from the same direction.

[0164] Furthermore, the laser element 300 can be manufactured by providing the lens 360 on the substrate 301 using the same method as in the first embodiment, and then stacking the first light reflective layer 306, the second light reflective layer 307, etc. The laser element 300 can also be manufactured by other manufacturing methods.

[0165] [Other configurations of laser elements] In the above description, the laminate 350 is fabricated by stacking each layer on the substrate 301. However, it is also possible to form the laminate 350 by stacking each layer on another support substrate, removing the support substrate, and bonding it to the substrate 301. Furthermore, the laser element 300 can also be provided with a wavelength conversion layer (see Figure 27) on the opposite side of the second light reflection layer 307 from the laminate 250, which changes the wavelength of the emitted light, similar to the first embodiment.

[0166] Furthermore, although the first semiconductor layer 302 is made of an n-type semiconductor material and the second semiconductor layer 303 is made of a p-type semiconductor material, the first semiconductor layer 302 may be made of a p-type semiconductor material and the second semiconductor layer 303 may be made of an n-type semiconductor material. In this case, the non-oxidized region 305a of the oxidation constriction layer 305 may be made of an n-type material with a high impurity concentration. In addition to the above-described configurations, the laser element 300 may also have other configurations that enable the operation of the laser element 300.

[0167] [About laser element arrays] The laser elements 300 can be arranged in an array, similar to the first embodiment. A laser element array consisting of laser elements 300 is a good line light source in which each laser element 300 emits laser light E without brightness uniformity, and high output power can be achieved by arraying, for example, by achieving an output of more than 1W. The laser element array consisting of laser elements 300 may also include a wavelength conversion layer (see Figure 28).

[0168] (Regarding this disclosure) The effects described in this disclosure are merely illustrative and not limiting, and other effects may also occur. The description of multiple effects above does not necessarily mean that they will necessarily occur simultaneously. It means that at least one of the effects described above may be obtained depending on the conditions, and effects not described in this disclosure may also occur. Furthermore, it is possible to arbitrarily combine at least two of the feature elements described in this disclosure.

[0169] Furthermore, this technology can also be configured as follows. (1) A first light-reflecting layer that reflects light of a specific wavelength, A second light-reflecting layer that reflects light of the above wavelength, A laminate comprising: a first semiconductor layer made of a semiconductor material having a first conduction type; a second semiconductor layer made of a semiconductor material having a second conduction type; and an active layer disposed between the first and second semiconductor layers and generating light emission by carrier recombination; and disposed between the first and second light reflection layers, having a first surface on the first light reflection layer side and a second surface on the second light reflection layer side, with a lens provided on the first surface. It is equipped with, The above lens has a longitudinal direction in a first direction parallel to a plane perpendicular to the optical axis direction of the emitted light, a short direction in a second direction parallel to the plane and perpendicular to the first direction, a lens shape that protrudes toward the first light reflection layer, a first width in the central part in the first direction which is the minimum width along the second direction, a second width in the non-central part in the first direction which is the maximum width along the second direction, a shape in which the height from the plane is uniform or the central part is higher than the ends, and the radius of curvature of the lens top in the second direction is uniform. The first light-reflecting layer described above is laminated onto the first surface, forming a concave mirror having a concave shape on the lens. Laser element. (2) The laser element described in (1) above, The above laminate has a current-constricting structure that narrows the current and forms a current injection region where the current is concentrated. The current injection region described above has a planar shape, as viewed from the optical axis direction, where the first direction is the longitudinal direction and the second direction is the short direction, and the shape overlaps with the lens when viewed from the optical axis direction. Laser element. (3) The laser element described in (1) or (2) above, The length of the lens along the first direction is greater than the second width. Laser element. (4) A laser element described in any one of (1) to (3) above, The length of the above lens along the first direction is 40 μm or more. Laser element. (5) A laser element described in any one of (1) to (4) above, The second width of the above lens is 10 μm or more. Laser element. (6) A laser element described in any one of (1) to (5) above, The resonator length of the above laser element is the distance between the concave mirror and the second light-reflecting layer. The radius of curvature mentioned above is greater than or equal to the resonator length mentioned above. Laser element. (7) A laser element described in any one of (1) to (6) above, The surface precision of the above lens is such that the RMS (Root Mean Square) is 1.0 nm or less. Laser element. (8) A laser element described in any one of (1) to (7) above, The first semiconductor layer and the second semiconductor layer described above are made of GaN. Laser element. (9) A laser element described in any one of (1) to (7) above, The first semiconductor layer and the second semiconductor layer described above are made of GaAs. Laser element. (10) A laser element described in any one of (1) to (7) above, The first semiconductor layer and the second semiconductor layer described above are made of InP. Laser element. (11) A laser element described in any one of (1) to (10) above, A wavelength conversion layer made of a wavelength conversion material is provided on the side of the second light reflection layer opposite to the laminate. A laser element further equipped with the following features. (12) A laser element described in any one of (1) to (11) above, The first light-reflecting layer and the second reflective layer described above are DBRs (Distributed Bragg Reflectors) consisting of multilayer light-reflecting films. Laser element. (13) A laser element array in which multiple individually drivable laser elements are arranged, The above laser element is A first light-reflecting layer that reflects light of a specific wavelength, A second light-reflecting layer that reflects light of the above wavelength, A laminate comprising: a first semiconductor layer made of a semiconductor material having a first conduction type; a second semiconductor layer made of a semiconductor material having a second conduction type; and an active layer disposed between the first and second semiconductor layers and generating light emission by carrier recombination; and disposed between the first and second light reflection layers, having a first surface on the first light reflection layer side and a second surface on the second light reflection layer side, with a lens provided on the first surface. It is equipped with, The above lens has a longitudinal direction in a first direction parallel to a plane perpendicular to the optical axis direction of the emitted light, a short direction in a second direction parallel to the plane and perpendicular to the first direction, a lens shape that protrudes toward the first light reflection layer, a first width in the central part in the first direction which is the minimum width along the second direction, a second width in the non-central part in the first direction which is the maximum width along the second direction, a shape in which the height from the plane is uniform or the central part is higher than the ends, and the radius of curvature of the lens top in the second direction is uniform. The first light-reflecting layer described above is laminated onto the first surface, forming a concave mirror having a concave shape on the lens. Laser element array. (14) A laminate comprising a first semiconductor layer made of a semiconductor material having a first conduction type, a second semiconductor layer made of a semiconductor material having a second conduction type, and an active layer disposed between the first and second semiconductor layers and generating light emission by carrier recombination, is fabricated having a first surface and a second surface. If we define a first direction as one direction parallel to a plane perpendicular to the optical axis of the emitted light, and a second direction as one direction parallel to the plane and perpendicular to the first direction, then a structure is formed on the first surface that is made of a fluid material, has a constant thickness, has the first direction as the longitudinal direction, the second direction as the short direction, has a first width in the central part in the first direction which is the minimum width along the second direction, and has a second width in the non-central part in the first direction which is the maximum width along the second direction. The above structure is heated, the above fluid material is allowed to flow and deform the structure, and the shape of the structure is used to form a lens in which the height from the plane is uniform on the first surface or the center is higher than the edges, and the radius of curvature in the second direction of the lens top is uniform. A first light-reflecting layer that reflects light of a specific wavelength is laminated on the first surface, and a concave mirror having a concave shape is formed on the lens. A second light-reflecting layer that reflects light of the above wavelength is formed on the second surface side of the laminate. A method for manufacturing laser elements. (15) A method for manufacturing a laser element as described in (14) above, In the process of forming the above lens, the structure is deformed to have a lens shape that protrudes toward the first light-reflecting layer, with the first direction being the longitudinal direction and the second direction being the short direction, the central part having the first width, the non-central part having the second width, the height from the plane being uniform or the central part being higher than the ends, and the radius of curvature of the apex in the second direction being uniform. A method for manufacturing laser elements. (16) A method for manufacturing a laser element as described in (15) above, In the step of forming the lens, the laminate is etched using the structure deformed into the above shape as an etching mask, and the lens is formed on the first surface. Method for manufacturing a laser element. (17) The method for manufacturing a laser element according to the above (15), In the step of forming the lens, the structure deformed into the above shape is used as the lens. Method for manufacturing a laser element. (18) The method for manufacturing a laser element according to any one of the above (14) to (17), The length of the structure along the first direction is greater than the second width. Laser element. (19) The method for manufacturing a laser element according to any one of the above (14) to (18), The length of the structure along the first direction is 40 μm or more. Laser element. (20) The method for manufacturing a laser element according to any one of the above (14) to (19), The etching is dry etching or wet etching. Laser element.

Explanation of reference numerals

[0170] 100, 200, 300... Laser elements 201, 301... Substrates 101, 202, 302... First semiconductor layers 102, 203, 303... Second semiconductor layers 204... Third semiconductor layer 103, 205, 304... Active layers 206... Tunnel junction layer 305... Oxidation constriction layer 104, 207, 306... First light reflection layers 104c, 207c, 306c... Concave mirrors 105, 208, 307... Second light reflection layers 106, 209, 308...1st electrode 107, 210, 309…Second electrode 121, 221, 321…Current injection area 122, 222, 322... Insulation zone 150, 250, 350... Laminate 160, 260, 360... lenses 170, 270, 370...Structure 175, 275, 375...Structure 181...Wavelength conversion layer

Claims

1. A first light-reflecting layer that reflects light of a specific wavelength, A second light-reflecting layer that reflects light of the aforementioned wavelength, A laminate comprising: a first semiconductor layer made of a semiconductor material having a first conduction type; a second semiconductor layer made of a semiconductor material having a second conduction type; an active layer disposed between the first and second semiconductor layers, which generates spontaneous emission light containing the wavelength component by carrier recombination; a laminate disposed between the first and second optical reflection layers, which has a first surface on the first optical reflection layer side and a second surface on the second optical reflection layer side, with a lens provided on the first surface that defines an optical confinement region for light of the wavelength, and the first surface having a principal surface perpendicular to the optical axis direction of the emitted light and a lens surface which is the surface of the lens; It is equipped with, The lens has a lens shape that protrudes toward the first light reflection layer, with a first direction parallel to a plane perpendicular to the optical axis direction of the emitted light as the longitudinal direction, and a second direction parallel to the plane and perpendicular to the first direction as the short direction, the central part in the first direction having a first width which is the minimum width along the second direction, and the non-central part in the first direction having a second width which is the maximum width along the second direction, the lens surface has a shape in which the height of the lens apex, which is the part that protrudes the most from the main surface in a third direction perpendicular to the first and second directions, is uniform in the third direction from the main surface, or the central part in the first direction is higher in the third direction from the main surface than the edge in the first direction, and the radius of curvature of the lens apex in the second direction is uniform. The first light-reflecting layer is laminated on the first surface to form a concave mirror having a concave shape on the lens. Laser element.

2. A laser element according to claim 1, The laminate has a current-constricting structure that narrows the current and forms a current injection region where the current is concentrated. The current injection region has a planar shape, as viewed from the optical axis direction, where the first direction is the longitudinal direction and the second direction is the short direction, and the shape overlaps with the lens as viewed from the optical axis direction. Laser element.

3. A laser element according to claim 1, The length of the lens along the first direction is greater than the second width. Laser element.

4. A laser element according to claim 1, The length of the lens along the first direction is 40 μm or more. Laser element.

5. A laser element according to claim 1, The second width of the lens is 10 μm or more. Laser element.

6. A laser element according to claim 1, The resonator length of the laser element is the distance between the concave mirror and the second light-reflecting layer. The radius of curvature is greater than or equal to the length of the resonator. Laser element.

7. A laser element according to claim 1, The surface accuracy of the aforementioned lens is such that the RMS (Root Mean Square) is 1.0 nm or less. Laser element.

8. A laser element according to claim 1, The first semiconductor layer and the second semiconductor layer are made of GaN. Laser element.

9. A laser element according to claim 1, The first semiconductor layer and the second semiconductor layer are made of GaAs. Laser element.

10. A laser element according to claim 1, The first semiconductor layer and the second semiconductor layer are made of InP. Laser element.

11. A laser element according to claim 1, A wavelength conversion layer made of a wavelength conversion material is provided on the side of the second light-reflecting layer opposite to the laminate. A laser element further equipped with the following features.

12. A laser element according to claim 1, The first and second light-reflecting layers are a DBR (Distributed Bragg Reflector) consisting of a multilayer light-reflecting film. Laser element.

13. A laser element array in which multiple individually drivable laser elements are arranged, The aforementioned laser element is A first light-reflecting layer that reflects light of a specific wavelength, A second light-reflecting layer that reflects light of the aforementioned wavelength, A laminate comprising: a first semiconductor layer made of a semiconductor material having a first conduction type; a second semiconductor layer made of a semiconductor material having a second conduction type; an active layer disposed between the first and second semiconductor layers, which generates spontaneous emission light containing the wavelength component by carrier recombination; a laminate disposed between the first and second optical reflection layers, which has a first surface on the first optical reflection layer side and a second surface on the second optical reflection layer side, with a lens provided on the first surface that defines an optical confinement region for light of the wavelength, and the first surface having a principal surface perpendicular to the optical axis direction of the emitted light and a lens surface which is the surface of the lens; It is equipped with, The lens has a lens shape that protrudes toward the first light reflection layer, with a first direction parallel to a plane perpendicular to the optical axis direction of the emitted light as the longitudinal direction, and a second direction parallel to the plane and perpendicular to the first direction as the short direction, the central part in the first direction having a first width which is the minimum width along the second direction, and the non-central part in the first direction having a second width which is the maximum width along the second direction, the lens surface has a shape in which the height of the lens apex, which is the part that protrudes the most from the main surface in a third direction perpendicular to the first and second directions, is uniform in the third direction from the main surface, or the central part in the first direction is higher in the third direction from the main surface than the edge in the first direction, and the radius of curvature of the lens apex in the second direction is uniform. The first light-reflecting layer is laminated on the first surface to form a concave mirror having a concave shape on the lens. Laser element array.

14. A laminate comprising a first semiconductor layer made of a semiconductor material having a first conduction type, a second semiconductor layer made of a semiconductor material having a second conduction type, and an active layer disposed between the first and second semiconductor layers, which generates spontaneous emission light containing components of a specific wavelength through carrier recombination, is fabricated having a first surface and a second surface. If we define a first direction as one direction parallel to a plane perpendicular to the optical axis direction of the emitted light, and a second direction as one direction parallel to the plane and perpendicular to the first direction, then a structure is formed on the first surface that is made of a fluid material, has a constant thickness, has the first direction as the longitudinal direction, the second direction as the short direction, has a first width in the central part in the first direction which is the minimum width along the second direction, and has a second width in the non-central part in the first direction which is the maximum width along the second direction. The structure is heated, the fluid material is made to flow and deform the structure, and a lens is formed on the first surface by etching using the deformed structure as an etching mask, or the deformed structure is used as the lens, and a principal surface perpendicular to the optical axis direction of the emitted light and a lens surface which is the surface of the lens are formed on the first surface, and the lens has a shape in which the height of the lens apex, which is the part of the lens surface that protrudes the most from the principal surface in a third direction perpendicular to the first and second directions, is uniform in the third direction from the principal surface, or the central part in the first direction is higher in the third direction from the principal surface than the edge in the first direction, and the radius of curvature of the lens apex in the second direction is uniform and defines the optical confinement region of light of the wavelength, A first light-reflecting layer that reflects light of the aforementioned wavelength is laminated on the first surface, and a concave mirror having a concave shape is formed on the lens. A second light-reflecting layer that reflects light of the aforementioned wavelength is formed on the second surface side of the laminate. A method for manufacturing laser elements.

15. A method for manufacturing a laser element according to claim 14, The length of the structure along the first direction is greater than the second width. A method for manufacturing laser elements.

16. A method for manufacturing a laser element according to claim 14, The length of the structure along the first direction is 40 μm or more. A method for manufacturing laser elements.

17. A method for manufacturing a laser element according to claim 14, The etching is either dry etching or wet etching. A method for manufacturing laser elements.

Images