Semiconductor laser element

Abstract

To provide a semiconductor laser element having high power conversion efficiency.SOLUTION: A semiconductor laser element has a semiconductor lamination section including an active layer and an electrode provided on the semiconductor lamination section, and has a waveguide structure. The semiconductor lamination section has: (i) a first region including a diffraction grating: and (ii) a second region having a core region with a refractive index n21 and cladding regions with a refractive index n22 provided on both sides of the core region, the second region propagating laser light in a plurality of transverse modes. From a top view, the first region propagates light incident from the second region and includes: a center region having a refractive index of n1; and a peripheral region located outside the center region. A current shielding structure is provided at a position overlapping with at least part of the peripheral region.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] In recent years, there has been a demand for semiconductor laser elements with higher laser output. High-output semiconductor laser elements have come to be used, for example, as light sources for processing. For example, Patent Document 1 discloses a multiple transverse mode laser that can prevent optical damage on the stripe side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-151238 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the semiconductor laser device disclosed in Patent Document 1 does not have sufficient power conversion efficiency, and there is room for improvement.

[0005] Therefore, an object of the present disclosure is to provide a semiconductor laser element with high power conversion efficiency. [Means for solving the problem]

[0006] The semiconductor laser device according to an embodiment of the present disclosure comprises: A semiconductor laser element having a waveguide structure, the semiconductor laser element having a semiconductor laminate including an active layer and an electrode provided on the semiconductor laminate, The semiconductor laminate portion is (i) a first region including a diffraction grating; (ii) a second region having a core region and cladding regions provided on both sides of the core region, and propagating laser light in a plurality of transverse modes; Including, In top view, The first region propagates light incident from the second region and includes a central region and a peripheral region located outside the central region, A current shielding structure is provided at a position overlapping at least a portion of the peripheral region. Effect of the Invention

[0007] A semiconductor laser device according to an embodiment of the present disclosure can provide a semiconductor laser device with high power conversion efficiency. [Brief description of the drawings]

[0008] [Figure 1] 1 is a top view of a semiconductor laser device according to a first embodiment of the present disclosure. [Diagram 2] 1 is a top view diagrammatically illustrating a regional structure of a semiconductor laser device according to a first embodiment. [Diagram 3] 2 is a schematic cross-sectional view of the semiconductor laser device shown in FIG. 1 taken along line III-III. [Figure 4] 4 is a schematic cross-sectional view of the semiconductor laser device shown in FIG. 1 taken along line IV-IV. [Diagram 5] FIG. 1 is a diagram showing an outline of a method for measuring a beam waist radius W0 and a beam divergence angle φ. [Figure 6] 11 is a schematic cross-sectional view of a first region of a semiconductor laser device according to a second embodiment of the present disclosure. FIG. [Figure 7] FIG. 11 is a schematic cross-sectional view of a first region of a semiconductor laser device according to a third embodiment of the present disclosure. [Figure 8] FIG. 11 is a schematic cross-sectional view of a first region of a semiconductor laser device according to a fourth embodiment of the present disclosure. [Figure 9] 4 is a top view diagrammatically illustrating another configuration of the semiconductor laser device of the first embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments, modifications, and examples for carrying out the present disclosure will be described with reference to the drawings. Note that the semiconductor laser device according to the present disclosure described below is intended to embody the technical idea of ​​the present disclosure, and unless otherwise specified, the present disclosure is not limited to the following. In each drawing, the same reference numerals may be used for components having the same function. In consideration of the explanation or ease of understanding of the main points, the embodiments, modifications, and examples may be shown separately for convenience, but partial replacement or combination of the configurations shown in different embodiments, modifications, and examples is possible. In the embodiments, modifications, and examples described below, descriptions of matters common to the above will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment, modification, and example. The size and positional relationship of the components shown in each drawing may be exaggerated to clarify the explanation.

[0010] EMBODIMENT 1 The semiconductor laser element L1 of the first embodiment is a semiconductor laser element L1 including an active layer 120 and a semiconductor laminate portion 101 having a waveguide structure shown in Fig. 2. Here, Fig. 1 is a schematic top view of the semiconductor laser element L1 of the first embodiment as viewed from above. Specifically, the semiconductor laminate 101 in the semiconductor laser device L1 of the first embodiment has, as shown in FIGS. 1 to 4, (i) a first region 1 including a diffraction grating 105; (ii) a second region 2 having a core region 21 and cladding regions 22 provided on both sides of the core region 21, and propagating laser light in a plurality of transverse modes; Includes. In the semiconductor laser element L1 of embodiment 1, the first region 1, when viewed from above, propagates light incident from the second region 2, and includes a central region 11 and a peripheral region 12 located outside the central region 11, and a current shielding structure 10 is provided at a position overlapping at least a portion of the peripheral region 12. The refractive index of the core region 21 is n 21 and the refractive index of the cladding region 22 is n22 and the refractive index of the central region 11 is n1. In the semiconductor laser element L1 having the above-described configuration and including the first region 1 and the second region 2, the laser light emitted from the second region 2 has a refractive index n1 and a refractive index n 21 and the refractive index n 22 The maximum diffusion angle Θ is determined by max1 It propagates through the first region 1. Here, in the semiconductor laser element L1 of the first embodiment, the current shielding structure 10 is configured by an insulating film 140 provided on the semiconductor laminate portion 101 of the first region 1, as described later. For example, the semiconductor laser element L1 is a transverse multimode semiconductor laser element. By being a transverse multimode semiconductor laser element, the effect of improving the light emission efficiency can be further obtained by reducing heat generation due to reactive current in parts that do not contribute to oscillation (light propagation) compared to a transverse single mode semiconductor laser element.

[0011] The semiconductor laser device L1 of the first embodiment configured as described above can increase the light emission output relative to the power consumption, and can efficiently obtain high-output light. The reasons for this are explained below. First, a semiconductor laser element including a diffraction grating 105 in the first region 1 and a waveguide structure in the second region 2 generates laser light by, for example, injecting a current into a core region 21 in the second region 2 to generate light that propagates through the waveguide including the core region 21 and enters the first region 1, is reflected by the diffraction grating 105 provided in the first region 1, and returns to the second region 2, where the returned light is amplified and this process is repeated to produce laser oscillation. In order to more effectively oscillate laser light, the semiconductor laser element L1 according to the first embodiment may be coated on one or both of the end face of the first region 1 opposite to the second region 2 and the end face of the second region 2 opposite to the first region 1. The semiconductor laser element L1 may include an anti-reflection coating (AR coating) provided on the end face of the first region 1 opposite to the second region 2, and a high-reflection coating (HR coating) provided on the end face of the second region 2 opposite to the first region 1. As described above, the laser light that is incident on the first region 1 including the central region 11 having the refractive index n1 and is emitted from the second region 2 has a refractive index of n 21 and the refractive index n 22 The maximum diffusion angle Θ is determined by max1 In consideration of this point, it is preferable to set the width of the region into which the current is injected in the first region 1 to be wider than the width of the region into which the current is injected in the second region 2. This is because the region into which the current is injected in the first region 1 functions as a diffraction grating 105. As a result, the maximum diffusion angle Θ max1 The light propagating through the first region 1 while diverging can be reflected by the diffraction grating 105. However, the inventors of the present application have found that while they have achieved a certain effect of increasing the light-emitting efficiency by setting the width of the region into which current is injected in the first region 1 wider than the width of the region into which current is injected in the second region 2, the light-emitting efficiency begins to decrease if the width of the region into which current is injected in the first region 1 is widened too much.

[0012] In the first region 1, the portion that does not contribute to oscillation (propagation of light) is located at a maximum diffusion angle Θ max1 This corresponds to the area outside the imaginary line that extends Therefore, in the semiconductor laser element of the embodiment, the maximum divergence angle Θ max1 A current shielding structure 10 is provided in at least a part of a peripheral region 12 including the region outside the imaginary line extending in the direction of the arrow A to reduce reactive current. In the semiconductor laser device L1 of the first embodiment, the central region 11 is arranged such that the maximum divergence angle Θ max1 In addition, for example, the region including the region inside the imaginary line that spreads at the maximum diffusion angle Θ max1 The region outside the imaginary line that spreads at a maximum diffusion angle Θ can be defined as the peripheral region 12. max1 The region inside the imaginary line that spreads out at the maximum diffusion angle Θ can be defined as the central region 11. max1By making the region include the region inside the virtual line extending in the direction of the light, it is possible to efficiently inject current into the region through which light propagates while reducing reactive current into regions that do not contribute to the propagation of light. In this specification, the refractive index n 21 , refractive index n 22 The refractive index in this case is the effective refractive index taking into account the light confinement in the stacking direction of the semiconductor laminated portion 101, and is also called the equivalent refractive index. The refractive index n1 is the effective refractive index taking into account the light confinement in the stacking direction of the semiconductor laminated portion 101 and averaging the modulation of the refractive index of the diffraction grating 105. In addition, the maximum diffusion angle Θ max1 is equal to the maximum acceptance angle of the optical waveguide in the second region 2. The semiconductor laser device L1 of the first embodiment will be described in detail below with reference to the drawings.

[0013] Here, Fig. 1 is a top view of the semiconductor laser device L1 according to the embodiment 1. Fig. 2 is a top view typically showing a regional structure of the semiconductor laser device L1 according to the embodiment 1. Fig. 3 is a schematic cross-sectional view taken along line III-III of the semiconductor laser device shown in Fig. 1. Fig. 4 is a schematic cross-sectional view taken along line IV-IV of the semiconductor laser device L1 shown in Fig. 1.

[0014] The semiconductor laser device L1 according to the first embodiment includes a semiconductor laminate 101 provided on a substrate 100. The semiconductor laminate 101 includes, for example, as shown in FIGS. (a) an n-side semiconductor layer 110 including an n-side cladding layer 111 and an n-side optical guide layer 112; (b) an active layer 120 provided on the n-side semiconductor layer 110; (c) a p-side semiconductor layer 130 provided on the active layer 120 and including a p-side optical guide layer 131, a p-side cladding layer 132, and a p-side contact layer 133; Includes. Moreover, the semiconductor laminate portion 101 includes, for example, a ridge 135 provided in the p-side contact layer 133 and the p-side cladding layer 132. The ridge 135 includes a first ridge 135a provided in the first region 1 and a second ridge 135b provided in the second region 2. In a top view, the first ridge 135a and the second ridge 135b are provided such that their center lines coincide with each other in the traveling direction of the laser light. In addition, in Figure 1, the outer surface of the first ridge 135a and the outer surface of the second ridge 135b are drawn to coincide with the outer surface of the second electrode 152 described below, and therefore in Figure 1, the first ridge 135a and the second ridge 135b are represented by dashed lines extending from the outer surfaces of the first ridge 135a and the second ridge 135b. Furthermore, as described above, the light emitted from the second region 2 and incident on the first region 1 spreads and propagates in the first region 1, so the width of the first ridge 135a is set wider than the width of the second ridge 135b. Furthermore, the outer surface of the first region 1 and the outer surface of the first ridge 135a are close to each other, and the refractive index n1 of the central region 11 is constant without change in the light propagation direction and width direction. In this specification, the width direction refers to a direction perpendicular to both the light propagation direction and the stacking direction of the semiconductor stack 101 .

[0015] A p-electrode 150 is provided on the semiconductor laminate 101 so as to be in contact with an upper surface of the ridge 135. The p-electrode 150 includes a first electrode 151 and a second electrode 152, and the first electrode 151 is provided so as to be in contact with the p-side contact layer 133. As will be described later, the first electrode 151 and the second electrode 152 are connected via an opening in the insulating film to provide current shielding. That is, in the first embodiment, the current shielding structure 10 is configured by the insulating film 140 provided at a position overlapping at least a portion of the peripheral region 12. Specifically, first, the first electrode 151 is provided so as to contact, for example, the entire upper surface of the p-side contact layer 133 on the ridge 135 of the semiconductor laminate portion 101. Then, an insulating film 140 is provided on the first electrode 151. The insulating film 140 has a first opening 140a located on the first ridge 135a and a second opening 140b located on the second ridge 135b. The first opening 140a and the second opening 140b are provided, for example, continuously, and are provided so as to have the central axes of the first opening 140a and the second opening 140b coincide with the center lines of the first ridge 135a and the second ridge 135b in the traveling direction of the laser light. Here, in consideration of the fact that the light incident from the second region 2 to the first region 1 spreads and propagates in the first region 1, it is preferable that the width of the first opening 140a is made wider than the second opening 140b and the width of the region into which the current is injected in the first region 1 is made wider than the width of the region into which the current is injected in the second region 2 in order to increase the light emission efficiency. However, as described above, if the width of the region into which the current is injected in the first region 1 is made too wide, there is a risk that a reactive current due to heat generation or the like outside the waveguide region will be generated, reducing the efficiency. In consideration of these, the width of the first opening 140a is set to a width that can effectively reduce heat generation due to reactive current or the like outside the waveguide region, i.e., in the peripheral region 12, while being made wider than the second opening 140b. The width of the first opening 140a is set to a maximum diffusion angle Θ from both ends of the output end face of the core region 21. max1 It is preferable that the distance between the peripheral region 12 and the periphery 13 coincides with the virtual line extending in the direction of the arrow A. With this configuration, heat generation due to reactive current or the like in the peripheral region 12 can be effectively reduced. In this specification, the term "opening" does not only refer to a region surrounded on all four sides. For example, a region sandwiched between two insulating films can be expressed as an opening in an insulating film.

[0016] In the first embodiment, the second electrode 152 is provided so as to cover the first opening 140a and the second opening 140b, and the second electrode 152 is connected to the first electrode 151 through the first opening 140a and the second opening 140b. That is, a current is injected into the second region 2 through the second opening 140b. Here, in the first embodiment, as shown in FIG. 4, the width of the second opening 140b in the second region 2 is set to be substantially equal to the width of the second ridge 135b. On the other hand, in the first region 1, if the width of the region into which the current is injected is too wide, heat is generated due to reactive current or the like outside the waveguide region, which may reduce the efficiency. Therefore, the insulating film 140 is provided so as to overlap at least a part of the peripheral region 12 to configure the current shielding structure 10. Specifically, in the first region 1, the width of the portion where the second electrode 152 and the first electrode 151 contact each other is limited to the width of the first opening 140a by the insulating film 140, thereby blocking the current in the peripheral region 12. That is, the current is injected from the region where the insulating film 140 is not provided. Here, since the first electrode 151 is formed, for example, on the entire upper surface of the p-side contact layer 133, the current injected from the second electrode 152 may spread in the width direction in the first electrode 151 and be injected into the p-side contact layer 133. Therefore, in the first embodiment, it is preferable to configure the first electrode 151 so as to reduce the spread of the current in the width direction. For example, in the first embodiment, it is preferable to form the first electrode 151 thin so as to reduce the spread of the current in the width direction. For example, it is preferable that the thickness of the first electrode 151 in the stacking direction of the semiconductor stacking portion 101 is 0.05 μm or more and 2 μm or less. In addition, the first electrode 151 may be configured from indium tin oxide (ITO) to reduce the spread of the current in the width direction. This can reduce heat generation due to reactive currents and the like outside the waveguide region. In addition, by injecting a current into the second region 2 through the second opening 140b, it becomes possible to provide a core region 21 and cladding regions 22 on both sides of it in the second region 2, and light of multiple transverse modes can be oscillated in accordance with the width of the second opening 140b. As described above, the shielding range of the current to the p-side contact layer 133 in the first embodiment is determined by parameters including the width of the first opening 140a provided in the insulating film 140, the resistance value and thickness of the first electrode 151, etc. In other words, it is preferable to appropriately adjust parameters including the width of the first opening 140a provided in the insulating film 140, the resistance value and thickness of the first electrode 151, etc., so as to effectively reduce heat generation due to reactive currents and the like in the peripheral region 12. For example, the width of the first opening 140a is determined by the width of the insulating film 140 at which the insulating film 140 has a maximum diffusion angle Θ max1 Under the condition that the width of the first electrode 151 does not reach the region inside the virtual line, the width of the first electrode 151 is preferably 90% or less, and more preferably 40% or less, of the width of the first region 1. With this configuration, the reactive current to the peripheral region 12 can be effectively reduced. Also, for example, the resistance value of the first electrode 151 can be set to 300 μΩ or more and 2600 μΩ or less.

[0017] In the semiconductor laser device L1 of the first embodiment, the width of the ridge 135 is set as follows so as to propagate laser light in a desired plurality of transverse modes. First, the second region 2 has a refractive index n 21 The core region 21 and the refractive index n 22 The second ridge 135b is provided at a predetermined distance from both side surfaces of the second region 2 in the center of the p-side semiconductor layer 130 in the second region 2. As a result, in the second region 2, a region with a refractive index n 21 The core region 21 has a refractive index of n 22 The cladding region 22 is formed, and the waveguide structure of the second region 2 is formed. In the semiconductor laser device L1 of the first embodiment, the width of the core region 21, i.e., the width of the second ridge 135b, is set so that laser light including a desired number of transverse modes is propagated. The first electrode 151 is preferably provided so as to be in contact with the upper surface of the second ridge 135b without being in contact with the upper surfaces of the p-side cladding layer 132 on both sides of the second ridge 135b. With this configuration, the flow of current through the cladding region 22 can be reduced. In addition, in embodiment 1, by providing the second ridge 135b, a core region 21 is formed in a top view, and cladding regions 22 are formed on both sides of the core region 21. However, for example, without forming the second ridge 135b, the core region 21 and the cladding region 22 may be formed by, for example, making the width of the portion in the second region 2 into which current is injected narrower than the entire width of the second region 2.

[0018] On the other hand, the first region 1 is incident from the second region 2 and has a maximum diffusion angle Θ max1 The light propagating from the second region 2 is not confined to a specific waveguide (core region 21) and propagates therethrough, but is incident from the second region 2 at a maximum divergence angle Θ max1 As long as the laser beam can be propagated in a wide range, the first ridge 135a is not an essential component of the first region 1. For example, the first ridge 135a may not be formed, and the portion of the semiconductor laminate 101 excluding the second region 2 may be the first region 1. In addition, in the case where the first ridge 135a is included, for example, both side surfaces of the first ridge 135a may be provided close to both side surfaces of the first region 1, as shown in FIG. 3. The width of the semiconductor laminate 101 constituting the first region 1, and the width of the first ridge 135a in the case where the first ridge 135a is included, are determined based on the maximum diffusion angle Θ of the laser beam emitted from the second region 2 and incident on the first region 1, so that the equivalent refractive indexes of the laser beam incident on the first region 1 from the second region 2 are substantially the same for a plurality of transverse modes. max1 Taking this into consideration, the light is set so as not to leak from the side surfaces of the semiconductor laminate portion 101 . Specifically, in a cross section perpendicular to the optical axis of the laser light, both ends of the first region 1 in the direction perpendicular to the stacking direction of the semiconductor stack 101 are spaced apart from both ends of the output end face of the core region 21 on the first region 1 side by a maximum divergence angle Θ max1 The width of the first region 1 is set so that it is positioned outside the virtual line extending from the left to the right. Then, a diffraction grating 105 is provided in the first region 1. The diffraction grating 105 is provided such that both ends of the diffraction grating 105 extend to both ends of the first region 1, for example. Here, the cross-sectional shape of the ridge 135 may be a rectangle with a constant width, as shown in Figures 3 and 4, or may be, for example, a trapezoid whose width narrows as it moves away from the substrate 100, or an inverted trapezoid whose width widens as it moves away from the substrate 100.

[0019] In the semiconductor laser element L1 of embodiment 1 according to the present disclosure configured as described above, the width of the waveguide in the second region 2 is set so as to enable laser oscillation including a desired number of transverse modes, and a current shielding structure 10 is provided in the first region 1. As a result, the semiconductor laser of the first embodiment can oscillate and propagate laser light in a plurality of transverse modes, thereby enabling a high output power to be achieved, and a semiconductor laser device L1 with high power conversion efficiency can be provided.

[0020] Hereinafter, each component of the semiconductor laser device L1 of the first embodiment will be described in detail with reference to a specific example. It should be noted that the semiconductor laser device L1 of the first embodiment is not limited to the following specific example as long as it has a basic configuration that can provide the above-mentioned effects.

[0021] (Substrate 100) The substrate 100 of the semiconductor laser element L1 of the first embodiment is, for example, a semiconductor substrate. The substrate 100 is, for example, a nitride semiconductor substrate such as a GaN substrate. The nitride semiconductor substrate may contain n-type impurities. The n-type impurity element may be, for example, O, Si, or Ge. The substrate 100 may be a nitride semiconductor substrate, and the upper surface of the substrate 100 may be a +c-plane (i.e., a (0001) plane). In the first embodiment, the c-plane is not limited to a plane that strictly coincides with the (0001) plane, but also includes a plane having an off-angle of ±1 degree or less, preferably ±0.03 degrees or less. The semiconductor laser element L1 may not have the substrate 100. The upper surface of the substrate may be, for example, an m-plane, an a-plane, or an r-plane.

[0022] (Semiconductor laminate 101) As described above, the semiconductor laminate portion 101 may include, for example, an n-side semiconductor layer 110 including an n-side cladding layer 111 and an n-side light guiding layer 112, an active layer 120 provided on the n-side semiconductor layer 110, and a p-side semiconductor layer 130 provided on the active layer 120 and including a p-side light guiding layer 131, a p-side cladding layer 132, and a p-side contact layer 133. The semiconductor layer of the semiconductor laminate 101 is, for example, a III-V group semiconductor layer. α Al β Ga 1-α-β N, a nitride semiconductor layer formed with a composition of (0≦α, 0≦β, α+β≦1). Examples of the n-type impurity element used in the nitride semiconductor layer include Si and Ge. Examples of the p-type impurity element include Mg. In this way, nitride semiconductor layers of each conductivity type can be formed.

[0023] (n-side semiconductor layer 110) The n-side semiconductor layer 110 has one or more semiconductor layers containing n-type impurities. The n-side semiconductor layer 110 has a refractive index of, for example, n 111 The n-side cladding layer 111 has a refractive index of n 112 The n-side semiconductor layer 110 may further include an undoped layer that is not intentionally doped with impurities. Refractive index n 111 and the refractive index n 112 is the refractive index n of the active layer 120 120 The refractive index n 111 and the refractive index n 112 are different from each other, for example, the refractive index n 111 is the refractive index n 112 Less than.

[0024] The n-side cladding layer 111 is disposed between the active layer 120 and the substrate 100. The n-side cladding layer 111 may be, for example, a nitride semiconductor layer. Examples of nitride semiconductors include AlGaN and GaN. The thickness of the n-side cladding layer 111 may be, for example, 0.45 μm or more and 3.0 μm or less. The content of n-type impurities may be, for example, 1×10 17 cm -3 5×10 or more 18 cm -3 It may be the following:

[0025] The n-side light guiding layer 112 is disposed between the active layer 120 and the n-side cladding layer 111. The n-side light guiding layer 112 may be, for example, a nitride semiconductor layer. Examples of nitride semiconductors include AlGaN, GaN, and InGaN. The thickness of the n-side light guiding layer 112 may be, for example, 0.05 μm or more and 0.5 μm or less. The content of n-type impurities may be, for example, 1×10 17 cm -3 5×10 or more 18 cm -3 It may be the following:

[0026] (active layer 120) An active layer 120 is formed on the n-side optical guide layer 112. The active layer 120 emits light having a wavelength of, for example, 360 nm or more and 800 nm or less. The active layer 120 may have a quantum well structure composed of one or more well layers and multiple barrier layers. The well layer and the barrier layer are, for example, GaN, InGaN, AlGaN, or AlInGaN. The well layer is, for example, AlGaN, GaN, or InGaN, and is a nitride semiconductor having a smaller band gap energy than the barrier layer. The active layer 120 may have a multiple quantum well structure or a single quantum well structure. Note that impurities may be contained in either or both of the well layer and the barrier layer.

[0027] (p-side semiconductor layer 130) The p-side semiconductor layer 130 has one or more semiconductor layers containing p-type impurities. The p-side semiconductor layer 130 is formed on the active layer 120. The p-side semiconductor layer 130 has a refractive index of n 131 The p-side optical guide layer 131 has a refractive index of n 132 The p-side cladding layer 132 has a refractive index of n 133 The p-side semiconductor layer 130 may include a p-side contact layer 133 which is a p-side semiconductor layer having a thickness of 100 nm to 150 nm. The p-side semiconductor layer 130 may include layers other than these. The p-side semiconductor layer 130 may include an undoped layer which is not intentionally doped with impurities. Refractive index n 131 , refractive index n 132 and the refractive index n 133 is the refractive index n of the active layer 120 120 The refractive index n 131 , refractive index n 132 and the refractive index n 133 For example, the refractive index n 131 is the refractive index n 132 Greater than.

[0028] The p-side light guide layer 131 may be, for example, a nitride semiconductor layer. Examples of nitride semiconductors include AlGaN and GaN. The thickness of the p-side light guide layer 131 may be, for example, 0.05 μm or more and 0.25 μm or less. The p-side light guide layer 131 may be an undoped layer, for example, 1×10 16 cm -3 More than 1×10 18 cm -3 The p-type impurity may be contained within the following range.

[0029] The p-side cladding layer 132 may be, for example, a nitride semiconductor layer. Examples of the nitride semiconductor include AlGaN and GaN. It may have a single-layer structure or a multi-layer structure in which nitride semiconductor layers having different compositions are stacked. The content of the p-type impurity is, for example, 1×10 17 cm -3 More than 1×10 20 cm -3or less. It is not necessary to provide the p-side cladding layer 132. When the p-side cladding layer 132 is not provided, the amount of p-type impurities in the semiconductor laminate 101 is reduced, and the optical loss in the semiconductor laminate 101 can be reduced.

[0030] The p-side contact layer 133 may be, for example, a nitride semiconductor. Examples of the nitride semiconductor include AlGaN and GaN. It may have a single-layer structure or a multi-layer structure in which nitride semiconductor layers having different compositions are stacked. The content of the p-type impurity is 1×10 19 cm -3 More than 1×10 22 cm -3 It may be the following:

[0031] (Waveguide structure) The waveguide structure of the semiconductor laser device L1 of the first embodiment will now be described in detail. Here, first the waveguide structure in the second region 2 will be described, and then the waveguide structure in the first region 1 will be described. The waveguide structure in the second region 2 has a refractive index n 21 and a core region 21 having a refractive index n 22 The cladding region 22 has a thickness of 100 nm and a thickness of 100 nm, and the cladding region 22 has a thickness of 100 nm. The cladding region 22 has a thickness of 100 nm and ... 21 and the refractive index n 22 The width of the core region 21 is determined by the difference between the lamination direction of the semiconductor laminate 101 in a plane perpendicular to the optical axis of the waveguide. The thickness of the core region 21 is determined by the thickness of the semiconductor laminate 101 in the lamination direction in a plane perpendicular to the optical axis of the waveguide. The cladding regions 22 are provided on both sides of the core region 21, and the refractive indexes of the two cladding regions 22 may be the same or different. When the refractive indexes are different, the respective refractive indices are expressed as n 22A and n 22B and the maximum diffusion angle Θ max1 is 22A and n22B It can be calculated using:

[0032] The number of transverse modes will be described below. In the following explanation, a symmetric three-layer planar waveguide will be explained for simplicity. The number of transverse modes N of light propagating through the core region 21 is determined by the refractive index n 21 , the refractive index n of the cladding region 22 22 By determining the normalized frequency V defined by the width of the core region 21, it can be set based on the following formula 1.

[0033] V≧Nπ / 2 (Formula 1) (N is an integer greater than or equal to 1)

[0034] Here, the normalized frequency V is V=k0n 21 a(2Δ) 1 / 2 where k0 is the wave number in a vacuum, a is the half-width of the core region 21, and Δ(=(n 21 2 -n 22 2 ) / (2n 21 2 ) is the relative refractive index difference.

[0035] In formula 1, N is the mode order of the transverse mode, and for example, when the normalized frequency V is equal to or greater than π / 2 and less than 2π / 2 (i.e., π), light can propagate in two modes, the 0th mode (fundamental mode) and the 1st mode. When the normalized frequency V is equal to or greater than Nπ / 2 and less than (N+1)π / 2, light can propagate in multiple modes, the 0th, 1st, 2nd,...Nth modes, i.e., (N+1).

[0036] In this way, the number of transverse modes of light propagating through the second region 2 can be set based on Equation 1. Specifically, it can be set based on the width of the second ridge 135b. Note that even in a semiconductor laser element that does not have a ridge structure, it can be similarly set based on parameters constituting the waveguide. The number of transverse modes is preferably as large as possible for achieving high output, and is, for example, 10 or more, preferably 30 or more, and more preferably 50 or more. The number of transverse modes is preferably as large as possible for achieving high output, but if the number is too large, problems such as deterioration of light collecting properties arise, and the number is, for example, 500 or less, preferably 300 or less, and more preferably 100 or less. As can be understood from the above explanation of Equation 1, the number of transverse modes is determined by parameters including the width of core region 21. In consideration of the number of transverse modes and heat dissipation properties described above, the width of core region 21 is, for example, 15 μm or more and 120 μm or less, and more preferably 45 μm or more and 100 μm or less.

[0037] (Diffraction Grating 105) Diffraction grating 105 is provided in first region 1 as shown in Fig. 3 etc. Diffraction grating 105 is preferably provided over the entire first region 1. Diffraction grating 105 is not provided in second region 2. The Bragg wavelength of the diffraction grating is expressed by the following formula 2. Formula 2 indicates that the effective period of the diffraction grating is the product of the equivalent refractive index and the pitch of the diffraction grating.

[0038] Bragg wavelength (λ B ) = (equivalent refractive index (n1) × diffraction grating pitch (P)) × 2 (Equation 2)

[0039] The diffraction grating 105 can be formed by alternately (periodically) arranging regions having different refractive indices in the light propagation direction. The diffraction grating 105 is provided, for example, between two adjacent semiconductor layers. The pitch of the diffraction grating 105 can be appropriately selected in consideration of the wavelength of the light emitted by the active layer 120. The equivalent refractive index n1 of the diffraction grating 105 is approximately the same for each transverse mode, and therefore the Bragg wavelength λ B As a result, the full width at half maximum of the oscillation wavelength of the laser light emitted from the semiconductor laser element L1 becomes smaller. For example, the full width at half maximum of the oscillation wavelength of the laser light emitted from the semiconductor laser element L1 is 0.01 nm or more and 0.5 nm or less.

[0040] In the first embodiment, the diffraction grating 105 is provided, for example, between the n-side light guide layer 112 and the n-side cladding layer 111. Specifically, the diffraction grating 105 is provided on the surface of the n-side cladding layer 111 and includes one or more first convex portions protruding toward the n-side light guide layer 112 side and one or more second convex portions provided on the surface of the n-side light guide layer 112 and protruding toward the n-side cladding layer 111 side, which are alternately arranged in the light traveling direction. Here, the pitch (P) in formula 2 is the sum of the length of one first convex portion and the length of one second convex portion in the light propagation direction. In the first embodiment, the diffraction grating 105 is provided between the n-side light guiding layer 112 and the n-side cladding layer 111, but it may be provided only in either the n-side light guiding layer 112 or the n-side cladding layer 111, or it may be provided between the n-side light guiding layer 112 and the active layer 120. In addition, the diffraction grating 105 may be provided on the p-side semiconductor layer 130 side.

[0041] (electrode) The semiconductor laser device L1 includes a p-electrode 150 and an n-electrode 160, as shown in FIGS. For example, when the substrate 100 is conductive, the n-electrode 160 can be disposed on the lower surface of the substrate 100. When the substrate 100 is insulating, a part of the n-side cladding layer 111 is exposed and the n-electrode 160 can be formed on the exposed surface. Examples of materials for the p-electrode 150 and the n-electrode 160 include metals or alloys such as Ni, Rh, Cr, Au, W, Pt, Ti, and Al, and single-layer or multilayer films of conductive oxides containing at least one selected from Zn, In, and Sn.

[0042] The p-electrode 150 may include a transparent conductive film in contact with the ridge 135 as a first electrode. By selecting a material for the transparent conductive film whose refractive index is smaller than that of the active layer 120 and that of the p-side semiconductor layer 130, the transparent conductive film can be treated as a p-side cladding layer. The transparent conductive film is, for example, ITO (indium tin oxide), IGZO (indium gallium zinc oxide), or the like. The insulating film 140 may be, for example, silicon oxide, aluminum oxide, or aluminum nitride.

[0043] (maximum diffusion angle Θ max1 (Calculation of In the semiconductor laser element L1 of the first embodiment, the maximum divergence angle Θ max1 is an index of the quality of the laser beam given by the following equation 3, M 2 It can be calculated using the factor M 2 The factor is a measure of the spread from an ideal Gaussian beam, and for an ideal Gaussian beam, M 2 The factor is 1. That is, the M of the laser light output from the semiconductor laser element L1 2 Knowing this factor tells us how much the laser light diverges compared to an ideal Gaussian beam, and the maximum divergence angle Θ max1 can be sought.

[0044] M 2 =πφW0 / λ (Equation 3) Here, W0 is the beam waist radius and φ is the beam divergence angle. Also, λ is the wavelength of the laser light in a vacuum.

[0045] The beam waist radius W0 and the beam divergence angle φ can be measured as follows using an optical system equipped with a collimator lens 81 and a condenser lens 82 shown in FIG. The laser light emitted from the first region 1 is collimated by a collimating lens 81 and then collected by a collecting lens 82, and the trajectory of the collected laser light is traced. Specifically, the beam diameter of the collected laser light is measured at various positions Bmp, the position where the beam diameter is smallest is estimated, and the beam diameter at that position (beam waist radius W0) is obtained. The beam spread from the position where the beam diameter is smallest is measured to obtain the beam divergence angle φ. Note that, M 2 The definition of the parameters required to calculate the factor is based on the international standard ISO 11146-1:2021 or ISO 11146-2:2021. For example, the beam diameter is defined as D4σ (second moment width). Note that M 2 When measuring the factor, the current value input to the semiconductor laser element L1 is within a predetermined range of operating current. 2 The factors can be determined, for example, using a commercially available measuring device (THORLABS BP209-VIS / M).

[0046] From the beam waist radius W0 and beam divergence angle φ obtained as above, M is calculated from Equation 3. 2 Calculate the factors and use M as described above. 2 Maximum diffusion angle Θ based on the factor max1 M 2 Factor and M 2 The trajectory of the laser light emitted from the second region 2 can be determined by the trajectory of the laser light measured in the process of determining the factor. max1 By comparing the positional relationship between this virtual line and both ends of the first region 1, the spread of the laser light in the first region 1 can be examined. Here, the maximum diffusion angle Θ max1 As shown in FIG. 5 etc., the angle between a straight line excluding curved portions in an imaginary line and a straight line extending the boundary between the core region 21 and the cladding region 22. In addition, M of the laser beam in the first embodiment 2 The factor may be between 2 and 100 inclusive. In addition, when the beam diameter of the laser light at the laser light emitting end face is smaller than the width of the first region 1 and the width of the first region 1 is substantially constant, it is clear that both ends of the first region 1 are located outside the above-mentioned virtual line v1. Therefore, by first measuring the beam diameter of the laser light at the laser light emitting end face, the positional relationship between the width of the first region 1 and the virtual line v1 can be found.

[0047] In the above embodiment 1, the semiconductor laser element L1 of embodiment 1 has been described taking as an example a semiconductor laser element having a ridge structure. However, the semiconductor laser element L1 of the first embodiment is not limited to a semiconductor laser element having a ridge structure, and may be a semiconductor laser element of a rib waveguide type or a semiconductor laser element of a buried heterostructure waveguide type.

[0048] The semiconductor materials constituting the semiconductor laser element described so far may be materials other than nitride semiconductors. The semiconductor materials may be, for example, GaAs, InP, GaInP, GaInAsP, GaAlAs, or AlInGaP. In this case, the semiconductor laser element may have an oscillation wavelength of 760 nm or more and 1060 nm or less. The semiconductor laser element may also be made of materials other than these. For example, a semiconductor laser element that emits ultraviolet light may be made of aluminum nitride or boron nitride.

[0049] The semiconductor laser element described so far can also be expressed as follows. That is, the semiconductor laser element has a semiconductor laminate 101 including an active layer 120 and a p-electrode 150 provided on the semiconductor laminate 101, and may have a waveguide structure. The semiconductor laminate 101 is (i) a first region 1 which includes a diffraction grating 105 and is a slab waveguide; (ii) a second region 2 having a core region 21 and cladding regions 22 provided on both sides of the core region 21; Includes. When viewed from the top, the first region 1 propagates light incident from the second region 2, and includes a central region 11 and a peripheral region 12 located outside the central region 11, and a current shielding structure 10 is provided at a position overlapping at least a portion of the peripheral region 12. Here, the first region 1 is a slab waveguide. That is, in the first region 1, light is confined only in the stacking direction. Since the diffraction grating 105 is provided in the first region 1, which is a slab waveguide, the equivalent refractive index is almost the same even for different transverse modes, and the selected wavelength (Bragg wavelength) in the diffraction grating 105 is uniform. Note that there may be a light confinement region in the peripheral region 12. Even in this case, the central region 11 of the first region 1 is a slab waveguide.

[0050] EMBODIMENT 2 The semiconductor laser device L2 of the second embodiment is the same as the semiconductor laser device L1 of the first embodiment in that it includes a current shielding structure 10 made of a part of the insulating film 140; however, the configuration of the p-electrode 150 is different. Specifically, in the semiconductor laser element L2 of embodiment 2, in the first region 1, the first electrode 151 is not provided so as to be in contact with the entire upper surface of the p-side contact layer 133 on the ridge 135 of the semiconductor laminate portion 101, but as shown in FIG. 6, the first electrode 151 is provided so as to be embedded in the first opening 140a, and the first electrode 151 is in contact with the p-side contact layer 133 within the width of the first opening 140a. The semiconductor laser device L2 of the second embodiment configured as above can block the current in the peripheral region 12, and can suppress the reactive current in the peripheral region 12 to reduce heat generation. Therefore, the semiconductor laser device L2 of the second embodiment can achieve high output by oscillating and propagating laser light in a plurality of transverse modes, thereby providing the semiconductor laser device L1 with high power conversion efficiency. Here, in the semiconductor laser element L2 of embodiment 2, the first electrode 151 is provided so as to be embedded in the first opening 140a and is limited to the width of the first opening 140a, and the first electrode 151 is in contact with the p-side contact layer 133. Therefore, there is no concern that the current will spread laterally within the first electrode 151, and the current can be blocked more effectively. In the semiconductor laser element L2 of embodiment 2, the structure of the p-electrode 150 in the second region 2 is not particularly limited and may be the same as that of embodiment 1, or may be provided so that the first electrode 151 is embedded in the second opening 140b, as in the first region 1. In addition, the semiconductor laser device L2 of the second embodiment has the same configuration as the semiconductor laser device L1 of the first embodiment except for the p-electrode 150. For example, the semiconductor laser device L2 is a transverse multimode semiconductor laser device.

[0051] EMBODIMENT 3 The semiconductor laser device L3 of the third embodiment differs from the semiconductor laser device L1 of the first embodiment in the configuration of the current shielding structure. Specifically, the current shielding structure 13 in the semiconductor laser element L3 of embodiment 3 is provided on the surface of the semiconductor laminate 101 (the surface of the p-side contact layer 133), as shown in FIG. 7, and is composed of an oxide film 133a having an opening 13a above the central region 11, and current is injected from the p-electrode 150 into the central region 11 through the opening 13a. In the semiconductor laser device L3 of the third embodiment, for example, in the first region 1, the first electrode 151 can be provided so as to be in contact with the entire upper surface of the p-side contact layer 133 on the ridge 135 of the semiconductor laminate portion 101.

[0052] In the semiconductor laser element L3 of the third embodiment, the oxide film 133a constituting the current shielding structure 13 can be formed, for example, by oxidizing the surface of the p-side contact layer 133. In this way, the first electrode 151 and the p-side contact layer 133 can be connected to each other through the oxide film 133a to form a Schottky junction, thereby forming the current shielding structure 13. The semiconductor laser device L3 of the third embodiment configured as above can block the current in the peripheral region 12, and suppress the reactive current in the peripheral region 12, thereby reducing heat generation. Therefore, the semiconductor laser device L3 of the third embodiment can achieve high output by oscillating and propagating laser light in a plurality of transverse modes, and can provide a semiconductor laser device L3 with high power conversion efficiency. In the semiconductor laser device L3 of the third embodiment, the current injection structure in the second region 2 is not particularly limited, and may be the same as that in the first embodiment, or may have another configuration. For example, in the second region 2, a second oxide film may be provided in the semiconductor laminate portion 101, the second oxide film having a second opening 140b narrower than the opening 13a on the waveguide, and a current may be injected into the second region 2 through the second opening 140b. In this way, it becomes possible to provide the core region 21 and the cladding regions 22 on both sides of the core region 21 in the second region 2, and light in a plurality of transverse modes can be oscillated in accordance with the width of the second opening 140b. In the semiconductor laser element L3 of the embodiment 3, the configuration of the semiconductor laminate portion 101 and the like other than the current shielding structure 13 is similar to that of the semiconductor laser element L1 of the embodiment 1. For example, the semiconductor laser element L3 is a transverse multimode semiconductor laser element.

[0053] EMBODIMENT 4 The semiconductor laser device L4 of the fourth embodiment differs from the semiconductor laser device L1 of the first embodiment in the configuration of the current shielding structure. Specifically, the current shielding structure 14 in the semiconductor laser element L4 of embodiment 4 is provided in the p-side semiconductor layer 130 of the semiconductor laminate portion 101, as shown in FIG. 8, and is composed of a block layer 132a having an opening 14a in the central region 11, and is configured by restricting the current injected from the p-electrode 150 by the opening 14a. Here, in the semiconductor laser element L4 of the fourth embodiment, for example, in the first region 1, the first electrode 151 can be provided so as to be in contact with the entire upper surface of the p-side contact layer 133 on the ridge 135 of the semiconductor laminate portion 101. Also, the block layer 132a can be provided by forming an undoped layer in a part of the p-side semiconductor layer 130.

[0054] 8 shows an example in which the block layer 132a is provided by making a part of the p-side cladding layer 132 undoped, but it may be provided on the active layer 120, i.e., on the p-electrode 150 side, and may be provided, for example, on the p-side light guide layer 131 or the p-side contact layer 133. The block layer 132a may be provided in the p-side semiconductor layer 130 by providing an undoped layer as a new layer in addition to the p-side light guide layer 131, the p-side cladding layer 132, and the p-side contact layer 133. The semiconductor laser device L4 of the fourth embodiment configured as above can block the current in the peripheral region 12, and can suppress the reactive current in the peripheral region 12 to reduce heat generation. Therefore, the semiconductor laser device L4 of the fourth embodiment can achieve high output by oscillating and propagating laser light in a plurality of transverse modes, thereby providing the semiconductor laser device L3 with high power conversion efficiency. In the semiconductor laser device L3 of the third embodiment, the current injection structure in the second region 2 is not particularly limited, and may be the same as that in the first embodiment, or may have another configuration. For example, in the second region 2, a second block layer may be provided in the semiconductor laminate portion 101, the second block layer having a second opening 140b narrower than the opening 14a on the waveguide, and a current may be injected into the second region 2 through the second opening 140b. In this way, it becomes possible to provide the core region 21 and the cladding regions 22 on both sides of the core region 21 in the second region 2, and light in a plurality of transverse modes can be oscillated in accordance with the width of the second opening 140b. In the semiconductor laser element L4 of the embodiment 4, the configuration of the semiconductor laminate 101 and the like other than the current shielding structure 14 is similar to that of the semiconductor laser element L1 of the embodiment 1. For example, the semiconductor laser element L4 is a transverse multimode semiconductor laser element.

[0055] Variations In the description of the above embodiments, for example, in the description of the semiconductor laser element L1 of embodiment 1, an example was illustrated in which the width of the first opening 140a provided in the insulating film 140 constituting the current shielding structure 10 is constant. However, the laser light emitted from the second region 2 has a maximum divergence angle Θ max1 Considering that the light propagates through the first region 1 at a constant angle, the width of the first opening 140a does not need to be constant, and the width of the opening may be wider toward the output end surface of the first region 1, as shown in the first opening 140c in FIG. 9. With this configuration, it is possible to efficiently inject current into the opening while efficiently reducing the region through which reactive current flows. The width of the opening is, for example, max1 Preferably, the axial length of the slit extends along an imaginary line extending at . The same applies to embodiments 2 to 4, and the width of the opening 13a provided in the oxide film 133a of embodiment 3 and the opening 14a provided in the block layer 132a of embodiment 4 may also be increased toward the output end surface of the first region 1.

[0056] Examples 1 to 3 and Comparative Example 1 The semiconductor laser element L2 was fabricated, and the output of the laser light was measured. The fabricated semiconductor laser element L2 was obtained by stacking the n-side cladding layer 111, the n-side optical guide layer 112, the active layer 120, the p-side optical guide layer 131, the p-side cladding layer 132, and the p-side contact layer 133 on a GaN substrate. The first ridge 135a and the second ridge 135b were obtained by removing the p-side cladding layer 132 to a part of the p-side optical guide layer 131. The width of the first ridge 135a was 345 μm, and the width of the second ridge 135b was 90 μm. The diffraction grating 105 was provided in the n-side semiconductor layer 110 of the first region 1, and the period of the diffraction grating 105 was 96 nm. The width of the diffraction grating 105 was 350 μm. In addition, the first electrode 151 and the insulating film 140 were stacked in this order on the p-side contact layer 133. At this time, the width of second opening 140b was set to 84 μm, and the shape of first opening 140a or first opening 140c of insulating film 140 was varied to obtain four samples of Examples 1 to 3 and Comparative Example 1. The width of first opening 140a or first opening 140c in each example is as shown in Table 1. In Example 3, first opening 140c was made so that its width gradually increased from 90 μm to 101 μm. That is, in Comparative Example 1, the width of the first opening 140a is set to be approximately the same as the width of the diffraction grating 105, while in Examples 1 and 2, the width of the first opening 140a is set to be narrower than that of the sample of Comparative Example 1, and in Example 3, the first opening 140a is set to be oriented such that the maximum diffusion angle Θ max1 The shape is designed to expand along an imaginary line extending from the center. A current was injected into the semiconductor laser devices fabricated in Examples 1 to 3 and Comparative Example 1, and the data shown in Table 1 was obtained.

[0057] [Table 1]

[0058] From this result, it can be said that in Examples 1 to 3, a semiconductor laser element having a higher power conversion efficiency was obtained compared to Comparative Example 1. Also, from the results of Examples 2 and 3, it can be seen that the width of the first opening 140a is set to the maximum divergence angle Θ max1It was found that the output, slope efficiency, and WPE of the semiconductor laser element L2 can be improved by matching the virtual line spreading out at .

[0059] For sample (4), a current of 9.5 A was applied, and the full width at half maximum of the emitted light wavelength was measured to be 0.15 nm. Although the semiconductor laser element L2 is a transverse multimode semiconductor laser, the wavelength variation was small.

[0060] Other configurations Furthermore, for example, the present disclosure can have the following configuration. (Section 1) A semiconductor laser element having a waveguide structure, the semiconductor laser element comprising a semiconductor laminate including an active layer and an electrode provided on the semiconductor laminate, The semiconductor laminate portion is (i) a first region including a diffraction grating; (ii) a second region having a core region and cladding regions provided on both sides of the core region, and propagating laser light in a plurality of transverse modes; Including, In top view, The first region propagates light incident from the second region and includes a central region and a peripheral region located outside the central region, A semiconductor laser element, comprising: a current shielding structure provided at a position overlapping at least a portion of the peripheral region. (Section 2) A semiconductor laser element having a waveguide structure, the semiconductor laser element having a semiconductor laminate including an active layer and an electrode provided on the semiconductor laminate, The semiconductor laminate portion is (i) a first region including a diffraction grating and being a slab waveguide; (ii) a second region having a core region and cladding regions disposed on both sides of the core region; Including, In top view, The first region propagates light incident from the second region and includes a central region and a peripheral region located outside the central region; A semiconductor laser element, comprising: a current shielding structure provided at a position overlapping at least a portion of the peripheral region. (Section 3) The refractive index of the core region is n 21 and the refractive index of the cladding region is n 22 and the refractive index of the central region is n1; The laser light emitted from the second region has a refractive index of n1 and a refractive index of n 21 and the refractive index n 22 The maximum diffusion angle Θ is determined by max1 propagating through the first region with The central region is arranged such that the maximum diffusion angle Θ max1 3. The semiconductor laser element according to item 1 or 2, comprising an area inside an imaginary line extending in the direction of the arrow. (Section 4) 4. The semiconductor laser element according to any one of items 1 to 3, wherein the current shielding structure includes an insulating film provided on the semiconductor laminate and having an opening on the central region, and at least a part of the electrode is provided in the opening. (Section 5) 5. The semiconductor laser element according to item 4, wherein the electrodes include a first electrode provided in the opening, and the first electrode is in contact with the semiconductor laminate inside the opening. (Section 6) 5. The semiconductor laser element according to item 4, wherein the electrodes include a first electrode provided on and in contact with the semiconductor laminate and a second electrode provided on the first electrode, and the second electrode is connected to the first electrode through the opening. (Section 7) 7. The semiconductor laser device according to any one of items 4 to 6, wherein a width of the opening portion increases toward the light-emitting end face of the first region. (Section 8) The semiconductor laser element according to any one of items 4 to 7, wherein the second region includes a second insulating film provided in the semiconductor stack and having a second opening on the second region that is narrower than the opening, and a current is injected into the second region through the second opening. (Section 9) 4. The semiconductor laser element according to any one of items 1 to 3, wherein the current shielding structure includes an oxide film provided on a surface of the semiconductor laminate and having an opening on the central region, and the electrode injects a current into the central region through the opening. (Section 10) 10. The semiconductor laser device according to item 9, wherein the opening portion widens toward the light-emitting end face of the first region. (Section 11) 10. The semiconductor laser device according to item 9, wherein the width of the opening is constant. (Section 12) The semiconductor laser element according to any one of items 9 to 11, wherein the second region includes a second oxide film provided in the semiconductor stack and having a second opening on the second region that is narrower than the opening, and a current is injected into the second region through the second opening. (Section 13) 4. The semiconductor laser element according to any one of items 1 to 3, wherein the current shielding structure includes a block layer provided in the semiconductor laminate and having an opening on the central region, and injects a current into the central region through the opening. (Section 14) Item 14. The semiconductor laser device according to item 13, wherein a width of the opening portion increases toward the light-emitting end face of the first region. (Section 15) Item 14. The semiconductor laser device according to item 13, wherein the width of the opening is constant. (Section 16) The semiconductor laser element according to any one of items 13 to 15, wherein the second region includes a second blocking layer provided in the semiconductor stack and having a second opening on the second region that is narrower than the opening, and a current is injected into the second region through the second opening.

[0061] Although the embodiment and modifications of the present disclosure have been described above, various modifications are possible as long as they have a configuration based on the technical concept of the present disclosure. Furthermore, the combination and order of the components in the embodiment and modifications can be changed in various ways within the scope and concept of the present disclosure. [Explanation of symbols]

[0062] L1, L2, L3, L4 Semiconductor laser element 1 1st area 11 Central area 12 Surrounding Areas 2 Second area 21 Core Areas 22 Cladding region 100 Substrates 101 Semiconductor laminate 150p electrode 160n electrode 110 n-side semiconductor layer 111 n-side cladding layer 112 n-side optical guide layer 120 Active layer 130 p-side semiconductor layer 131 p-side optical guide layer 132 p-side cladding layer 133 p-side contact layer 105 Diffraction Grating 135 Ridge 135a First Ridge 135b 2nd Ridge

Claims

1. A semiconductor laser element having a waveguide structure, the semiconductor laser element having a semiconductor laminate including an active layer and an electrode provided on the semiconductor laminate, The semiconductor laminate portion is (i) a first region including a diffraction grating; (ii) a second region having a core region and cladding regions provided on both sides of the core region, and propagating laser light in a plurality of transverse modes; Including, In top view, The first region propagates light incident from the second region and includes a central region and a peripheral region located outside the central region, A semiconductor laser element, comprising: a current shielding structure provided at a position overlapping at least a portion of the peripheral region.

2. The refractive index of the core region is n ２１ and the refractive index of the cladding region is n ２２ and the refractive index of the central region is n １ and The laser light emitted from the second region has a refractive index n １ and the refractive index n ２１ and the refractive index n ２２ The maximum diffusion angle Θ is determined by max１ propagating through the first region with The central region is arranged such that the maximum diffusion angle Θ max１ 2. The semiconductor laser device according to claim 1, comprising a region inside an imaginary line extending from

3. 2. The semiconductor laser device according to claim 1, wherein the current shielding structure includes an insulating film provided on the semiconductor laminate and having an opening above the central region, and at least a portion of the electrode is provided in the opening.

4. The semiconductor laser device according to claim 3 , wherein the electrodes include a first electrode provided in the opening, the first electrode being in contact with the semiconductor laminate inside the opening.

5. 4. The semiconductor laser element according to claim 3, wherein the electrodes include a first electrode provided on and in contact with the semiconductor laminate, and a second electrode provided on the first electrode, the second electrode being connected to the first electrode through the opening.

6. 6. The semiconductor laser device according to claim 3, wherein a width of the opening increases toward the light-emitting end face of the first region.

7. The semiconductor laser element according to any one of claims 3 to 5, wherein the second region includes a second insulating film provided in the semiconductor stack and having a second opening on the second region that is narrower than the opening, and a current is injected into the second region through the second opening.

8. 2. The semiconductor laser device according to claim 1, wherein the current shielding structure includes an oxide film provided on a surface of the semiconductor laminate and having an opening above the central region, and the electrode injects a current into the central region through the opening.

9. The semiconductor laser device according to claim 8 , wherein the opening widens toward the light-emitting end face of the first region.

10. 9. The semiconductor laser device according to claim 8, wherein the width of the opening is constant.

11. 9. The semiconductor laser element according to claim 8, wherein the second region includes a second oxide film provided in the semiconductor stack and having a second opening on the second region that is narrower than the opening, and a current is injected into the second region through the second opening.

12. 2. The semiconductor laser device according to claim 1, wherein the current shielding structure includes a block layer provided in the semiconductor laminate and having an opening above the central region, and injects a current into the central region through the opening.

13. The semiconductor laser device according to claim 12 , wherein a width of the opening increases toward the light-emitting end face of the first region.

14. The semiconductor laser device according to claim 12 , wherein the width of the opening is constant.

15. 13. The semiconductor laser element according to claim 12, wherein the second region includes a second block layer provided in the semiconductor stack and having a second opening on the second region that is narrower than the opening, and a current is injected into the second region through the second opening.

16. A semiconductor laser element having a waveguide structure, the semiconductor laser element having a semiconductor laminate including an active layer and an electrode provided on the semiconductor laminate, The semiconductor laminate portion is (i) a first region including a diffraction grating and being a slab waveguide; (ii) a second region having a core region and cladding regions disposed on both sides of the core region; Including, In top view, The first region propagates light incident from the second region and includes a central region and a peripheral region located outside the central region, A semiconductor laser element, comprising: a current shielding structure provided at a position overlapping at least a portion of the peripheral region.

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