Semiconductor laser element

Abstract

Provided is a semiconductor laser element having high power conversion efficiency. The semiconductor laser element has a waveguide structure and a semiconductor laminated part including an active layer and an electrode provided on the semiconductor laminated part, and the semiconductor laminated part includes: (i) a first region including a diffraction grating; and (ii) a second region having a core region having a refractive index n21 and cladding regions having a refractive index n22 provided on both sides of the core region, the laser beam propagating in a plurality of lateral modes, the light incident from the second region on the first region propagating in a plan view, the second region including a central region having a refractive index n1 and a peripheral region located outside the central region, a current shield structure is provided at a position overlapping at least a part of the peripheral region.

Description

Technical Field

[0001] The present disclosure relates to a semiconductor laser element. Background Art

[0002] In recent years, there is a demand for higher output laser beams from semiconductor laser elements. High-output semiconductor laser elements are increasingly used as light sources for processing, for example. For example, Patent Document 1 discloses a multi-transverse mode semiconductor laser that can prevent optical damage on the stripe side.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-151238 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] However, the power conversion efficiency of the semiconductor laser element disclosed in Patent Document 1 is insufficient and there is room for improvement.

[0008] Therefore, an object of the present disclosure is to provide a semiconductor laser element having high power conversion efficiency.

[0009] Means for solving problems

[0010] A semiconductor laser device according to one embodiment of the present disclosure includes a semiconductor stack portion including an active layer and an electrode provided on the semiconductor stack portion, and has a waveguide structure, wherein the semiconductor stack portion includes:

[0011] (i) a first region comprising a diffraction grating; and

[0012] (ii) a second region having a core region and cladding regions provided on both sides of the core region, and causing the laser beam to propagate in a plurality of transverse modes,

[0013] When looking down,

[0014] The first region propagates the light incident from the second region, and includes a central region and a peripheral region located outside the central region.

[0015] A current shielding structure is provided at a position overlapping with at least a portion of the peripheral region.

[0016] Effects of the Invention

[0017] The semiconductor laser device according to one embodiment of the present disclosure can provide a semiconductor laser device with high power conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a top view of the semiconductor laser element according to the first embodiment of the present disclosure.

[0019] Figure 2 This is a plan view schematically showing the regional structure of the semiconductor laser element according to the first embodiment.

[0020] Figure 3 yes Figure 1 A schematic cross-sectional view of the semiconductor laser element taken along line III-III shown.

[0021] Figure 4 yes Figure 1 A schematic cross-sectional view of the semiconductor laser element taken along line IV-IV is shown.

[0022] Figure 5 It represents the beam waist radius W0 and the beam divergence angle A diagram showing an overview of the measurement method.

[0023] Figure 6 It is a schematic cross-sectional view of a first region of a semiconductor laser element according to a second embodiment of the present disclosure.

[0024] Figure 7 It is a schematic cross-sectional view of a first region of a semiconductor laser element according to a third embodiment of the present disclosure.

[0025] Figure 8 It is a schematic cross-sectional view of a first region of a semiconductor laser element according to a fourth embodiment of the present disclosure.

[0026] Fig. 9 This is a plan view schematically showing another form of the semiconductor laser element according to the first embodiment. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments, variations, and examples for implementing the invention disclosed herein will be described with reference to the accompanying drawings. In addition, the semiconductor laser element disclosed herein described below is used to embody the technical concept of the invention disclosed herein, and the invention disclosed herein is not limited to the following contents unless otherwise specified.

[0028] In the various drawings, there are cases where the same figure numbers are marked for components with the same functions. Taking into account the ease of explanation or understanding of the key points, for convenience, they are sometimes divided into implementation modes, variations, or embodiments for presentation, but the structures shown in different implementation modes, variations, and embodiments can be partially replaced or combined. In the implementation modes, variations, and embodiments described later, the description of matters common to the aforementioned matters is omitted, and only the different points are described. In particular, the same effects brought about by the same structure are not mentioned one by one according to the implementation modes, variations, and embodiments. The size, positional relationship, etc. of the components shown in the various drawings are sometimes exaggerated for the purpose of clear description.

[0029] Implementation Method 1

[0030] The semiconductor laser element L1 of the first embodiment is a semiconductor laser element L1 including a semiconductor stacked portion 101 including an active layer 120 and having Figure 2 Here, Figure 1 This is a schematic plan view of the semiconductor laser element L1 according to the first embodiment.

[0031] Specifically, the semiconductor stacked portion 101 in the semiconductor laser element L1 of the first embodiment is as follows: Figure 1 to Figure 4 As shown, including:

[0032] (i) a first region 1 comprising a diffraction grating 105; and

[0033] (ii) The second region 2 includes a core region 21 and cladding regions 22 provided on both sides of the core region 21, and propagates the laser beam in a plurality of transverse modes.

[0034] Moreover, in the semiconductor laser element L1 of embodiment 1, the first region 1 propagates light incident from the second region 2 when viewed from above, 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 with at least a portion of the peripheral region 12.

[0035] In addition, the refractive index of the core region 21 is n 21 The refractive index of the cladding region 22 is n 22 , the refractive index of the central region 11 is n1.

[0036] In the semiconductor laser element L1 having the above-described structure and including the first region 1 and the second region 2, the laser beam emitted from the second region 2 has a refractive index n1 and a refractive index n2. 21 and refractive index n 22 Determine the maximum diffusion angle θ max1 Transmission in a first area 1.

[0037] Here, in the semiconductor laser element L1 of the first embodiment, the current shielding structure 10 is composed of an insulating film 140 provided on the semiconductor stacked portion 101 of the first region 1 as described later. For example, the semiconductor laser element L1 is a lateral multi-mode semiconductor laser element. Since it is a lateral multi-mode semiconductor laser element, compared with a lateral single mode semiconductor laser element, the heat caused by the reactive current in the portion that does not contribute to the oscillation (propagation of light) is reduced, thereby further achieving the effect of improving the luminous efficiency.

[0038] The semiconductor laser element L1 according to the first embodiment configured as described above can improve the light emission output relative to the power consumption, and can efficiently obtain high-output light.

[0039] The reason is described below.

[0040] First, in a semiconductor laser element including a diffraction grating 105 in the first region 1 and having a waveguide structure in the second region 2, for example, current is repeatedly injected into the core region 21 of the second region 2, and the emitted light propagates in the waveguide including the core region 21 and is incident on the first region 1, is reflected by the diffraction grating 105 provided in the first region 1 and returns to the second region 2, and the returned light is amplified, thereby performing laser oscillation.

[0041] In addition, in order to more efficiently perform laser oscillation, the semiconductor laser element L1 of the first embodiment may be coated on one or both of the end face of the first region 1 on the side opposite to the second region 2 and the end face of the second region 2 on the side 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 on the side opposite to the second region 2, and a high-reflection coating (HR coating) provided on the end face of the second region 2 on the side opposite to the first region 1.

[0042] Here, as described above, the laser beam is incident on the first region 1 including the central region 11 having a refractive index n1 and is emitted from the second region 2 with a refractive index n1 and a refractive index n2. 21 , and refractive index n 22 Determine the maximum diffusion angle θ max1 The current is transmitted in the first region 1. Considering this point, the width of the region where the current is injected in the first region 1 is preferably set wider than the width of the region where the current is injected in the second region 2. This is because the region where the current is injected in the first region 1 functions as the diffraction grating 105. Thus, the diffraction grating 105 can be used to reflect the light while diffraction at the maximum diffusion angle θ. max1 The light transmitted in the first region 1 is expanded.

[0043] However, the inventors of the present application have obtained the following insight: although a certain effect of improving the luminous efficiency is obtained by setting the width of the region for injecting current in the first region 1 to be wider than the width of the region for injecting current in the second region 2, if the width of the region for injecting current in the first region 1 is further increased, the luminous efficiency begins to decrease.

[0044] In addition, in the first region 1, the portion that does not contribute to the oscillation (propagation of light) corresponds to the portion of the optical fiber 21 extending from both ends of the emission end face at the maximum diffusion angle θ. max1 The area outside the extended virtual line.

[0045] Therefore, in the semiconductor laser element of the embodiment, the emission end faces from the core region 21 are arranged at the maximum diffusion angle θ. max1 The current shielding structure 10 is provided in at least a portion of the peripheral region 12 outside the extended virtual line to reduce reactive current.

[0046] Here, in the semiconductor laser element L1 of the first embodiment, the central region 11 includes the emission end faces of the core region 21 at both ends with the maximum diffusion angle θ. max1 In addition, for example, the two ends of the emission end face of the core region 21 can be expanded at the maximum diffusion angle θ max1 The area outside the extended virtual line is defined as the peripheral area 12. In addition, for example, the two ends of the emission end face of the core region 21 can be expanded at the maximum diffusion angle θ max1 The area inside the extended virtual line is defined as the central area 11. By setting the central area 11 to include the emission ends from the core area 21 at the maximum diffusion angle θ max1 The region inside the expanded virtual line can efficiently inject current into the region where light is transmitted while reducing reactive current in the region that does not contribute to light transmission.

[0047] In this specification, the refractive index n is referred to as 21 , refractive index n 22 The refractive index when is an effective refractive index that takes into account the light confinement in the stacking direction of the semiconductor stack portion 101, and is also called an equivalent refractive index. The refractive index n1 refers to the effective refractive index that takes into account the light confinement in the stacking direction of the semiconductor stack portion 101 and averages the modulation portion of the refractive index of the diffraction grating 105. In addition, the maximum diffusion angle θ is max1 It is equal to the maximum light acceptance angle of the optical waveguide in the second region 2.

[0048] Hereinafter, the semiconductor laser element L1 according to the first embodiment will be described in detail with reference to the drawings.

[0049] here, Figure 11 is a plan view of the semiconductor laser element L1 according to the first embodiment. Figure 2 It is a plan view schematically showing the regional structure of the semiconductor laser element L1 according to the first embodiment. Figure 3 yes Figure 1 A schematic cross-sectional view of the semiconductor laser element taken along line III-III shown. Figure 4 yes Figure 1 1 is a schematic cross-sectional view taken along line IV-IV of the semiconductor laser element L1 shown.

[0050] The semiconductor laser element L1 of the first embodiment includes a semiconductor stacked portion 101 provided on a substrate 100. The semiconductor stacked portion 101 is, for example, Figure 3-4 As shown, including:

[0051] (a) an n-side semiconductor layer 110 including an n-side cladding layer 111 and an n-side optical guide layer 112;

[0052] (b) an active layer 120 provided on the n-side semiconductor layer 110; and

[0053] (c) The p-side semiconductor layer 130 is provided on the active layer 120 and includes a p-side optical guide layer 131 , a p-side cladding layer 132 , and a p-side contact layer 133 .

[0054] In addition, the semiconductor stacked portion 101 includes, for example, ridges 135 provided in the p-side contact layer 133 and the p-side cladding layer 132. The ridges 135 include a first ridge 135a provided in the first region 1 and a second ridge 135b provided in the second region 2. When viewed from above, the first ridge 135a and the second ridge 135b are provided so that, for example, the center lines coincide with each other in the traveling direction of the laser beam.

[0055] In addition, Figure 1 In FIG. 1 , the outer side surface of the first ridge 135a and the outer side surface of the second ridge 135b are drawn to be consistent with the outer side surface of the second electrode 152 described later, so Figure 1 In FIG. 1 , the first ridge 135 a and the second ridge 135 b are represented by dotted lines drawn from the outer side surfaces of the first ridge 135 a and the second ridge 135 b.

[0056] Furthermore, as described above, since the light emitted from the second region 2 and incident on the first region 1 spreads and propagates in the first region 1 , the width of the first ridge 135 a is set to be larger than the width of the second ridge 135 b .

[0057] Furthermore, the outer side surface of the first region 1 is close to the outer side surface of the first ridge 135 a , and the refractive index n1 of the central region 11 does not change in the light propagation direction and the width direction but remains constant.

[0058] Here, in this specification, the width direction refers to a direction orthogonal to both the propagation direction of light and the stacking direction of the semiconductor stack portion 101 .

[0059] On the semiconductor stacked portion 101, a p-electrode 150 is provided in contact with the upper surface of the ridge 135. The p-electrode 150 includes a first electrode 151 and a second electrode 152. The first electrode 151 is provided in contact with the p-side contact layer 133. As described later, the first electrode 151 and the second electrode 152 are connected via an opening of the insulating film to shield the current. That is, in the first embodiment, the current shielding structure 10 is formed by the insulating film 140 provided at a position overlapping with at least a part of the peripheral region 12.

[0060] Specifically, first, the first electrode 151 is, for example, provided to be in contact with the entire upper surface of the p-side contact layer 133 on the ridge 135 of the semiconductor stack 101. Furthermore, 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, for example, provided continuously, and are provided in such a manner that the central axes of the first opening 140a and the second opening 140b coincide with the central lines of the laser beams of the first ridge 135a and the second ridge 135b in the traveling direction. Here, considering that the light incident from the second region 2 to the first region 1 spreads and propagates in the first region 1, the width of the first opening 140a is, for example, preferably wider than the second opening 140b, and the width of the region where the current is injected in the first region 1 is made wider than the width of the region where the current is injected in the second region 2, so as to improve the light emission efficiency. However, as described above, if the width of the region where the current is injected into the first region 1 is too wide, there is a risk that reactive current will be generated due to heat generation outside the waveguide region, resulting in reduced efficiency. In consideration of these circumstances, the width of the first opening 140a is set to be wider than the second opening 140b so as to effectively reduce heat generation caused by reactive current, etc., outside the waveguide region, that is, in the peripheral region 12. The width of the first opening 140a is preferably set to be equal to the maximum diffusion angle θ from both ends of the emission end face of the core region 21. max1 With this configuration, heat generation due to reactive current or the like in the peripheral area 12 can be effectively reduced.

[0061] In this specification, the term "opening" does not only refer to a region surrounded on all sides. For example, a region sandwiched between two insulating films can be expressed as an opening of the insulating film.

[0062] In the first embodiment, the second electrode 152 is provided to cover the first opening 140a and the second opening 140b, and the second electrode 152 is connected to the first electrode 151 via the first opening 140a and the second opening 140b. That is, the current is injected into the second region 2 via the second opening 140b. Figure 4 As shown, in the second region 2, the width of the second opening 140b is set to be substantially equal to the width of the second ridge 135b. In contrast, in the first region 1, if the width of the region where the current is injected is made too wide, there is a risk of heat generation caused by reactive current or the like outside the waveguide region, which may lead to reduced efficiency. Therefore, the insulating film 140 is provided in a manner that at least a portion overlaps with the peripheral region 12 to form the current shielding structure 10.

[0063] Specifically, in the first region 1, the insulating film 140 limits the width of the portion where the second electrode 152 contacts the first electrode 151 to the width of the first opening 140a, thereby shielding the current in the peripheral region 12. That is, the current is injected from the region where the insulating film 140 is not provided.

[0064] Here, the first electrode 151 is formed, for example, on the entire upper surface of the p-side contact layer 133, so the current injected from the second electrode 152 may be injected into the p-side contact layer 133 while spreading in the width direction in the first electrode 151. Therefore, in Embodiment 1, the first electrode 151 is preferably configured to reduce the spread of the current in the width direction. For example, in Embodiment 1, the first electrode 151 is preferably formed thinner to reduce the spread of the current in the width direction. For example, the thickness of the first electrode 151 in the stacking direction of the semiconductor stacking part 101 is preferably 0.05 μm or more and 2 μm or less. In addition, the spread of the current in the width direction can also be reduced by forming the first electrode 151 with indium-tin oxide (ITO). Thus, the heat generated by the reactive current and the like outside the waveguide region can be reduced. In addition, by injecting current into the second region 2 through the second opening 140b, the core region 21 and the cladding regions 22 on both sides thereof can be provided in the second region 2, and multiple transverse mode lights can be oscillated corresponding to the width of the second opening 140b.

[0065] As described above, the range of shielding the current of 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 the 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 the heat generated by the reactive current in the peripheral region 12. For example, when the insulating film 140 does not reach the maximum diffusion angle θ, the p-side contact layer 133 is shielded from the current.max1 Under the condition of the area inside the extended virtual line, the width of the first opening 140a is preferably less than 90% of the width of the first area 1, and more preferably less than 40%. By adopting this structure, it is possible to effectively reduce the reactive current to the peripheral area 12. In addition, for example, the resistance value of the first electrode 151 can be set to 300 μΩ or more and 2600 μΩ or less.

[0066] In the semiconductor laser element L1 according to the first embodiment, the width of the ridge 135 is set as follows so that the laser beam propagates in a desired plurality of transverse modes.

[0067] First, the second region 2 has a refractive index n 21 The core region 21 and the refractive index n provided on both sides of the core region 21 22 The second ridge 135b is provided at a predetermined interval from both side surfaces of the second region 2 in the center of the p-side semiconductor layer 130 of the second region 2. Thus, a refractive index n is formed below the second ridge 135b in the second region 2. 21 The core region 21 has a refractive index of n formed on both sides of the core region 21. 22 The cladding region 22 of the second region 2 is formed to form a waveguide structure of the second region 2. In the semiconductor laser element L1 of the first embodiment, the width of the core region 21, that is, the width of the second ridge 135b is set to propagate a laser beam including a desired plurality of transverse modes. In addition, the first electrode 151 is preferably set not to be in contact with the upper surface of the p-side cladding 132 on both sides of the second ridge 135b, but to be in contact with the upper surface of the second ridge 135b. With this configuration, it is possible to reduce the flow of current in the cladding region 22.

[0068] In addition, in embodiment 1, by providing the second ridge 135b, a core region 21 is formed when viewed from above, and cladding regions 22 are formed on both sides of the core region 21. However, it is also possible that, for example, the second ridge 135b is not formed, and the width of the part where the injected current is injected in the second region 2 is made narrower than the overall width of the second region 2, thereby forming the core region 21 and the cladding region 22.

[0069] In contrast, the first region 1 does not allow the incident light from the second region 2 to diffuse at the maximum angle θ. max1 The light transmitted by the expansion is limited to a specific waveguide (core region 21) and propagates in the region where the light incident from the second region 2 can be diffused at the maximum diffusion angle θ. max1 The first ridge 135a in the first region 1 is not necessarily formed. For example, the first ridge 135a may not be formed, and the portion other than the second region 2 in the semiconductor stack 101 may be the first region 1. In addition, when the first ridge 135a is included, Figure 3 As shown, for example, the two side surfaces of the first ridge 135a can be set close to the two side surfaces of the first region 1. Regarding the width of the semiconductor stack portion 101 constituting the first region 1, and the width of the first ridge 135a when including the first ridge 135a, in order to make the equivalent refractive indexes corresponding to the multiple transverse modes of the laser beam incident from the second region 2 to the first region 1 substantially the same, the maximum diffusion angle θ of the laser beam emitted from the second region 2 and incident on the first region 1 is considered. max1 The propagating light is set not to leak from the side surfaces of the semiconductor stack portion 101 .

[0070] Specifically, the width of the first region 1 is set so that, in a cross section perpendicular to the optical axis of the laser beam, both ends of the first region 1 in a direction perpendicular to the stacking direction of the semiconductor stack portion 101 are located at the two ends of the emission end face of the core region 21 on the first region 1 side at a maximum diffusion angle θ. max1 Extend the outside of the virtual line.

[0071] Furthermore, the diffraction grating 105 is provided in the first region 1. The diffraction grating 105 is provided so that both ends of the diffraction grating 105 extend to both ends of the first region 1, for example.

[0072] Here, the cross-sectional shape of the ridge 135 is as follows Figure 3 as well as Figure 4 As shown, it may be a rectangle with a constant width, or, for example, a trapezoidal shape whose width becomes narrower as it moves away from the substrate 100 , or an inverted trapezoidal shape whose width becomes wider as it moves away from the substrate 100 .

[0073] In the semiconductor laser element L1 according to the first embodiment of the present disclosure configured as described above, the width of the waveguide in the second region 2 is set to enable laser oscillation including a plurality of desired transverse modes, and the current-shielding structure 10 is provided in the first region 1 .

[0074] Thus, according to the semiconductor laser of the first embodiment, it is possible to oscillate and propagate the laser beam in a plurality of transverse modes, so that it is possible to provide a semiconductor laser element L1 having high output and high power conversion efficiency.

[0075] Hereinafter, each configuration of the semiconductor laser element L1 according to the first embodiment will be described in detail with reference to specific examples.

[0076] It is to be noted that the semiconductor laser element L1 according to the first embodiment is not limited to the following specific examples as long as it has a basic configuration capable of obtaining the above-mentioned effects.

[0077] (Substrate 100)

[0078] The substrate 100 of the semiconductor laser element L1 of Embodiment 1 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 also contain n-type impurities. The element that becomes the n-type impurity may be, for example, O, Si, or Ge. The substrate 100 may use a nitride semiconductor substrate so that its upper surface is a +c plane (i.e., (0001) plane). In Embodiment 1, the c plane is not limited to a plane that is strictly consistent with the (0001) plane, but also includes a plane with a deviation angle of less than ±1 degree, preferably less than ±0.03 degrees. The semiconductor laser element L1 may not have the substrate 100. As the upper surface of the substrate, an m plane, an a plane, or an r plane may also be used.

[0079] (Semiconductor stacked portion 101)

[0080] The semiconductor stack portion 101 may also be as described above, for example, including: an n-side semiconductor layer 110 including an n-side cladding layer 111 and an n-side optical waveguide layer 112; an active layer 120 disposed on the n-side semiconductor layer 110; and a p-side semiconductor layer 130, disposed on the active layer 120, including a p-side optical waveguide layer 131, a p-side cladding layer 132 and a p-side contact layer 133.

[0081] The semiconductor layer of the semiconductor stacked portion 101 is, for example, a III-V semiconductor layer. Examples of the III-V semiconductor layer include In α Al β Ga 1-α-β A nitride semiconductor layer is formed with a composition of N, (0≤α, 0≤β, α+β≤1).

[0082] Examples of elements that serve as n-type impurities used in the nitride semiconductor layer include Si and Ge. Examples of elements that serve as p-type impurities include Mg. Thus, nitride semiconductor layers of various conductivity types can be formed.

[0083] (n-side semiconductor layer 110)

[0084] The n-side semiconductor layer 110 includes one or more semiconductor layers containing n-type impurities. 111 The n-side cladding 111 has a refractive index of n 112 The n-side optical guiding layer 112. The n-side semiconductor layer 110 may further include an undoped layer that is not intentionally doped with impurities.

[0085] Refractive index n 111 And the refractive index n 112 Less than the refractive index n of the active layer 120 120 . Refractive index n 111 And the refractive index n 112Different from each other, for example, the refractive index n 111 Refractive index n 112 Small.

[0086] 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 film 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 Above 5×10 18 cm －3 the following.

[0087] The n-side optical guide layer 112 is disposed between the active layer 120 and the n-side cladding layer 111. The n-side optical guide layer 112 may be, for example, a nitride semiconductor layer. Examples of nitride semiconductors include AlGaN, GaN, or InGaN. The film thickness of the n-side optical guide layer 112 may be, for example, not less than 0.05 μm and not more than 0.5 μm. The content of n-type impurities may be, for example, 1×10 17 cm －3 Above 5×10 18 cm －3 the following.

[0088] (Active layer 120)

[0089] An active layer 120 is formed on the n-side optical guide layer 112. The active layer 120 emits light with a wavelength of, for example, 360 nm to 800 nm. The active layer 120 may also adopt a quantum well structure consisting of one or more well layers and a plurality of barrier layers. The well layers and barrier layers may be, for example, GaN, InGaN, AlGaN, and AlInGaN. The well layers may be, for example, AlGaN, GaN, and InGaN, and are nitride semiconductors with a smaller band gap energy than the barrier layers. The active layer 120 may also be a multi-quantum well structure or a single quantum well structure. In addition, impurities may be contained in one or both of the well layers and the barrier layers.

[0090] (p-side semiconductor layer 130)

[0091] The p-side semiconductor layer 130 includes 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 may include, for example, 131 The p-side optical guide layer 131 has a refractive index of n 132 The p-side cladding 132 has a refractive index of n 133The p-side semiconductor layer 130 may include layers other than these. The p-side semiconductor layer 130 may include an undoped layer that is not intentionally doped with impurities.

[0092] Refractive index n 131 , refractive index n 132 And the refractive index n 133 Less than the refractive index n of the active layer 120 120 . Refractive index n 131 , refractive index n 132 And the refractive index n 133 They can also be different from each other. For example, the refractive index n 131 Refractive index n 132 big.

[0093] The p-side optical waveguide layer 131 may be, for example, a nitride semiconductor layer. Examples of nitride semiconductors include AlGaN and GaN. The thickness of the p-side optical waveguide layer 131 may be, for example, 0.05 μm or more and 0.25 μm or less. In addition, the p-side optical waveguide layer 131 may be a non-doped layer, for example, 1×10 16 cm －3 Above 1×10 18 cm －3 The following range contains p-type impurities.

[0094] The p-side cladding layer 132 may be, for example, a nitride semiconductor layer. Examples of nitride semiconductors include AlGaN and GaN. It may be a single-layer structure or a multilayer structure in which nitride semiconductor layers of different compositions are stacked. The content of p-type impurities may be, for example, 1×10 17 cm －3 Above 1×10 20 cm －3 In addition, the p-side cladding layer 132 may not be provided. When the p-side cladding layer 132 is not provided, the amount of p-type impurities in the semiconductor stack portion 101 is reduced, and the light loss in the semiconductor stack portion 101 can be reduced.

[0095] The p-side contact layer 133 may be a nitride semiconductor, for example. Examples of nitride semiconductors include AlGaN and GaN. It may be a single-layer structure or a multilayer structure in which nitride semiconductor layers of different compositions are stacked. The content of p-type impurities may be 1×10 19 cm －3 Above 1×10 22 cm －3 the following.

[0096] (Waveguide structure)

[0097] Hereinafter, the waveguide structure of the semiconductor laser element L1 according to the first embodiment will be described in detail.

[0098] Here, the waveguide structure of the second region 2 will be described first, and then the waveguide structure of the first region 1 will be described.

[0099] The waveguide structure of the second region 2 has a refractive index n 21 The core region 21 and the refractive index n on both sides of the core region 21 22 The cladding region 22 is a waveguide that propagates light along the length direction of the core region 21 in multiple transverse modes (i.e., transverse multimode). The number of transverse modes is determined by the width of the core region 21, the refractive index n of the core region 21, and the 21 The refractive index n of the cladding regions 22 located on both sides of the core region 21 is 22 Here, the width of the core region 21 is the width in the direction perpendicular to the stacking direction of the semiconductor stacking part 101 in the plane perpendicular to the optical axis of the waveguide. In addition, the thickness of the core region 21 is the thickness in the stacking direction of the semiconductor stacking part 101 in the plane perpendicular to the optical axis of the waveguide. In addition, although the cladding region 22 is provided on both sides of the core region 21, the refractive indexes of the two cladding regions 22 may be the same or different. In the case of different refractive indices, each refractive index may be set to n 22A and n 22B , using n 22A and n 22B Calculate the maximum diffusion angle Θ max1 .

[0100] The number of horizontal modes will be described below.

[0101] In the following description, a symmetric three-layer slab waveguide is briefly described. The transverse mode number N of light propagating in the core region 21 can be obtained by calculating the refractive index n of the core region 21. 21 , the refractive index n of the cladding region 22 22 , and the normalized frequency V specified by the width of the core region 21 is set based on the following formula 1.

[0102] V ≥ Nπ / 2··· (Formula 1)

[0103] (N is an integer greater than 1)

[0104] Here, the normalized frequency V becomes

[0105] V=k0n 21 a(2Δ) 1 / 2 k0 is the wave number in vacuum, a is the half width of the core region 21, Δ(=(n 21 2 -n 222 ) / (2n 21 2 )) is the relative refractive index difference.

[0106] In Formula 1, N is the mode order of the transverse mode. For example, if the normalized frequency V is greater than or equal to π / 2 and less than 2π / 2 (i.e., π), light can be propagated in two modes, namely, the 0th mode (basic mode) and the 1st mode. If the normalized frequency V is greater than or equal to Nπ / 2 and less than (N+1)π / 2, light can be propagated in multiple modes, namely, the 0th, 1st, 2nd, ..., Nth, i.e., (N+1)th, order.

[0107] Thus, the number of transverse modes of light propagating in 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. In addition, in a semiconductor laser element without a ridge structure, it can also be set based on the parameters constituting the waveguide.

[0108] For high output, the more the number of transverse modes, the more preferred, for example, 10 or more, preferably 30 or more, more preferably 50 or more. Although the more the number of transverse modes, the more preferred for high output, if too many, there are problems such as deterioration of light focusing, for example, 500 or less, preferably 300 or less, more preferably 100 or less.

[0109] As can be understood from the above description of Formula 1, the number of transverse modes is determined by parameters including the width of the core region 21. Considering the number of transverse modes and heat dissipation, the width of the core region 21 is, for example, 15 μm to 120 μm, more preferably 45 μm to 100 μm.

[0110] (Diffraction grating 105)

[0111] like Figure 3 As shown in FIG. 1 , the diffraction grating 105 is provided in the first region 1. The diffraction grating 105 is preferably provided in the entire first region 1. In addition, the diffraction grating 105 is not provided in the second region 2. The Bragg wavelength in the diffraction grating is expressed by the following formula 2. Formula 2 shows that the period of the effective diffraction grating is the product of the equivalent refractive index and the pitch of the diffraction grating.

[0112] Bragg wavelength (λ B )=(equivalent refractive index (n1)×pitch of diffraction grating (P))×2···(Formula 2)

[0113] The diffraction grating 105 can be formed by alternately (periodically) arranging regions with different refractive indices in the propagation direction of light. 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 light emitted from the active layer 120 .

[0114] In addition, the equivalent refractive index n1 of the diffraction grating 105 is substantially the same in each transverse mode, so the Bragg wavelength λ corresponding to each transverse mode is B Therefore, the full width at half maximum of the oscillation wavelength of the laser beam emitted by the semiconductor laser element L1 becomes small. For example, the full width at half maximum of the oscillation wavelength of the laser beam emitted by the semiconductor laser element L1 is 0.01 nm or more and 0.5 nm or less.

[0115] In Embodiment 1, the diffraction grating 105 is provided, for example, between the n-side light guiding layer 112 and the n-side cladding layer 111. Specifically, the diffraction grating 105 includes one or more first protrusions provided on the surface of the n-side cladding layer 111 and protruding toward the n-side light guiding layer 112 side, and one or more second protrusions provided on the surface of the n-side light guiding layer 112 and protruding toward the n-side cladding layer 111 side, alternately in the light traveling direction.

[0116] 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 propagation direction of light.

[0117] In Embodiment 1, the diffraction grating 105 is provided between the n-side optical waveguide layer 112 and the n-side cladding layer 111, but it may be provided only in one of the n-side optical waveguide layer 112 or the n-side cladding layer 111, or it may be provided between the n-side optical waveguide layer 112 and the active layer 120. In addition, the diffraction grating 105 may be provided on the p-side semiconductor layer 130 side.

[0118] (electrode)

[0119] like Figure 3-4 As shown, the semiconductor laser element L1 includes a p-electrode 150 and an n-electrode 160 .

[0120] For example, when the substrate 100 is conductive, the n-electrode 160 may be disposed on the lower surface of the substrate 100. When the substrate 100 is insulating, the n-side cladding layer 111 may be partially exposed and formed on the exposed surface.

[0121] As materials for the p-electrode 150 and the n-electrode 160, for example, metals or alloys such as Ni, Rh, Cr, Au, W, Pt, Ti, and Al, and single-layer films or multilayer films containing at least one conductive oxide selected from Zn, In, and Sn can be listed.

[0122] In addition, the p-electrode 150 may also include a translucent conductive film in contact with the ridge 135 as a first electrode. By selecting a material whose refractive index of the translucent conductive film is smaller than the refractive index of the active layer 120 and the refractive index of the p-side semiconductor layer 130, the translucent conductive film can also be treated as a cladding layer on the p-side. The translucent conductive film is, for example, ITO (indium-tin oxide), IGZO (indium-gallium-zinc oxide), etc. The insulating film 140 may also be, for example, silicon oxide, aluminum oxide, or aluminum nitride.

[0123] (Maximum diffusion angle Θ max1 Calculation of

[0124] In the semiconductor laser element L1 of the first embodiment, the maximum diffusion angle θ is referred to when setting the position of the current screen structure 10. max1 The index M representing the quality of the laser beam given by the following formula 3 can be used. 2 Factor it. M 2 The factor is an indicator of the expansion from an ideal Gaussian beam, in which M 2 The factor is 1. That is, if it is known that M of the laser beam output from the semiconductor laser element L1 2 factor, we can know how much the laser beam expands compared to an ideal Gaussian beam, and we can find the maximum diffusion angle θ max1 .

[0125]

[0126] Here, W0 is the beam waist radius, is the beam divergence angle.

[0127] In addition, λ is the wavelength of the laser beam in vacuum.

[0128] Beam waist radius W0 and beam divergence angle Able to use Figure 5 The optical system shown includes a collimator lens 81 and a condenser lens 82 and is measured as follows.

[0129] The laser beam emitted from the first region 1 is made parallel by the collimating lens 81, and the focusing lens 82 is used to focus the laser beam and trace the trajectory of the focused laser beam. Specifically, the beam diameter of the focused laser beam is measured at each position Bmp, the position with the smallest beam diameter is estimated, and the beam diameter (beam waist radius W0) at this position is calculated. The expansion of the beam from the position with the smallest beam diameter is measured and the beam divergence angle is calculated. In addition, find M 2The definition of the parameters required for the factor is based on the international standard ISO11146-1:2021 or ISO11146-2:2021. For example, the beam diameter is defined by D4σ (secondary moment width). In addition, when measuring M 2 The current value introduced into the semiconductor laser element L1 when the factor is M is within the range of a predetermined driving current (Operating current). 2 The factor can be determined using, for example, a commercially available measuring device (THORLABS BP209-VIS / M).

[0130] Using the beam waist radius W0 and beam divergence angle obtained above Calculate M according to Formula 3 2 Factor, as above based on M 2 Factor to find the maximum diffusion angle Θ max1 According to M 2 Factor and in finding M 2 The trajectory of the laser beam measured during the process of the factor can be known, and the trajectory of the laser beam emitted from the second region 2 can be known. Therefore, the trajectory of the laser beam emitted from the two ends of the emission end face of the core region 21 with the maximum diffusion angle θ can be obtained. max1 Expanded virtual line v1. By comparing the positional relationship between this virtual line and both ends of the first region 1, the expansion of the laser beam in the first region 1 can be investigated.

[0131] Here, if Figure 5 As shown in the figure, the maximum diffusion angle θ max1 It refers to the angle formed by a straight line excluding the curved portion of the virtual line and a straight line extending the boundary between the core region 21 and the cladding region 22 .

[0132] In addition, the laser beam M in Embodiment 1 2 The factor may be greater than 2 and less than 100.

[0133] In addition, when the beam diameter of the laser beam on the laser beam emission 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 obvious that both ends of the first region 1 are located outside the virtual line v1. Therefore, if the beam diameter of the laser beam on the laser beam emission end face is first measured, the positional relationship between the width of the first region 1 and the virtual line v1 can be known.

[0134] In the above first embodiment, the semiconductor laser element L1 of the first embodiment is described by taking the semiconductor laser element having the ridge structure as an example.

[0135] 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 rib waveguide type semiconductor laser element or a buried heterostructure waveguide type semiconductor laser element.

[0136] The semiconductor material constituting the semiconductor laser element described so far may also be a material other than a nitride semiconductor. The semiconductor material may be, for example, GaAs, InP, GaInP, GaInAsP, GaAlAs, or AlInGaP. In this case, it may also be used as a semiconductor laser element having an oscillation wavelength of 760 nm or more and 1060 nm or less. In addition, a semiconductor laser element may also be formed of materials other than these materials. For example, aluminum nitride, boron nitride, etc. may also be used to form a semiconductor laser element that emits ultraviolet light.

[0137] In addition, the semiconductor laser element described so far may also be expressed as follows. That is, the semiconductor laser element may also include a semiconductor stack portion 101 including an active layer 120 and a p-electrode 150 provided on the semiconductor stack portion 101, and have a waveguide structure. The semiconductor stack portion 101 includes:

[0138] (i) a first region 1 as a slab waveguide, including a diffraction grating 105; and

[0139] (ii) The second region 2 includes a core region 21 and cladding regions 22 provided on both sides of the core region 21 .

[0140] Furthermore, in a plan view, the first region 1 propagates light incident from the second region 2 , 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 .

[0141] Here, the first region 1 becomes a slab waveguide. That is, in the first region 1, light is limited only in the stacking direction. A diffraction grating 105 is provided in the first region 1 as a slab waveguide, so that even in different transverse modes, the equivalent refractive index is substantially the same, and the selected wavelength (Bragg wavelength) in the diffraction grating 105 is consistent. In addition, a light confinement region may be provided in the peripheral region 12. In this case, the central region 11 in the first region 1 is also a slab waveguide.

[0142] Implementation Method 2

[0143] The semiconductor laser element L2 according to the second embodiment is similar to the semiconductor laser element L1 according to the first embodiment in that it includes a current screen structure 10 formed of a part of the insulating film 140 , but differs in the structure of the p-electrode 150 .

[0144] Specifically, in the semiconductor laser element L2 of the second embodiment, in the first region 1, the first electrode 151 is not provided in contact with the entire upper surface of the p-side contact layer 133 on the ridge 135 of the semiconductor stack 101, but is provided as follows. Figure 6As shown, the first electrode 151 is provided to fill the first opening 140 a , and the first electrode 151 is limited to the width of the first opening 140 a so as to be in contact with the p-side contact layer 133 .

[0145] The semiconductor laser element L2 according to the second embodiment configured as described above can shield the current in the peripheral region 12 , thereby suppressing the reactive current in the peripheral region 12 and reducing the heat generation.

[0146] Therefore, the semiconductor laser element L2 according to the second embodiment can provide the semiconductor laser element L1 with high output and high power conversion efficiency by oscillating and propagating the laser beam in a plurality of transverse modes.

[0147] Here, in the semiconductor laser element L2 of embodiment 2, the first electrode 151 is set to be buried in the first opening portion 140a, and the width of the first opening portion 140a is limited to make the first electrode 151 contact the p-side contact layer 133. Therefore, there is no longer a risk of the current in the first electrode 151 expanding laterally, and the current can be shielded more effectively.

[0148] In the semiconductor laser element L2 of the second embodiment, the structure of the p-electrode 150 in the second region 2 is not particularly limited and may be the same as in the first embodiment or may be such that the first electrode 151 is buried in the second opening 140 b as in the first region 1 .

[0149] In addition, in the semiconductor laser element L2 of the second embodiment, the configuration other than the p-electrode 150 is the same as that of the semiconductor laser element L1 of the first embodiment. For example, the semiconductor laser element L2 is a lateral multimode semiconductor laser element.

[0150] Implementation 3

[0151] The semiconductor laser element L3 according to the third embodiment differs from the semiconductor laser element L1 according to the first embodiment in the configuration of the current-shield structure.

[0152] Specifically, the current shielding structure 13 in the semiconductor laser element L3 of the third embodiment is as follows: Figure 7 As shown, it is composed of an oxide film 133a provided on the surface of the semiconductor stack portion 101 (the surface of the p-side contact layer 133) and having an opening 13a in the central region 11, and current is injected from the p-electrode 150 into the central region 11 through the opening 13a.

[0153] Here, in the semiconductor laser element L3 according to the third embodiment, for example, in the first region 1 , the first electrode 151 may be provided in contact with the entire upper surface of the p-side contact layer 133 on the ridge 135 of the semiconductor stack portion 101 .

[0154] In the semiconductor laser element L3 of the third embodiment, the oxide film 133a constituting the current screening 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 Schottky-bonded via the oxide film 133a, and the current screening structure 13 can be formed.

[0155] The semiconductor laser element L3 according to the third embodiment having the above-described structure can shield the current in the peripheral region 12 , thereby suppressing the reactive current in the peripheral region 12 and reducing the heat generation.

[0156] Therefore, the semiconductor laser element L3 according to the third embodiment can provide a semiconductor laser element L3 having high output and high power conversion efficiency by oscillating and propagating the laser beam in a plurality of transverse modes.

[0157] In the semiconductor laser element 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 of the first embodiment or may be another structure.

[0158] For example, a second oxide film provided in the semiconductor stacked portion 101 and having a second opening 140b narrower than the opening 13a on the waveguide may be provided in the second region 2, and current may be injected into the second region 2 through the second opening 140b. In this way, the core region 21 and the cladding regions 22 on both sides thereof may be provided in the second region 2, and a plurality of transverse mode lights may be oscillated in accordance with the width of the second opening 140b.

[0159] In the semiconductor laser device L3 of the third embodiment, the configuration of the semiconductor stacked portion 101 and the like other than the current-shielding structure 13 is the same as that of the semiconductor laser device L1 of the first embodiment. For example, the semiconductor laser device L3 is a lateral multimode semiconductor laser device.

[0160] Implementation 4

[0161] The semiconductor laser element L4 according to the fourth embodiment differs from the semiconductor laser element L1 according to the first embodiment in the configuration of the current-shield structure.

[0162] Specifically, the current shielding structure 14 in the semiconductor laser element L4 of the fourth embodiment is as follows: Figure 8 As shown, the barrier layer 132 a is provided in the p-side semiconductor layer 130 of the semiconductor stacked portion 101 and has an opening 14 a in the central region 11 , and is configured to limit the current injected from the p-electrode 150 by the opening 14 a.

[0163] Here, in the semiconductor laser element L4 of the fourth embodiment, for example, the first electrode 151 is provided in contact with the entire upper surface of the p-side contact layer 133 on the ridge 135 of the semiconductor stack 101 in the first region 1. In addition, the barrier layer 132a can be provided by forming a non-doped layer on a part of the p-side semiconductor layer 130.

[0164] exist Figure 8 , an example is shown in which the barrier layer 132a is provided by making a part of the p-side cladding layer 132 undoped, but it only needs to be provided on the active layer 120, that is, on the p-electrode 150 side, and may be provided on the p-side optical waveguide layer 131 or the p-side contact layer 133, for example. In addition to the p-side optical waveguide layer 131, the p-side cladding layer 132, and the p-side contact layer 133, an undoped layer may be provided as a new layer on the p-side semiconductor layer 130 to serve as the barrier layer 132a.

[0165] The semiconductor laser element L4 according to the fourth embodiment configured as described above can shield the current in the peripheral region 12 , thereby suppressing the reactive current in the peripheral region 12 and reducing the heat generation.

[0166] Therefore, the semiconductor laser element L4 according to the fourth embodiment can provide the semiconductor laser element L3 with high output and high power conversion efficiency by oscillating and propagating the laser beam in a plurality of transverse modes.

[0167] In the semiconductor laser element 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 of the first embodiment or may be another structure.

[0168] For example, a second barrier layer provided in the semiconductor stacked portion 101 and having a second opening 140b narrower than the opening 14a on the waveguide may be provided in the second region 2, and current may be injected into the second region 2 through the second opening 140b. In this way, the core region 21 and the cladding regions 22 on both sides thereof can be provided in the second region 2, and a plurality of transverse mode lights can be oscillated in accordance with the width of the second opening 140b.

[0169] In the semiconductor laser device L4 of the fourth embodiment, the configuration of the semiconductor stacked portion 101 and the like other than the current-shielding structure 14 is the same as that of the semiconductor laser device L1 of the first embodiment. For example, the semiconductor laser device L4 is a lateral multimode semiconductor laser device.

[0170] Modifications

[0171] In the above description of the embodiments, for example, in the description of the semiconductor laser element L1 of the first embodiment, an example in which the width of the first opening 140 a provided in the insulating film 140 constituting the current screen structure 10 is constant is described.

[0172] However, if we consider that the laser beam emitted from the second region 2 has a maximum diffusion angle θ max1 In the first region 1, the width of the first opening 140a does not have to be constant. Fig. 9 As shown in the first opening 140c, the width of the opening may also be expanded toward the emission end face of the first region 1. With this configuration, current can be efficiently injected into the opening, and the area where ineffective current flows can be efficiently reduced. The width of the opening is preferably, for example, along the maximum diffusion angle θ. max1 Extended virtual line extension.

[0173] The same applies to embodiments 2 to 4. For the opening 13a provided in the oxide film 133a of embodiment 3 and the opening 14a provided in the barrier layer 132a of embodiment 4, the width of the opening may also be expanded toward the emission end face of the first region 1.

[0174] Examples 1 to 3 and Comparative Example 1

[0175] A semiconductor laser element L2 was fabricated, and the output of the laser beam was measured. The fabricated semiconductor laser element L2 was obtained by stacking an n-side cladding layer 111, an n-side optical waveguide layer 112, an active layer 120, a p-side optical waveguide layer 131, a p-side cladding layer 132, and a p-side contact layer 133 on a GaN substrate. The first ridge 135a and the second ridge 135b were obtained by removing a portion from the p-side cladding layer 132 to the p-side optical waveguide layer 131. The width of the first ridge 135a was 345 μm, and the width of the second ridge 135b was set to 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 set to 96 nm. The width of the diffraction grating 105 was set to 350 μm. In addition, the first electrode 151 and the insulating film 140 were stacked in sequence on the p-side contact layer 133. At this time, the width of the second opening 140b was unified to 84 μm, and the shapes of the first opening 140a or the first opening 140c of the insulating film 140 were made different, and four samples of Examples 1 to 3 and Comparative Example 1 were obtained. The width of the first opening 140a or the first opening 140c in each Example is as shown in Table 1. In Example 3, the width of the first opening 140c was gradually expanded from 90 μm to 101 μm.

[0176] That is, in Comparative Example 1, the width of the first opening 140a is made substantially the same as the width of the diffraction grating 105, in Examples 1 and 2, the width of the first opening 140a is made narrower than that of the sample of Comparative Example 1, and in Example 3, the first opening 140a is set to be along the maximum diffusion angle θ. max1 The extended virtual line extends the shape.

[0177] Current was injected into the semiconductor laser elements produced in Examples 1 to 3 and Comparative Example 1, and the data shown in Table 1 were obtained.

[0178]

Table 1

[0179]

[0180] According to the results, it can be said that in Examples 1 to 3, a semiconductor laser element with high power conversion efficiency can be obtained compared with Comparative Example 1. In addition, according to the results of Examples 2 and 3, it can be seen that by making the width of the first opening 140a and the two ends of the emission end face of the core region 21 at the maximum diffusion angle θ max1 The extended virtual lines are aligned, and the output, slope efficiency, and WPE of the semiconductor laser element L2 can be improved.

[0181] When a current of 9.5 A was applied to sample (4), the wavelength of the emitted light was measured and its full width at half maximum was found to be 0.15 nm. Although the semiconductor laser element L2 is a lateral multimode semiconductor laser, the wavelength variation can be reduced.

[0182] Other components

[0183] In addition, for example, the present disclosure may have the following configurations.

[0184] (Item 1)

[0185] A semiconductor laser element comprises a semiconductor stack portion including an active layer and an electrode provided on the semiconductor stack portion, and has a waveguide structure, wherein the semiconductor stack portion comprises:

[0186] (i) a first region comprising a diffraction grating; and

[0187] (ii) a second region having a core region and cladding regions provided on both sides of the core region, and causing the laser beam to propagate in a plurality of transverse modes,

[0188] When looking down,

[0189] The first region propagates the light incident from the second region, and includes a central region and a peripheral region located outside the central region.

[0190] A current shielding structure is provided at a position overlapping with at least a portion of the peripheral region.

[0191] (Item 2)

[0192] A semiconductor laser element comprises a semiconductor stack portion including an active layer and an electrode provided on the semiconductor stack portion, and has a waveguide structure, wherein the semiconductor stack portion comprises:

[0193] (i) a first region as a slab waveguide including a diffraction grating; and

[0194] (ii) a second region including a core region and cladding regions provided on both sides of the core region,

[0195] When looking down,

[0196] The first region propagates the light incident from the second region, and includes a central region and a peripheral region located outside the central region.

[0197] A current shielding structure is provided at a position overlapping with at least a portion of the peripheral region.

[0198] (Item 3)

[0199] The semiconductor laser device according to item 1 or 2,

[0200] The refractive index of the core region is n 21 The refractive index of the cladding region is n 22 , the refractive index of the central region is n1,

[0201] The laser beam emitted from the second region has a refractive index n1, a refractive index n2 and a refractive index n4. 21 , and the refractive index n 22 Determine the maximum diffusion angle θ max1 Transmitted in the first area,

[0202] The central region includes the maximum diffusion angle θ from both ends of the exit end face of the core region. max1 The area inside the extended imaginary line.

[0203] (Item 4)

[0204] The semiconductor laser device according to any one of items 1 to 3,

[0205] The current shield structure includes an insulating film provided on the semiconductor stacked portion and having an opening in the central region, and at least a portion of the electrode is provided in the opening.

[0206] (Item 5)

[0207] According to the semiconductor laser device described in item 4,

[0208] The electrode includes a first electrode provided in the opening, and the first electrode is in contact with the semiconductor stacked portion inside the opening.

[0209] (Item 6)

[0210] According to the semiconductor laser device described in item 4,

[0211] The electrodes include a first electrode provided in contact with the semiconductor stack portion and a second electrode provided on the first electrode, and the second electrode is connected to the first electrode via the opening.

[0212] (Item 7)

[0213] The semiconductor laser device according to any one of items 4 to 6,

[0214] The width of the opening increases toward the emission end surface of the first region.

[0215] (Item 8)

[0216] The semiconductor laser device according to any one of items 4 to 7,

[0217] The second region includes a second insulating film provided in the semiconductor stacked portion and having a second opening narrower than the opening on the second region, and current is injected into the second region through the second opening.

[0218] (Item 9)

[0219] The semiconductor laser device according to any one of items 1 to 3,

[0220] The current shielding structure includes an oxide film provided on the surface of the semiconductor stacked portion and having an opening in the central region, and the electrode injects current into the central region through the opening.

[0221] (Item 10)

[0222] According to the semiconductor laser device described in item 9,

[0223] The opening portion expands toward the emission end surface of the first region.

[0224] (Item 11)

[0225] According to the semiconductor laser device described in item 9,

[0226] The width of the opening is constant.

[0227] (Item 12)

[0228] The semiconductor laser device according to any one of items 9 to 11,

[0229] The second region includes a second oxide film provided in the semiconductor stacked portion and having a second opening narrower than the opening on the second region, and current is injected into the second region through the second opening.

[0230] (Item 13)

[0231] The semiconductor laser device according to any one of items 1 to 3,

[0232] The current shielding structure includes a barrier layer provided in the semiconductor stacked portion and having an opening in the central region, and current is injected into the central region through the opening.

[0233] (Item 14)

[0234] According to the semiconductor laser device described in item 13,

[0235] The width of the opening increases toward the emission end surface of the first region.

[0236] (Item 15)

[0237] According to the semiconductor laser device described in item 13,

[0238] The width of the opening is constant.

[0239] (Item 16)

[0240] The semiconductor laser device according to any one of items 13 to 15,

[0241] The second region includes a second barrier layer provided in the semiconductor stacked portion and having a second opening narrower than the opening on the second region, and current is injected into the second region through the second opening.

[0242] The above describes the embodiments and variations of the present disclosure, but various modifications can be made as long as the configuration is based on the technical idea of ​​the present disclosure. In addition, various changes can be made to the combination and order of the constituent elements in the embodiments and variations within the scope of the present disclosure and the scope of the idea.

[0243] Description of Reference Numerals

[0244] L1, L2, L3, L4 semiconductor laser elements

[0245] 1. First Area

[0246] 11 Central Area

[0247] 12 Surrounding Areas

[0248] 2 Second Area

[0249] 21 Core area

[0250] 22 Cladding area

[0251] 100 substrates

[0252] 101 Semiconductor stacking unit

[0253] 150 p electrode

[0254] 160n electrode

[0255] 110n side semiconductor layer

[0256] 111n side cladding

[0257] 112n side light guide layer

[0258] 120 active layer

[0259] 130p side semiconductor layer

[0260] 131p side light guide layer

[0261] 132p side cladding

[0262] 133p side contact layer

[0263] 105 Diffraction Grating

[0264] 135 Ridge

[0265] 135a First Ridge

[0266] 135b Second Ridge

Claims

1. A semiconductor laser element comprising a semiconductor stacked portion including an active layer and an electrode provided on the semiconductor stacked portion, and having a waveguide structure, characterized in that: The semiconductor stacking portion comprises: (i) a first region comprising a diffraction grating; and (ii) a second region having a core region and cladding regions provided on both sides of the core region, and causing the laser beam to propagate in a plurality of transverse modes, When looking down, The first region propagates the 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 with at least a portion of the peripheral region.

2. The semiconductor laser element according to claim 1, wherein The refractive index of the core region is n 21 The refractive index of the cladding region is n 22 , the refractive index of the central region is n1, The laser beam emitted from the second region has a refractive index n1, a refractive index n2 and a refractive index n4. 21 , and the refractive index n 22 Determine the maximum diffusion angle θ max1 Transmitted in the first area, The central region includes the maximum diffusion angle θ from both ends of the exit end face of the core region. max1 The area inside the extended imaginary line.

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

4. The semiconductor laser element according to claim 3, wherein: The electrode includes a first electrode provided in the opening, and the first electrode is in contact with the semiconductor stacked portion inside the opening.

5. The semiconductor laser element according to claim 3, wherein: The electrodes include a first electrode provided in contact with the semiconductor stack portion and a second electrode provided on the first electrode, and the second electrode is connected to the first electrode via the opening.

6. The semiconductor laser element according to any one of claims 3 to 5, characterized in that The width of the opening increases toward the emission end surface of the first region.

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

8. The semiconductor laser element according to claim 1, wherein The current shielding structure includes an oxide film provided on the surface of the semiconductor stacked portion and having an opening in the central region, and the electrode injects current into the central region through the opening.

9. The semiconductor laser element according to claim 8, wherein: The opening portion expands toward the emission end surface of the first region.

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

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

12. The semiconductor laser element according to claim 1, wherein The current shielding structure includes a barrier layer provided in the semiconductor stacked portion and having an opening in the central region, and current is injected into the central region through the opening.

13. The semiconductor laser element according to claim 12, wherein: The width of the opening increases toward the emission end surface of the first region.

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

15. The semiconductor laser element according to claim 12, wherein: The second region includes a second barrier layer provided in the semiconductor stacked portion and having a second opening narrower than the opening on the second region, and current is injected into the second region through the second opening.

16. A semiconductor laser element comprising a semiconductor stacked portion including an active layer and an electrode provided on the semiconductor stacked portion, and having a waveguide structure, characterized in that: The semiconductor stacking portion comprises: (i) a first region as a slab waveguide including a diffraction grating; and (ii) a second region including a core region and cladding regions provided on both sides of the core region, When looking down, The first region propagates the 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 with at least a portion of the peripheral region.

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