Semiconductor laser device

Abstract

The semiconductor laser device disclosed herein comprises a first conductivity type cladding layer (3), a first conductivity type photoconductor layer (61) on the first conductivity type side, an active layer (7), a second conductivity type photoconductor layer (81), a second conductivity type cladding layer (11), and a second conductivity type contact layer (14) stacked on a first conductivity type semiconductor substrate (2), and a length of L. c The resonator is composed of a length L f The current-limiting region and its length are L c -L f The current injection region is formed by the current confinement region, which consists of the inner ridge region (I). a i ), located in the medial region of the spine (I a i The lateral region of the ridge (I) on both sides and having a non-injected current structure a o ), and located in the lateral spinal region (I a o The areas covered by the contact layer (14) and the covering layer (11) are located on both sides of the area (II). c The current injection region is composed of ridge regions (I) a ) and the covering areas (II) located on both sides of the ridge region. c )constitute.

Description

Technical Field

[0001] This disclosure relates to semiconductor laser devices. Background Technology

[0002] Broad-area semiconductor laser devices have advantages such as high output.

[0003] Patent Document 1 discloses a ridge-shaped large-area semiconductor laser device with an actual refractive index distribution along the horizontal direction. This device utilizes a thick guiding layer that allows for higher-order modes (1st order or more) in the crystallization stacking direction. Furthermore, it incorporates stepped regions on both sides of the ridge with a refractive index lower than the effective refractive index of the ridge region but higher than the refractive index of the cladding region via grooves. This reduces the number of modes allowed in the horizontal direction and narrows the horizontal propagation angle. Here, the actual refractive index distribution refers to the refractive index distribution described by real numbers. The waveguide mechanism is a refractive index waveguide, and the electric field distribution, magnetic field distribution, propagation constant, etc., obtained by solving the wave equation are real numbers.

[0004] Patent document 2 discloses a ridge-type large-area semiconductor laser device in which a refractive index difference is provided in the horizontal direction by embedding the two sides of the ridge using a semiconductor layer. The peak value of the near field pattern (NFP) that appears near the two ends of the ridge is suppressed by setting the ridge side of the boundary between the ridge and the semiconductor layer as non-injected current. In order to suppress the increase of loss, the non-injected current width is preferably 10 μm or less.

[0005] Patent document 3 discloses a ridge-type large-area semiconductor laser device. For a ridge structure with a ridge width of 30 μm that allows higher-order modes, a proton injection region with high resistance is set up by proton injection from the ridge surface to a depth of 1.6 μm, leaving a central portion with a width of 15 μm to the bottom of the ridge. Current is allowed to flow in the central portion of the 15 μm width of the ridge structure to improve the gain of the fundamental mode and selectively oscillate the fundamental mode.

[0006] Patent Document 1: International Publication No. 2019 / 053854

[0007] Patent Document 2: Japanese Patent Application Publication No. 2006-294745

[0008] Patent Document 3: Japanese Patent Application Publication No. 03-196689

[0009] Non-patent document 1: N. Yonezu, I. Sakuma, K. Kobayashi, T. Kamejima, M. Ueno, and Y. Nannichi, "A GaAs-AlxGa1-xAs Double Heterostructure Planar Stripe Laser", Jpn.J.Appl.Phys., vol.12, no.10, pp.1585-1592, 1973

[0010] Non-patent literature 2: Kawakami, “Optical Waveguides”, pp. 18-31, Asakura Shoten (1992).

[0011] Non-Patent Document 3: Ohmsha, ed., "Semiconductor Lasers", pp. 35-38, October 25, 2017.

[0012] Non-patent document 4: GBHocker and WKBurns, "Mode dispersion in diffusedchannel waveguides by the effective index method", Appl.Opt., Vol.16, No.1, pp.113-118, 1977

[0013] Non-patent document 5: S.Arsian et.Al., "Non-uniform longitudinal currentdensity induced power saturation in GaAs-based high power diode laser", Appl.Phys.Lett., Vol.117, pp.203506, 2020

[0014] In existing ridge-type large-area semiconductor laser devices with actual refractive index distributions, there is a problem where the horizontal spread angle deviates depending on which of the allowed modes oscillates. This is because the gain difference between the allowed modes is small.

[0015] Furthermore, unlike existing ridge-type large-area semiconductor laser devices with actual refractive index distributions, which utilize embedded semiconductor layers, existing ridge-type large-area semiconductor laser devices do not exhibit peak NFP near the ridge ends. Additionally, the NFP in these areas does not weaken when the current is locally reduced. This is because, for ridge-type large-area semiconductor laser devices with actual refractive index distributions, the NFP depends on the linear combination of the allowed modes, and the effect of locally reducing the current affects all modes.

[0016] Furthermore, the unusual phenomena observed in large-area semiconductor laser devices with embedded semiconductor layers are believed to be caused by the embedded semiconductor layers acting as either gain waveguides or loss waveguides. Therefore, the structure with embedded semiconductor layers has not been applied to ridge-type large-area semiconductor laser devices with actual refractive index distributions.

[0017] Furthermore, in existing ridge-type large-area semiconductor laser devices, proton implantation for high resistivity occurs up to the bottom of the ridge, causing light generated in the active layer to extend into the proton implantation region. Since proton implantation disrupts the crystallinity of the crystal layer, the light extending into the proton implantation region suffers significant loss due to scattering caused by crystal defects. This results in a decrease in slope efficiency, and consequently, a decrease in power conversion efficiency. Moreover, because the proton implantation region, which contains numerous crystal defects, is close to the active layer, there is a problem where the reliability of the large-area semiconductor laser device is significantly reduced due to crystal defects in the proton implantation region.

[0018] Furthermore, since the current non-injection structure formed by proton injection is set the same in the resonator, there is a problem that leads to an increase in operating voltage and a decrease in power conversion efficiency. Summary of the Invention

[0019] This disclosure was made to solve the aforementioned problems, and its purpose is to obtain a ridge-type large-area semiconductor laser device that maintains high power conversion efficiency and achieves high reliability by narrowing the horizontal expansion angle in a ridge-type large-area semiconductor laser device with an actual refractive index distribution, suppressing the rise in operating voltage caused by the introduction of current non-injection structure, and suppressing the increase in scattering loss caused by crystal defects.

[0020] The semiconductor laser device disclosed herein has the following structure: a semiconductor substrate of a first conductivity type; a cladding layer of the first conductivity type, a photoconductive layer on the first conductivity type side, an active layer, a photoconductive layer on the second conductivity type side, a cladding layer of the second conductivity type, and a contact layer of the second conductivity type sequentially stacked on the semiconductor substrate of the first conductivity type; and a front end facet and a rear end facet for reciprocating the laser beam, with a length of L. c The resonator of the semiconductor laser device has an oscillation wavelength of λ, wherein the resonator consists of a component of length L. f The current-limiting region and its length are L c -L f The current injection region is formed by the current confinement region, which is composed of an inner ridge region, an outer ridge region, and a covering region. The width of the inner ridge region is 2W. i This indicates that the effective refractive index is n. a iThe aforementioned outer ridge region is located on both sides of the aforementioned inner ridge region, and its width is defined by W. o This indicates that the effective refractive index is n. a o It also has a current-free structure, with the aforementioned coating region located on both sides of the outer region of the ridge, having removed the contact layer of the second conductivity type and at least a portion of the coating layer of the second conductivity type, and an effective refractive index of n. c The average refractive index n of the aforementioned inner ridge region and the aforementioned outer ridge region a e Expressed as follows:

[0021]

Number 1

[0022] n a e =(n a i ·W i +n a o ·W o ) / (W i +W o ),

[0023] And it satisfies the following relationship:

[0024]

Number 2

[0025]

[0026] The number of modes allowed in the aforementioned current-limiting region in the ridge width direction is m (an integer greater than 2), and the width W of the aforementioned outer ridge region is... o The distance from the lower end of the aforementioned non-injected current structure to the active layer is wider than the distance from the lower end of the current-injected structure to the active layer. The current-injected region is composed of the aforementioned ridge region and the aforementioned covering region. The effective refractive index of the aforementioned ridge region is a real number n. a The width in the ridge width direction is represented by 2W. The aforementioned covering region is located on both sides of the aforementioned ridge region. The number of modes allowed in the current injection region in the ridge width direction is the same as the number of modes allowed in the aforementioned current limiting region, which is m. The length L of the aforementioned current limiting region is... f Longer than zero and longer than the length L of the aforementioned resonator c short.

[0027] According to the semiconductor laser device disclosed in this application, since it is configured such that a current-free structure, i.e., a current-limiting region, is provided in a part of the resonator and a current-injection region is provided in the remaining part of the resonator, the gain of the low-order mode becomes higher than the gain of the high-order mode, and laser oscillation can be performed in the low-order mode while the horizontal spread angle is narrowed. Moreover, compared with the structure in which the current-free structure is provided throughout the entire resonator, the resistance is reduced, thus achieving the effect of reducing the operating voltage and increasing the power conversion efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram showing the current flow and refractive index distribution at a cross-section of the current injection region of the present disclosure, representing a comparative example of a ridge-shaped large-area semiconductor laser device with an actual refractive index distribution.

[0029] Figure 2 This is a schematic diagram showing the current flow and refractive index distribution at a cross-section of the current-limited region of a ridge-shaped large-area semiconductor laser device with actual refractive index distribution as disclosed herein.

[0030] Figure 3A , Figure 3B This is a perspective view and a cross-sectional view of a ridge-shaped large-area semiconductor laser device with an actual refractive index distribution in the 975nm band according to Embodiment 1.

[0031] Figure 4 This is a graph showing the gain of each mode of the 975nm ridge-type large-area semiconductor laser device with actual refractive index distribution according to Embodiment 1.

[0032] Figure 5 This is a graph showing the gain of each mode of the 975nm ridge-type large-area semiconductor laser device with actual refractive index distribution according to Embodiment 1.

[0033] Figure 6 This is a graph showing the gain of each mode of the 975nm ridge-type large-area semiconductor laser device with actual refractive index distribution according to Embodiment 1.

[0034] Figure 7A , Figure 7B This is a perspective view and a cross-sectional view of a ridge-shaped large-area semiconductor laser device with an actual refractive index distribution in the 975nm band according to Embodiment 2.

[0035] Figure 8 This is a graph showing the gain of each mode of the 975nm ridge-type large-area semiconductor laser device with actual refractive index distribution according to Embodiment 2.

[0036] Figure 9This is a graph showing the gain of each mode of the 975nm ridge-type large-area semiconductor laser device with actual refractive index distribution according to Embodiment 2.

[0037] Figure 10 This is a graph showing the gain of each mode of the 975nm ridge-type large-area semiconductor laser device with actual refractive index distribution according to Embodiment 2.

[0038] Figure 11A , Figure 11B This is a perspective view and a cross-sectional view of a 975nm ridge-shaped large-area semiconductor laser device with an actual refractive index distribution according to Embodiment 3.

[0039] Figure 12 This is a graph showing the gain of each mode of the 975nm ridge-type large-area semiconductor laser device with actual refractive index distribution according to Embodiment 3.

[0040] Figure 13 This is a graph showing the gain of each mode of the 975nm ridge-type large-area semiconductor laser device with actual refractive index distribution according to Embodiment 3.

[0041] Figure 14 This is a graph showing the gain of each mode of the 975nm ridge-type large-area semiconductor laser device with actual refractive index distribution according to Embodiment 3.

[0042] Figure 15A , Figure 15B This is a perspective view and a cross-sectional view of a ridge-shaped large-area semiconductor laser device with an actual refractive index distribution in the 975nm band according to Embodiment 4.

[0043] Figure 16A , Figure 16B This is a perspective view and a cross-sectional view of a ridge-shaped large-area semiconductor laser device with an actual refractive index distribution in the 975nm band according to Embodiment 5.

[0044] Figure 17A , Figure 17B This is a perspective view and a cross-sectional view of a ridge-shaped large-area semiconductor laser device with an actual refractive index distribution in the 975nm band according to Embodiment 6. Detailed Implementation

[0045] Implementation Method 1

[0046] First, use Figure 1 and Figure 2 The differences between the ridge-type large-area semiconductor laser device disclosed herein and the comparative example will be explained. Figure 1This is a schematic diagram showing the current flow and refractive index distribution at a cross-section of the current injection region in a ridge-type large-area semiconductor laser device with an actual refractive index distribution, used as a comparative example, and in the ridge-type large-area semiconductor laser device of this disclosure. Furthermore, Figure 2 This is a schematic diagram showing the current flow and refractive index distribution at a cross-section of the current-limited region of the ridge-shaped large-area semiconductor laser device with actual refractive index distribution of the present disclosure.

[0047] exist Figure 1 In the diagram, starting from the lower semiconductor substrate (not shown), the following layers are shown: active layer 101, guide layer 102, first etch stop layer 103 (first ESL layer), p-type first cover layer 104, second etch stop layer 105 (second ESL layer), p-type second cover layer 106, and p-type contact layer 107.

[0048] If the distance from the upper end of the first ESL layer 103 to the upper end of the active layer 101 is defined as h1, then in the ridge region (I a The current I flowing from the upper end of the first ESL layer 103 also extends in the horizontal direction (x-axis direction). The current distribution J(x) at the upper end of the active layer 101 can be calculated using Non-Patent Document 1. Here, the x-axis direction is sometimes also referred to as the ridge width direction.

[0049] A ridge region with a width of 2W (I) a Formation of the covered area (II) c The clamping structure. Ridge region (I) a ) and the covered area (II) c The effective refractive index of n is respectively used to express the effective refractive index of n. a and n c According to non-patent literature 2, the normalized frequency v can be defined as shown in equation (1) below.

[0050]

Number 3

[0051]

[0052] Here, λ is the oscillation wavelength of the semiconductor laser. The number obtained by dividing the normalized frequency v by π / 2, taking the integer part, and adding 1, i.e., INT[v / (π / 2)]+1, becomes the number of allowed modes in the x-direction.

[0053] Figure 2 This refers to the current-confined region (C) with a current-non-injection structure in the ridge-shaped large-area semiconductor laser device with actual refractive index distribution disclosed in this application. n A schematic diagram of the flow of current I and the refractive index distribution at a cross-section orthogonal to the direction of the optical guide wave.

[0054] It becomes the following structure: with a width of W o The lateral region (hereinafter referred to as the lateral region width) of the lateral region (I) a o The effective refractive index and width are 2W. i (hereinafter referred to as the medial region width) medial region (I) a i The effective refractive index becomes essentially the same range, from the p-type contact layer 107 on the surface to the upper end of the second ESL layer 105, which is removed by etching.

[0055] The aforementioned effective refractive index is essentially the same, meaning that in the inner region of the ridge (I) a i Let the effective refractive index be n. a i and the lateral spinal region (I a o Let the effective refractive index be n. a o In this case, the average refractive index n will be calculated using the following equation (2). a e Substituting n into equation (1) a The calculated number of permissible patterns, compared to the number without the lateral spinal region (I) a o ) time (W o The number of allowed modes is the same for all modes (=0).

[0056]

Number 4

[0057] n a e =(n a i ·W i +n a o ·W o ) / (W i +W o (2)

[0058] Due to etching of the lateral ridge region (I) a o The upper part of the ridge is removed up to the upper end of the second ESL layer 105 and covered with an insulating film (not shown), so that the current I is specifically in the inner region of the ridge (I a i) flow. If the distance from the upper end of the first ESL layer 103 to the upper end of the second ESL layer 105 is defined as h2, then the current I extends horizontally from the upper end of the second ESL layer 105 and reaches the active layer 101 via a distance h1+h2. The distance h1+h2 that the current I extends is longer than the distance h1 that the current I extends in the comparative example structure, but since the current itself is only injected into the inner region of the ridge (I a i Therefore, the current spread at the active layer location is narrower, resulting in a narrower structure in this disclosure.

[0059] On the other hand, in the ridge-type large-area semiconductor laser device disclosed in this application, in the region where no current non-injection structure is provided, i.e., the current injection region (C i In ) and Figure 1 The comparative example shown has the same construction, with the current extending from the upper end of the first ESL layer 103 in the horizontal (x) direction.

[0060] The allowed i-th order mode in the horizontal direction will be set to φ. i (x), and standardized as shown in equation (3) below. Wherein, the allowed patterns φ i (x) can be calculated based on non-patent literature 2, etc.

[0061]

Number 5

[0062]

[0063] On the other hand, let the width of the element be W in the ridge width direction so that a current of 1 ampere (A) is 1 ampere (A). ch And the resonator length is L c The flow is in the semiconductor laser device and is standardized as shown in equation (4) below.

[0064]

Number 6

[0065]

[0066] Suppose that there exists a length L within the resonator. f Current limiting region (C) n And define the gain G when the light travels one round trip within the resonator as shown in equation (5) below. i Since both the light intensity distribution (mode) and the current distribution are normalized, the gain G is used to determine the optimal distribution. i The magnitude relationship between the two modes reveals the differences in gain between them.

[0067]

Number 7

[0068]

[0069] Figure 3A This is a perspective view of a ridge-type large-area semiconductor laser device 100 with an actual refractive index distribution in the 975nm band, according to Embodiment 1. Additionally, Figure 3B It is the current injection region (C) of the ridge-type large-area semiconductor laser device 100. i A sectional view, that is, along Figure 3A A sectional view of line A-A.

[0070] exist Figure 3A For ease of explanation, an orthogonal xyz coordinate system is defined. The x-axis is an axis perpendicular to the yz plane and coincides with the width direction of the ridge-type large-area semiconductor laser device 100. As mentioned above, the x-axis direction is also referred to as the "ridge width direction." A horizontal transverse mode is generated in the ridge-type large-area semiconductor laser device 100 along the x-axis. The y-axis direction coincides with the crystal growth direction of each semiconductor layer formed on the n-type GaAs substrate 2. The y-axis direction is also referred to as the "stack direction." The y-axis is parallel to the normal to the upper surface of the n-type GaAs substrate 2.

[0071] The z-axis is the direction in which the laser beam is emitted from the ridge-type large-area semiconductor laser device 100, and it is also the length axis of the resonator in the ridge-type large-area semiconductor laser device 100. The z-direction is also referred to as the "resonator direction". The rules related to the above-mentioned orthogonal coordinate system also apply to the perspective view of the ridge-type large-area semiconductor laser device in other embodiments described later.

[0072] like Figure 3A As shown, the ridge-type large-area semiconductor laser device 100, starting from the lower surface side (also called the back side), consists of an n-type electrode 1 (electrode of the first conductivity type), an n-type GaAs substrate 2 (semiconductor substrate of the first conductivity type), and an n-type AlGaAs cladding layer 3 (cladding layer of the first conductivity type, with an Al composition ratio of 0.20 and a layer thickness of 1.5 μm, and a refractive index n...). cn The Al composition ratio is 0.25 and the layer thickness d ln A 200nm n-type AlGaAs low-refractive-index layer 4 (refractive index n ln The Al composition ratio is 0.16 and the layer thickness is dg 2n The second photoconductive layer 5 of AlGaAs on the n-side with a refractive index of 1050 nm is... g2n The Al composition ratio is 0.14 and the layer thickness d g1n The first photoconductive layer 6 of AlGaAs on the n-side is 100nm thick (refractive index n). g1n The In composition ratio is 0.119 and the layer thickness d am The active layer 7 of the 8nm InGaAs quantum well (refractive index n) am The Al composition ratio is 0.14 and the layer thickness d g1pThe first photoconductive layer of AlGaAs on the p-side is 350 nm thick (refractive index n). g1p The Al composition ratio is 0.16 and the layer thickness d is... g2p The second photoconductive layer 9 of p-side AlGaAs with a refractive index of 300 nm is... g2p The Al composition ratio is 0.55 and the layer thickness d is... lp This is an 80nm p-type AlGaAs first etch barrier layer 10 (also known as the p-type AlGaAs first ESL layer, p-type AlGaAs low refractive index layer, or second conductivity type low refractive index layer, with refractive index n). lp The first cladding layer 11 of p-type AlGaAs with an Al composition ratio of 0.20 and a layer thickness of 0.50 μm (the first cladding layer of the second conductivity type, with a refractive index n) is a p-type AlGaAs. cp It consists of a p-type AlGaAs second etch barrier layer 12 (p-type AlGaAs second ESL layer 12) with an Al composition ratio of 0.55 and a layer thickness of 40 nm, a p-type AlGaAs second cladding layer 13 (second cladding layer of the second conductivity type) with an Al composition ratio of 0.20 and a layer thickness of 0.96 μm, a p-type GaAs contact layer 14 (contact layer of the second conductivity type) with a layer thickness of 0.2 μm, a SiN insulating film 15 with a film thickness of 0.2 μm, and a p-type electrode 16 (electrode of the second conductivity type) on the upper surface side.

[0073] Specifically, the n-side AlGaAs second photoconductor layer 5 and the n-side AlGaAs first photoconductor layer 6 are collectively referred to as the n-side photoconductor layer 61 or the photoconductor layer 61 with the first conductivity type, and the p-side AlGaAs first photoconductor layer 8 and the p-side AlGaAs second photoconductor layer 9 are collectively referred to as the p-side photoconductor layer 81 or the photoconductor layer 81 with the second conductivity type. Since each photoconductor layer is usually an undoped layer, the term "side" is used to distinguish which side of the InGaAs quantum well active layer 7 it is located on. That is, the n-side or the first conductivity type side refers to the side with each n-type or first conductivity type layer disposed relative to the InGaAs quantum well active layer 7. Similarly, the p-side or the second conductivity type side refers to the side with each p-type or second conductivity type layer disposed relative to the InGaAs quantum well active layer 7.

[0074] The first coating layer 11 of the second conductivity type (p-type AlGaAs first coating layer 11) and the second coating layer 13 of the second conductivity type (p-type AlGaAs second coating layer 13) are collectively referred to as the coating layer of the second conductivity type.

[0075] The reason for setting the In composition ratio of the InGaAs quantum well active layer 7 to 0.119 and the layer thickness to 8nm is to set the oscillation wavelength to approximately 975nm.

[0076] In addition, at both ends of the ridge-shaped large-area semiconductor laser device 100, a front end face and a rear end face constituting a resonator that causes the laser to reciprocate are provided by means of, for example, cleavage.

[0077] First, the structural features of the ridge-shaped large-area semiconductor laser device 100 according to Embodiment 1 will be described.

[0078] The ridge-type large-area semiconductor laser device 100 according to Embodiment 1 includes: a semiconductor substrate 2 of a first conductivity type; a first conductivity type cladding layer 3, a first conductivity type photoconductor layer 61 on the first conductivity type side, a quantum well active layer 7, a second conductivity type photoconductor layer 81, a second conductivity type cladding layer composed of a first conductivity type cladding layer 11 and a second conductivity type cladding layer 13, and a second conductivity type contact layer 14 sequentially stacked on the first conductivity type semiconductor substrate 2; and a front end surface and a rear end surface formed by reciprocating the laser and having a length of L. c A resonator with an oscillation wavelength of λ, the resonator consists of a component of length L. f Current limiting region (C) n ) and length L c -L f Current injection region (C) i )constitute.

[0079] Length L f Current limiting region (C) n ) from the medial region of the spine (I a i ), lateral spinal region (I a o ) and the covered area (II) c ) constitutes, wherein the aforementioned medial region of the spine (I a i Its width is 2W, which is the width of the inner side region of the spine. i This indicates that the effective refractive index is n. a i The aforementioned lateral spinal region (I a o ) Set in the medial region of the spine (I a i On both sides of the ridge, the width is W, which is the width of the outer region of the ridge. o This indicates that the effective refractive index is n. a o Furthermore, it has a non-injection current structure, and the aforementioned covered region (II) c ) Set in the lateral spinal region (I a o On both sides of the second conductivity type, the contact layer 14 and the coating layer of the second conductivity type are removed, and the effective refractive index is n. c .

[0080] Medial spinal region (I) a i ) and the lateral spinal region (I a o The average refractive index n a e Expressed by the above equation (1), and the current limiting region (C) n The normalized frequency V nc It satisfies the following equation (6).

[0081]

Number 8

[0082]

[0083] Lateral spinal region (I a o The width W of the lateral region of the spine o It is wider than the distance from the lower end of the non-current-injected structure to the quantum well active layer 7, and narrower than half the width of the ridge region, i.e., width W. Additionally, from the encapsulation region (II) c The height from the upper end of the ridge to the lower end of the non-current-injected structure is the lateral region of the ridge (I). a o The effective refractive index n a o With the medial region of the spine (I a i The effective refractive index n a i They are essentially the same height.

[0084] On the other hand, such as Figure 3A 3D diagram and Figure 3B As shown in the cross-sectional view, the length in the resonator direction is L. c -L f Current injection region (C) i The length of the resonator is L. c -L f The region, consisting of the ridge region (I a ) and the covered area (II) c ) constitutes, wherein the aforementioned ridge region (I a Its ridge region width is represented by 2W, and its effective refractive index is a real number n. a It also has a current injection structure, the aforementioned covered region (II) c ) Set in the spine region (I a On both sides of the second conductivity type, the contact layer 14 and the coating layer of the second conductivity type are removed, and the effective refractive index is a real number n. c Additionally, the current injection region (C) i The normalized frequency V icIt satisfies the following equation (7).

[0085]

Number 9

[0086]

[0087] Here, "effective refractive index is essentially the same" means that in the current-limited region (C... n The medial region of the spine (I) a i Let the effective refractive index be n. a i and the lateral spinal region (I a o Let the effective refractive index be n. a o At that time, the number of permissible patterns calculated according to equations (2) and (6) is compared with the number of patterns in the absence of the lateral spinal region (I). a o In the case of ), that is, in the lateral region of the spine, the width W o When the number is zero, the number of allowed modes calculated according to equation (7) is the same, which satisfies the following equation (8).

[0088]

Number 10

[0089] INT[V ic / (π / 2)]+1=INT[V nc / (π / 2)]+1 (8) where, if the current limiting region (C n Let m be the number of patterns allowed in the ridge width direction, where m is an integer greater than or equal to 2.

[0090] The above describes the structural features of the ridge-shaped large-area semiconductor laser device 100 described in Embodiment 1.

[0091] The following describes a method for manufacturing a ridge-shaped large-area semiconductor laser device 100 according to Embodiment 1.

[0092] On an n-type GaAs substrate 2, semiconductor layers from the n-type AlGaAs cladding layer 3 to the p-type GaAs contact layer 14 are sequentially crystallized and grown on the substrate using crystallization growth methods such as Metal Organic Chemical Vapor Deposition (MOCVD).

[0093] Next, cover a length of L with resist. f Current limiting region (C) n The medial region of the spine (I) a i and length L c -L fCurrent injection region (C) i ) in the ridge region (I a After dry etching to the second ESL layer 12, the resist is stripped off.

[0094] Then, a resist is applied to a length of L. f Current limiting region (C) n The medial region of the spine (I) a i ) and the lateral spinal region (2I a o and length L c -L f Current injection region (C) i ) in the ridge region (I a Dry etching is performed down to the first ESL layer 10 of p-type AlGaAs to remove the resist.

[0095] The resist is used to cover a length of L. f Current limiting region (C) n The medial region of the spine (I) a i and length L c -L f Current injection region (C) i ) ridge region (I a A SiN insulating film 15 is formed and peeled off, and the resist is stripped off.

[0096] Furthermore, a p-type electrode 16 is formed on the upper surface side, and an n-type electrode 1 is formed on the lower surface side.

[0097] In the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, since the current-limiting region (C) is removed by etching... n ) in the lateral spinal region (I a o The p-type GaAs contact layer 14 and the p-type AlGaAs second cladding layer 13 are covered by a SiN insulating film 15, which covers the exposed surface obtained by etching, thus forming a current-non-injected structure. Therefore, the current injected into the ridge-type large-area semiconductor laser device 100 is specifically concentrated in the inner region of the ridge (I). a i )flow.

[0098] The effects of the ridge-shaped large-area semiconductor laser device 100 according to Embodiment 1 caused by its characteristic structure will be described in detail below.

[0099] For example, if the refractive index and its calculation method described in Non-Patent Document 3, namely "Semiconductor Lasers" edited by Iga, pp. 35-38, are used, the refractive indices of AlGaAs layers with Al composition ratios of 0.14, 0.16, 0.20, 0.25, and 0.55 at a wavelength of 975 nm are 3.432173, 3.419578, 3.394762, 3.364330, and 3.191285, respectively.

[0100] In addition, the refractive indices of InGaAs constituting the InGaAs quantum well active layer 7 with an In composition ratio of 0.119 and SiN constituting the SiN insulating film 15 are empirically 3.542393 and 2.00, respectively.

[0101] First, consider the width W of the lateral spinal region. o The ridge structure when the current injection is zero is the current injection region (C i ) ridge structure.

[0102] Width W in the lateral region of the spine o When the value is zero, the ridge region (I) a The effective refractive index n a and the covered area (II) c The effective refractive index n c For example, they can be calculated using the equivalent refractive index method described in Non-Patent Document 4, and are 3.41773 and 3.41723 respectively.

[0103] In the ridge region (I a When the ridge region width 2W is 100μm, the value v / (π / 2) obtained by dividing the normalized frequency v of equation (1) by π / 2 is 11.991, allowing 12 modes from the 0th order (fundamental mode) to the 11th order.

[0104] Width W in the lateral region of the spine o When the current is zero, it extends from the position of the first ESL layer 10 in the ±x direction with the two ends of the ridge region width 2W as the starting point, and reaches the quantum well active layer 7 via a distance h1 (0.73μm) from the first ESL layer 10 to the quantum well active layer 7.

[0105] Next, consider the resonator length L. c (L c =4mm) The entire area, for example, is etched to make the width W of the outer region of the ridge. o =12μm, removing up to the top of the second ESL layer 12 to form a current-free structure. This is the case where the entire resonator in the ridge-type large-area semiconductor laser device 100 is considered as a current-limited region (C n (The situation is as follows.)

[0106] The effective refractive index of this current-injected structure is 3.41773, independent of removal by etching, in the ridge region (inner ridge region (I)). a i ) and the lateral spinal region (I a o The refractive index of the )) is the same as that of the unetched )) is, of course, the same as the condition of equation (8). Therefore, the number of allowed modes is also the same.

[0107] On the other hand, the current injected from the p-type GaAs contact layer 14 flows from the upper end of the second ESL layer 12 through the inner region of the ridge (I a i The width of the medial region of the spine is 2W. i Starting from both ends, it extends in the ±x direction. That is, it extends in the ±x direction via a distance h1 (0.73 μm) from the upper end of the quantum well active layer 7 to the upper end of the first ESL layer 10 and a distance h2 (0.54 μm) from the upper end of the first ESL layer 10 to the upper end of the second ESL layer 12, reaching the quantum well active layer 7.

[0108] For simplicity, the resistivity ρ from the point where the current extends in the ±x direction to the quantum well active layer 7 is set to 0.35 Ωcm. Furthermore, even if the value of resistivity ρ changes, the gain G... i The same trend has been confirmed.

[0109] As an example, consider the L inside the resonator. f = 1mm in length and W in width of the outer region of the spine o =12μm, the length L of the current-non-injection structure formed by etching away the material from the upper surface of the p-type GaAs contact layer 14 to the upper end of the second ESL layer 12. f =1mm current limiting area (C) n Since the effective refractive index of this non-injected current structure is 3.41773, the number of allowed modes remains unchanged.

[0110] In the current-limited region (C) with a current-non-injection structure n In the second ESL layer 12, the current flows from the upper end of the ridge inner region (I). a i The width of the medial region of the spine is 2W. i Starting from both ends, it extends and reaches the quantum well active layer 7 via a distance h2 (0.54 μm) from the upper end of the second ESL layer 12 to the upper end of the first ESL layer 10 and a distance h1 (0.73 μm) from the upper end of the first ESL layer 10 to the upper end of the quantum well active layer 7.

[0111] On the other hand, in the remaining current injection region (C) within the resonator i Length: L c -L f =3mm) in, such as Figure 3B As shown, the current extends from the upper end of the first ESL layer 10, starting from both ends of the ridge region width 2W.

[0112] exist Figure 4 In the diagram, black circles, white triangles, and diamonds are used to indicate the absence of current injection throughout the resonator (W). o =0μm), when the resonator is configured with a non-injection current structure throughout (L f =L c =4mm, W o =12μm) and when a non-injected current structure is set in a part of the resonator (L f =1mm, W o =12μm) that is, setting the length L f =1mm current limiting area (C) n Gain G in each mode at time ) i .

[0113] When there is no current non-injection structure throughout the resonator (W) o =0μm, Figure 4 As indicated by the black circles in the diagram, there is almost no gain difference between the modes. This trend of no gain difference between modes is particularly pronounced when the mode order is below 9.

[0114] The width W of the lateral ridge region is set with a length of 1 mm. o It is a current-non-injection structure of 12μm, i.e., with a length L. f =1mm current limiting area (C) n )hour( Figure 4 (The diamond-shaped markers in the diagram) show the gain difference between the modes, with the gain G of low-order modes such as 0th to 2nd order being different. i Compared to other higher-order modes, the gain G i It gets taller.

[0115] Typically, due to the gain G of semiconductor laser devices i Oscillation occurs in a high-order mode, so a low-order mode is chosen, resulting in a narrower beam spread angle. This occurs throughout the resonator length L. c (L c =4mm) Overall setting of the width W of the outer ridge area o When the current is not injected into a 12μm structure ( Figure 4(The white triangle markings in the diagram) indicate that the gain difference between modes further increases, oscillates in lower-order modes, and the horizontal expansion angle further narrows.

[0116] If the turn-on voltage of the pn junction is set to 1.335V, the voltage drop from the quantum well active layer 7 down to the first conductivity type (n-type) side is set to 0.14V, and the operating current for a light output of 5W is set to 5.0A, then in the absence of a current-free structure (W... o =0μm), when a non-injection current structure is set throughout the resonator (L f =L c =4mm, W o =12μm) and when a non-injected current structure is set in a part of the resonator (L f =1mm, W o =12μm) that is, setting the length L f =1mm current limiting area (C) n The operating voltages at the specified times are 1.518V, 1.552V, and 1.525V, respectively, and the power conversion efficiencies at a light output of 5W are 63.4%, 62.0%, and 63.1%, respectively.

[0117] In the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, a current limiting region (C) as described above is provided. n In the case of a non-injection structure throughout the resonator, the gain difference between modes becomes larger compared to the case where there is no current injection. Based on this, the gain G of the lower-order modes (0th to 2nd order) increases. i The gain G becomes higher than other higher-order modes. i Therefore, laser oscillations are induced in a low-order mode, resulting in a narrower horizontal spread angle.

[0118] Furthermore, the ridge-type large-area semiconductor laser device 100 according to Embodiment 1 is provided with the aforementioned current-limiting region (C). n In the case of ), and in the case of not setting a current limiting region at all (C) n Compared to the case where the current injection area is smaller, the ridge-type large-area semiconductor laser device 100 according to Embodiment 1 has a higher operating voltage and a lower power conversion efficiency compared to a structure in which there is no current injection structure throughout the resonator.

[0119] On the other hand, compared to a structure where current is not injected throughout the resonator, the aforementioned current-limited region (C) is... n In the case of ), the current injection area becomes larger, but this means that the resistance becomes smaller, thus resulting in a lower operating voltage and higher power conversion efficiency.

[0120] exist Figure 5 In the diagram, white triangles and diamonds are used to indicate the presence of a non-injected current configuration throughout the resonator (L). f =L c =4mm, W o =8μm) and when a non-injection current structure is set in a part of the resonator (L f =2mm, W o =8μm) that is, setting the length L f =2mm current limiting area (C) n Gain G in each mode at time ) i Additionally, for comparison, black circles are used to indicate the absence of current non-injection throughout the resonator (W). o Gain G of each mode (=0μm) i .

[0121] When a current-non-injection structure is set in a part of the resonator (L f =2mm, W o =8μm) that is, the length L f =2mm current limiting area (C) n When this occurs, a gain difference is observed between the modes, with the gain G of lower-order modes such as 0-4 being significantly different. i Gain G higher than other higher-order modes i .

[0122] Typically, due to the gain G of semiconductor laser devices i Oscillation occurs in the higher-order mode, so a lower-order mode is selected, resulting in a narrower beam spread angle. This applies across the resonator length L. c (L c =4mm) Overall setting of the width W of the outer ridge area o When the current is not injected at 8μm, the gain difference between modes increases further, oscillates in a lower order mode, and the horizontal spread angle becomes narrower.

[0123] If the turn-on voltage of the pn junction is set to 1.335V, the voltage drop from the quantum well active layer 7 down to the first conductivity type (n-type) side is set to 0.14V, and the operating current at a light output of 5W is set to 5.0A, then when the entire resonator is configured with a non-injection current structure (L... f =L c =4mm, W o =8μm) and when a non-injection current structure is set in a part of the resonator (L f =2mm, W o =8μm) that is, setting the length L f=2mm current limiting area (C) n The operating voltages at the two times were calculated to be 1.538V and 1.527V, respectively, and the power conversion efficiencies at the light output of 5W were 62.5% and 63.0%, respectively.

[0124] In the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, a current limiting region (C) as described above is provided. n In the case of a non-injection structure throughout the resonator, the gain difference between modes becomes larger compared to the case where there is no current injection. Based on this, the gain G of the lower-order modes (0th to 4th orders) increases. i The gain G becomes higher than other higher-order modes. i Therefore, laser oscillations are induced in a low-order mode, resulting in a narrower horizontal spread angle.

[0125] Furthermore, the ridge-type large-area semiconductor laser device 100 according to Embodiment 1 is provided with the aforementioned current-limiting region (C). n In the case of ), and in the case of not setting a current limiting region at all (C) n Compared to the case where the current injection area is smaller, the ridge-type large-area semiconductor laser device 100 according to Embodiment 1 has a higher operating voltage and a lower power conversion efficiency compared to a structure in which there is no current injection structure throughout the resonator.

[0126] On the other hand, compared to a structure where current is not injected throughout the resonator, the aforementioned current-limited region (C) is... n In the case of ), the current injection area becomes larger, but this means that the resistance becomes smaller, thus resulting in a lower operating voltage and higher power conversion efficiency.

[0127] exist Figure 6 In the diagram, white triangles and diamonds are used to indicate the presence of a non-injected current configuration throughout the resonator (L). f =L c =4mm, W o =15μm) and when a non-injection current structure is set in a part of the resonator (L f =3mm, W o =15μm) that is, setting the length L f =3mm current limiting area (C) n Gain G in each mode at time ) i Additionally, for comparison, black circles are used to indicate the absence of current non-injection throughout the resonator (W). o Gain G of each mode (=0μm) i .

[0128] When a current-non-injection structure is set in a part of the resonator (L f =3mm, W o =15μm) that is, the length L f =3mm current limiting area (C) n When this occurs, a gain difference is observed between the different modes, with the gain G of lower-order modes such as 0th to 2nd order being significantly different. i The gain G becomes higher than other higher-order modes. i .

[0129] Typically, due to the gain G of semiconductor laser devices i Oscillation occurs in the higher-order mode, so a lower-order mode is selected, resulting in a narrower beam spread angle. This applies across the resonator length L. c (L c =4mm) Overall setting of the width W of the outer ridge area o When the current is not injected at 15μm, the gain difference between modes increases further, oscillates in a lower order mode, and the horizontal spread angle becomes narrower.

[0130] If the turn-on voltage of the pn junction is set to 1.335V, the voltage drop from the quantum well active layer 7 down to the first conductivity type (n-type) side will be 0.14V. If the operating current for a light output of 5W is set to 5.0A, then with a non-injection current structure throughout the resonator (L... f =L c =4mm, W o =15μm) and when a non-injection current structure is set in a part of the resonator (L f =3mm, W o =15μm) that is, setting the length L f =3mm current limiting area (C) n The operating voltages at the two times were calculated to be 1.564V and 1.549V, respectively, and the power conversion efficiencies at the light output of 5W were 61.5% and 62.1%, respectively.

[0131] In the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, a current limiting region (C) as described above is provided. n In the case of a non-injection structure throughout the resonator, the gain difference between modes becomes larger compared to the case where there is no current injection. Based on this, the gain G of the lower-order modes (0th to 2nd order) increases. i The gain G becomes higher than other higher-order modes. i Therefore, laser oscillations are induced in a low-order mode, resulting in a narrower horizontal spread angle.

[0132] Furthermore, the ridge-type large-area semiconductor laser device 100 according to Embodiment 1 is provided with the aforementioned current-limiting region (C).n In the case of ), and in the case of not setting a current limiting region at all (C) n Compared to the case of a ridge-type large-area semiconductor laser device 100, the current injection area is smaller. Therefore, compared to a structure in which there is no current non-injection structure throughout the resonator, the operating voltage of the ridge-type large-area semiconductor laser device 100 according to Embodiment 1 is higher to some extent, and the power conversion efficiency is also lower to some extent.

[0133] On the other hand, compared to a structure where current is not injected throughout the resonator, the aforementioned current-limited region (C) is... n In the case of ), the current injection area becomes larger, but this means that the resistance becomes smaller, thus resulting in a lower operating voltage and higher power conversion efficiency.

[0134] Based on the above, when a current-free injection structure, i.e., a current-limited region (C) is set in a part of the resonator... n When, regardless of the current limiting region (C) n ) length or width of the lateral region of the spine W o How wide is it, compared to the area without current limiting (C)? n Compared to the previous case, both can set the gain difference between the allowed modes. Based on this, the gain G of the lower-order mode can be increased. i Gain G becomes higher than that of higher-order modes i Therefore, laser oscillation is achieved in a low-order mode, and the horizontal spread angle becomes narrower. Additionally, because the loss is not limited by the current-constrained region (C... n The gain G varies depending on the presence or absence of ) i Oscillation occurs, and the threshold current decreases.

[0135] Furthermore, in the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, compared with the structure in which a current non-injection structure is provided throughout the resonator, the operating voltage is reduced and the power conversion efficiency is increased.

[0136] In the n-type AlGaAs coating layer 3 (refractive index n) cn An n-type AlGaAs low-refractive-index layer 4 (layer thickness d) is inserted between the n-side optical guide layer 61 and the n-side optical guide layer 61. ln Refractive index n ln ) and in the first cladding layer 11 of p-type AlGaAs (refractive index n) cp A p-type AlGaAs low-refractive-index layer 10 (layer thickness d) is inserted between the p-side optical guide layer 81 and the p-side optical guide layer 81. lp Refractive index n lp u at time p with u n Substituting the size relationship into equation (1), we can express it using the following equation (9).

[0137]

Number 11

[0138]

[0139] In the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, due to u n It is 0.29227, u p The value is 0.29840, therefore u n <u p When established, the light intensity distribution in the y-direction, i.e. the stacking direction, is shifted to the n-type GaAs substrate 2 side, which becomes a structure that reduces the number of built-in allowed modes in the x-direction, i.e. the ridge width direction.

[0140] For example, if the thickness of the p-type AlGaAs low-refractive-index layer 10 is increased from 80 nm to 140 nm, then u p Increasing the value to 0.52221 further shifts the light intensity distribution towards the 2-side of the n-type GaAs substrate, thus further reducing the fixed number of allowed modes. In this way, reducing the fixed number of allowed modes in advance facilitates the oscillation of lower-order modes.

[0141] In the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, although the n-type AlGaAs low-refractive-index layer 4 is disposed between the n-type AlGaAs cladding layer 3 and the n-side photoconductor layer 61, and the p-type AlGaAs low-refractive-index layer 10 is disposed between the p-type AlGaAs first cladding layer 11 and the p-side photoconductor layer 81, the n-type AlGaAs low-refractive-index layer 4 can also be disposed within the n-type AlGaAs cladding layer 3, and the p-type AlGaAs low-refractive-index layer 10 can be disposed within the p-type AlGaAs first cladding layer 11. In this case, although the upper p-type AlGaAs first cladding layer 11 of the first ESL layer 10 is removed by etching, the lower p-type AlGaAs first cladding layer 11 of the first ESL layer 10 will remain, which helps with current spread.

[0142] As a method to reduce the fixed number of allowed modes by shifting the light intensity distribution within the resonator towards the n-type GaAs substrate 2, in addition to the above, one example is to reduce the refractive index n of the p-type AlGaAs low-refractive-index layer 10. lp To increase the refractive index n of the n-type AlGaAs coating layer 3 cn The refractive index n is higher than that of the first cladding layer 11 of p-type AlGaAs. cp Or the refractive index of the second cladding layer 13 of p-type AlGaAs, etc.

[0143] The following describes the case where the ridge-type large-area semiconductor laser device 100 according to Embodiment 1 has a total optical layer thickness of 1.8 μm, which allows for the construction of multiple waveguide modes in the stacking direction (y direction).

[0144] First, the sum of the thicknesses of the optical guide layers including the quantum well active layer 7 is d. gy m (=d g2n +d g1n +d am +d g1p +d g2p The value is 1.808 μm.

[0145] In addition, the average refractive index n of the optical guide layer containing the quantum well active layer 7 gy m As expressed in equation (11) below, its value is 3.423256. The refractive index n of the n-type AlGaAs cladding layer 3... cn The refractive index n of the first cladding layer 11 of p-type AlGaAs cp In this case, the refractive index of the higher one is set as n. ch In Embodiment 1, since the Al composition ratio of the n-type AlGaAs cladding layer 3 and the p-type AlGaAs first cladding layer 11 is the same (0.20), the refractive index n cn and refractive index n cp The refractive index n becomes the same value. ch It is 3.394762.

[0146]

Number 12

[0147] d gy m =d g2n +d g1n +d am +d g1p +d 2p (10)

[0148]

[0149]

[0150] If the normalized frequency V in the stacking direction is obtained according to the above equations (10), (11), and (12), y The value is 2.5677, which is greater than π / 2, indicating a multi-mode configuration. Furthermore, since V... y Since (π / 2) is 1.6347, we can also conclude that the 0th and 1st order modes are allowed.

[0151] If the structure is configured to allow multiple modes in the stacking direction, a large amount of light is confined within the n-side light guide layer 61 and the p-side light guide layer 81, and less light permeates into the AlGaAs cladding layer. Therefore, the fixed refractive index difference in the horizontal direction can be reduced, thus having the effect of reducing the fixed number of allowed modes in the horizontal direction.

[0152] Furthermore, in the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, the n-side photoconductor layer 61 and the p-side photoconductor layer 81 are each provided as two layers. However, each photoconductor layer may be only one layer, or it may be composed of three or more layers, as long as it is considered in the same way as the two-layer case of this disclosure.

[0153] Furthermore, in the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, the thickness of the n-side photoconductor layer 61 is set to 1150 nm, and the thickness of the p-side photoconductor layer 81 is set to 650 nm. This causes the position of the quantum well active layer 7 in the stacking direction to shift towards the p-type AlGaAs cladding layer side, thereby reducing the number of carriers retained in the n-side photoconductor layer 61 and the p-side photoconductor layer 81, and preventing the reduction in slope efficiency caused by carrier absorption.

[0154] Furthermore, in the ridge-type large-area semiconductor laser device 100 according to Embodiment 1, although a current-limiting region (C) is shown... n ) length L f The width W of the lateral region of the spine is 1mm, 2mm, and 3mm. o Examples include 8μm, 12μm, and 15μm, but are not limited to these examples.

[0155] In the ridge-type large-area semiconductor laser device 100 described in Embodiment 1, since the structure is configured such that a current-free structure, i.e., a current-limiting region, is provided in a part of the resonator and a current-injection region is provided in the remaining part of the resonator, the gain of the low-order mode becomes higher than the gain of the high-order mode, laser oscillation can be performed in the low-order mode and the horizontal spread angle is narrowed. Moreover, compared with the structure in which the current-free structure is provided throughout the entire resonator, the resistance is smaller, thus achieving the effect of reducing the operating voltage and increasing the power conversion efficiency.

[0156] Implementation Method 2

[0157] Figure 7A This is a perspective view showing the 975nm ridge-shaped large-area semiconductor laser device 110 with an actual refractive index distribution according to Embodiment 2. Additionally, Figure 7B It is the current injection region (C) of the ridge-type large-area semiconductor laser device 110. i A sectional view, that is, along Figure 7A A sectional view taken along line A-A.

[0158] The ridge-type large-area semiconductor laser device 110 according to Embodiment 2 differs from the ridge-type large-area semiconductor laser device 100 according to Embodiment 1 in that: a second ESL layer 12 is not provided; instead of the first p-type AlGaAs cladding layer 11 with an Al composition ratio of 0.20 and a layer thickness of 0.50 μm and the second p-type AlGaAs cladding layer 13 with an Al composition ratio of 0.20 and a layer thickness of 0.96 μm in Embodiment 1, a single p-type AlGaAs cladding layer consisting of a p-type AlGaAs cladding layer 11a (a cladding layer of the second conductivity type) with an Al composition ratio of 0.20 and a layer thickness of 1.5 μm is provided; and a proton injection region 17 is provided as a current-non-injection structure. The other layer structures are the same as those of the ridge-type large-area semiconductor laser device 100 according to Embodiment 1.

[0159] The following describes a method for manufacturing the ridge-shaped large-area semiconductor laser device 110 according to Embodiment 2.

[0160] On an n-type GaAs substrate 2, semiconductor layers from the n-type AlGaAs cladding layer 3 to the p-type GaAs contact layer 14 are sequentially crystallized and grown using crystallization growth methods such as MOCVD.

[0161] Next, cover a length of L with resist. f Current limiting region (C) n The medial region of the spine (I) a i and length L c -L f Current injection region (C) i ) in the ridge region (I a Protons are implanted to form a proton implantation region 17, and the resist is stripped off.

[0162] Then, a resist is applied to a length of L. f Current limiting region (C) n The medial region of the spine (I) a i ) and the lateral spinal region (2I a o and length L c -L f Current injection region (C) i ) ridge region (I a Dry etching is performed down to the first ESL layer 10 to remove the resist. In this step, the resist is formed in the encapsulated region (II). c The proton-injected region was also etched away.

[0163] The resist is used to cover a length of L. f Current limiting region (C) n The medial region of the spine (I) a i ) and the lateral spinal region (2I a o and length L c -L f Current injection region (C) i ) ridge region (I a A SiN insulating film 15 is formed and peeled off, and the resist is stripped off.

[0164] Furthermore, a p-type electrode 16 is formed on the upper surface side, and an n-type electrode 1 is formed on the lower surface side.

[0165] The current limiting region (C) in Implementation Method 2 n ) lateral spinal region (I a o Instead of the etching removal and SiN insulating film 15 covering as in Embodiment 1, it is formed by insulatorization of the semiconductor layer through proton implantation. In the structure of Embodiment 2, although there is no second ESL layer 12, the inner ridge region (I a i The effective refractive index n a i It is 3.41773.

[0166] Coverage area (II) c The effective refractive index n c In the current-limiting region (C) n ) and current injection region (C i The value is the same as 3.41723 in the ridge region, which is 2W (W). o When the value of v in equation (1) is 100 μm (0 μm), the value of v / (π / 2) obtained by dividing v by π / 2 is 11.991, allowing 12 modes from the 0th (basic) to the 11th order.

[0167] The lateral ridge region (I) obtained by proton ion implantation a o The effective refractive index n a o For the medial region of the spine (I a i The effective refractive index n a iThe same value is 3.41773. As an example, if protons are implanted from the p-type GaAs contact layer 14 to a depth of 1.0 μm, the distance h2 from the upper end of the first ESL layer 10 to the lower end of the proton implantation region 17 is 0.7 μm.

[0168] If the distance h2 from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17 is set to 0.5 μm, then the region outside the ridge after removing the p-type AlGaAs cladding layer 11a and the p-type GaAs contact layer 14 on the upper side of the first ESL layer 10 (I a o The effective refractive index n a o Calculations are performed, then n a o The value was 3.41773, which corresponds to the medial region of the spine (I). a i The effective refractive index n a i The same value. That is, a value indicating that light is substantially absent in the region that is more than 0.5 μm away from the first ESL layer 10 in the y direction. This means that the proton injection region 17 is a region where light is substantially absent. In the construction of Embodiment 2, as described above, the distance h2 from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17 is set to 0.7 μm.

[0169] Consider passing through the resonator length L c (L c =4mm) overall, for example, the width W of the outer region of the spine o =12μm, from the upper surface of the p-type GaAs contact layer 14 to a depth of 1μm, protons are implanted to form a proton implantation region 17 to set up a current-free structure (distance h2 = 0.7μm).

[0170] Current flows from the lower end of proton injection region 17 through the inner ridge region (I a i The width of the inner lateral region of the spine is 2W. i The current extends in the ±x direction from both ends. That is, between the distance h1 (0.73 μm) from the upper end of the quantum well active layer 7 to the upper end of the first ESL layer 10 and the distance h2 (0.7 μm) from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17, the current extends in the ±x direction and reaches the quantum well active layer 7.

[0171] As an example, the length L within the resonator f =2mm area with width W of the outer region of the spine oIn the case of forming a current-free structure by ion implanting protons from the surface of the p-type GaAs contact layer to a depth of 1 μm (12 μm), that is, when setting a length L... f =2mm and the width W of the lateral region of the spine o =12μm current-limited region (C n In the case of ), the current flows from the lower end of the proton injection region 17 through the inner ridge region (I a i The width of the medial region of the spine is 2W. i Starting from both ends, the distance extends from the lower end of the proton injection region 17 to the upper end of the first ESL layer 10 via a distance h2 (0.7 μm) and from the upper end of the first ESL layer 10 to the upper end of the quantum well active layer 7 via a distance h1 (0.73 μm) to the upper end of the quantum well active layer 7, reaching the quantum well active layer 7.

[0172] On the other hand, the remaining portion within the resonator, namely the current injection region (C... i Length: L c -L f =2mm), the current extends from the upper end of the first ESL layer 10 with the two ends of the ridge region width 2W as the starting point.

[0173] exist Figure 8 In the diagram, black circles, white triangles, and diamonds are used to indicate the absence of current injection throughout the resonator (W). o =0μm), when the resonator is configured with a non-injection current structure throughout (L f =L c =4mm, W o =12μm) and when a non-injected current structure is set in a part of the resonator (L f =2mm, W o =12μm) that is, setting the length L f =2mm current limiting area (C) n Gain G in each mode at time ) i When there is no current non-injection structure throughout the resonator (W) o =0μm, Figure 8 As indicated by the black circles in the diagram, there is almost no gain difference between the modes. This trend of no gain difference between modes is particularly pronounced when the mode order is below 9.

[0174] When a current-non-injection structure is set in a part of the resonator (L f =2mm, W o =12μm) that is, the length L f =2mm current limiting area (C) nWhen this occurs, a gain difference is observed between the modes. Lower-order modes (0-2 orders) show a greater gain (G) compared to higher-order modes. i It gets taller.

[0175] Typically, due to the gain G of semiconductor laser devices i Oscillation occurs in a high-order mode, so a low-order mode is selected, resulting in a narrower beam spread angle. This occurs across the resonator length L. c (L c When a non-injected current structure with an overall ridge outer region width of 12μm is set (=4mm), the gain difference between modes further increases, oscillates in a lower-order mode, and the horizontal expansion angle further narrows.

[0176] If the turn-on voltage of the pn junction is set to 1.335V, the voltage drop from the quantum well active layer 7 down to the first conductivity type (n) side is set to 0.14V, and the operating current for a light output of 5W is set to 5.0A, then without current injection (W) o =0μm), when the resonator is configured with a non-injection current structure throughout (L f =L c =4mm, W o =12μm) and when a non-injected current structure is set in a part of the resonator (L f =2mm, W o =12μm) that is, setting L f =2mm current limiting area (C) n The operating voltages at the specified values ​​are 1.518V, 1.551V, and 1.532V, respectively, and the power conversion efficiencies at a light output of 5W are 63.4%, 62.0%, and 62.8%, respectively.

[0177] In the ridge-type large-area semiconductor laser device 110 according to Embodiment 2, a current limiting region (C) as described above is provided. n In the case of a non-injection structure throughout the resonator, the gain difference between modes becomes larger compared to the case where there is no current injection. Based on this, the gain G of the lower-order modes (0th to 2nd order) increases. i The gain G becomes higher than other higher-order modes. i Therefore, laser oscillations are induced in a low-order mode, resulting in a narrower horizontal spread angle.

[0178] Furthermore, the ridge-type large-area semiconductor laser device 110 according to Embodiment 2 is provided with the aforementioned current-limiting region (C). n In the case of ), and in the case of not setting a current limiting region at all (C) nCompared to the case of ), the current injection area is smaller. Therefore, the operating voltage of the ridge-type large-area semiconductor laser device 110 according to Embodiment 2 is higher to some extent compared to the structure in which there is no current non-injection structure throughout the resonator, and the power conversion efficiency is also lower to some extent.

[0179] On the other hand, compared to a structure where current is not injected throughout the resonator, the aforementioned current-limited region (C) is... n In the case of ), the current injection area becomes larger, but this means that the resistance becomes smaller, thus resulting in a lower operating voltage and higher power conversion efficiency.

[0180] exist Figure 9 In the diagram, white triangles and diamonds are used to indicate that the entire resonator has a non-injection current structure (L). f =L c =4mm, W o =8μm) and when a non-injection current structure is set in a part of the resonator (L f =3mm, W o =8μm) that is, setting the length L f =3mm current limiting area (C) n Gain G in each mode at time ) i Additionally, for comparison, black circles are used to indicate the absence of current non-injection throughout the resonator (W). o =0μm, Figure 9 Gain G for each mode (marked by the black circle in the image) i .

[0181] When a current-non-injection structure is set in a part of the resonator (L f =3mm, W o =8μm) that is, the length L f =3mm current limiting area (C) n When this occurs, a gain difference is observed between the modes, with the gain G of lower-order modes such as 0-4 being significantly different. i The gain G becomes higher than other higher-order modes. i .

[0182] Typically, due to the gain G of semiconductor laser devices i Oscillation occurs in the higher-order mode, so a lower-order mode is selected, resulting in a narrower beam spread angle. This applies across the resonator length L. c (L c =4mm) Overall setting of the width W of the outer ridge area o When the current is not injected at 8μm, the gain difference between modes increases further, oscillates in a lower order mode, and the horizontal spread angle becomes narrower.

[0183] If the turn-on voltage of the pn junction is set to 1.335V, the voltage drop from the quantum well active layer 7 down to the first conductivity type (n-type) side is set to 0.14V, and the operating current at a light output of 5W is set to 5.0A, then when the entire resonator is configured with a non-injection current structure (L... f =L c =4mm, W o =8μm) and when a non-injection current structure is set in a part of the resonator (L f =3mm, W o =8μm) that is, setting the length L f =3mm current limiting area (C) n The operating voltages at the two times were calculated to be 1.538V and 1.532V, respectively, and the power conversion efficiencies at the light output of 5W were 62.5% and 62.8%, respectively.

[0184] In the ridge-type large-area semiconductor laser device 110 according to Embodiment 2, a current limiting region (C) as described above is provided. n In the case of a non-injection structure throughout the resonator, the gain difference between modes becomes larger compared to the case where there is no current injection. Based on this, the gain G of the lower-order modes (0th to 4th orders) increases. i The gain G becomes higher than other higher-order modes. i Therefore, laser oscillations are induced in a low-order mode, resulting in a narrower horizontal spread angle.

[0185] Furthermore, the ridge-type large-area semiconductor laser device 110 according to Embodiment 2 is provided with the aforementioned current-limiting region (C). n In the case of ), and in the case of not setting a current limiting region at all (C) n Compared to the case of ), the current injection area is smaller. Therefore, the operating voltage of the ridge-type large-area semiconductor laser device 110 according to Embodiment 2 is higher to some extent compared to the structure in which there is no current non-injection structure throughout the resonator, and the power conversion efficiency is also lower to some extent.

[0186] On the other hand, compared to a structure where current is not injected throughout the resonator, the aforementioned current-limited region (C) is... n In the case of ), the current injection area becomes larger, but this means that the resistance becomes smaller, thus resulting in a lower operating voltage and higher power conversion efficiency.

[0187] exist Figure 10 In the diagram, white triangles and diamonds are used to indicate the presence of a non-injected current configuration throughout the resonator (L). f =L c =4mm, Wo =15μm) and when a non-injection current structure is set in a part of the resonator (L f =1mm, W o =15μm) that is, setting the length L f =1mm current limiting area (C) n Gain G in each mode at time ) i Additionally, for comparison, black circles are used to indicate the absence of current non-injection throughout the resonator (W). o Gain G of each mode (=0μm) i .

[0188] When a current-non-injection structure is set in a part of the resonator (L f =1mm, W o =15μm) that is, setting the length L f =1mm current limiting area (C) n When this occurs, a gain difference is observed between the different modes, with the gain G of lower-order modes such as 0th to 2nd order being significantly different. i The gain G becomes higher than other higher-order modes. i .

[0189] Typically, due to the gain G of semiconductor laser devices i Oscillation occurs in the higher-order mode, so a lower-order mode is selected, resulting in a narrower beam spread angle. This applies across the resonator length L. c (L c =4mm) Overall setting of the width W of the outer ridge area o When the current is not injected at 15μm, the gain difference between modes increases further, oscillates in a lower order mode, and the horizontal spread angle becomes narrower.

[0190] If the turn-on voltage of the pn junction is set to 1.335V, the voltage drop from the quantum well active layer 7 down to the first conductivity type (n-type) side is set to 0.14V, and the operating current at a light output of 5W is set to 5.0A, then when the entire resonator is configured with a non-injection current structure (L... f =L c =4mm, W o =15μm) and when a non-injection current structure is set in a part of the resonator (L f =1mm, W o =15μm) that is, setting the length L f =1mm current limiting area (C) n The operating voltages at the two times were calculated to be 1.563V and 1.526V, respectively, and the power conversion efficiencies at the light output of 5W were 61.5% and 63.0%, respectively.

[0191] In the ridge-type large-area semiconductor laser device 110 according to Embodiment 2, a current limiting region (C) as described above is provided. n In the case of a non-injection structure throughout the resonator, the gain difference between modes becomes larger compared to the case where there is no current injection. Based on this, the gain G of the lower-order modes (0th to 2nd order) increases. i The gain G becomes higher than other higher-order modes. i Therefore, laser oscillations are induced in a low-order mode, resulting in a narrower horizontal spread angle.

[0192] Furthermore, the ridge-type large-area semiconductor laser device 110 according to Embodiment 2 is provided with the aforementioned current-limiting region (C). n In the case of ), and in the case of not setting a current limiting region at all (C) n Compared to the case where the current injection area is smaller, the operating voltage is higher to some extent compared to the case where there is no current injection structure throughout the resonator. In addition, the power conversion efficiency is also lower to some extent.

[0193] Furthermore, in the ridge-type large-area semiconductor laser device 110 according to Embodiment 2, compared with the structure in which a current-non-injection structure is provided throughout the resonator, the operating voltage is reduced and the power conversion efficiency is increased.

[0194] Based on the above, when a current-free injection structure, i.e., a current-limited region (C) is set in a part of the resonator... n When, regardless of the current limiting region (C) n ) length or width of the lateral region of the spine W o How wide is it, compared to the area without current limiting (C)? n Compared to the previous case, both can set the gain difference between the allowed modes. Based on this, the gain G of the lower-order mode can be increased. i Gain G becomes higher than that of higher-order modes i Therefore, laser oscillation is achieved in a low-order mode, and the horizontal spread angle becomes narrower. Additionally, because the loss is not limited by the current-constrained region (C... n The gain G varies depending on the presence or absence of ) i Oscillation occurs, and the threshold current decreases.

[0195] In the large-area semiconductor laser device 110 according to Embodiment 2, although the first ESL layer 10 is disposed between the p-side second guiding layer 9 and the p-type AlGaAs cladding layer 11a, the first ESL layer 10 may also be disposed within the p-type AlGaAs cladding layer 11a. In this case, although the upper p-type AlGaAs cladding layer 11a of the first ESL layer 10 is removed by etching, the lower p-type AlGaAs cladding layer 11a of the first ESL layer 10 remains, which facilitates current propagation.

[0196] The ridge-shaped large-area semiconductor laser device 110 described in Embodiment 2 also has the same structure as that described in Embodiment 1. n <u p This structure shifts the light intensity distribution in the y-direction (i.e., the stacking direction) towards the n-type GaAs substrate 2 side, thus reducing the fixed number of allowed modes in the x-direction (i.e., the ridge width direction). By reducing the fixed number of allowed modes in advance, it becomes easier to set gain differences between allowed modes, which is advantageous from the perspective of oscillating in lower-order modes.

[0197] As a method to reduce the fixed number of allowed modes by shifting the light intensity distribution towards the n-type GaAs substrate 2, examples include increasing the thickness of the p-type AlGaAs low-refractive-index layer 10 and decreasing the refractive index n of the p-type AlGaAs low-refractive-index layer 10. lp To increase the refractive index n of the n-type AlGaAs coating layer 3 cn The refractive index n becomes higher than that of the p-type AlGaAs cladding layer 11a. cp wait.

[0198] Furthermore, in the ridge-shaped large-area semiconductor laser device 110 according to Embodiment 2, proton implantation is used as a means of insulating the semiconductor layer, so there is no need for an etching process. Therefore, compared with the structure of Embodiment 1, the number of manufacturing processes can be reduced, and on this basis, the fabrication of the ridge-shaped large-area semiconductor laser device itself becomes easier.

[0199] The distance h1 from the upper end of the first ESL layer 10 to the lower end of the current-free structure, i.e., the proton-injected region 17, is 0.70 μm. However, in the region with a distance h1 of 0.70 μm, light is almost non-existent and is not affected by scattering caused by crystallization damage due to proton injection or the loss caused by such scattering. Furthermore, there is no reduction in reliability caused by crystallization defects.

[0200] In the ridge-type large-area semiconductor laser device 110 according to Embodiment 2, since it is configured such that a current-non-injection structure, i.e., a current-limiting region, is provided in a part of the resonator and a current-injection region is provided in the remaining part of the resonator, and a current-non-injection structure is formed by further providing a proton injection region, the gain of the low-order mode becomes higher than the gain of the high-order mode, laser oscillation can be performed in the low-order mode and the horizontal spread angle is narrowed. Compared with the structure in which the current-non-injection structure is provided throughout the entire resonator, the resistance is smaller. Therefore, the operating voltage is reduced and the power conversion efficiency is increased. By suppressing the increase in scattering loss caused by crystal defects, high reliability can be achieved.

[0201] Implementation Method 3

[0202] Figure 11A This is a perspective view showing the 975nm ridge-type large-area semiconductor laser device 120 with an actual refractive index distribution according to Embodiment 3. Additionally, Figure 11B It is the current injection region (C) of the ridge-type large-area semiconductor laser device 120. i The sectional view along Figure 11A A sectional view taken along line A-A.

[0203] The ridge-type large-area semiconductor laser device 120 according to Embodiment 3 differs from the ridge-type large-area semiconductor laser device 100 according to Embodiment 1 in that: a second ESL layer 12 is not provided; instead of the first p-type AlGaAs cladding layer 11 with an Al composition ratio of 0.20 and a layer thickness of 0.50 μm and the second p-type AlGaAs cladding layer 13 with an Al composition ratio of 0.20 and a layer thickness of 0.96 μm in Embodiment 1, a single p-type AlGaAs cladding layer consisting of a p-type AlGaAs cladding layer 11a (a cladding layer of the second conductivity type) with an Al composition ratio of 0.20 and a layer thickness of 1.5 μm is provided in Embodiment 3; and in Embodiment 3, the current-limiting region (C) is not included. n ) lateral spinal region (I a o Instead of etching to remove and cover the insulating film, the SiN insulating film 15a is disposed on a portion of the upper surface of the p-type GaAs contact layer 14. The other layer structures are the same as those of the ridge-type large-area semiconductor laser device 100 according to Embodiment 1.

[0204] The following describes a method for manufacturing the ridge-shaped large-area semiconductor laser device 120 according to Embodiment 3.

[0205] On an n-type GaAs substrate 2, semiconductor layers from the n-type AlGaAs cladding layer 3 to the p-type GaAs contact layer 14 are sequentially crystallized and grown using crystallization growth methods such as MOCVD.

[0206] Next, cover the current-limiting area (C) with a photoresist. n The medial region of the spine (I) a i ) and the lateral spinal region (2I a o ) and the current injection region (C i ) ridge region (I a Dry etching down to the first ESL layer 10 and stripping the resist.

[0207] Then, a resist is applied to a length of L. fCurrent limiting region (C) n The medial region of the spine (I) a i ) and length L c -L f Current injection region (C) i ) ridge region (I a A SiN insulating film 15a is formed and peeled off, and the resist is stripped off.

[0208] Furthermore, a p-type electrode 16 is formed on the upper surface side, and an n-type electrode 1 is formed on the lower surface side.

[0209] In the ridge-type large-area semiconductor laser device 120 according to embodiment 3, although there is no second ESL layer 12, the inner region of the ridge (I a i The effective refractive index n a i It is 3.41773. Coverage area (II) c The effective refractive index n c In the current-limiting region (C) n ) and current injection region (C i The value is the same as 3.41723 in the ridge region, which is 2W (W). o When the diameter of the contact layer is 100 μm (0 μm), the value of v / (π / 2) obtained by dividing v by π / 2 in equation (1) is 11.991, allowing 12 modes from the 0th (basic) to the 11th order. Since the current extends from the upper surface of the p-type GaAs contact layer 14, the distance h2 is 1.7 μm.

[0210] Considering the length L of the resonator c (L c =4mm) Overall, for example, the width W of the outer region of the spine o =12μm, forming a non-injected current structure (distance h2 = 1.7μm). Current flows from the upper surface of the p-type GaAs contact layer 14 through the inner region of the ridge (I a i The width of the medial region of the spine is 2W. i Starting from both ends, it extends in the ±x direction. That is, it extends in the ±x direction between the distance h1 (0.73 μm) from the upper end of the quantum well active layer 7 to the upper end of the first ESL layer 10 and the distance h2 (1.7 μm) from the upper end of the first ESL layer 10 to the upper surface of the p-type GaAs contact layer 14, reaching the quantum well active layer 7.

[0211] As an example, the length L within the resonator f =3mm area covers the outer side of the spine, width W o=12μm through the SiN insulating film 15a to set the length L of the current non-injection structure f =3mm current limiting area (C) n In the process, current flows from the upper surface of the p-type GaAs contact layer 14 through the inner region of the ridge (I). a i The width of the medial region of the spine is 2W. i Starting from both ends, the distance extends from the upper surface of the p-type GaAs contact layer 14 to the upper end of the first ESL layer 10 via a distance h2 (1.7 μm) and from the upper end of the first ESL layer 10 to the upper end of the quantum well active layer 7 via a distance h1 (0.73 μm).

[0212] On the other hand, the remaining portion within the resonator, namely the current injection region (C... i Length: L c -L f =1mm), the current extends from the upper end of the first ESL layer 10, starting from both ends of the ridge region width 2W.

[0213] exist Figure 12 In the diagram, black circles, white triangles, and diamonds are used to indicate the absence of current injection throughout the resonator (W). o =0μm), when a non-injection current structure is set throughout the resonator (L f =L c =4mm, W o =12μm) and when a non-injected current structure is set in a part of the resonator (L f =3mm, W o =12μm) that is, setting the length L f =3mm current limiting area (C) n Gain G in each mode at time ) i In the absence of current-free structures throughout the resonator, there is almost no gain difference between modes. This trend is particularly pronounced when the mode order is below 9.

[0214] When a current-non-injection structure is set in a part of the resonator (L f =3mm, W o =12μm) that is, the length L f =3mm current limiting area (C) n When this occurs, a gain difference is observed between the different modes, with the gain G of lower-order modes such as 0th to 2nd order being significantly different. i The gain G becomes higher than other higher-order modes. i .

[0215] Typically, due to the gain G of semiconductor laser devices i Oscillation occurs in the higher-order mode, so a lower-order mode is selected, resulting in a narrower beam spread angle. This applies across the resonator length L. c (L c =4mm) Overall setting of the width W of the outer ridge area o When the current is not injected at 12μm, the gain difference between modes increases further, oscillates in a lower order mode, and the horizontal spread angle becomes narrower.

[0216] If the turn-on voltage of the pn junction is set to 1.335V, the voltage drop from the quantum well active layer 7 down to the first conductivity type (n) side is set to 0.14V, and the operating current for a light output of 5W is set to 5.0A, then without current injection (W) o =0μm), when the resonator is configured with a non-injection current structure throughout (L f =L c =4mm, W o =12μm) and when a non-injected current structure is set in a part of the resonator (L f =3mm, W o =12μm) that is, setting L f =3mm current limiting area (C) n The operating voltages at the specified times are 1.518V, 1.548V, and 1.539V, respectively, and the power conversion efficiencies at a light output of 5W are 63.4%, 62.1%, and 62.5%, respectively.

[0217] In the ridge-type large-area semiconductor laser device 120 according to Embodiment 3, a current limiting region (C) as described above is provided. n In the case of a non-injection structure throughout the resonator, the gain difference between modes becomes larger compared to the case where there is no current injection. Based on this, the gain G of the lower-order modes (0th to 2nd order) increases. i The gain G becomes higher than other higher-order modes. i Therefore, laser oscillations are induced in a low-order mode, resulting in a narrower horizontal spread angle.

[0218] Furthermore, the ridge-type large-area semiconductor laser device 120 according to Embodiment 3 is provided with the aforementioned current-limiting region (C). n In the case of ), and in the case of not setting a current limiting region at all (C) n Compared to the case where the current injection area is smaller, the operating voltage is higher to some extent compared to the case where there is no current injection structure throughout the resonator. In addition, the power conversion efficiency is also lower to some extent.

[0219] On the other hand, compared to a structure where current is not injected throughout the resonator, the current injection area is larger, but this means that the resistance is smaller, thus resulting in a lower operating voltage and higher power conversion efficiency.

[0220] exist Figure 13 In the diagram, white triangles and diamonds are used to indicate the presence of a non-injection current structure throughout the resonator (L). f =L c =4mm, W o =8μm) and when a non-injection current structure is set in a part of the resonator (L f =1mm, W o =8μm) that is, setting the length L f =1mm current limiting area (C) n Gain G in each mode at time ) i Additionally, for comparison, black circles are used to indicate the absence of current non-injection throughout the resonator (W). o Gain G of each mode (=0μm) i .

[0221] When a current-non-injection structure is set in a part of the resonator (L f =1mm, W o =8μm) that is, setting the length L f =1mm current limiting area (C) n When this occurs, a gain difference is observed between the modes, with the gain G of lower-order modes such as 0th to 3rd order being significantly different. i The gain G becomes higher than other higher-order modes. i .

[0222] Typically, due to the gain G of semiconductor laser devices i Oscillation occurs in the higher-order mode, so a lower-order mode is selected, resulting in a narrower beam spread angle. This applies across the resonator length L. c (L c =4mm) Overall setting of the width W of the outer ridge area o When the current is not injected at 8μm, the gain difference between modes increases further, oscillates in a lower order mode, and the horizontal spread angle becomes narrower.

[0223] If the turn-on voltage of the pn junction is set to 1.335V, the voltage drop from the quantum well active layer 7 down to the first conductivity type (n-type) side is set to 0.14V, and the operating current at a light output of 5W is set to 5.0A, then when a non-injection current structure is configured throughout the resonator (L... f =L c =4mm, W o=8μm) and when a non-injection current structure is set in a part of the resonator (L f =1mm, W o =8μm) that is, setting the length L f =1mm current limiting area (C) n The operating voltages at the two times were calculated to be 1.535V and 1.522V, respectively, and the power conversion efficiencies at the light output of 5W were 62.6% and 63.2%, respectively.

[0224] In the ridge-type large-area semiconductor laser device 120 according to Embodiment 3, a current limiting region (C) as described above is provided. n In the case of a non-injection structure throughout the resonator, the gain difference between modes becomes larger compared to the case where there is no current injection. Based on this, the gain G of the lower-order modes (0th to 3rd orders) increases. i The gain G becomes higher than other higher-order modes. i Therefore, laser oscillations are induced in a low-order mode, resulting in a narrower horizontal spread angle.

[0225] Furthermore, the ridge-type large-area semiconductor laser device 120 according to Embodiment 3 is provided with the aforementioned current-limiting region (C). n In the case of ), and in the case of not setting a current limiting region at all (C) n Compared to the case where the current injection area is smaller, the operating voltage is higher to some extent compared to the case where there is no current injection structure throughout the resonator. In addition, the power conversion efficiency is also lower to some extent.

[0226] On the other hand, compared to a structure where current is not injected throughout the resonator, the current injection area is larger, but this means that the resistance is smaller, thus resulting in a lower operating voltage and higher power conversion efficiency.

[0227] exist Figure 14 In the diagram, white triangles and diamonds are used to indicate the presence of a non-injection current structure throughout the resonator (L). f =L c =4mm, W o =15μm) and when a non-injection current structure is set in a part of the resonator (L f =2mm, W o =15μm) that is, setting the length L f =2mm current limiting area (C) n Gain G in each mode at time ) i Additionally, for comparison, black circles are used to indicate the absence of current non-injection throughout the resonator (W). o Gain G of each mode (=0μm) i .

[0228] When a current-non-injection structure is set in a part of the resonator (L f =2mm, W o =8μm) that is, setting the length L f =2mm current limiting area (C) n When this occurs, a gain difference is observed between the different modes, with the gain G of lower-order modes such as 0th to 2nd order being significantly different. i The gain G becomes higher than other higher-order modes. i .

[0229] Typically, due to the gain G of semiconductor laser devices i Oscillation occurs in the higher-order mode, so a lower-order mode is selected, resulting in a narrower beam spread angle. This applies across the resonator length L. c (L c =4mm) Overall setting of the width W of the outer ridge area o When the current is not injected at 8μm, the gain difference between modes increases further, oscillates in a lower order mode, and the horizontal spread angle becomes narrower.

[0230] If the turn-on voltage of the pn junction is set to 1.335V, the voltage drop from the quantum well active layer 7 down to the first conductivity type (n-type) side is set to 0.14V, and the operating current at a light output of 5W is set to 5.0A, then when a non-injection current structure is configured throughout the resonator (L... f =L c =4mm, W o =15μm) and when a non-injection current structure is set in a part of the resonator (L f =2mm, W o =15μm) that is, setting the length L f =2mm current limiting area (C) n The operating voltages at the two times were calculated to be 1.560V and 1.535V, respectively, and the power conversion efficiencies at the light output of 5W were 61.6% and 62.6%, respectively.

[0231] In the ridge-type large-area semiconductor laser device 120 according to Embodiment 3, a current limiting region (C) as described above is provided. n In the case of a non-injection structure throughout the resonator, the gain difference between modes becomes larger compared to the case where there is no current injection. Based on this, the gain G of the lower-order modes (0th to 3rd orders) increases. i The gain G becomes higher than other higher-order modes. i Therefore, laser oscillations are induced in a low-order mode, resulting in a narrower horizontal spread angle.

[0232] Furthermore, the ridge-type large-area semiconductor laser device 120 according to Embodiment 3 is provided with the aforementioned current-limiting region (C). n In the case of ), and in the case of not setting a current limiting region at all (C) n Compared to the case where the current injection area is smaller, the operating voltage is higher to some extent compared to the case where there is no current injection structure throughout the resonator. In addition, the power conversion efficiency is also lower to some extent.

[0233] On the other hand, compared to a structure where current is not injected throughout the resonator, the current injection area is larger, but this means that the resistance is smaller, thus resulting in a lower operating voltage and higher power conversion efficiency.

[0234] Based on the above, when a current-free injection structure, i.e., a current-limited region (C) is set in a part of the resonator... n When, regardless of the current limiting region (C) n ) length or width of the lateral region of the spine W o How wide is it, compared to the area without current limiting (C)? n Compared to the previous case, both can set the gain difference between the allowed modes. Based on this, the gain G of the lower-order mode can be increased. i Gain G becomes higher than that of higher-order modes i Therefore, laser oscillation is achieved in a low-order mode, and the horizontal spread angle becomes narrower. Additionally, because the loss is not limited by the current-constrained region (C... n The gain G varies depending on the presence or absence of ) i Oscillation occurs, and the threshold current decreases.

[0235] Furthermore, in the ridge-type large-area semiconductor laser device 120 according to Embodiment 3, compared with the structure in which a current-non-injection structure is provided throughout the resonator, the operating voltage is reduced and the power conversion efficiency is increased.

[0236] The ridge-shaped large-area semiconductor laser device 120 described in Embodiment 3 also has the same structure as that described in Embodiment 1. n <u p This structure shifts the light intensity distribution in the y-direction (i.e., the stacking direction) towards the n-type GaAs substrate 2 side, thereby reducing the fixed number of allowed modes in the x-direction (i.e., the ridge width direction). By reducing the fixed number of allowed modes in advance, it becomes easier to set gain differences between allowed modes, which is advantageous from the perspective of oscillating in lower-order modes.

[0237] In the large-area semiconductor laser device 120 according to Embodiment 3, although the first ESL layer 10 is disposed between the p-side second guiding layer 9 and the p-type AlGaAs cladding layer 11a, the first ESL layer 10 may also be disposed within the p-type AlGaAs cladding layer 11a. In this case, although the upper p-type AlGaAs cladding layer 11a of the first ESL layer 10 is removed by etching, the lower p-type AlGaAs cladding layer 11a of the first ESL layer 10 remains, which facilitates current propagation.

[0238] As a method to reduce the fixed number of allowed modes by shifting the light intensity distribution towards the n-type GaAs substrate 2, examples include increasing the thickness of the p-type AlGaAs low-refractive-index layer 10 and decreasing the refractive index n of the p-type AlGaAs low-refractive-index layer 10. lp To increase the refractive index n of the n-type AlGaAs coating layer 3 cn The refractive index n is higher than that of the p-type AlGaAs cladding layer 11a. cp wait.

[0239] Furthermore, in the ridge-type large-area semiconductor laser device 120 according to Embodiment 3, a current-free structure is formed by disposing a SiN insulating film 15a on a portion of the upper surface of the p-type GaAs contact layer 14. Therefore, there are fewer etching processes and no proton injection processes, which has the advantage of being extremely easy to manufacture compared with the structures of Embodiment 1 and Embodiment 2.

[0240] In the ridge-type large-area semiconductor laser device 120 according to Embodiment 3, since it is configured such that a current-non-injection structure, i.e., a current-limiting region, is provided in a part of the resonator and a current-injection region is provided in the remaining part of the resonator, and a current-non-injection structure is formed by providing a SiN insulating film 15a on a part of the upper surface of the p-type GaAs contact layer 14, the gain of the low-order mode becomes higher than the gain of the high-order mode, laser oscillation can be performed in the low-order mode and the horizontal spread angle is narrowed. Compared with the structure in which the current-non-injection structure is provided throughout the entire resonator, the resistance is reduced. Therefore, the operating voltage is reduced and the power conversion efficiency is increased. Furthermore, by suppressing the increase in scattering loss caused by crystal defects, high reliability can be achieved and the fabrication is extremely easy.

[0241] Implementation Method 4

[0242] Figure 15A This is a perspective view showing the 975nm ridge-shaped large-area semiconductor laser device 130 with an actual refractive index distribution according to Embodiment 4. Additionally, Figure 15B It is the current injection region (C) of the ridge-type large-area semiconductor laser device 130. i The sectional view along Figure 15A A sectional view taken along line A-A.

[0243] The ridge-type large-area semiconductor laser device 130 according to Embodiment 4 includes a first p-type AlGaAs cladding layer 11b with an Al composition ratio of 0.20 and a layer thickness of 0.50 μm, a second p-type AlGaAs etch barrier layer 12a (second ESL layer 12a) with an Al composition ratio of 0.55 and a layer thickness of 40 nm, a second p-type AlGaAs cladding layer 13a with an Al composition ratio of 0.20 and a layer thickness of 0.96 μm, a p-type GaAs contact layer 14a with a layer thickness of 0.2 μm, a SiN insulating film 15b with a film thickness of 0.2 μm, and a p-type electrode 16a.

[0244] The ridge-shaped large-area semiconductor laser device 130 involved in embodiment 4 and Figure 3A , Figure 3B The difference in construction between the ridge-shaped large-area semiconductor laser device 100 according to Embodiment 1 shown is that, in the length L f Current limiting region (C) n ) and current injection region (C i Between ), there is a section of length L. t The cone-shaped current-limiting region (C) t Furthermore, the following describes the cone-shaped current-limiting region (C). t Also known as the cone region (C) t ).

[0245] In the cone-shaped current-limiting region (C) t The width of the ridge region in the ridge width direction of the non-injected current structure in the current-limited region (C) n At the end that contacts the ridge, the outer region (I) a o The width W of the lateral region of the spine o Consistent, and with the current-limited region (C) n ) Towards the current injection region (C i This decreases in the region with current injection (C) i The part that is in contact becomes zero.

[0246] The following describes a method for manufacturing the ridge-shaped large-area semiconductor laser device 130 according to Embodiment 4.

[0247] Except for the length of L covered by the resist f Current limiting region (C) n The medial region of the spine (I) a i ), length L t The cone-shaped current-limiting region (C) tThe medial region of the spine (I) a i and length L c -(L f +L t The current injection region (C) i ) ridge region (I a It is then dry-etched beyond the second ESL layer 12a, using the same fabrication method as the structure in Embodiment 1.

[0248] Even if etched down to the second ESL layer 12a, the effective refractive index of this etched area becomes the same as that of the inner ridge region (I). a i The effective refractive index n a i The same value is applied in the cone-shaped current limiting region (C). t The number of modes allowed in the construction of ) becomes the same as the number of modes without a cone region.

[0249] If a cone-shaped current limiting region (C) is set t Since the gain distribution in the ridge width direction (x-direction) perceived by the reciprocating light within the resonator gradually expands or shrinks, it effectively suppresses the nonlinearity (kink) of the light output-current characteristics (P-I characteristics) of the semiconductor laser device. Furthermore, the cone-shaped current-limiting region (C... t ) length L t It satisfies 0 < L t <L c Any value of .

[0250] In the ridge-type large-area semiconductor laser device 130 described in Embodiment 4, since the length is L f Current limiting region (C) n ) and current injection region (C i A length of L is set between ) t The cone-shaped current-limiting region (C) t Therefore, in addition to the effects of the ridge-type large-area semiconductor laser device 100 involved in Embodiment 1, it also has the effect of suppressing the nonlinearity (kink) of the light output-current characteristic (P-I characteristic).

[0251] Implementation Method 5

[0252] Figure 16A This is a perspective view showing the 975nm ridge-shaped large-area semiconductor laser device 140 with an actual refractive index distribution according to Embodiment 5. Additionally, Figure 16B It is the current injection region (C) of the ridge-type large-area semiconductor laser device 140. i The sectional view along Figure 16A A sectional view taken along line A-A.

[0253] exist Figure 16A In the diagram, 17a is the proton injection region. This is related to the construction shown in Embodiment 2. Figure 7A , Figure 7B The difference is that, in length L f Current limiting region (C) n ) and current injection region (C i A length of L is set between ) t The cone-shaped current-limiting region (C) t ).

[0254] The method for fabricating the ridge-shaped large-area semiconductor laser device 140 according to Embodiment 5, except for covering a length of L with a resist... f Current limiting region (C) n The medial region of the spine (I) a i ), length L t The cone-shaped current-limiting region (C) t The medial region of the spine (I) a i and length L c -(L f +L t The current injection region (C) i ) ridge region (I a The method of fabrication is the same as that of embodiment 2, except for the proton implantation region 17a formed by proton ion implantation.

[0255] The depth of proton ion implantation is such that even if the proton implantation site is removed by etching, the effective refractive index of that site becomes the same as that of the inner ridge region (I). a i The effective refractive index n a i At essentially the same depth, there is no region where light is practically absent. Therefore, there will be no decrease in slope efficiency due to increased light loss caused by scattering, nor a decrease in reliability due to crystal defects.

[0256] If a cone-shaped current limiting region (C) is set t The gain distribution along the ridge width direction (x-direction) perceived by the reciprocating light within the resonator gradually expands or shrinks, thus suppressing the nonlinearity (kink) of the light output-current characteristics (P-I characteristics) of the semiconductor laser device. Furthermore, the cone-shaped current-limiting region (C... t ) length L t It satisfies 0 < L t <Lc Any value of .

[0257] In the ridge-type large-area semiconductor laser device 140 described in Embodiment 5, since the length is L f Current limiting region (C) n ) and current injection region (C i A length of L is set between ) t The cone-shaped current-limiting region (C) t Therefore, in addition to the effects of the ridge-type large-area semiconductor laser device 110 involved in Embodiment 2, it also has the effect of suppressing the nonlinearity (kink) of the light output-current characteristic (P-I characteristic).

[0258] Implementation Method 6

[0259] Figure 17A This is a perspective view showing the 975nm ridge-shaped large-area semiconductor laser device 150 with an actual refractive index distribution according to Embodiment 6. Additionally, Figure 17B It is the current injection region (C) of the ridge-type large-area semiconductor laser device 150. i The sectional view along Figure 17A A sectional view taken along line A-A.

[0260] exist Figure 17A In the diagram, 15c is a SiN insulating film with a thickness of 0.2 μm. This is consistent with the structure shown in Embodiment 3. Figure 11A , Figure 11B The difference is that, in length L f Current limiting region (C) n ) and current injection region (C i A length of L is set between ) t The cone-shaped current-limiting region (C) t ).

[0261] The method for fabricating the ridge-shaped large-area semiconductor laser device 150 according to Embodiment 6, except for covering a length of L with a photoresist, f Current limiting region (C) n The medial region of the spine (I) a i ), length L t The cone-shaped current-limiting region (C) t The medial region of the spine (I) a i and length L c -(L f +L t The current injection region (C) i ) ridge region (I aThe fabrication method is the same as that of the structure in Embodiment 3, except that a SiN insulating film 15c is formed and then peeled off.

[0262] Since the current-non-injection structure is formed by the SiN insulating film 15c disposed on the upper surface of the p-type GaAs contact layer 14, the outer region of the ridge (I a o ) and the conical region (C t The effective refractive index of the current-injected structure and the inner ridge region (I) a i The effective refractive index n a i Similarly, regardless of the presence or absence of current non-injection structures, the number of allowed modes becomes the same.

[0263] If a cone-shaped current limiting region (C) is set t The gain distribution along the ridge width direction (x-direction) perceived by the reciprocating light within the resonator gradually expands or shrinks, thus suppressing the nonlinearity (kink) of the light output-current characteristics (P-I characteristics) of the semiconductor laser device. Furthermore, the cone-shaped current-limiting region (C... t ) length L t It satisfies 0 < L t <L c Any value of .

[0264] In the ridge-type large-area semiconductor laser device 150 described in Embodiment 6, since the length is L f Current limiting region (C) n ) and length L c -(L f +L t The current injection region (C) i A length of L is set between ) t The cone-shaped current-limiting region (C) t Therefore, in addition to the effect of the ridge-type large-area semiconductor laser device 120 involved in Embodiment 3, it also has the effect of suppressing the nonlinearity (kink) of the light output-current characteristic (P-I characteristic).

[0265] In the ridge-type large-area semiconductor laser devices described in embodiments 1 to 6, although the current-non-injection structure is configured to contact the end face, it can be arranged at any position as long as it is within the resonator. However, typically, for high-output semiconductor laser devices, the front end face is configured to have low reflectivity and the rear end face to have high reflectivity, and a large amount of light is emitted from the front end face. As disclosed in Non-Patent Document 5, the current density is higher on the low-reflectivity side within the resonator compared to the high-reflectivity side.

[0266] To achieve high power conversion efficiency by suppressing the rise in operating voltage, a current-free structure can be configured on the high reflectivity side with low current density. Conversely, to impart a large gain difference between permitted modes, a current-free structure can be configured on the low reflectivity side with high current density.

[0267] In this disclosure, a semiconductor laser device with an oscillation wavelength of 975 nm is described as an example, but it is not limited to this wavelength. For example, GaN-based lasers in the 400 nm band, GaInP-based lasers in the 600 nm band, and InGaAsP-based lasers in the 1550 nm band can also achieve the same effect.

[0268] Furthermore, in this disclosure, an n-type substrate is used to form a ridge structure on the p-type contact layer side, but conversely, a p-type substrate is used to form a ridge structure on the n-type contact layer side, and the same effect can be obtained.

[0269] Furthermore, this disclosure illustrates a large-area semiconductor laser device with a ridge region width of 2W and 100μm, but it is not limited to this value. As long as higher-order modes above the first order are allowed in the horizontal direction, it does not depend on the width.

[0270] Furthermore, in this disclosure, the resonator length L is illustrated. c It is a large-area semiconductor laser device with a diameter of 4mm, but it is not limited to this value and can take any value.

[0271] In embodiments 1 to 6, a ridge-type large-area semiconductor laser device is shown that uses a structure that reduces the number of allowed horizontal transverse modes, sets a gain difference between allowed horizontal transverse modes and oscillates in a low-order mode to narrow the horizontal extension angle. However, it is not limited to this. Even a typical ridge-type large-area semiconductor laser device that does not reduce the number of horizontal transverse modes will achieve the same effect.

[0272] In embodiments 1 to 6, the lateral spinal region (I a o The effective refractive index n a o With the medial region of the spine (I a i The effective refractive index n a i They are equal, but only if they are substantially the same as described in Implementation 1.

[0273] This disclosure describes various exemplary embodiments and examples, but the various features, methods and functions described in one or more embodiments are not limited to the application of a specific embodiment, but can be applied to the embodiment alone or in various combinations.

[0274] Therefore, numerous variations not illustrated can be conceived within the scope of the technology disclosed in this application. These include variations, additions, or omissions of at least one constituent element, as well as the extraction of at least one constituent element and its combination with constituent elements of other embodiments.

[0275] Explanation of reference numerals in the attached figures:

[0276] 1…n-type electrode (first conductivity type electrode); 2…n-type GaAs substrate; 3…n-type AlGaAs cladding layer; 4…n-type AlGaAs low refractive index layer; 5…n-side AlGaAs second photoconductor layer; 6…n-side AlGaAs first photoconductor layer; 7…InGaAs quantum well active layer; 8…p-side AlGaAs first photoconductor layer; 9…p-side AlGaAs second photoconductor layer; 10…p-type AlGaAs first ESL layer (p-type AlGaAs low refractive index layer); 11…p-type AlGaAs first cladding layer; 11a…p-type AlGaAs cladding layer; 11b…p-type AlGaAs first cladding layer; 12, 12a…p-type AlGaAs second etch barrier layer (second ESL layer); 13, 13a …p-type AlGaAs second cladding layer; 14, 14a…p-type GaAs contact layer; 15, 15a, 15b, 15c…SiN insulating film; 16, 16a…p-type electrode (second conductivity electrode); 17, 17a…proton implantation region; 61…n-side photoconductor layer (first conductivity side photoconductor layer); 81…p-side photoconductor layer (second conductivity side photoconductor layer); 100, 110, 120, 130, 140, 150…ridge-type large-area semiconductor laser device; 101…active layer; 102…guide layer; 103…first etch barrier layer (first ESL layer); 104…p-type first cladding layer; 105…second etch barrier layer (second ESL layer); 106…p-type second cladding layer; 107…p-type contact layer.

Claims

1. A semiconductor laser device, have: Semiconductor substrate of the first conductivity type; A first conductivity type cladding layer, a first conductivity type photoconductive layer, an active layer, a second conductivity type photoconductive layer, a second conductivity type cladding layer, and a second conductivity type contact layer are sequentially stacked on the first conductivity type semiconductor substrate; and It consists of a front face and a rear face that cause the laser to reciprocate, and has a length of L. c The resonator, The oscillation wavelength of the semiconductor laser device is λ. Its features are, The resonator has a length of L f The current-limiting region and its length are L c -L f The current injection region is formed. The current-limiting region consists of an inner ridge region, an outer ridge region, and a covering region. The width of the inner ridge region is 2W. i This indicates that the effective refractive index is n. a i The outer region of the spine is located on both sides of the inner region of the spine, and its width is defined by W. o This indicates that the effective refractive index is n. a o It also has a current-free injection structure, the coating region is located on both sides of the outer region of the ridge, the contact layer of the second conductivity type and at least a portion of the coating layer of the second conductivity type are removed, and the effective refractive index is n. c , The average refractive index n of the inner and outer regions of the ridge a e Expressed as follows: ， And it satisfies the following relationship: ， The number of modes allowed in the ridge width direction of the current limiting region is m, where m is an integer greater than or equal to 2. The width W of the lateral region of the spine o It is wider than the distance from the lower end of the current-injected structure to the active layer. The current injection region consists of a ridge region and a covering region, wherein the effective refractive index of the ridge region is a real number n. a The width in the ridge direction is represented by 2W, and the covering area is located on both sides of the ridge area. The number of modes allowed in the ridge width direction of the current injection region is the same as the number of modes allowed in the current limiting region, which is m. The length L of the current limiting region f Longer than zero and longer than the length L of the resonator c short.

2. The semiconductor laser device according to claim 1, characterized in that, The second conductivity type coating layer is composed of a first coating layer of the second conductivity type and a second coating layer of the second conductivity type. The non-injection current structure in the outer region of the ridge has an insulating film covering the exposed surface obtained by removing the contact layer of the second conductivity type and at least a portion of the second coating layer of the second conductivity type in the outer region of the ridge.

3. The semiconductor laser device according to claim 1, characterized in that, The non-injection structure of the lateral region of the ridge is composed of a proton-injected region.

4. The semiconductor laser device according to claim 1, characterized in that, The current-injection-free structure of the outer ridge region is composed of an insulating film that covers a portion of the surface at both ends of the contact layer of the second conductivity type in the ridge width direction of the outer ridge region.

5. The semiconductor laser device according to any one of claims 1 to 4, characterized in that, The refractive index of the coating layer of the first conductivity type is set to n. cn The refractive index of the coating layer of the second conductivity type is set to n. cp , Between the photoconductive layer on the first conductivity type side and the cladding layer of the first conductivity type, or within the cladding layer of the first conductivity type, there is a layer with a thickness of d. ln And the refractive index n ln The refractive index n of the coating layer of the first conductivity type cn A low-refractive-index layer of the first conductivity type, and having a layer thickness of d between or within the cladding layer of the second conductivity type on the second conductivity type side. lp And the refractive index n lp A low-refractive-index layer of the second conductivity type with a lower refractive index than the coating layer of the second conductivity type, and satisfying the following equation: 。 6. The semiconductor laser device according to any one of claims 1 to 4, characterized in that, The thickness of the photoconductor layer on the first conductivity type side is greater than the thickness of the photoconductor layer on the second conductivity type side.

7. The semiconductor laser device according to any one of claims 1 to 4, characterized in that, Let d be the sum of the thicknesses of the photoconductor layer on the first conductivity type side, the active layer, and the photoconductor layer on the second conductivity type side. gy m The average refractive index of the photoconductor layer on the first conductivity type side, the active layer, and the photoconductor layer on the second conductivity type side is set to n. gy m And the refractive index n of the coating layer of the first conductivity type cn and the refractive index n of the coating layer of the second conductivity type cp Let the refractive index of the higher of these two be n. c h In the case of stacking direction, the normalized frequency V is expressed by the following formula. y Greater than π / 2, 。 8. The semiconductor laser device according to any one of claims 1 to 4, characterized in that, The refractive index n of the coating layer of the first conductivity type cn The refractive index n of the coating layer is higher than that of the second conductivity type. cp .

9. A semiconductor laser device, have: Semiconductor substrate of the first conductivity type; A first conductivity type cladding layer, a first conductivity type photoconductive layer, an active layer, a second conductivity type photoconductive layer, a second conductivity type cladding layer, and a second conductivity type contact layer are sequentially stacked on the first conductivity type semiconductor substrate; and It consists of a front face and a rear face that cause the laser to reciprocate, and has a length of L. c The resonator, The oscillation wavelength of the semiconductor laser device is λ. Its features are, The resonator has a length of L f The current-limiting region has a length of L. c - (L) f +L t The current injection region and the length L between the current limiting region and the current injection region. t It consists of a cone-shaped region. The current-limiting region consists of an inner ridge region, an outer ridge region, and a covering region. The width of the inner ridge region is 2W. i This indicates that the effective refractive index is n. a i The outer region of the spine is located on both sides of the inner region of the spine, and its width is defined by W. o This indicates that the effective refractive index is n. a o It also has a current-free injection structure, the coating region is located on both sides of the outer region of the ridge, the contact layer of the second conductivity type and at least a portion of the coating layer of the second conductivity type are removed, and the effective refractive index is n. c , The average refractive index n of the inner and outer regions of the ridge a e Expressed as follows: ， And it satisfies the following relationship: ， The number of modes allowed in the ridge width direction of the current limiting region is m, where m is an integer greater than or equal to 2. The width W of the lateral region of the spine o It is wider than the distance from the lower end of the current-injected structure to the active layer. The current injection region consists of a ridge region and a covering region, wherein the effective refractive index of the ridge region is a real number n. a The width in the ridge width direction is represented by 2W, and the covering area is located on the outside of the ridge area. The number of modes allowed in the ridge width direction of the current injection region is the same as the number of modes allowed in the current limiting region, which is m. The length L of the current limiting region f Longer than zero For the conical region, the length L of the conical region t The width of the non-injected current structure in the conical region in the ridge width direction is longer than zero, and the width W of the outer region of the ridge is greater than zero at the end that contacts the current-limiting region. o It is consistent and decreases from the current limiting region toward the current injection region, and becomes zero at the portion that contacts the current injection region.

10. The semiconductor laser device according to claim 9, characterized in that, The second conductivity type coating layer is composed of a first coating layer of the second conductivity type and a second coating layer of the second conductivity type. The non-injection current structure in the outer region of the ridge has an insulating film covering the exposed surface obtained by removing the contact layer of the second conductivity type and at least a portion of the second coating layer of the second conductivity type in the outer region of the ridge.

11. The semiconductor laser device according to claim 9, characterized in that, The non-injection structure of the lateral region of the ridge is composed of a proton-injected region.

12. The semiconductor laser device according to claim 9, characterized in that, The current-injection-free structure of the outer ridge region is composed of an insulating film that covers a portion of the surface at both ends of the contact layer of the second conductivity type in the ridge width direction of the outer ridge region.

13. The semiconductor laser device according to any one of claims 9 to 12, characterized in that, The refractive index of the coating layer of the first conductivity type is set to n. cn The refractive index of the coating layer of the second conductivity type is set to n. cp , Between the photoconductive layer on the first conductivity type side and the cladding layer of the first conductivity type, or within the cladding layer of the first conductivity type, there is a layer with a thickness of d. ln And the refractive index n ln The refractive index n of the coating layer of the first conductivity type cn A low-refractive-index layer of the first conductivity type, and having a layer thickness of d between or within the cladding layer of the second conductivity type on the second conductivity type side. lp And the refractive index n lp A low-refractive-index layer of the second conductivity type with a lower refractive index than the coating layer of the second conductivity type, and satisfying the following equation: 。 14. The semiconductor laser device according to any one of claims 9 to 12, characterized in that, The thickness of the photoconductor layer on the first conductivity type side is greater than the thickness of the photoconductor layer on the second conductivity type side.

15. The semiconductor laser device according to any one of claims 9 to 12, characterized in that, Let d be the sum of the thicknesses of the photoconductor layer on the first conductivity type side, the active layer, and the photoconductor layer on the second conductivity type side. gy m The average refractive index of the photoconductor layer on the first conductivity type side, the active layer, and the photoconductor layer on the second conductivity type side is set to n. gy m And the refractive index n of the coating layer of the first conductivity type cn and the refractive index n of the coating layer of the second conductivity type cp Let the refractive index of the higher of these two be n. c h In the case of stacking direction, the normalized frequency V is expressed by the following formula. y Greater than π / 2, 。 16. The semiconductor laser device according to any one of claims 9 to 12, characterized in that, The refractive index n of the coating layer of the first conductivity type cn The refractive index n of the coating layer is higher than that of the second conductivity type. cp .

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