Semiconductor laser device

Abstract

The semiconductor laser device of the present disclosure includes: a cladding layer (3) of a first conductive type stacked on a semiconductor substrate (2), a light guide layer (61) on the first conductive type side, an active layer (7), a light guide layer (81) on the second conductive type side, a cladding layer (11) of a second conductive type, and a contact layer (14) of the second conductive type; a resonator composed of a front end face and a back end face; and a ridge region that guides a laser wave between the front end face and the back end face, characterized in that the ridge region is composed of an inner ridge region and an outer ridge region, the effective refractive index of the inner ridge region is n a i the outer ridge region is provided on both sides of the inner ridge region, the effective refractive index is n a o and has a current non-injection structure, and the width W o of the outer ridge region is greater than the distance from the lower end of the current non-injection structure to the active layer.

Description

Technical Field

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

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

[0003] Patent Document 1 discloses the following: A ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the horizontal direction has a light guiding layer with a thickness sufficient to allow higher-order modes of order one or more in the crystal stacking direction. Furthermore, on both sides of the ridge structure, a terrace region is provided via grooves, with a refractive index lower than the effective refractive index of the ridge region and a higher refractive index than the cladding region. This reduces the number of modes allowed in the horizontal direction and narrows the horizontal diffusion angle. Here, the real refractive index distribution refers to the refractive index distribution described by real numbers. The waveguide mechanism is called a refractive index waveguide, and the electric field distribution, magnetic field distribution, and propagation constant obtained by solving the wave equation are real numbers.

[0004] Patent document 2 discloses the following: In a ridge-type large-area semiconductor laser device in which a refractive index difference is set in the horizontal direction by embedding a semiconductor layer on both sides of the ridge structure, 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 structure and the semiconductor layer to be current non-injected; and the current non-injection width is preferably set to 10 μm or less in order to suppress the increase of loss.

[0005] Patent document 3 discloses a ridge-type large-area semiconductor laser device as follows: by leaving a central region with a ridge width of 15 μm in a ridge structure that allows higher-order modes, and injecting protons from the ridge surface to a depth of 1.6 μm up to the bottom of the ridge, the high resistance of the proton injection region is implemented, and current flows in the central region with a ridge width of 15 μm in the ridge structure, thereby increasing the gain of the fundamental mode and enabling the fundamental mode to oscillate selectively.

[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: Iga, ed., "Semiconductor Lasers", pp. 35-38, October 25, 2017 (Ohm Corporation).

[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] In conventional ridge-type large-area semiconductor laser devices with a real refractive index distribution, reducing the number of allowed modes in the horizontal direction can narrow the average horizontal spread angle compared to when there are more allowed modes. However, there is a problem that 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.

[0014] Furthermore, unlike conventional ridge-type large-area semiconductor laser devices with real refractive index distribution, large-area semiconductor laser devices with embedded semiconductor layers do not exhibit peak NFP near the two ends of the ridge structure. In addition, when the current is locally reduced, the NFP in this area does not decrease.

[0015] In the case of a ridge-type large-area semiconductor laser device with a real refractive index distribution, although the NFP is determined by the linear coupling of the allowed modes, this is because when the current is reduced locally, its effect affects all modes.

[0016] Furthermore, the unique phenomenon observed in large-area semiconductor laser devices with embedded semiconductor layers is 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 a real refractive index distribution.

[0017] Furthermore, in conventional ridge-type large-area semiconductor laser devices, proton injection for high resistivity occurs only up to the bottom of the ridge structure, causing light emitted from the active layer to diffuse into this proton injection region. Since the proton injection region disrupts the crystallinity of the crystal layer constituting the ridge-type large-area semiconductor laser device, the light diffused into the proton injection region suffers significant loss due to scattering caused by crystal defects. This results in a significant reduction in slope efficiency and even a significant reduction in power conversion efficiency. Moreover, because the proton injection region, containing numerous crystal defects, is close to the active layer, there is a problem of a significant decrease in the reliability of the ridge-type large-area semiconductor laser device due to these crystal defects. Summary of the Invention

[0018] This disclosure is made to address the aforementioned problems, with the aim of obtaining a ridge-type large-area semiconductor laser device with a real refractive index distribution that narrows the horizontal diffusion angle by causing the low-order mode to oscillate, thereby improving the coupling efficiency with optical components, in a configuration that reduces the number of modes allowed in the horizontal direction by making the gain of the low-order mode greater than that of the high-order mode. This also improves the coupling efficiency with optical components.

[0019] The semiconductor laser device disclosed in this application comprises: a semiconductor substrate of a first conductivity type; a cladding layer of the first conductivity type, a light guiding layer on the first conductivity type side, an active layer, a light guiding layer on the second conductivity type side, a cladding layer of the second conductivity type, and a contact layer of the second conductivity type stacked on the semiconductor substrate of the first conductivity type; a resonator composed of a front end facet and a rear end facet for reciprocating laser light; and a ridge region guiding the laser light between the front end facet and the rear end facet, the ridge region having a width represented by 2W. The oscillation wavelength of the semiconductor laser device is λ, and higher-order modes of first order or above are allowed in the stacking direction of the layers. The semiconductor laser device is characterized in that...

[0020] The aforementioned vertebral region consists of an inner vertebral region and an outer vertebral region, with the width of the inner vertebral region being 2W. i It is indicated that the effective refractive index is n. a i The outer region of the spine is located on both sides of the aforementioned inner region of the spine, and its width is W. o This indicates that the effective refractive index is n. a o Furthermore, it has a current-free injection structure, wherein at least the contact layer and the cladding layer of the second conductivity type are removed on both sides of the outer region of the ridge, and an effective refractive index of n is provided. c The average refractive index n of the covered region, the inner region of the ridge and the outer region of the ridge a e Represented as:

[0021] [Number 1]

[0022] Number 1(n a i ·W i +n a o ·W o ) / (W i +W o )

[0023] And satisfy the following formula:

[0024] [Number 2]

[0025] Number 2

[0026] The width of the aforementioned lateral region of the spine, i.e., W o It is greater than the distance from the lower end of the above-mentioned non-injected current structure to the above-mentioned active layer, and less than 1 / 2 of the width of the above-mentioned ridge region and W.

[0027] The semiconductor laser device disclosed in this application can achieve the following effects: Since the ridge region consists of an inner ridge region and an outer ridge region, and a current non-injection structure is provided in the outer ridge region, the current injected into the semiconductor laser device flows specifically in the inner ridge region. Therefore, the gain of the low-order mode can be greater than the gain of the high-order mode, and laser oscillation of the low-order mode can be performed, thereby narrowing the horizontal diffusion angle. In addition, since a current non-injection structure is provided in the region where there is no light emitted by the active layer, the increase in loss can be suppressed, and a semiconductor laser device with high efficiency and high reliability can be obtained. Attached Figure Description

[0028] Figure 1 This is a schematic diagram showing the current flow and refractive index distribution in a cross-section of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution, used as a comparative example.

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

[0030] Figure 3 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real 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 ridge-type large-area semiconductor laser device according to Embodiment 1.

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

[0033] Figure 6 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 1.

[0034] Figure 7 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 1.

[0035] Figure 8 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 1.

[0036] Figure 9 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, as described in Modification 2 of Embodiment 1.

[0037] Figure 10 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 1.

[0038] Figure 11 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 1.

[0039] Figure 12 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band according to Embodiment 2.

[0040] Figure 13 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device according to Embodiment 2.

[0041] Figure 14 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device according to Embodiment 2.

[0042] Figure 15 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 2, Example 1.

[0043] Figure 16 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 2.

[0044] Figure 17This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 2.

[0045] Figure 18 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 2.

[0046] Figure 19 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 2.

[0047] Figure 20 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 2.

[0048] Figure 21 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band according to Embodiment 3.

[0049] Figure 22 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device according to Embodiment 3.

[0050] Figure 23 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device according to Embodiment 3.

[0051] Figure 24 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 3, Example 1.

[0052] Figure 25 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 3.

[0053] Figure 26 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 3.

[0054] Figure 27 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to Variation 2 of Embodiment 3.

[0055] Figure 28 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 3.

[0056] Figure 29This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 3.

[0057] Figure 30 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band according to Embodiment 4.

[0058] Figure 31 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device according to Embodiment 4.

[0059] Figure 32 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device according to Embodiment 4.

[0060] Figure 33 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 4, Example 1.

[0061] Figure 34 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 4.

[0062] Figure 35 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 4.

[0063] Figure 36 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to Variation 2 of Embodiment 4.

[0064] Figure 37 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 4.

[0065] Figure 38 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 4.

[0066] Figure 39 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band according to Embodiment 5.

[0067] Figure 40 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device according to Embodiment 5.

[0068] Figure 41 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device according to Embodiment 5.

[0069] Figure 42 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 5, Example 1.

[0070] Figure 43 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 5.

[0071] Figure 44 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 1 of Embodiment 5.

[0072] Figure 45 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to Variation 2 of Embodiment 5.

[0073] Figure 46 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 5.

[0074] Figure 47 This is a graph showing the gain of each mode of the ridge-type large-area semiconductor laser device involved in Variation 2 of Embodiment 5.

[0075] Figure 48 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band according to Embodiment 6.

[0076] Figure 49 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 6, Example 1.

[0077] Figure 50 This is a perspective view of a ridge-shaped large-area semiconductor laser device with a real refractive index distribution in the 975nm band, according to Variation 2 of Embodiment 6. Detailed Implementation

[0078] Implementation Method 1

[0079] First, use Figure 1 as well as Figure 2 The differences between this disclosure and the comparative examples will be explained.

[0080] Figure 1 This is a schematic diagram showing the flow of current I and the refractive index distribution in a cross section orthogonal to the direction of the optical guide wave in a ridge-shaped large-area semiconductor laser device with a real refractive index distribution, used as a comparative example.

[0081] exist Figure 1 The structure consists of the following layers, starting from the bottom semiconductor substrate (not shown): active layer 101, light guiding layer 102, first etch stop layer 103 (first ESL layer), p-type first cladding layer 104, second etch stop layer 105 (second ESL layer), and p-type second cladding layer 106.

[0082] If the distance from the upper end of the active layer 101 to the upper end of the first ESL layer 103 is defined as h2, then in the ridge region I a The current I flowing in the middle also flows from the upper end of the first ESL layer 103 in the horizontal direction. Figure 1 The current diffuses in the x-direction. The current distribution J(x) at the upper end of the active layer 101 can be determined using Non-Patent Document 1. Here, the x-direction is sometimes also referred to as the ridge width direction.

[0083] Ridge region I with a ridge width of 2W a Forming regions II that are covered on both sides in the horizontal direction (x direction). c The sandwiched structure. Ridge region I a and the covered area II c The effective refractive index is respectively determined by n a and n c Based on non-patent literature 2, the normalized frequency v can be defined as shown in equation (1) below.

[0084] [Number 3]

[0085] Number 3

[0086] Here, λ is the oscillation wavelength of the semiconductor laser device. The normalized frequency v divided by π / 2, rounded to the nearest integer, and then incremented by 1, yields the number INT[v / (π / 2)]+1, which represents the wavelength in the horizontal direction. Figure 1 The number of patterns allowed in the x-direction.

[0087] Figure 2 This is a schematic diagram illustrating the current flow and refractive index distribution in a cross-section orthogonal to the optical guide wave direction of the ridge-shaped large-area semiconductor laser device with a real refractive index distribution disclosed in this application. The configuration is such that a section with a width of W... o Lateral region I (hereinafter referred to as the lateral region width) a o In essence, the effective refractive index and width are 2W. i (Hereinafter referred to as the width of the medial spinal region) Medial spinal region I a i The same area of ​​the structure is removed by etching.

[0088] Lateral spinal region I a o In the ridge region I a Internally located in the medial region I a i On both sides of the ridge width direction, covering area II c Located in the lateral spinal region I a o Both sides of the ridge width direction.

[0089] Here, "effectively the same refractive index" essentially means that in the inner region I of the ridge... a i The effective refractive index is set to n a i And the lateral spinal region I a o The effective refractive index is set to n a o When the average refractive index n is calculated by equation (2), a e Substituting n into equation (1) a The number of permissible patterns calculated is related to the absence of lateral spinal region I. a o The case is that the width W of the lateral region of the spine o The number of allowed modes is the same when the value is zero.

[0090] [Number 4]

[0091] Number 4n a e =(n a i ·W i +n a o ·W o ) / (W i +W o (2)

[0092] Due to etching, the lateral ridge region I a o The upper part is removed up to the top of the first ESL layer 103 and covered with an insulating film (not shown), so the current I is specifically in the inner region of the ridge I. a i The current I flows in the middle. 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 h1, then the current I also starts to diffuse horizontally from the upper end of the second ESL layer 105 and reaches the active layer 101 via a distance of h1+h2.

[0093] The allowed i-th order mode in the horizontal direction will be set to And it is standardized as shown in equation (3) below. Wherein, the allowed patterns... It can be determined from non-patent literature such as document 2.

[0094] [Number 5]

[0095] Number 5

[0096] On the other hand, the current is set to a width of 2W in the inner region of the ridge. i And the inner region I of the ridge with resonator length L a i A current of 1 ampere (A) flows through the active layer 101, and the current distribution J(x) at the upper end of the active layer 101 is normalized as shown in equation (4) below.

[0097] [Number 6]

[0098] Number 6

[0099] Gain G i Since it is generated by the interaction of light and current, it is defined as shown in equation (5) below. Here, since both the light distribution (mode) and the current distribution are normalized, the gain G is... i The magnitude of the gain indicates the difference in gain between different modes.

[0100] [Number 7]

[0101] Number 7

[0102] Figure 3 This is a perspective view of a ridge-shaped large-area semiconductor laser device 500 with a real refractive index distribution in the 975nm band according to Embodiment 1.

[0103] exist Figure 3 For ease of explanation, an orthogonal xyz coordinate system is defined. The z-axis is the direction in which the laser emitted from the ridge-type large-area semiconductor laser device 500 is emitted, and it is also the length direction axis of the resonator in the ridge-type large-area semiconductor laser device 500. The z-direction is also referred to as the "resonator length direction". The y-axis is parallel to the normal to the upper surface of the n-type GaAs substrate 2. The y-axis direction is consistent with the crystal growth direction of the semiconductor layer formed on the n-type GaAs substrate 2. The y-axis direction is also referred to as the "stack direction". The x-axis is an axis perpendicular to the yz plane and is consistent with the width direction axis of the ridge-type large-area semiconductor laser device 500. The x-axis direction is also referred to as the "ridge width direction". Horizontal transverse modes are generated in the ridge-type large-area semiconductor laser device 500 along the x-axis. The rules related to the orthogonal coordinate system described above also apply to the three-dimensional diagrams of other ridge-type large-area semiconductor laser devices described later.

[0104] like Figure 3 As shown, the ridge-type large-area semiconductor laser device 500 is composed of the following parts starting from the lower surface side (also called the back side): 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 ), an n-type AlGaAs low-refractive-index layer 4 (first conductivity type low-refractive-index layer, refractive index n) with an Al composition ratio of 0.25 and a layer thickness of 200 nm. n 5. An n-side AlGaAs second light guiding layer with an Al composition ratio of 0.16 and a layer thickness of 1100 nm; 6. An n-side AlGaAs first light guiding layer with an Al composition ratio of 0.14 and a layer thickness of 100 nm; 7. An InGaAs quantum well active layer with an In composition ratio of 0.119 and a layer thickness of 8 nm; 8. A p-side AlGaAs first light guiding layer with an Al composition ratio of 0.14 and a layer thickness of 300 nm; 9. A p-side AlGaAs second light guiding layer with an Al composition ratio of 0.16 and a layer thickness of 300 nm; 10. A p-type AlGaAs first ESL layer with an Al composition ratio of 0.55 and a layer thickness of 140 nm (also known as a p-type AlGaAs low refractive index layer or a low refractive index layer of the second conductivity type). Refractive index n p A p-type AlGaAs first cladding layer 11 (a first cladding layer of the second conductivity type, with an Al composition ratio of 0.20 and a layer thickness of 0.55 μm, and a refractive index n) is formed. cp 11) A p-type AlGaAs second ESL layer with an Al composition ratio of 0.55 and a layer thickness of 40 nm; 12) A p-type AlGaAs second cladding layer with an Al composition ratio of 0.20 and a layer thickness of 0.95 μm (a second cladding layer of the second conductivity type, with a refractive index n). cp The film consists of a p-type GaAs contact layer 14 (a second conductivity type contact layer) with a thickness of 0.2 μm, a SiN film 15 with a thickness of 0.2 μm, and a p-type electrode 16 (a second conductivity type electrode) on the upper surface side.

[0105] Specifically, the n-side AlGaAs second light guiding layer 5 and the n-side AlGaAs first light guiding layer 6 are collectively referred to as the n-side light guiding layer 61 or the first conductivity type side light guiding layer 61, and the p-side AlGaAs first light guiding layer 8 and the p-side AlGaAs second light guiding layer 9 are collectively referred to as the p-side light guiding layer 81 or the second conductivity type side light guiding layer 81. Since each light guiding layer is typically undoped, the term "side" is added to distinguish which side of the InGaAs quantum well active layer 7 it is located on. That is, the n-side or first conductivity type side refers to the side relative to the InGaAs quantum well active layer 7 where each n-type or first conductivity type layer is disposed. Similarly, the p-side or second conductivity type side refers to the side relative to the InGaAs quantum well active layer 7 where each p-type or second conductivity type layer is disposed.

[0106] The first coating layer of the second conductivity type (p-type AlGaAs first coating layer 11) and the second coating layer 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.

[0107] 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 make the oscillation wavelength approximately 975nm.

[0108] In addition, at both ends of the ridge-shaped large-area semiconductor laser device 500, for example by cleaving, a front end face and a rear end face are provided to form a resonator that causes the laser to reciprocate.

[0109] In the ridge-type large-area semiconductor laser device 500, the above-described n-type and p-type conductivity types can also be interchanged. That is, the first conductivity type can be n-type and the second conductivity type can be p-type; alternatively, the first conductivity type can be p-type and the second conductivity type can be n-type. Hereinafter, they may also be referred to as the first conductivity type and the second conductivity type.

[0110] The following illustrates the fabrication method of the ridge-shaped large-area semiconductor laser device 500.

[0111] 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 Metal Organic Chemical Vapor Deposition (MOCVD).

[0112] Next, cover the inner ridge area I with a photoresist. a i It is then dry etched to the second ESL layer 12 and the resist is stripped off.

[0113] Subsequently, the inner ridge region I was covered with a photoresist. ai and lateral spinal region I a o Dry etch up to the first ESL layer 10 and strip the resist.

[0114] Cover the inner ridge area with corrosion resist I a i SiN film 15 is formed and stripped, and the resist is also stripped.

[0115] Finally, 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.

[0116] In the ridge-shaped large-area semiconductor laser device 500 according to Embodiment 1, at least the outer region I of the ridge is removed by etching. a o The device consists of a p-type GaAs contact layer 14 and a p-type AlGaAs second cladding layer 13, and the exposed surface after being removed by etching is covered by a SiN film 15 as an insulating film, thus creating a current-non-injected structure. Therefore, the current injected into the ridge-type large-area semiconductor laser device 500 is specifically concentrated in the inner region I of the ridge. a i Flowing in the middle.

[0117] For example, if the refractive index and its calculation method described in "Semiconductor Lasers" edited by Iga in Non-Patent Document 3 (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.

[0118] In addition, based on experience, the refractive indices of InGaAs with an In composition ratio of 0.119 constituting the InGaAs quantum well active layer 7 and SiN constituting the SiN film 15 are 3.542393 and 2.00, respectively.

[0119] In the ridge-type large-area semiconductor laser device 500 according to Embodiment 1, the total thickness of the light guiding layer, i.e., the sum of the p-side light guiding layer 81 and the n-side light guiding layer 61, is 1.8 μm, allowing modes of first order or higher in the stacking direction. Therefore, if a low-refractive-index layer is inserted between the cladding layer and the light guiding layer, the NFP (Near Field Pattern) becomes narrower, and the FFP (Far Field Pattern) becomes wider.

[0120] In addition, since the center of the InGaAs quantum well active layer 7 is displaced towards the p-type AlGaAs first cladding layer 11 and the p-type AlGaAs second cladding layer 13 relative to the n-side light guiding layer 61 and the p-side light guiding layer 81, the number of carriers retained in the light guiding layer when driving the laser can be reduced, thereby achieving high slope efficiency.

[0121] Instead of equation (1), use the u of equation (6) below. i Indicating at refractive index n ci The intercalation layer with a refractive index of n between the cladding layer and the light guiding layer i And the layer thickness is d i The size relationship in the case of a low refractive index layer.

[0122] [Number 8]

[0123] Number 8

[0124] In the case of the ridge-shaped large-area semiconductor laser device 500 according to Embodiment 1, u n It is 0.292273, u p It is 0.522208, u p >u n This is valid. Therefore, the light intensity distribution in the y-direction, i.e., the stacking direction, shifts towards the n-type GaAs substrate 2 side, which can reduce the number of allowed modes in the x-direction, i.e., the ridge width direction.

[0125] First, consider the width W of the lateral spinal region. o The case where the value is zero corresponds to the ridge structure of the comparative example. In this case, ridge region I... a and the covered area II c The effective refractive index can be calculated, for example, by the equivalent refractive index method described in Non-Patent Document 4, and is 3.41697 and 3.41672 respectively. When the ridge width 2W is 100 μm, v in Equation (1) is 13.31, allowing for 9 modes from the 0th order (basic mode) to the 8th order.

[0126] As with the ridge-shaped large-area semiconductor laser device 500 described in Embodiment 1, in the outer region I of the ridge a o The effective refractive index of this region, which is removed by etching up to the second ESL layer 12, is 3.41697, regardless of the removal by etching. Ridge region I a (Medial region I) a i and the lateral spinal region I a o The refractive indices of the two modes are the same. Therefore, the number of allowed modes is the same.

[0127] On the other hand, the current also diffuses in the x-direction, i.e., the ridge width direction, from the upper end of the second ESL layer 12. That is, the current diffuses in the x-direction along a distance h2 (0.74 μm) from the upper end of the InGaAs quantum well active layer 7 to the upper end of the first ESL layer 10 and a distance h1 (0.59 μm) from the upper end of the second ESL layer 12 to the upper end of the first ESL layer 10, reaching the InGaAs quantum well active layer 7. For simplicity, the resistivity ρ from the point where the current begins to diffuse in the x-direction to the InGaAs quantum well active layer 7 is set to 0.35 Ωcm. It has been confirmed that even if the value of the resistivity ρ changes, the gain G... i The trend is the same.

[0128] exist Figure 4 as well as Figure 5 The width W of the lateral region of the spine is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, so laser oscillation can be performed in any mode. Therefore, the horizontal spread angle deviates depending on which mode is used for laser oscillation.

[0129] When setting the lateral spine region I a o Make the current specifically in the inner side region I of the ridge a i During flow, a gain difference arises between the modes, with the gain of lower-order modes becoming greater than that of higher-order modes. Therefore, laser oscillation in lower-order modes is possible, thereby enabling the achievement of a narrow horizontal diffusion angle.

[0130] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 3rd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0131] Even if the width W of the lateral spinal region o Beyond 10 μm, the gain of the low-order mode also becomes greater than that of the comparative example without increasing the loss. In the outer region of the ridge, the width W... o At a width greater than 15 μm, a gain difference exceeding 11% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillations. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0132] In order to allow higher-order modes above the first order in the horizontal direction, i.e. the x-direction (ridge width direction), the following conditions need to be met.

[0133] That is, half the width of the aforementioned medial region of the spine, i.e., W. i The width W of the aforementioned lateral ridge region o The average refractive index n expressed by equation (4) a e and the aforementioned covered area II c Effective refractive index n c It needs to satisfy the following equation (7).

[0134] [Number 9]

[0135] Number 9

[0136] In addition, in order to allow higher-order modes above first order in the stacking direction of each layer, the following conditions need to be met.

[0137] That is, when the refractive index of the n-type AlGaAs coating layer 3 is set to n... cn The refractive index of the first cladding layer 11 of p-type AlGaAs is set to n. cp The thickness of the n-type AlGaAs low refractive index layer 4 is set to d. n Set the refractive index to be greater than the refractive index n of the n-type AlGaAs coating layer 3. cn low n n The thickness of the p-type AlGaAs low-refractive-index layer 10 disposed between the p-side light guiding layer 81 and the p-type AlGaAs first cladding layer 11 is set as d. p And setting the refractive index to be lower than that of the first p-type AlGaAs cladding layer 11 by n. p In this case, the following equation (8) needs to be satisfied.

[0138] [Number 10]

[0139] Count 10

[0140] In the ridge-type large-area semiconductor laser device 500 according to Embodiment 1, both the n-type AlGaAs low-refractive-index layer 4 and the p-type AlGaAs low-refractive-index layer 10 are disposed between the cladding layer and the light guiding layer. However, even if one or both of the low-refractive-index layers are disposed within the cladding layer, the same effect is achieved.

[0141] Furthermore, since the current diffuses isotropically within the semiconductor layer, the width W of the region outside the ridge is... oIt is acceptable as long as it is within a range that is wider than the distance h1+h2 (1.33μm) and narrower than W (50μm).

[0142] In the ridge-shaped large-area semiconductor laser device 500 described in Embodiment 1, the outer region I of the ridge is removed by etching after covering it with a SiN film 15. a o The exposed surfaces behind the p-type GaAs contact layer 14 and the p-type AlGaAs second cladding layer 13 are configured with a current-non-injection structure, so that the current injected into the ridge-type large-area semiconductor laser device 500 is specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the low-order mode to be greater than that of the high-order mode, enabling laser oscillation in the low-order mode and thus narrowing the horizontal diffusion angle.

[0143] Variation 1 of Implementation Method 1

[0144] Figure 6 This is a perspective view of a ridge-shaped large-area semiconductor laser device 510 with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 1.

[0145] The ridge-type large-area semiconductor laser device 510 according to Variation 1 of Embodiment 1 differs from the ridge-type large-area semiconductor laser device 500 according to Embodiment 1 as follows: In Variation 1 of Embodiment 1, the second ESL layer 12 is not provided; instead of the p-type AlGaAs first cladding layer 11 (first cladding layer of the second conductivity type) with an Al composition ratio of 0.20 and a layer thickness of 0.55 μm in the ridge-type large-area semiconductor laser device 500 according to Embodiment 1, a p-type AlGaAs first cladding layer 11a (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 in Variation 1 of Embodiment 1, a proton injection region 17 is provided as a non-current injection structure. Other layer structures are the same as those in the ridge-type large-area semiconductor laser device 500 according to Embodiment 1.

[0146] The following describes a method for manufacturing a ridge-shaped large-area semiconductor laser device 510 according to a variation of Embodiment 1.

[0147] 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 vapor deposition (MOCVD).

[0148] Next, cover the inner ridge area I with a photoresist. ai Protons are then implanted to form a proton implantation region 17, and the resist is stripped off.

[0149] Subsequently, the inner ridge region I was covered with a photoresist. a i and lateral spinal region I a o Dry etching is then performed up to the first ESL layer 10, and the resist is stripped. At this point, the encapsulated region II... c The proton injection region was also etched away.

[0150] Cover the inner ridge area with corrosion resist I a i and lateral spinal region I a o SiN film 15 is formed and stripped, and the resist is also stripped.

[0151] Finally, 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.

[0152] and Figure 3 The main difference between the ridge-type large-area semiconductor laser device 500 shown in Embodiment 1 is that it does not have a second ESL layer 12, and for the outer ridge region I... a o Instead of being removed by etching, the proton-injected region 17 is formed by insulating the semiconductor layer through proton injection. In the proton-injected region 17, the semiconductor layer functions as a current-non-injected structure due to the implementation of high resistance.

[0153] In the ridge-shaped large-area semiconductor laser device 510 according to the variation 1 of embodiment 1, by means of the outer region I of the ridge a o A portion of the p-type GaAs contact layer 14 and the p-type AlGaAs first cladding layer 11a forms a proton injection region 17, thus constituting a current-non-injection structure. Therefore, the current injected into the ridge-type large-area semiconductor laser device 510 is specifically concentrated in the inner ridge region I. a i Flowing in the middle.

[0154] Since there is no second ESL layer 12, the inner ridge region I in the ridge-shaped large-area semiconductor laser device 510 a i The effective refractive index is 3.41698. On the other hand, the cladding region II... c The effective refractive index is the same at 3.41672, with a ridge width of 2W and a ridge width of 100μm (the ridge outer region width W). oIn the case of =0μm), the v of equation (1) is 13.58, allowing 9 modes from order 0 (basic mode) to order 8.

[0155] The lateral region I of the proton injection region 17, which functions as a non-current injection structure, is provided. a o The effective refractive index is related to the inner ridge region I a i The same 3.41698. As an example, when protons are injected from the surface of the p-type GaAs contact layer 14 to a depth of 0.7 μm, the distance h1 from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17 is 1.0 μm.

[0156] If the distance h1 from the upper end of the first ESL layer 10 to the lower end of the current-non-injection structure, i.e., the proton injection region 17, is 0.59 μm or more, then the outer ridge region I... a o Effective refractive index and inner ridge region I a i The effective refractive index is essentially the same. That is, there is almost no light in the region above 0.59 μm from h1, so it is not affected by scattering caused by crystallization damage due to proton injection and the loss caused by such scattering, and there is no reduction in reliability caused by crystal defects.

[0157] exist Figure 7 as well as Figure 8 Showing the lateral spinal region I a o Width W of the lateral region of the spine o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, allowing laser oscillation regardless of the mode. Therefore, in the comparative example, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0158] On the other hand, in the ridge-shaped large-area semiconductor laser device 510 according to the variation 1 of embodiment 1, a ridge outer region I is provided, in which a proton injection region 17 is formed to function as a current non-injection structure. a o This causes the current to flow specifically in the inner region of the ridge, I. a iThe flow creates gain differences between modes, with lower-order modes having greater gain than higher-order modes. Therefore, laser oscillations in lower-order modes can be performed, enabling the achievement of narrow horizontal spread angles.

[0159] Furthermore, due to the low-order modes involved in this disclosure, such as the width W of the lateral ridge region... o The gain of the 0th to 3rd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0160] In the ridge-shaped large-area semiconductor laser device 510 according to the variation 1 of embodiment 1, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o When the gain is greater than 15 μm, a gain difference exceeding 11% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillations. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0161] In the ridge-type large-area semiconductor laser device 510 described in Variation 1 of Embodiment 1, both the n-type AlGaAs low-refractive-index layer 4 and the p-type AlGaAs low-refractive-index layer 10 are disposed between the cladding layer and the light guiding layer. However, even if one or both of the low-refractive-index layers are disposed within the cladding layer, the same effect can be obtained.

[0162] In addition, the width W of the lateral region of the spine o Any range wider than the distance h1+h2 (1.74 μm) and narrower than W (50 μm) is acceptable. Although a distance h1 of 0.59 μm or more from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17 is sufficient, the distance h1 is set to 1.0 μm in the ridge-shaped large-area semiconductor laser device 510 according to the variation 1 of embodiment 1 in order to further move the damaged portion of the semiconductor layer caused by proton injection away from the light intensity distribution, thereby achieving higher reliability.

[0163] In the method for manufacturing the ridge-shaped large-area semiconductor laser device 510 according to the variation 1 of embodiment 1, as an example, a structure for ion implantation of protons is shown, but it is not limited to this, as long as the resistance of the semiconductor layer can be increased.

[0164] If proton implantation is used as the insulator of the semiconductor layer, an etching process is not required, thus reducing the number of fabrication steps and making the fabrication of ridge-shaped large-area semiconductor laser devices easier.

[0165] In the ridge-shaped large-area semiconductor laser device 510 according to the above-described variation 1 of embodiment 1, a ridge outer region I is provided, in which a proton injection region 17 is formed to function as a current non-injection structure. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 510 to be specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the low-order mode to be greater than that of the high-order mode, enabling laser oscillation in the low-order mode and thus narrowing the horizontal diffusion angle.

[0166] Variation 2 of Implementation Method 1

[0167] Figure 9 This is a perspective view of a ridge-shaped large-area semiconductor laser device 520 with a real refractive index distribution in the 975nm band, as described in Modification 2 of Embodiment 1. Figure 9 As shown, the ridge-type large-area semiconductor laser device 520 has a SiN film 15a with a thickness of 0.2 μm.

[0168] The following describes a method for manufacturing a ridge-shaped large-area semiconductor laser device 520 according to a variation 2 of Embodiment 1.

[0169] 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 vapor deposition (MOCVD).

[0170] Next, cover the inner ridge area I with a photoresist. a i and lateral spinal region I a o Dry etch up to the first ESL layer 10 and strip the resist.

[0171] Subsequently, the inner ridge region I was covered with a photoresist. a i SiN film 15a was formed and stripped, and the resist was also stripped.

[0172] Finally, 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.

[0173] and Figure 3 The difference between the ridge-shaped large-area semiconductor laser device 500 shown in Embodiment 1 is that it does not have a second ESL layer 12, and for the outer ridge region I... a oInstead of removing it by etching, the SiN film 15a is respectively disposed on a portion of the surface at both ends of the ridge width direction of the p-type GaAs contact layer 14.

[0174] In the ridge-shaped large-area semiconductor laser device 520 according to the variation 2 of embodiment 1, since the outer region I of the ridge is covered by SiN film 15a respectively a o A portion of the surface at both ends of the ridge width direction of the p-type GaAs contact layer 14 is configured as a current-non-injection structure, so the current injected into the ridge-type large-area semiconductor laser device 520 is specifically concentrated in the inner region I of the ridge. a i Flowing in the middle.

[0175] Medial region I a i Lateral spinal region I a o and the covered area II c The effective refractive indices are 3.41698, 3.41698, and 3.41672, respectively, allowing nine modes from order 0 (fundamental mode) to order 8 with a ridge width of 2W of 100 μm. Since the current diffuses from the top of the p-type GaAs contact layer 14, the distance h1 is 1.7 μm.

[0176] exist Figure 10 as well as Figure 11 The width W of the lateral region of the spine is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, allowing laser oscillation regardless of the mode. Therefore, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0177] On the other hand, in the ridge-type large-area semiconductor laser device 520 according to the variation 2 of embodiment 1, a ridge-outer region I is provided, which has a current-non-injection structure formed by covering a portion of the surfaces at both ends of the p-type GaAs contact layer 14 in the ridge width direction with SiN films 15a. a o This causes the current to flow specifically in the inner region of the ridge, I. a i The flow in the medium creates a gain difference between modes, with lower-order modes having a larger gain than higher-order modes. Therefore, laser oscillation in lower-order modes is possible, enabling the achievement of narrow horizontal spread angles.

[0178] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 3rd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0179] In the ridge-shaped large-area semiconductor laser device 520 according to the variation 2 of embodiment 1, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o When the width is above 15 μm, a gain difference exceeding 10% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillation. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0180] In addition, the width W of the lateral region of the spine o Any range that is wider than the distance h1+h2 (2.44μm) and narrower than W (50μm) is acceptable. In this embodiment, the lateral ridge region I a o The current-free structure is formed by a SiN film 15a acting as an insulating film. Therefore, the distance from the p-type GaAs contact layer 14, which diffuses from the current in the x-direction (ridge width direction), to the InGaAs quantum well active layer 7 becomes longer, reaching 2.44 μm. The width W in the outer region of the ridge is... o It is difficult to obtain a gain difference in a narrow case, but if the width W of the outer region of the ridge is increased... o The effect is enhanced, so there are no particular problems. Furthermore, although SiN is used as the insulating film, other materials such as SiO2 can also be used.

[0181] In the method for manufacturing the ridge-shaped large-area semiconductor laser device 520 according to the variation 2 of embodiment 1, since there are no processes such as etching or proton implantation, the manufacturing of the ridge-shaped large-area semiconductor laser device is extremely easy.

[0182] In the ridge-shaped large-area semiconductor laser device 520 described in the modified example 2 of embodiment 1, since the outer region I of the ridge is covered by SiN film 15a, a o A portion of the surface at both ends of the ridge width direction of the p-type GaAs contact layer 14 is configured as a current-non-injection structure, so the current injected into the ridge-type large-area semiconductor laser device 520 is specifically concentrated in the inner region I of the ridge. a iThe flow in the middle results in the gain of the lower-order mode being greater than that of the higher-order mode, which can enable laser oscillation in the lower-order mode and thus narrow the horizontal diffusion angle.

[0183] Implementation Method 2

[0184] Figure 12 This is a perspective view of a ridge-type large-area semiconductor laser device 530 with a real refractive index distribution in the 975nm band according to Embodiment 2. The ridge-type large-area semiconductor laser device 530 with a real refractive index distribution in the 975nm band according to Embodiment 2 is characterized in that the InGaAs quantum well active layer 7 is positioned at the center of the light guiding layers 62 and 82, i.e., it is symmetrical with respect to the InGaAs quantum well active layer 7.

[0185] Figure 12 The ridge-type large-area semiconductor laser device 530 shown includes an n-side AlGaAs second light guiding layer 5a with an Al composition ratio of 0.16 and a layer thickness of 700 nm, an n-side AlGaAs first light guiding layer 6a with an Al composition ratio of 0.14 and a layer thickness of 200 nm, a p-side AlGaAs first light guiding layer 8a with an Al composition ratio of 0.14 and a layer thickness of 200 nm, a p-side AlGaAs second light guiding layer 9a with an Al composition ratio of 0.16 and a layer thickness of 700 nm, a p-type AlGaAs first cladding layer 11b (a first cladding layer of the second conductivity type) with an Al composition ratio of 0.20 and a layer thickness of 0.40 μm, and a p-type AlGaAs second cladding layer 13a (a second cladding layer of the second conductivity type) with an Al composition ratio of 0.20 and a layer thickness of 1.10 μm. Other structures are similar to those in Embodiment 1. Figure 3 The structures shown are the same.

[0186] That is, the ridge-shaped large-area semiconductor laser device 530 according to Embodiment 2 is similar to the ridge-shaped large-area semiconductor laser device 500 according to Embodiment 1, in that at least the outer region I of the ridge is removed by etching. a o The device consists of a p-type GaAs contact layer 14 and a p-type AlGaAs second cladding layer 13a, and a SiN film 15 serving as an insulating film covering the exposed surfaces removed by etching. This creates a current-non-injection structure, so the current injected into the ridge-type large-area semiconductor laser device 530 is specifically concentrated in the inner region I of the ridge. a i Flowing in the middle.

[0187] Furthermore, the n-side AlGaAs second light guiding layer 5a and the n-side AlGaAs first light guiding layer 6a are collectively referred to as the n-side light guiding layer 62 or the first conductivity type side light guiding layer 62, and the p-side AlGaAs first light guiding layer 8a and the p-side AlGaAs second light guiding layer 9a are collectively referred to as the p-side light guiding layer 82 or the second conductivity type side light guiding layer 82.

[0188] The fabrication method of the ridge-shaped large-area semiconductor laser device 530 is the same as that of embodiment 1.

[0189] The total thickness of the ridge-type large-area semiconductor laser device 530, consisting of the p-side light guiding layer 82 and the n-side light guiding layer 62, is 1.8 μm. It allows modes of order one or higher in the y-direction (i.e., the stacking direction). Additionally, u... n It is 0.292273, u p It is 0.522208, u p >u n This is valid. Therefore, the light intensity distribution in the y-direction shifts towards the n-type GaAs substrate 2 side, which can reduce the number of allowed modes in the x-direction.

[0190] First, the width W in the lateral region of the spine o Ridge region I when it is zero a (Medial region I) a i and the lateral spinal region I a o ) and covered area II c The effective refractive indices are 3.41839 and 3.41828, respectively. With a ridge width of 2W and a value of 100 μm, v is 8.83, allowing for six modes from the 0th order (fundamental mode) to the 5th order.

[0191] Since the p-side light guiding layer 82 of the ridge-type large-area semiconductor laser device 530 has the same layer thickness as the n-side light guiding layer 62, although the loss caused by carriers retained during operation increases compared to the structure of Embodiment 1, the ridge region I can be reduced. a (Medial region I) a i and the lateral spinal region I a o ) and Coverage Area II c The difference in refractive index between the two modes has the advantage of reducing the number of permissible modes.

[0192] Lateral spinal region I a o The effective refractive index of this region, when removed by etching up to the second ESL layer 12, is 3.41839, independent of the removal by etching, ridge region I.a (Medial region I) a i and the lateral spinal region I a o The refractive indices of the two modes are the same. Therefore, the number of allowed modes is the same.

[0193] On the other hand, the current also diffuses from the upper end of the second ESL layer 12 in the x-direction, i.e., the ridge width direction. That is, it diffuses in the x-direction at a distance h2 (1.04 μm) from the upper end of the InGaAs quantum well active layer 7 to the upper end of the first ESL layer 10 and a distance h1 (0.44 μm) from the upper end of the second ESL layer 12 to the upper end of the first ESL layer 10, and reaches the InGaAs quantum well active layer 7.

[0194] exist Figure 13 as well as Figure 14 The width W of the lateral region of the spine is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, so laser oscillation can be performed in any mode. Therefore, the horizontal spread angle deviates depending on which mode is used for laser oscillation.

[0195] On the other hand, in the ridge-type large-area semiconductor laser device 530, a ridge outer region I is formed by covering the exposed surface after the p-type GaAs contact layer 14 and the p-type AlGaAs second cladding layer 13a have been etched away with a SiN film 15 to create a current-non-injection structure. a o This causes the current to flow specifically in the inner region of the ridge, I. a i The flow creates gain differences between modes, with lower-order modes having greater gain than higher-order modes. Therefore, laser oscillations in lower-order modes can be performed, enabling the achievement of narrow horizontal spread angles.

[0196] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 2nd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0197] In the ridge-shaped large-area semiconductor laser device 530, even if the width W of the outer region of the ridge is... oBeyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o At a width greater than 15 μm, a gain difference exceeding 13% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillations. In the lateral ridge region, the width W... o This trend is more pronounced when the size is above 20 μm.

[0198] Furthermore, due to the isotropic diffusion of current, the width W of the outer region of the ridge is... o It is acceptable as long as the range is wider than the distance h1+h2 (1.48μm) and narrower than W (50μm).

[0199] In the ridge-shaped large-area semiconductor laser device 530 described in Embodiment 2, the outer region I of the ridge is removed by etching after covering it with a SiN film 15. a o The exposed surfaces behind the p-type GaAs contact layer 14 and the p-type AlGaAs second cladding layer 13a are configured with a current-non-injection structure, so that the current injected into the ridge-type large-area semiconductor laser device 530 is specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the low-order mode to be greater than that of the high-order mode, enabling laser oscillation in the low-order mode and thus narrowing the horizontal diffusion angle. Furthermore, by setting the layer thickness of the p-side light guiding layer 82 to be the same as that of the n-side light guiding layer 62, the ridge region I can be reduced. a (Medial region I) a i and the lateral spinal region I a o ) and Coverage Area II c The difference in refractive index between the two modes has the effect of reducing the number of allowed modes.

[0200] Variation 1 of Implementation Method 2

[0201] Figure 15 This is a perspective view of a variation of Embodiment 2, namely a ridge-shaped large-area semiconductor laser device 540 having a real refractive index distribution in the 975nm band.

[0202] and Figure 12 The difference between the ridge-shaped large-area semiconductor laser device 530 shown in Embodiment 2 is that it does not have a second ESL layer 12, and for the outer ridge region I... a o It is not removed by etching, but formed by insulating the semiconductor layer through proton injection.

[0203] The fabrication method of the ridge-shaped large-area semiconductor laser device 540 is the same as that of Variation 1 of Embodiment 1.

[0204] In the ridge-type large-area semiconductor laser device 540, since there is no second ESL layer 12, the ridge region I... a (Medial region I) a i and the lateral spinal region I a o The effective refractive index is 3.41840. The ridge-type large-area semiconductor laser device 540 has a cladding region II. c With the same effective refractive index of 3.41828, and with a ridge width of 2W of 100μm, the v of Equation (1) is 9.22, allowing for 6 modes from the 0th order (basic mode) to the 5th order.

[0205] The lateral spinal region I was injected with protons a o The effective refractive index is related to the inner ridge region I a i The same 3.41840. As an example, when protons are injected from the surface of the p-type GaAs contact layer 14 to a depth of 0.95 μm, the distance h1 from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17 is 0.75 μm.

[0206] If the distance h1 from the upper end of the first ESL layer 10 to the lower end of the current-non-injection structure, i.e., the proton injection region 17, is greater than 0.44 μm, then the outer ridge region I... a o The effective refractive index becomes related to the inner ridge region I a i The effective refractive index is essentially the same. That is, there is almost no light in the region above 0.44 μm from h1, so it is not affected by scattering caused by crystallization damage due to proton injection into the crystal layer and the loss caused by such scattering, nor does it produce a decrease in reliability caused by crystal defects.

[0207] exist Figure 16 as well as Figure 17 The width W of the lateral region of the spine is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The comparative example W is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, allowing laser oscillation regardless of the mode. Therefore, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0208] On the other hand, in the ridge-type large-area semiconductor laser device 540, a ridge outer region I is provided, in which a proton injection region 17 is formed, which functions as a current non-injection structure. a o This causes the current to flow specifically in the inner region of the ridge, I. a i The flow creates a gain difference between modes, with lower-order modes having a greater gain than higher-order modes. Laser oscillation in lower-order modes is possible, enabling the achievement of narrow horizontal spread angles.

[0209] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 2nd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0210] In the ridge-shaped large-area semiconductor laser device 540, even if the width W of the outer region of the ridge... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o At a width greater than 15 μm, a gain difference exceeding 13% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillations. In the lateral ridge region, the width W... o This trend is more pronounced when the size is above 20 μm.

[0211] In addition, the width W of the lateral region of the spine o Any range wider than the distance h1+h2 (1.79 μm) and narrower than W (50 μm) is acceptable. Although a distance h1 of 0.44 μm or more from the first ESL layer 10 to the lower end of the proton injection region 17 is sufficient, in the ridge-shaped large-area semiconductor laser device 540 according to the variation 1 of embodiment 2, the distance h1 is set to 0.75 μm to further move the damaged portion of the semiconductor layer caused by proton injection away from the light intensity distribution, thereby achieving higher reliability.

[0212] In this embodiment, as an example, a structure for proton ion implantation is shown, but it is not limited to this, as long as the resistance of the semiconductor layer can be increased.

[0213] If proton implantation is used as the insulator of the semiconductor layer, an etching process is not required, thus reducing the number of fabrication steps and making the fabrication of ridge-shaped large-area semiconductor laser devices easier.

[0214] In the ridge-shaped large-area semiconductor laser device 540 described in Modification 1 of Embodiment 2, an outer region I of the ridge is provided, in which a proton injection region 17 is formed to function as a current non-injection structure. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 540 to be specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the lower-order mode to be greater than that of the higher-order mode, enabling laser oscillation in the lower-order mode and thus narrowing the horizontal diffusion angle. Furthermore, by setting the layer thickness of the p-side light guiding layer 82 to be the same as that of the n-side light guiding layer 62, the ridge region I can be reduced. a (Medial region I) a i and the lateral spinal region I a o ) and Coverage Area II c The difference in refractive index between the two modes has the effect of reducing the number of allowed modes.

[0215] Variation 2 of Implementation Method 2

[0216] Figure 18 This is a perspective view of a variation of Embodiment 2, namely a ridge-shaped large-area semiconductor laser device 550 having a real refractive index distribution in the 975nm band.

[0217] and Figure 12 The difference between the ridge-shaped large-area semiconductor laser device 530 shown in Embodiment 2 is that it does not have a second ESL layer 12, and for the outer ridge region I... a o Instead of removing it by etching, the SiN film 15a is respectively disposed on a portion of the surface at both ends of the ridge width direction of the p-type GaAs contact layer 14.

[0218] The fabrication method of the ridge-shaped large-area semiconductor laser device 550 is the same as that of variation 2 of embodiment 1.

[0219] Ridge-shaped large-area semiconductor laser device 550, inner ridge region I a i Lateral spinal region I a o and the covered area II c The effective refractive indices are 3.41840, 3.41840, and 3.41828, respectively, allowing for six modes from order 0 (fundamental mode) to order 5 with a ridge width of 2W of 100 μm. Since the current diffuses from the top of the p-type GaAs contact layer 14, the distance h1 is 1.7 μm.

[0220] exist Figure 19 as well as Figure 20 The width W of the lateral region of the spine is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, allowing laser oscillation regardless of the mode. Therefore, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0221] On the other hand, in the ridge-type large-area semiconductor laser device 550, a ridge-outer region I is provided, which has a current-non-injection structure formed by covering a portion of the surfaces at both ends of the p-type GaAs contact layer 14 in the ridge width direction with SiN films 15a. a o This causes the current to flow specifically in the inner region of the ridge, I. a i The flow creates a gain difference between modes, with lower-order modes having a greater gain than higher-order modes. Laser oscillation in lower-order modes is possible, enabling the achievement of narrow horizontal spread angles.

[0222] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 2nd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0223] In the ridge-shaped large-area semiconductor laser device 550, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o When the width is above 15 μm, a gain difference exceeding 12% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillation. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0224] In addition, the width W of the lateral region of the spine o Any range that is wider than the distance h1+h2 (2.74μm) and narrower than W (50μm) is acceptable. In this embodiment, due to the lateral ridge region I a oThe current-injection-free structure is formed by a SiN film 15a acting as an insulating film. Therefore, the distance from the p-type GaAs contact layer 14, where the current diffuses in the x-direction, to the InGaAs quantum well active layer 7 becomes longer, reaching 2.74 μm, and the width W in the outer region of the ridge increases. o It is difficult to obtain a gain difference in a narrow case, but if the width W of the outer region of the ridge is increased... o The effect is enhanced, so there are no particular problems. Furthermore, although SiN is used as the insulating film, other materials such as SiO2 can also be used.

[0225] Because there are no processes such as etching or proton implantation, the fabrication of ridge-shaped large-area semiconductor laser devices is extremely easy.

[0226] In the ridge-type large-area semiconductor laser device 550 described in Embodiment 2, a ridge-outer region I is provided, which has a current-non-injection structure formed by covering a portion of the surfaces at both ends of the p-type GaAs contact layer 14 in the ridge width direction with SiN films 15a. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 550 to be specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the lower-order mode to be greater than that of the higher-order mode, enabling laser oscillation in the lower-order mode and thus narrowing the horizontal diffusion angle. Furthermore, by setting the layer thickness of the p-side light guiding layer 82 to be the same as that of the n-side light guiding layer 62, the ridge region I can be reduced. a (Medial region I) a i and the lateral spinal region I a o ) and Coverage Area II c The difference in refractive index between the two modes has the effect of reducing the number of allowed modes.

[0227] Implementation Method 3

[0228] Figure 21 This is a perspective view of a ridge-shaped large-area semiconductor laser device 560 with a real refractive index distribution in the 975nm band according to Embodiment 3.

[0229] In the ridge-type large-area semiconductor laser device 560, the slope efficiency is improved by setting an asymmetric structure in which the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11c and the p-type AlGaAs second cladding layer 13b.

[0230] Figure 21 The ridge-type large-area semiconductor laser device 560 shown has a p-type AlGaAs first cladding layer 11c (a first cladding layer of the second conductivity type) with an Al composition ratio of 0.25 and a layer thickness of 0.3 μm, and a p-type AlGaAs second cladding layer 13b (a second cladding layer of the second conductivity type) with an Al composition ratio of 0.25 and a layer thickness of 1.2 μm. Other layer structures are similar to... Figure 12 The ridge-shaped large-area semiconductor laser device 530 shown in Embodiment 2 is the same.

[0231] The fabrication method of the ridge-shaped large-area semiconductor laser device 560 is the same as that of embodiment 1.

[0232] In the ridge-type large-area semiconductor laser device 560, since the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11c and the p-type AlGaAs second cladding layer 13b, the light intensity distribution shifts significantly towards the n-type GaAs substrate 2, which can reduce carrier absorption in the p-type AlGaAs first cladding layer 11c and the p-type AlGaAs second cladding layer 13b, thereby improving the slope efficiency.

[0233] Furthermore, due to the more significant shift in light intensity distribution towards the n-type GaAs substrate 2 side, the ridge region I... a (Medial region I) a i and the lateral spinal region I a o ) and Coverage Area II c The refractive index difference becomes smaller, which makes it easier to reduce the number of allowed modes.

[0234] The total thickness of the ridge-type large-area semiconductor laser device 560, consisting of the p-side light guiding layer 82 and the n-side light guiding layer 62, is 1.8 μm, allowing modes above the first order in the stacking direction. Additionally, u n It is 0.292273, u p It is 0.480463, u p >u n This is valid. Therefore, the light intensity distribution in the y-direction shifts towards the n-type GaAs substrate 2 side, which can reduce the number of allowed modes in the x-direction.

[0235] The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 560 o Ridge region I when it is zero a (Medial region I) a i and the lateral spinal region I a o ) and covered area II cThe effective refractive indices are 3.41837 and 3.41828, respectively. With a ridge width of 2W and a value of 100 μm, v is 7.99, allowing for six modes from the 0th order (fundamental mode) to the 5th order.

[0236] In the ridge-type large-area semiconductor laser device 560, since the layer thickness of the p-side light guiding layer 82 is the same as that of the n-side light guiding layer 62, the loss caused by carriers retained during operation increases compared to Embodiment 1. On the other hand, since the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11c and the p-type AlGaAs second cladding layer 13b, the light distribution diffuses less into the p-type AlGaAs first cladding layer 11c and the p-type AlGaAs second cladding layer 13b, and the loss caused by carrier absorption in the p-type AlGaAs first cladding layer 11c and the p-type AlGaAs second cladding layer 13b is reduced.

[0237] Since the thickness of the p-side light guiding layer 82 is the same as that of the n-side light guiding layer 62, the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11c and the p-type AlGaAs second cladding layer 13b, thus reducing the ridge region I. a (Medial region I) a i and the lateral spinal region I a o ) and Coverage Area II c The difference in refractive index between the two modes can reduce the number of allowed modes.

[0238] Lateral spinal region I a o The effective refractive index of this region, which is removed by etching up to the second ESL layer 12, is 3.41837, regardless of the removal by etching. Ridge region I a (Medial region I) a i and the lateral spinal region I a o The refractive indices of the two modes are the same. Therefore, the number of allowed modes is the same.

[0239] On the other hand, the current also diffuses from the upper end of the second ESL layer 12 in the x-direction, i.e., the ridge width direction. That is, it diffuses in the x-direction between the distance h2 (1.04 μm) from the upper end of the InGaAs quantum well active layer 7 to the upper end of the first ESL layer 10 and the distance h1 (0.34 μm) from the upper end of the second ESL layer 12 to the upper end of the first ESL layer 10, and reaches the InGaAs quantum well active layer 7.

[0240] exist Figure 22 as well as Figure 23 The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 560 is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, so laser oscillation can be performed in any mode. Therefore, the horizontal spread angle deviates depending on which mode is used for laser oscillation.

[0241] On the other hand, in the ridge-type large-area semiconductor laser device 560, a ridge outer region I is formed by covering the exposed surface after the p-type GaAs contact layer 14 and the p-type AlGaAs second cladding layer 13b have been etched away with a SiN film 15 to create a current-non-injection structure. a o This causes the current to flow specifically in the inner region of the ridge, I. a i The flow creates gain differences between modes, with lower-order modes having greater gain than higher-order modes. Therefore, laser oscillations in lower-order modes can be performed, enabling the achievement of narrow horizontal spread angles.

[0242] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 2nd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0243] In the ridge-shaped large-area semiconductor laser device 560, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o At a width greater than 15 μm, a gain difference exceeding 14% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillations. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0244] Furthermore, due to the isotropic diffusion of current, the width W of the outer region of the ridge is... o It is acceptable as long as the range is wider than the distance h1+h2 (1.38μm) and narrower than W (50μm).

[0245] In the ridge-type large-area semiconductor laser device 560 according to Embodiment 3, a ridge outer region I with a current-non-injection structure is formed by covering the exposed surface after etching away the p-type GaAs contact layer 14 and the p-type AlGaAs second cladding layer 13b with a SiN film 15. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 560 to be specifically directed to the inner region I of the ridge. a i The flow in the middle generates a gain difference between modes, with the lower-order mode having a larger gain than the higher-order mode. This allows for laser oscillation in the lower-order mode, achieving a narrow horizontal diffusion angle. Furthermore, by setting the structure to be asymmetric, with the refractive index of the n-type AlGaAs cladding layer 3 being higher than that of the p-type AlGaAs first cladding layer 11c and the p-type AlGaAs second cladding layer 13b, it also reduces light absorption caused by carriers on the p-type AlGaAs first cladding layer 11c and the p-type AlGaAs second cladding layer 13b side, thereby improving the slope efficiency.

[0246] Variation 1 of Implementation Method 3

[0247] Figure 24 This is a perspective view of a variation of Embodiment 3, namely a ridge-shaped large-area semiconductor laser device 570 with a real refractive index distribution in the 975nm band.

[0248] Figure 24 The ridge-type large-area semiconductor laser device 570 shown has a p-type AlGaAs first cladding layer 11d (a second conductivity cladding layer) with an Al composition ratio of 0.25 and a layer thickness of 1.5 μm.

[0249] and Figure 21 The difference in the ridge-shaped large-area semiconductor laser device 560 shown is that it does not have a second ESL layer 12, and for the outer region I of the ridge... a o It is not removed by etching, but formed by the insulation of the semiconductor layer achieved by proton injection.

[0250] The fabrication method of the ridge-shaped large-area semiconductor laser device 570 is the same as that of variation 1 of embodiment 1.

[0251] In the ridge-type large-area semiconductor laser device 570, since there is no second ESL layer 12, the ridge region I... a (Medial region I) a i and the lateral spinal region I a o The effective refractive index is 3.41837. Encapsulated region II cThe effective refractive index is the same as 3.41827. With a ridge width of 2W of 100μm, the v of Equation (1) is 8.42, allowing for 6 modes from the 0th order (basic mode) to the 5th order.

[0252] The lateral spinal region I was injected with protons a o The effective refractive index is related to the inner ridge region I a i The same 3.41837. As an example, when protons are injected from the surface of the p-type GaAs contact layer 14 to a depth of 1.35 μm, the distance h1 from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17 is 0.35 μm.

[0253] If the distance h1 from the upper end of the first ESL layer 10 to the lower end of the current-non-injection structure, i.e., the proton injection region 17, is 0.34 μm or more, then the outer ridge region I a o The effective refractive index becomes related to the inner ridge region I a i The effective refractive index is essentially the same. That is, since there is almost no light in the region above 0.34 μm from h1, it is not affected by scattering caused by crystallization damage due to proton injection into the crystal layer and the loss caused by such scattering, nor does it produce a decrease in reliability caused by crystal defects.

[0254] exist Figure 25 as well as Figure 26 The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 570 is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, allowing laser oscillation regardless of the mode. Therefore, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0255] On the other hand, in the ridge-type large-area semiconductor laser device 570, an outer region I of the ridge is provided, which has a proton injection region 17 that functions as a current non-injection structure. a o This causes the current to flow specifically in the inner region of the ridge, I. a i The flow creates gain differences between modes, with lower-order modes having greater gain than higher-order modes. Therefore, laser oscillations in lower-order modes can be performed, enabling the achievement of narrow horizontal spread angles.

[0256] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 2nd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0257] In the ridge-shaped large-area semiconductor laser device 570, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o When the gain is above 15 μm, a 14% gain difference exists between the fundamental mode and all other modes, yet substantial fundamental mode oscillations are possible. The width W in the outer region of the ridge... o This trend is more pronounced when the size is above 20 μm.

[0258] In addition, the width W of the lateral region of the spine o Any range wider than the distance h1+h2 (1.39 μm) and narrower than W (50 μm) is acceptable. Although a distance h1 of 0.34 μm or more from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17 is sufficient, in the ridge-shaped large-area semiconductor laser device 570 according to the variation 1 of embodiment 3, the distance h1 is set to 0.35 μm to further move the damaged portion of the semiconductor layer caused by proton injection away from the light intensity distribution, thereby achieving higher reliability.

[0259] In this embodiment, as an example, a structure for proton ion implantation is shown, but it is not limited to this, as long as the resistance of the semiconductor layer can be increased.

[0260] If proton implantation is used as the insulator of the semiconductor layer, an etching process is not required, thus reducing the number of fabrication steps and making the fabrication of ridge-shaped large-area semiconductor laser devices easier.

[0261] In the ridge-shaped large-area semiconductor laser device 570 according to the above-described variation 1 of embodiment 3, a ridge outer region I is provided, in which a proton injection region 17 is formed to function as a current non-injection structure. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 570 to be specifically concentrated in the inner region I of the ridge. a iThe flow in the middle generates a gain difference between modes, and the gain of the lower-order mode becomes greater than that of the higher-order mode, which enables laser oscillation in the lower-order mode, thus achieving the effect of narrow horizontal diffusion angle. Furthermore, by setting it to an asymmetric structure in which the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11d, it also reduces the light absorption caused by carriers on the p-type AlGaAs first cladding layer 11d side, thereby improving the slope efficiency.

[0262] Variation 2 of Implementation Method 3

[0263] Figure 27 This is a perspective view of a variation of Embodiment 3, namely a ridge-shaped large-area semiconductor laser device 580 with a real refractive index distribution in the 975nm band.

[0264] and Figure 21 The difference in the ridge-shaped large-area semiconductor laser device 560 shown is that it does not have a second ESL layer 12, and for the outer region I of the ridge... a o Instead of being removed by etching, the SiN film 15a is disposed on a portion of the surface at both ends of the ridge width direction of the p-type GaAs contact layer 14. The other layer structures are the same as in variation 1 of embodiment 3.

[0265] The fabrication method of the ridge-shaped large-area semiconductor laser device 580 is the same as that of variation 2 of embodiment 1.

[0266] Ridge-shaped large-area semiconductor laser device 580, inner ridge region I a i Lateral spinal region I a o and the covered area II c The effective refractive indices are 3.41837, 3.41837, and 3.41827, respectively, allowing six modes from order 0 (fundamental mode) to order 5 with a ridge width of 2W of 100 μm. Since the current diffuses from the top of the p-type GaAs contact layer 14, the distance h1 is 1.7 μm.

[0267] exist Figure 28 as well as Figure 29 The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 580 is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. oIn the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, allowing laser oscillation regardless of the mode. Therefore, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0268] On the other hand, in the ridge-type large-area semiconductor laser device 580, a ridge-outer region I is provided, which has a current-non-injection structure consisting of a portion of the surfaces at both ends of the p-type GaAs contact layer 14 covered by SiN films 15a in the ridge width direction. a o This results in a gain difference between modes, with the gain of lower-order modes becoming greater than that of higher-order modes. Therefore, laser oscillation in lower-order modes can be performed, enabling the achievement of narrow horizontal diffusion angles.

[0269] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 2nd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0270] In the ridge-shaped large-area semiconductor laser device 580, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o At a width greater than 15 μm, a gain difference exceeding 13% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillations. In the lateral ridge region, the width W... o This trend is more pronounced when the size is above 20 μm.

[0271] In addition, the width W of the lateral region of the spine o Any range that is wider than the distance h1+h2 (2.74μm) and narrower than W (50μm) is acceptable. In this embodiment, due to the lateral ridge region I a o The current-free structure is formed by a SiN film 15a acting as an insulating film. Therefore, the distance from the p-type GaAs contact layer 14, which diffuses from the current in the x-direction (ridge width direction), to the InGaAs quantum well active layer 7 becomes longer, reaching 2.74 μm. The width W in the outer region of the ridge is... o In narrow cases, it is difficult to obtain a gain difference, but if the width W of the outer region of the ridge is increased... o The effect is enhanced, so there are no particular problems. Furthermore, although SiN is used as the insulating film, other materials such as SiO2 can also be used.

[0272] In addition, since there are no processes such as etching or proton injection, the fabrication of ridge-shaped large-area semiconductor laser devices is extremely easy.

[0273] In the ridge-type large-area semiconductor laser device 580 described in Modification 2 of Embodiment 3, a ridge-outer region I is provided, which has a current-non-injection structure formed by covering a portion of the surfaces at both ends of the p-type GaAs contact layer 14 in the ridge width direction with SiN films 15a. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 580 to be specifically directed to the inner region I of the ridge. a i The flow allows the gain of the lower-order mode to be greater than that of the higher-order mode, enabling laser oscillation in the lower-order mode and thus narrowing the horizontal diffusion angle. Furthermore, by setting it to an asymmetric structure in which the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11d, it also reduces light absorption caused by carriers on the p-type AlGaAs first cladding layer 11d side, thereby improving the slope efficiency.

[0274] Implementation Method 4

[0275] Figure 30 This is a perspective view of a ridge-shaped large-area semiconductor laser device 590 with a real refractive index distribution in the 975nm band according to Embodiment 4.

[0276] The ridge-type large-area semiconductor laser device 590 according to Embodiment 4 is configured with an asymmetric structure in which the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11e (the first cladding layer of the second conductivity type) and the p-type AlGaAs second cladding layer 13c (the second cladding layer of the second conductivity type). This reduces light absorption caused by charge carriers in the p-type AlGaAs first cladding layer 11e and the p-type AlGaAs second cladding layer 13c. Furthermore, by shifting the position of the InGaAs quantum well active layer 7 from the center of the light guiding layers 61 and 81 toward the p-type AlGaAs first cladding layer 11e and the p-type AlGaAs second cladding layer 13c, the light absorption caused by charge carriers retained in the light guiding layer during operation is also reduced, thereby improving the slope efficiency.

[0277] Figure 30 The ridge-type large-area semiconductor laser device 590 shown has a first p-type AlGaAs cladding layer 11e with an Al composition ratio of 0.25 and a layer thickness of 0.35 μm, and a second p-type AlGaAs cladding layer 13c with an Al composition ratio of 0.25 and a layer thickness of 1.15 μm. Other layer structures are similar to those in Embodiment 1. Figure 3 The ridge-shaped large-area semiconductor laser device 500 shown is the same.

[0278] The fabrication method of the ridge-shaped large-area semiconductor laser device 590 is the same as that of embodiment 1.

[0279] The total thickness of the ridge-type large-area semiconductor laser device 590, consisting of the p-side light guiding layer 81 and the n-side light guiding layer 61, is 1.8 μm, allowing modes above the first order in the stacking direction. Additionally, u n It is 0.292273, u p It is 0.480463, u p >u n This is valid. Therefore, the light intensity distribution in the y-direction shifts towards the n-type GaAs substrate 2 side, which can reduce the number of allowed modes in the x-direction.

[0280] Width W of the lateral region of the spine o Ridge region I when it is zero a (Medial region I) a i and the lateral spinal region I a o ) and covered area II c The effective refractive indices are 3.41692 and 3.41672, respectively. With a ridge width of 2W of 100 μm, v is 11.91, allowing for 8 modes from the 0th order (fundamental mode) to the 7th order.

[0281] Lateral spinal region I a o The effective refractive index of this region, when removed by etching up to the second ESL layer 12, is 3.41692, independent of the removal by etching. Ridge region I a (Medial region I) a i and the lateral spinal region I a o The refractive indices of the two modes are the same. Therefore, the number of allowed modes is the same.

[0282] On the other hand, the current also diffuses from the upper end of the second ESL layer 12 in the x-direction, i.e., the ridge width direction. That is, it diffuses in the x-direction at a distance h2 (0.74 μm) from the upper end of the InGaAs quantum well active layer 7 to the upper end of the first ESL layer 10 and at a distance h1 (0.39 μm) from the upper end of the second ESL layer 12 to the upper end of the first ESL layer 10, and reaches the InGaAs quantum well active layer 7.

[0283] exist Figure 31 as well as Figure 32 The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 590 is shown. oGain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, so laser oscillation can be performed in any mode. Therefore, the horizontal spread angle deviates depending on which mode is used for laser oscillation.

[0284] On the other hand, in the ridge-type large-area semiconductor laser device 590, a ridge outer region I is formed by covering the exposed surface after the p-type GaAs contact layer 14 and the p-type AlGaAs second cladding layer 13c have been etched away with a SiN film 15, which serves as an insulating film, to form a current-non-injection structure. a o This results in a gain difference between modes, with the gain of lower-order modes becoming greater than that of higher-order modes. Therefore, laser oscillation in lower-order modes can be performed, enabling the achievement of narrow horizontal diffusion angles.

[0285] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 3rd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0286] In the ridge-shaped large-area semiconductor laser device 590, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o When the width is above 15 μm, a gain difference exceeding 12% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillation. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0287] Furthermore, due to the isotropic diffusion of current, the width W of the outer region of the ridge is... o It is acceptable as long as the range is wider than the distance h1+h2 (1.13μm) and narrower than W (50μm).

[0288] In the ridge-shaped large-area semiconductor laser device 590 described in Embodiment 4, the outer region I of the ridge is removed by etching after covering it with a SiN film 15. a oThe exposed surfaces of the p-type GaAs contact layer 14 and the p-type AlGaAs second cladding layer 13c are configured with a current-non-injection structure, so that the current injected into the ridge-type large-area semiconductor laser device 590 is specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the low-order mode to be greater than that of the high-order mode, enabling laser oscillation in the low-order mode and thus narrowing the horizontal diffusion angle. Furthermore, by setting the asymmetric structure so that the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11e and the p-type AlGaAs second cladding layer 13c, it also reduces the light absorption caused by the charge carriers on the p-type AlGaAs first cladding layer 11e and the p-type AlGaAs second cladding layer 13c side, thereby improving the slope efficiency.

[0289] Variation 1 of Implementation Method 4

[0290] Figure 33 This is a perspective view of a ridge-shaped large-area semiconductor laser device 600 with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 4, Example 1.

[0291] and Figure 30 The difference between the ridge-shaped large-area semiconductor laser device 590 shown in Embodiment 4 is that it does not have a second ESL layer 12, and for the outer ridge region I... a o It is not removed by etching, but formed by the insulation of the semiconductor layer achieved by proton injection.

[0292] The fabrication method of the ridge-shaped large-area semiconductor laser device 600 is the same as that of variation 1 of embodiment 1.

[0293] In the ridge-type large-area semiconductor laser device 600, since there is no second ESL layer 12, the ridge region I... a (Medial region I) a i and the lateral spinal region I a o The effective refractive index is 3.41693. Encapsulated region II c With the same effective refractive index of 3.41672, and with a ridge width of 2W of 100μm, the v of Equation (1) is 12.20, allowing for 8 modes from the 0th order (basic mode) to the 7th order.

[0294] The lateral spinal region I was injected with protons a o The effective refractive index is related to the inner ridge region I a iThe same 3.41693. As an example, when protons are injected from the surface of the p-type GaAs contact layer 14 to a depth of 0.25 μm, the distance h1 from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17 is 1.45 μm.

[0295] If the distance h1 from the upper end of the first ESL layer 10 to the lower end of the current-non-injection structure, i.e., the proton injection region 17, is greater than 0.39 μm, then the outer ridge region I... a o The effective refractive index becomes related to the inner ridge region I a i The effective refractive index is essentially the same. That is, there is almost no light in the region above 0.39 μm from h1, so it is not affected by scattering caused by crystallization damage due to proton injection into the crystal layer and the loss caused by such scattering, nor does it produce a decrease in reliability caused by crystal defects.

[0296] exist Figure 34 as well as Figure 35 The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 600 is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, allowing laser oscillation regardless of the mode. Therefore, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0297] On the other hand, in the ridge-type large-area semiconductor laser device 600, the outer region I of the ridge, which is formed as a proton injection region 17 that functions as a current non-injection structure, is provided. a o This causes the current to flow specifically in the inner region of the ridge, I. a i The flow creates gain differences between modes, with lower-order modes having greater gain than higher-order modes. Therefore, laser oscillations in lower-order modes can be performed, enabling the achievement of narrow horizontal spread angles.

[0298] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 2nd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0299] In the ridge-shaped large-area semiconductor laser device 600, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o At a width greater than 15 μm, a gain difference exceeding 11% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillations. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0300] In addition, the width W of the lateral region of the spine o Any range wider than the distance h1+h2 (2.19 μm) and narrower than W (50 μm) is acceptable. Although a distance h1 of 0.39 μm or more from the upper end of the first ESL layer 10 to the lower end of the proton injection region 17 is sufficient, in the ridge-shaped large-area semiconductor laser device 600 according to the variation 1 of embodiment 4, the distance h1 is set to 1.45 μm to further move the damaged portion of the semiconductor layer caused by proton injection away from the light intensity distribution, thereby achieving higher reliability.

[0301] In this embodiment, as an example, a structure for proton ion implantation is shown, but it is not limited to this, as long as the resistance of the semiconductor layer can be increased.

[0302] If proton implantation is used as the insulator of the semiconductor layer, an etching process is not required, thus reducing the number of fabrication steps and making the fabrication of ridge-shaped large-area semiconductor laser devices easier.

[0303] In the ridge-shaped large-area semiconductor laser device 600 described in the above-described variation 1 of embodiment 4, a ridge outer region I is provided, in which a proton injection region 17 is formed to function as a current non-injection structure. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 600 to be specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the low-order mode to be greater than that of the high-order mode, enabling laser oscillation in the low-order mode and thus narrowing the horizontal diffusion angle. Furthermore, by setting it to an asymmetric structure in which the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11d, it also reduces light absorption caused by carriers on the p-type AlGaAs first cladding layer 11d side, thereby improving the slope efficiency.

[0304] Variation 2 of Implementation Method 4

[0305] Figure 36This is a perspective view of a ridge-shaped large-area semiconductor laser device 610 with a real refractive index distribution in the 975nm band, which is described in Modification 2 of Embodiment 4.

[0306] and Figure 30 The difference between the ridge-shaped large-area semiconductor laser device 590 shown in Embodiment 4 is that it does not have a second ESL layer 12, and for the outer ridge region I... a o Instead of removing it by etching, the SiN film 15a is respectively disposed on a portion of the surface at both ends of the ridge width direction of the p-type GaAs contact layer 14.

[0307] The fabrication method of the ridge-shaped large-area semiconductor laser device 610 is the same as that of variation 2 of embodiment 1.

[0308] Ridge inner region I in ridge-shaped large-area semiconductor laser device 610 a i Lateral spinal region I a o and the covered area II c The effective refractive indices are 3.41693, 3.41693, and 3.41672, respectively, allowing eight modes from order 0 (fundamental mode) to order 7 with a ridge width of 2W of 100 μm. Since the current diffuses from the top of the p-type GaAs contact layer 14, the distance h1 is 1.7 μm.

[0309] exist Figure 37 as well as Figure 38 The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 610 is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 1%, even if present, allowing laser oscillation regardless of the mode. Therefore, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0310] If the lateral spinal region I is set a o This results in a gain difference between the modes, with the gain of lower-order modes becoming greater than that of higher-order modes. Therefore, laser oscillation in lower-order modes can be performed, enabling the achievement of narrow horizontal diffusion angles.

[0311] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, oThe gain of the 0th to 2nd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0312] In the ridge-shaped large-area semiconductor laser device 610, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o At a width greater than 15 μm, a gain difference exceeding 11% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillations. In the lateral region of the ridge, the width W... o The effect is more pronounced when the size is above 20 μm.

[0313] In addition, the width W of the lateral region of the spine o Any range that is wider than the distance h1+h2 (2.44μm) and narrower than W (50μm) is acceptable. In this embodiment, due to the lateral ridge region I a o The current-free structure is formed by a SiN film 15a acting as an insulating film. Therefore, the distance from the p-type GaAs contact layer 14, which diffuses from the current in the x-direction (ridge width direction), to the InGaAs quantum well active layer 7 becomes longer, reaching 2.44 μm. The width W in the outer region of the ridge is... o It is difficult to obtain a gain difference in a narrow case, but if the width W of the outer region of the ridge is increased... o The effect is enhanced, so there are no particular problems. Furthermore, although SiN is used as the insulating film, other materials such as SiO2 can also be used.

[0314] Because there are no processes such as etching or proton implantation, the fabrication of ridge-shaped large-area semiconductor laser devices is extremely easy.

[0315] In the ridge-type large-area semiconductor laser device 610 described in Modification 2 of Embodiment 4, a ridge-outer region I is provided, which has a current-non-injection structure formed by covering a portion of the surfaces at both ends of the p-type GaAs contact layer 14 in the ridge width direction with SiN films 15a. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 610 to be specifically concentrated in the inner region I of the ridge. aThe flow allows the gain of the lower-order mode to be greater than that of the higher-order mode, enabling laser oscillation in the lower-order mode and thus narrowing the horizontal diffusion angle. Furthermore, by setting it to an asymmetric structure in which the refractive index of the n-type AlGaAs cladding layer 3 is higher than that of the p-type AlGaAs first cladding layer 11d, it also reduces light absorption caused by carriers on the p-type AlGaAs first cladding layer 11d side, thereby improving the slope efficiency.

[0316] Implementation Method 5

[0317] Figure 39 This is a perspective view of a ridge-shaped large-area semiconductor laser device 620 with a real refractive index distribution in the 975nm band according to Embodiment 5.

[0318] Figure 39 The ridge-type large-area semiconductor laser device 620 shown has a p-type AlGaAs first ESL layer 21 (also called a p-type AlGaAs low-refractive-index layer or a second conductivity type low-refractive-index layer) with an Al composition ratio of 0.55 and a layer thickness of 40 nm, a p-type AlGaAs first cladding layer 22 with an Al composition ratio of 0.20 and a layer thickness of 0.10 μm, a p-type AlGaAs second ESL layer 23 with an Al composition ratio of 0.55 and a layer thickness of 40 nm, and an Al composition ratio of... The structure includes a second p-type AlGaAs coating layer 24 with an Al composition ratio of 0.20 and a thickness of 0.75 μm, a third p-type AlGaAs ESL layer 25 with an Al composition ratio of 0.55 and a thickness of 40 nm, a third p-type AlGaAs coating layer 26 (a second coating layer of the second conductivity type) with an Al composition ratio of 0.20 and a thickness of 0.65 μm, a p-type GaAs contact layer 27 with a thickness of 0.2 μm, a SiN film 28 with a thickness of 0.4 μm, and a p-type electrode 29.

[0319] Other layer structures and implementation method 1 Figure 3 The ridge-shaped large-area semiconductor laser device 500 shown is the same.

[0320] Furthermore, the p-type AlGaAs first cladding layer 22 and the p-type AlGaAs second cladding layer 24 are collectively referred to as the first cladding layer of the second conductivity type.

[0321] The following describes the fabrication method of the ridge-shaped large-area semiconductor laser device 620.

[0322] On an n-type GaAs substrate 2, semiconductor layers from the n-type AlGaAs cladding layer 3 to the p-type GaAs contact layer 27 are sequentially crystallized and grown on the substrate 2 using methods such as metal-organic vapor deposition (MOCVD).

[0323] Next, cover the inner ridge area I with a photoresist. ai Dry etch up to the third ESL layer 25 and strip the resist.

[0324] Subsequently, the inner ridge region I was covered with a photoresist. a i and lateral spinal region I a o Dry etch up to the second ESL layer 23 and strip the resist.

[0325] Furthermore, the inner ridge region I was covered with a resist. a i Lateral spinal region I a o and stepped region II t Dry etch up to the first ESL layer 21 and strip the resist.

[0326] Then, cover the inner ridge region I with a resist. a i SiN film 28 is formed and stripped, and the resist is also stripped.

[0327] Finally, 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.

[0328] In the outer region I of the ridge of the ridge-shaped large-area semiconductor laser device 620 a o On both sides, there is a covering region II with a width d (e.g., 2 μm). c Set stepped area II t This step surface region II t The effective refractive index is less than that of the ridge region I. a (Medial region I) a i and the lateral spinal region I a o The effective refractive index is greater than that of the cladding region II. c The effective refractive index. In region II without step surfaces. t And this part is related to the covered area II c For the same structure, there are many higher-order modes, but if a step surface region II is set... t Then the value of the propagation constant of the higher-order mode divided by the wavenumber in free space becomes smaller than that of the step region II. t The effective refractive index makes these higher-order modes impossible to exist, thus reducing the number of modes allowed in the horizontal direction.

[0329] The ridge-type large-area semiconductor laser device 620 is characterized in that, in the encapsulated region II cThe outer side has a stepped region II with an effective refractive index of nt. t If m is set as a positive integer, then the following equation (9) is satisfied, and the following equation (10) is also satisfied.

[0330] [Number 11]

[0331] Number 11

[0332] In the ridge-shaped large-area semiconductor laser device 620, the width W in the outer region of the ridge o When the value is 0 μm, the ridge region I a (Medial region I) a i and the lateral spinal region I a o The effective refractive index becomes 3.41741, and the cladding region II... c The effective refractive index becomes 3.41637, therefore in region II where the ridge width 2W is 100μm and there are no step surfaces. t In the case of v=27.16, 18 modes from order 0 to order 17 are allowed.

[0333] On the other hand, when setting the stepped area II t At that time, the stepped region II t The effective refractive index is 3.41704, therefore, in the 11th to 17th order modes, the value of the propagation constant divided by the wavenumber in free space becomes smaller than that in the step region II. t The effective refractive index allows for 11 modes from order 0 to order 10.

[0334] The ridge-shaped large-area semiconductor laser device 620 has a limited width W of the outer ridge region. o , lateral spinal region I a o The effective refractive index of this region, after being removed by etching up to the third ESL layer 25, becomes 3.41741, independent of the removal by etching, in the ridge region I. a (Medial region I) a i and the lateral spinal region I a o The refractive indices of the two modes are the same. Therefore, the number of allowed modes becomes the same.

[0335] On the other hand, in the ridge-type large-area semiconductor laser device 620, the current also diffuses in the x-direction, i.e., the ridge width direction, from the upper end of the third ESL layer 25. That is, it diffuses in the x-direction at a distance h2 (0.64 μm) from the upper end of the InGaAs quantum well active layer 7 to the upper end of the first ESL layer 21 (p-type AlGaAs low refractive index layer 21) and a distance h1 (0.93 μm) from the upper end of the first ESL layer 21 to the upper end of the third ESL layer 25, and reaches the InGaAs quantum well active layer 7.

[0336] exist Figure 40 as well as Figure 41 The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 620 is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 2%, even if present, so laser oscillation can be performed in any mode. Therefore, the horizontal spread angle deviates depending on which mode is used for oscillation.

[0337] On the other hand, in the ridge-type large-area semiconductor laser device 620, the outer region I of the ridge, which is formed by covering the exposed surface after the p-type GaAs contact layer 27 and the p-type AlGaAs third cladding layer 26 have been etched away with a SiN film 28, becomes a current-non-injection structure. a o This results in a gain difference between modes, with the gain of lower-order modes becoming greater than that of higher-order modes. Therefore, laser oscillation in lower-order modes can be performed, enabling the achievement of narrow horizontal diffusion angles.

[0338] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 3rd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0339] In the ridge-shaped large-area semiconductor laser device 620, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o When the width is above 15 μm, a gain difference exceeding 10% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillation. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0340] Furthermore, due to the isotropic diffusion of current, the width W of the outer region of the ridge is... o It is acceptable as long as the range is wider than the distance h1+h2 (1.57μm) and narrower than W (50μm).

[0341] In the ridge-type large-area semiconductor laser device 620 described in Embodiment 5, the outer ridge region I, which is formed by covering the exposed surface after the p-type GaAs contact layer 27 and the p-type AlGaAs third cladding layer 26 have been etched away with a SiN film 28, becomes a current-non-injection structure. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 620 to be specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the lower-order mode to be greater than that of the higher-order mode, enabling oscillation of the lower-order mode and thus narrowing the horizontal diffusion angle. Furthermore, by setting the step surface region II... t This causes the value obtained by dividing the propagation constant of the higher-order mode by the wavenumber in free space to become smaller than that of the step region II. t The effective refractive index makes these higher-order modes impossible to exist, thus also having the effect of reducing the number of modes allowed in the horizontal direction.

[0342] Variation 1 of Implementation Method 5

[0343] Figure 42 This is a perspective view of a ridge-shaped large-area semiconductor laser device 630 with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 5, Example 1.

[0344] Figure 42 The ridge-type large-area semiconductor laser device 630 shown has a p-type AlGaAs second cladding layer 24a (a cladding layer of the second conductivity type) with an Al composition ratio of 0.20 and a layer thickness of 1.40 μm, a SiN film 28a with a film thickness of 0.4 μm, and a proton implantation region 30.

[0345] and Figure 39 The difference in the ridge-shaped large-area semiconductor laser device 620 shown is that it does not have a third ESL layer 25, and for the outer region I of the ridge... a o It is not removed by etching, but formed by the insulation of the semiconductor layer achieved by proton injection.

[0346] The following describes the fabrication method of the ridge-shaped large-area semiconductor laser device 630.

[0347] On an n-type GaAs substrate 2, semiconductor layers from the n-type AlGaAs cladding layer 3 to the p-type GaAs contact layer 27 are sequentially crystallized and grown on the substrate 2 using methods such as metal-organic vapor deposition (MOCVD).

[0348] Next, cover the inner ridge area I with a photoresist. a i Protons are implanted to form a proton implantation region 30, and the resist is stripped off.

[0349] Subsequently, the inner ridge region I was covered with a photoresist. a i and lateral spinal region I a o Dry etching is then performed up to the second ESL layer 23, and the resist is stripped. At this point, the encapsulated region II... c and stepped region II t The proton injection region 30 was also etched away.

[0350] Then, cover the inner ridge region I with a resist. a i Lateral spinal region I a o and stepped region II t Dry etch up to the first ESL layer 21 and strip the resist.

[0351] Furthermore, the inner ridge region I was covered with a resist. a i and lateral spinal region I a o SiN film 28a was formed and stripped, and the resist was also stripped.

[0352] Finally, 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.

[0353] In the ridge-shaped large-area semiconductor laser device 630, the width W in the outer region of the ridge o When the value is 0 μm, the ridge region I a (Medial region I) a i and the lateral spinal region I a o The effective refractive index becomes 3.41741, and the cladding region II... c The effective refractive index becomes 3.41637, therefore in region II where the ridge width 2W is 100μm and there are no step surfaces. t In the case of v=27.16, 18 modes from order 0 to order 17 are allowed.

[0354] On the other hand, when setting the stepped area II t At that time, the stepped region II t The effective refractive index is 3.41704, therefore, in the 11th to 17th order modes, the value obtained by dividing the propagation constant by the wavenumber in free space becomes smaller than that in the step region II. t The effective refractive index allows for 11 modes from order 0 to order 10.

[0355] As an example, when protons are injected from the p-type GaAs contact layer 27 to a depth of 0.74 μm, the distance h1 from the upper end of the first ESL layer 21 to the lower end of the proton injection region 30 is 1.00 μm.

[0356] Because the width of the lateral region of the spine is W o Lateral region of the spine I a o The effective refractive index is 3.41741, therefore the number of allowed modes is the same as in Implementation 5.

[0357] If the distance h1 from the upper end of the first ESL layer 21 to the lower end of the current-non-injection structure, i.e., the proton injection region 30, is greater than 0.93 μm, then the outer ridge region I a o The effective refractive index becomes related to the inner ridge region I a i The effective refractive index is essentially the same. That is, there is almost no light in the region above 0.93 μm from h1, so it is not affected by scattering caused by crystallization damage due to proton injection into the crystal layer and the loss caused by such scattering, nor does it produce a decrease in reliability caused by crystal defects.

[0358] On the other hand, the current also begins to diffuse in the x-direction, i.e., the ridge width direction, from the lower end of the proton injection region 30, so that the distance h2 (0.64 μm) from the upper end of the InGaAs quantum well active layer 7 to the upper end of the first ESL layer 21 and the distance h1 (1.00 μm) from the upper end of the first ESL layer 21 to the lower end of the proton injection region 30 diffuse in the x-direction and reach the InGaAs quantum well active layer 7.

[0359] exist Figure 43 as well as Figure 44 The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 630 is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. oIn the case of 0 μm, the gain difference between modes is almost negligible, or less than 2%, even if present, allowing laser oscillation regardless of the mode. Therefore, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0360] On the other hand, in the ridge-type large-area semiconductor laser device 630, a ridge outer region I is provided, which functions as a current non-injection structure for forming a proton injection region 30. a o This results in a gain difference between modes, with the gain of lower-order modes becoming greater than that of higher-order modes. Therefore, laser oscillation in lower-order modes can be performed, enabling the achievement of narrow horizontal diffusion angles.

[0361] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 3rd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0362] In the ridge-shaped large-area semiconductor laser device 630, even if the width W of the outer region of the ridge is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o When the width is above 15 μm, a gain difference exceeding 10% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillation. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0363] In addition, the width W of the lateral region of the spine o Any range wider than the distance h1+h2 (1.64 μm) and narrower than W (50 μm) is acceptable. Although a distance h1 of 0.93 μm or more from the upper end of the first ESL layer 21 to the lower end of the proton injection region 30 is sufficient, in the ridge-shaped large-area semiconductor laser device 630 according to the variation 1 of embodiment 5, the distance h1 is set to 1.00 μm to further move the damaged portion of the semiconductor layer caused by proton injection away from the light intensity distribution, thereby achieving higher reliability.

[0364] In this embodiment, as an example, a structure for proton ion implantation is shown, but it is not limited to this, as long as the resistance of the semiconductor layer can be increased.

[0365] If proton implantation is used as the insulator of the semiconductor layer, an etching process is not required, thus reducing the number of fabrication steps and making the fabrication of ridge-shaped large-area semiconductor laser devices easier.

[0366] In the ridge-shaped large-area semiconductor laser device 630 according to the above-described variation 1 of embodiment 5, since a ridge outer region I is provided, which functions as a current non-injection structure, is formed in the proton injection region 30, the ridge outer region I is provided in the embodiment 5. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 630 to be specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the lower-order mode to be greater than that of the higher-order mode, enabling laser oscillation in the lower-order mode and thus narrowing the horizontal diffusion angle. Furthermore, by setting the stepped region II... t This causes the value obtained by dividing the propagation constant of the higher-order mode by the wavenumber in free space to become smaller than that of the step region II. t The effective refractive index makes these higher-order modes impossible to exist, thus also having the effect of reducing the number of modes allowed in the horizontal direction.

[0367] Variation 2 of Implementation Method 5

[0368] Figure 45 This is a perspective view of a ridge-shaped large-area semiconductor laser device 640 with a real refractive index distribution in the 975nm band, which is described in Modification 2 of Embodiment 5.

[0369] Figure 45 The ridge-shaped large-area semiconductor laser device 640 shown has a SiN film 28b with a thickness of 0.4 μm.

[0370] and Figure 39 The difference in the ridge-shaped large-area semiconductor laser device 620 shown is that it does not have a third ESL layer 25, and in order to form the outer ridge region I a o Instead of removing it by etching, the SiN film 28b is respectively disposed on a portion of the surface at both ends of the ridge width direction of the p-type GaAs contact layer 27.

[0371] The following describes the fabrication method of the ridge-shaped large-area semiconductor laser device 640.

[0372] On an n-type GaAs substrate 2, semiconductor layers from the n-type AlGaAs cladding layer 3 to the p-type GaAs contact layer 27 are sequentially crystallized and grown on the substrate 2 using methods such as metal-organic vapor deposition (MOCVD).

[0373] Next, cover the inner ridge area I with a photoresist.a i and lateral spinal region I a o Dry etch up to the second ESL layer 23 and strip the resist.

[0374] Then, cover the inner ridge region I with a resist. a i Lateral spinal region I a o and stepped region II t Dry etch up to the first ESL layer 21 and strip the resist.

[0375] Subsequently, the inner ridge region I was covered with a photoresist. a i SiN film 28b is formed and stripped, and the resist is also stripped.

[0376] Finally, 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.

[0377] Ridge-inner region I in ridge-shaped large-area semiconductor laser device 640 a i Lateral spinal region I a o Coverage Area II c and stepped region II t The effective refractive indices are 3.41741, 3.41741, 3.41637, and 3.41704, respectively, allowing 11 modes from order 0 (fundamental mode) to order 10 with a ridge width of 2W of 100 μm. Since the current diffuses from the top of the p-type GaAs contact layer 27, the distance h1 is 1.64 μm.

[0378] exist Figure 46 as well as Figure 47 The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 640 is shown. o Gain G for each mode at 3, 6, 9, 10, 11, 15, 20, and 25 μm. i The width W of the lateral ridge region of the comparative example is also shown. o In the case of 0 μm, the gain difference between modes is almost negligible, or less than 2%, even if present, allowing laser oscillation regardless of the mode. Therefore, the horizontal spread angle deviates depending on the mode in which laser oscillation is performed.

[0379] On the other hand, in the ridge-type large-area semiconductor laser device 640, a ridge-outer region I is provided, which has a current-non-injection structure formed by covering a portion of the surfaces at both ends of the p-type GaAs contact layer 27 in the ridge width direction with SiN films 28b. a o This causes the current to flow specifically in the inner region I of the ridge. a i The flow in the medium creates a gain difference between modes, with lower-order modes having a larger gain than higher-order modes. Therefore, laser oscillation in lower-order modes is possible, enabling the achievement of narrow horizontal spread angles.

[0380] Additionally, the low-order modes involved in this disclosure, such as the width W of the lateral ridge region, o The gain of the 0th to 3rd order modes in the case of 10μm and below is greater than that of the low-order mode of the comparative example. Therefore, laser oscillation is achieved with less gain, and a ridge-type large-area semiconductor laser device with laser oscillation at a lower threshold current than that of the comparative example is obtained.

[0381] Even if the width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 640 is... o Beyond 10 μm, the gain of low-order modes is also greater than in the comparative example without increasing loss. In the outer ridge region, the width W... o When the width is above 15 μm, a gain difference exceeding 10% exists between the fundamental mode and all other modes, enabling substantial fundamental mode oscillation. In the lateral region of the ridge, the width W... o This trend is more pronounced when the size is above 20 μm.

[0382] The width W of the outer region of the ridge of the ridge-shaped large-area semiconductor laser device 640 o Any range that is wider than the distance h1+h2 (2.28μm) and narrower than W (50μm) is acceptable. In this embodiment, due to the lateral ridge region I a o The current-injection-free structure is formed by a SiN film 28b acting as an insulating film. Therefore, the distance from the p-type GaAs contact layer 27, where the current diffuses in the x-direction, to the InGaAs quantum well active layer 7 becomes longer, reaching 2.38 μm, with a width W in the outer region of the ridge. o It is difficult to obtain a gain difference in a narrow case, but if the width W of the outer region of the ridge is increased... o The effect is enhanced, so there are no particular problems. Furthermore, although SiN is used as the insulating film, other materials such as SiO2 can also be used.

[0383] In addition, since there are no processes such as etching or proton injection, the fabrication of ridge-shaped large-area semiconductor laser devices is extremely easy.

[0384] In this embodiment, a ridge-type large-area semiconductor laser device 640 is illustrated by using a structure that reduces the number of allowed horizontal lateral modes, sets a gain difference between allowed horizontal lateral modes, and performs laser oscillation in a low-order mode to narrow the horizontal diffusion angle. However, it is not limited to this and the same effect is achieved in a typical ridge-type large-area semiconductor laser device where the number of horizontal lateral modes does not decrease.

[0385] In this embodiment, the lateral spinal region I a o Effective refractive index and inner ridge region I a i The effective refractive indices are equal, but as explained in Implementation 1, they need to be substantially the same.

[0386] In the ridge-type large-area semiconductor laser device 640 described in Modification 2 of Embodiment 5, a ridge-outer region I is provided, which has a current-non-injection structure formed by covering a portion of the surfaces at both ends of the p-type GaAs contact layer 27 in the ridge width direction with SiN films 28b. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 640 to be specifically directed to the inner region I of the ridge. a i The flow allows the gain of lower-order modes to be greater than that of higher-order modes, enabling oscillations in lower-order modes and thus narrowing the horizontal diffusion angle. Furthermore, by setting the step surface region II... t This causes the value obtained by dividing the propagation constant of the higher-order mode by the wavenumber in free space to become smaller than that of the step region II. t The effective refractive index makes these higher-order modes impossible to exist, thus also having the effect of reducing the number of modes allowed in the horizontal direction.

[0387] Implementation Method 6

[0388] Figure 48 This is a perspective view of a ridge-shaped large-area semiconductor laser device 650 with a real refractive index distribution in the 975nm band according to Embodiment 6.

[0389] Figure 48The ridge-type large-area semiconductor laser device 650 shown includes a p-type AlGaAs first cladding layer 31 with an Al composition ratio of 0.20 and a layer thickness of 0.10 μm, a p-type AlGaAs first ESL layer 32 (also called a p-type AlGaAs low refractive index layer or a low refractive index layer of the second conductivity type) with an Al composition ratio of 0.55 and a layer thickness of 40 nm, a p-type AlGaAs second cladding layer 33 with an Al composition ratio of 0.20 and a layer thickness of 0.75 μm, a p-type AlGaAs second ESL layer 34 with an Al composition ratio of 0.55 and a layer thickness of 40 nm, a p-type AlGaAs third cladding layer 35 (a second cladding layer of the second conductivity type) with an Al composition ratio of 0.20 and a layer thickness of 0.65 μm, a p-type GaAs contact layer 36 with a layer thickness of 0.2 μm, a SiN film 37 with a film thickness of 0.2 μm, and a p-type electrode 38.

[0390] Furthermore, the p-type AlGaAs first coating layer 31 and the p-type AlGaAs second coating layer 33 are collectively referred to as the first coating layer of the second conductivity type.

[0391] For other layered structures, except for the absence of an n-type low-refractive-index layer, they are similar to those in Embodiment 1. Figure 3 The ridge-shaped large-area semiconductor laser device 500 shown is the same.

[0392] The fabrication method of the ridge-shaped large-area semiconductor laser device 650 is the same as that of Embodiment 1. The distance h2 from the upper end of the InGaAs quantum well active layer 7 to the upper end of the first ESL layer 32 is 0.74 μm, and the distance h1 from the upper end of the second ESL layer 34 to the upper end of the first ESL layer 32 is 0.79 μm.

[0393] The ridge-type large-area semiconductor laser device 650 is a ridge-type large-area semiconductor laser device with a typical real refractive index distribution in the 975nm band without an n-type low-refractive-index layer. A first ESL layer 32 (p-type AlGaAs low-refractive-index layer 32) is disposed between a p-type AlGaAs first cladding layer 31 and a p-type AlGaAs second cladding layer 33. The allowable inter-mode gain difference exhibits the same trend as in Embodiment 1.

[0394] In the ridge-type large-area semiconductor laser device 650, although the thickness of the p-type AlGaAs first cladding layer 31 is set to 0.1 μm, it is not limited to this thickness. If the thickness of this layer is increased, the number of modes allowed in the x-direction can be easily reduced.

[0395] In the ridge-type large-area semiconductor laser device 650 described in Embodiment 6, the outer ridge region I, which is formed by covering the exposed surface after the p-type GaAs contact layer 36 and the p-type AlGaAs third cladding layer 35 have been etched away with a SiN film 37, becomes a current-non-injection structure. a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 650 to be specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the lower-order mode to be greater than that of the higher-order mode, enabling oscillation of the lower-order mode and thus narrowing the horizontal diffusion angle.

[0396] Variation 1 of Implementation Method 6

[0397] Figure 49 This is a perspective view of a ridge-shaped large-area semiconductor laser device 660 with a real refractive index distribution in the 975nm band, according to a variation of Embodiment 6, Example 1.

[0398] Figure 49 The ridge-type large-area semiconductor laser device 660 shown has a p-type AlGaAs second cladding layer 33a with an Al composition ratio of 0.20 and a layer thickness of 1.40 μm, a SiN film 37a with a film thickness of 0.2 μm, and a proton injection region 40.

[0399] When protons are injected from the surface of the p-type GaAs contact layer 36 to a depth of 0.6 μm, the distance h1 from the upper end of the first ESL layer 32 to the lower end of the proton injection region 40 is 1.0 μm.

[0400] Ridge-type large-area semiconductor laser device 660 and Figure 48 The difference in the ridge-shaped large-area semiconductor laser device 650 shown is that it does not have a second ESL layer 34, and for the outer region I of the ridge... a o It is not removed by etching, but formed by the insulation of the semiconductor layer achieved by proton injection.

[0401] The method for manufacturing the ridge-shaped large-area semiconductor laser device 660 is the same as that of variation 1 of embodiment 1.

[0402] If the distance h1 from the upper end of the first ESL layer 32 to the lower end of the current-non-injection structure, i.e., the proton injection region 40, is greater than 0.79 μm, then the outer ridge region I a o The effective refractive index becomes related to the inner ridge region I a iThe effective refractive index is essentially the same. That is, there is almost no light in the region above 0.79 μm from h1, so it is not affected by scattering caused by crystallization damage due to proton injection into the crystal layer and the loss caused by such scattering, nor does it produce a decrease in reliability caused by crystal defects.

[0403] The ridge-type large-area semiconductor laser device 660 is a ridge-type large-area semiconductor laser device with a typical real refractive index distribution without an n-type low-refractive-index layer, wherein a first ESL layer 32 is disposed between a p-type AlGaAs first cladding layer 31 and a p-type AlGaAs second cladding layer 33a. The allowable inter-mode gain difference exhibits the same trend as in Variation 1 of Embodiment 1.

[0404] In the ridge-type large-area semiconductor laser device 660, although the thickness of the p-type AlGaAs first cladding layer 31 is set to 0.1 μm, it is not limited to this thickness. If the thickness of this layer is increased, the number of modes allowed in the x-direction, i.e. the ridge width direction, can be easily reduced.

[0405] In this embodiment, as an example, a structure for proton ion implantation is shown, but it is not limited to this, as long as the resistance of the semiconductor layer can be increased.

[0406] If proton implantation is used as the insulator of the semiconductor layer, an etching process is not required, thus reducing the number of fabrication steps and making the fabrication of ridge-shaped large-area semiconductor laser devices easier.

[0407] In the ridge-shaped large-area semiconductor laser device 660 described in Modification 1 of Embodiment 6, since a ridge outer region I is provided, which functions as a current non-injection structure, a o This causes the current injected into the ridge-shaped large-area semiconductor laser device 660 to be specifically concentrated in the inner region I of the ridge. a i The flow in the middle allows the gain of the low-order mode to be greater than that of the high-order mode, enabling laser oscillation in the low-order mode and thus narrowing the horizontal diffusion angle.

[0408] Variation 2 of Implementation Method 6

[0409] Figure 50 This is a perspective view of a ridge-shaped large-area semiconductor laser device 670 with a real refractive index distribution in the 975nm band, according to a modified example 2 of embodiment 6.

[0410] Figure 50 The ridge-shaped large-area semiconductor laser device 670 shown has a SiN film 37b with a thickness of 0.2 μm.

[0411] and Figure 48 The difference in the ridge-shaped large-area semiconductor laser device 650 shown is that it does not have a second ESL layer 34, and for the outer region I of the ridge... a o Instead of removing it by etching, the SiN film 37b is respectively disposed on a portion of the surface at both ends of the ridge width direction of the p-type GaAs contact layer 36.

[0412] The fabrication method of the ridge-shaped large-area semiconductor laser device 670 is the same as that of variation 2 of embodiment 1.

[0413] The ridge-type large-area semiconductor laser device 670 is a ridge-type large-area semiconductor laser device with a typical real refractive index distribution without an n-type low-refractive-index layer, wherein a first ESL layer 32 is disposed between a p-type AlGaAs first cladding layer 31 and a p-type AlGaAs second cladding layer 33a. The allowable inter-mode gain difference exhibits the same trend as in variant 2 of embodiment 1.

[0414] In the ridge-type large-area semiconductor laser device 670, the thickness of the p-type AlGaAs first cladding layer 31 is set to 0.1 μm, but it is not limited to this thickness. If the thickness of this layer is increased, the number of modes allowed in the x-direction can be easily reduced.

[0415] Furthermore, in this embodiment, since there are no processes such as etching or proton implantation, the fabrication of the ridge-shaped large-area semiconductor laser device is extremely easy.

[0416] In this embodiment, a ridge-type large-area semiconductor laser device is illustrated by using a structure that reduces the number of allowed horizontal lateral modes, setting a gain difference between allowed horizontal lateral modes and oscillating in a low-order mode to narrow the horizontal diffusion angle. However, it is not limited to this, and even a ridge-type large-area semiconductor laser device with a conventional ridge structure that does not reduce the number of horizontal lateral modes can achieve the same effect.

[0417] In this embodiment, the lateral spinal region I a o Effective refractive index and inner ridge region I a i The effective refractive indices are equal, but as explained in Implementation 1, they need to be substantially the same.

[0418] In the ridge-shaped large-area semiconductor laser device 670 described in Modification 2 of Embodiment 6, since the outer region I of the ridge is covered by SiN film 37b, a oA portion of the surface at both ends of the ridge width direction of the p-type GaAs contact layer 36 is configured as a current-non-injection structure, so the current injected into the ridge-type large-area semiconductor laser device 670 is specifically located in the inner region I of the ridge. a i The flow in the middle results in the gain of the lower-order mode being greater than that of the higher-order mode, which can enable laser oscillation in the lower-order mode and thus narrow the horizontal diffusion angle.

[0419] In this disclosure, a ridge-type large-area semiconductor laser device with an oscillation wavelength of 975 nm is used as an example, but it is not limited to this wavelength. For example, the same effect can also be achieved in ridge-type large-area semiconductor laser devices of GaN in the 400 nm band, GaInP in the 600 nm band, and InGaAsP in the 1550 nm band.

[0420] Furthermore, in this disclosure, an n-type GaAs substrate is used and a ridge structure is formed on the p-type GaAs contact layer side. However, conversely, the same effect can be obtained even if a p-type GaAs substrate is used and a ridge structure is formed on the n-type GaAs contact layer side.

[0421] Furthermore, in this disclosure, a ridge-type large-area semiconductor laser device with a ridge width 2W of 100 μm is illustrated, but the ridge width 2W is not limited to 100 μm. As long as higher-order modes of one order or above are allowed in the horizontal direction, i.e. the ridge width direction, it is also possible to operate independently of the ridge width 2W.

[0422] Although various exemplary embodiments and examples are described in this disclosure, the various features, forms and functions described in one or more embodiments are not limited to the application of a specific embodiment, and can also be applied to the embodiments alone or in various combinations.

[0423] Therefore, numerous variations not illustrated can be conceived within the scope of the technology disclosed in this application. For example, 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.

[0424] Explanation of reference numerals in the attached figures

[0425] 1...n-type electrode; 2...n-type GaAs substrate; 3...n-type AlGaAs cladding layer; 4...n-type AlGaAs low-refractive-index layer; 5, 5a...n-side AlGaAs second light-guiding layer; 6, 6a...n-side AlGaAs first light-guiding layer; 7...InGaAs quantum well active layer; 8, 8a...p-side AlGaAs first light-guiding layer; 9, 9a...p-side AlGaAs second light-guiding layer; 10, 21, 32...p-type AlGaAs low-refractive-index layer (first ESL layer); 11, 11a, 11b, 11c, 11d, 11e, 22, 31...p-type AlGaAs first cladding layer; 12, 23, 34...second ESL layer; 13, 13a, 13b 13c, 24, 24a, 33, 33a... p-type AlGaAs second cladding layer; 14, 27, 36... p-type GaAs contact layer; 15, 15a, 28, 28a, 28b, 37, 37a, 37b... SiN film; 16, 29, 38... p-type electrode; 17, 30, 40... proton implantation region; 25... third ESL layer; 26, 35... p-type AlGaAs third cladding layer; 61, 62... n-side light guiding layer; 81, 82... p-side light guiding layer; 101... active layer; 102... light guiding layer; 103... first etch stop layer; 104... p-type first cladding layer; 105... second etch stop layer; 106... p-type second cladding layer.

Claims

1. A semiconductor laser device, provided with: a semiconductor substrate of a first conductivity type; a cladding layer of the first conductivity type, a light guide layer of the first conductivity type side, an active layer, a light guide layer of the second conductivity type side, a cladding layer of the second conductivity type, and a contact layer of the second conductivity type, which are laminated on the semiconductor substrate of the first conductivity type; a resonator composed of a front end face and a back end face which reciprocate a laser light; and a ridge region which guides the laser light between the front end face and the back end face and whose width is represented by 2W, the semiconductor laser device having an oscillation wavelength of λ and allowing a high-order mode of one order or more in a lamination direction of the layers, characterized in that the ridge region is composed of a ridge inner side region and a ridge outer side region, The width of the intracostal region is represented by 2W i and the effective refractive index is n a i , The ridge outside region is provided on both sides of the ridge inside region, and the width is represented by W o The effective refractive index is represented by n a o and has a current non-injection configuration, On both sides of the ridge outside area, at least the contact layer of the second conductive type and the cladding layer of the second conductive type are removed, and a cladding area with an effective refractive index n c is arranged. The average refractive index n of the inner region of the ridge and the outer region of the ridge a e is represented as: [Num 1] norm 1 (n a i • W i + n a o • W o ) / (W i + W o ) and satisfies the following relationship: [Num 2] norm 2 width of the ridge lateral region, i.e., W o greater than the distance from the lower end of the current non-injection structure to the active layer, and less than 1 / 2 of the width of the ridge region, i.e., W.

2. The semiconductor laser device according to claim 1, characterized in that a distance from an upper end portion of the cladding region to a lower end portion of the current non-injection structure is set to a length at which a number of modes allowed by the distance and a number of modes allowed by a structure having the ridge region and the cladding region become the same.

3. The semiconductor laser device according to claim 1 or 2, characterized in that a number of modes allowed in a ridge width direction of the ridge region is the same as a number of modes allowed by a structure having the ridge region and the cladding region.

4. The semiconductor laser device according to claim 1 or 2, characterized in that the cladding layer of the second conductivity type is composed of a first cladding layer of the second conductivity type and a second cladding layer of the second conductivity type, the current non-injection structure has an insulating film which covers exposed surfaces after at least the contact layer of the second conductivity type and the second cladding layer of the second conductivity type are removed in the ridge outer side region.

5. The semiconductor laser device according to claim 1 or 2, characterized in that the current non-injection structure is composed of a proton injection region.

6. The semiconductor laser device according to claim 1 or 2, characterized in that the current non-injection structure is composed of insulating films which respectively cover a part of surfaces of both ends in a ridge width direction of the contact layer of the second conductivity type of the ridge outer side region.

7. The semiconductor laser device according to claim 1 or 2, characterized in that a layer thickness of the light guide layer of the first conductivity type side is thicker than a layer thickness of the light guide layer of the second conductivity type side.

8. The semiconductor laser device according to claim 1 or 2, characterized in that a layer thickness of the light guide layer of the first conductivity type side is the same as a layer thickness of the light guide layer of the second conductivity type side.

9. The semiconductor laser device according to claim 1 or 2, characterized in that The refractive index n of the cladding layer of the first conductivity type cn is higher than the refractive index n of the cladding layer of the second conductivity type cp is higher.

10. The semiconductor laser device according to claim 1 or 2, characterized in that The refractive index n of the cladding layer of the first conductivity type cn The refractive index n of the cladding layer of the second conductivity type cp The layer thickness of the light guiding layer on the first conductivity type side is thicker than the layer thickness of the light guiding layer on the second conductivity type side.

11. The semiconductor laser device according to claim 1 or 2, characterized in that A low-refractive layer of the second conductivity type having a lower refractive index than the cladding layer of the second conductivity type is provided between the light-guiding layer of the second conductivity type and the cladding layer of the second conductivity type or within the cladding layer of the second conductivity type.

12. The semiconductor laser device according to claim 1 or 2, wherein The refractive index of the cladding layer of the first conduction type is set to n cn The refractive index of the cladding layer of the second conduction type is set to n cp , a low-refractive layer of the first conductive type having a layer thickness d n and a refractive index n n lower than a refractive index n cn of the cladding layer of the first conductive type, between the light-guiding layer of the first conductive type and the cladding layer of the second conductive type or within the cladding layer of the second conductive type, a low-refractive layer of the second conductive type having a layer thickness d p and a refractive index n p lower than a refractive index n cp of the cladding layer of the second conductive type, and satisfying: [Num 3] norm 3 13. The semiconductor laser device according to claim 1 or 2, wherein A step region having an effective refractive index ntis provided on both sides of the cladding region, and satisfies: [Num 4] Norm 4 and satisfies: [Num 5] Norm 5

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