Semiconductor laser with light field guiding layer and method of manufacturing the same

Abstract

The application relates to a semiconductor laser with a light field guiding layer and a preparation method thereof, and belongs to the technical field of semiconductor lasers. The semiconductor laser comprises, in sequence along an epitaxial growth direction, a GaAs substrate, a buffer layer, an N-type limiting layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type limiting layer and a GaAs ohmic contact layer, a P-type ohmic electrode is arranged above the GaAs ohmic contact layer, an N-type ohmic electrode is arranged below the GaAs substrate, an AlGaAs lower light field guiding layer is inserted between the N-type limiting layer and the N-type waveguide layer, and an AlGaAs upper light field guiding layer is arranged above the N-type waveguide layer. x3 Ga 1‑x3 As x4 Ga 1‑x4 As The application has the advantages that by designing the gradually-changing guiding layer, the light field of the base mode and high-order modes is guided to the guiding layer, the semiconductor laser is helped to realize base mode oscillation, the distribution range of the base mode can be increased, and the semiconductor laser can realize a lower fast-axis far-field divergence angle.

Description

Technical Field

[0001] This invention relates to the technical field of semiconductor lasers, and more specifically to a semiconductor laser with an optical field guiding layer and its fabrication method. Background Technology

[0002] Semiconductor lasers are the core engine of modern optoelectronic technology, and their applications have expanded from traditional communications to all aspects of industry, defense, medicine, and consumer electronics, such as pump sources for high-power solid-state lasers, lidar, biosensoring, and laser projection and display. As applications continue to expand and improve, market demands for semiconductor laser performance are also constantly increasing. Semiconductor lasers with high power, high efficiency, and low far-field divergence angles hold immense commercial value in the market.

[0003] To reduce the far-field divergence angle, improve output power, and increase electro-optic conversion efficiency, existing technologies typically employ asymmetric waveguide layer designs. Since the P-region loss of a semiconductor laser is significantly higher than the N-region loss, reducing the growth thickness of the P-type waveguide layer and increasing the growth thickness of the N-type waveguide layer can create an asymmetry between the two waveguide layers. Due to this asymmetry, the optical field shifts towards the N-region, with only a small portion of the optical field residing in the P-region and the majority in the N-region. This reduces the overall light absorption within the semiconductor laser, contributing to higher output power. Furthermore, the optical field shift also reduces the optical confinement factor of the semiconductor laser, thus helping to lower the fast-axis far-field divergence angle. However, this does not mean that the growth thickness of the P-type waveguide layer can be arbitrarily reduced while the growth thickness of the N-type waveguide layer can be increased. As the asymmetry of the waveguide layer increases, the optical confinement factor of the fundamental mode gradually decreases, while the optical confinement factor of the first-order mode gradually increases. When the asymmetry of the waveguide layer reaches a certain level, the optical confinement factor of the first-order mode will be greater than that of the fundamental mode. At this point, the semiconductor laser will transition from fundamental mode lasing to first-order mode lasing. When first-order mode lasing occurs in a semiconductor laser, the fast-axis far-field divergence angle deteriorates significantly, internal losses increase sharply, and output power and electro-optical conversion efficiency decrease accordingly. Therefore, how to effectively reduce the fast-axis far-field divergence angle of semiconductor lasers without easily inducing high-order mode lasing is the current research focus. Summary of the Invention

[0004] To address the technical problem of high-order mode lasing caused by existing asymmetric waveguide layer designs, this invention provides a semiconductor laser with an optical field guiding layer and its fabrication method, thereby solving the problems of how to suppress high-order mode lasing in semiconductor lasers and effectively reduce the fast-axis far-field divergence angle.

[0005] The technical solution of this invention is as follows:

[0006] In a first aspect, the present invention provides a semiconductor laser with an optical field guiding layer, comprising, sequentially along the epitaxial growth direction, a GaAs substrate, a buffer layer, an N-type confinement layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type confinement layer, and a GaAs ohmic contact layer. A P-type ohmic electrode is disposed above the GaAs ohmic contact layer, and an N-type ohmic electrode is disposed below the GaAs substrate. An Al2O3 electrode is inserted between the N-type confinement layer and the N-type waveguide layer. x3 Ga 1-x3 As under light field guiding layer and Al x4 Ga 1-x4 As light field guiding layer;

[0007] The Al x3 Ga 1-x3 In the lower light field guiding layer, 0 ≤ x3 ≤ 0.7, x3 linearly changes from high to low within the range of 0 to 0.7, and the growth thickness is 0.1 μm to 0.5 μm; more preferably, the growth thickness is 0.2 μm to 0.4 μm; the refractive index of the lower light field guiding layer increases as the aluminum composition decreases.

[0008] The Al x4 Ga 1-x4 As an upper light field guiding layer, wherein 0≤x4≤0.7, x4 is linearly varied in the range of 0~0.7, gradually changing from a low value to a high value, and the growth thickness is 0.1 μm~0.5 μm; more preferably, the growth thickness is 0.2 μm~0.4 μm; the refractive index of the upper light field guiding layer decreases with the increase of aluminum composition.

[0009] Furthermore, the Al x3 Ga 1-x3 In the As light field guiding layer, x3 is linearly varied from 0.65 to 0.3, and the growth thickness is 0.26 μm.

[0010] Furthermore, the Al x3 Ga 1-x3 The light field guiding layer under As is N-type doped with a doping concentration of 1×10⁻⁶. 16 ~5×10 18 atoms / cm 3 Further preferably, the doping concentration is 1×10⁻⁶. 16 ~2×10 17 atoms / cm 3 The optimal doping concentration is 1.5 × 10⁻⁶. 17 atoms / cm 3 .

[0011] Furthermore, the Al x4 Ga 1-x4In the light field guiding layer on As, x4 is linearly varied from 0.3 to 0.65, and the growth thickness is 0.26 μm.

[0012] Furthermore, the Al x4 Ga 1-x4 The optical field guiding layer on As is N-type doped with a doping concentration of 1×10⁻⁶. 16 ~5×10 18 atoms / cm 3 Further preferably, the doping concentration is 1×10⁻⁶. 16 ~2×10 17 atoms / cm 3 The optimal doping concentration is 1.5 × 10⁻⁶. 17 atoms / cm 3 .

[0013] Furthermore, the semiconductor laser with the light field guiding layer includes one or more of the following conditions:

[0014] ① The GaAs substrate has a substrate angle of 0°, 10°, or 15°; more preferably, the substrate angle is 0°; the substrate angle refers to the deviation of the normal direction of the substrate (100) crystal plane from the substrate. <111> The angle of crystal orientation;

[0015] ② The material of the buffer layer is Al x1 Ga 1-x1 As, where 0 ≤ x1 ≤ 0.05, is an N-type doped material with a doping concentration of 1 × 10⁻⁵. 18 ~5×10 18 atoms / cm 3 The growth thickness is 0.1 μm to 0.3 μm; more preferably, 0 ≤ x1 ≤ 0.03, and the doping concentration is 8 × 10⁻⁶. 17 ~3×10 18 atoms / cm 3 The growth thickness is 0.2 μm to 0.3 μm; the optimal value is x1=0, and the doping concentration is 3×10⁻⁶. 18 atoms / cm 3 The growth thickness is 0.3 μm;

[0016] ③ The material of the N-type confinement layer is Al. x2 Ga 1-x2 As, where 0.55≤x2≤1, is N-type doped with a doping concentration of 5×10⁻⁶. 17 ~5×10 18 atoms / cm 3 Further preferred, 0.6 ≤ x2 ≤ 0.8, with a doping concentration of 8 × 10⁻⁶. 17 ~3×10 18 atoms / cm3 The optimal value is x2 = 0.65, with a doping concentration of 2 × 10⁻⁶. 18 atoms / cm 3 ;

[0017] ④ The material of the N-type waveguide layer is Al. x5 Ga 1-x5 As, where 0 ≤ x5 ≤ 0.5, is an N-type doped compound with a doping concentration of 1 × 10⁻⁶. 16 ~5×10 18 atoms / cm 3 Further preferably, 0.1 ≤ x5 ≤ 0.4, and the doping concentration is 1 × 10⁻⁶. 15 ~2×10 17 atoms / cm 3 The optimal choice is x5 = 0.4, with a doping concentration of 1.5 × 10⁻⁴. 17 atoms / cm 3 ;

[0018] ⑤ The active layer is composed of Al x6 Ga 1-x6 As quantum barrier layer and In y1 Ga 1-y1 As quantum well layers are stacked, with an overlap period of 1 to 5, where 0 ≤ x6 ≤ 0.5, 0 ≤ y1 ≤ 0.5, and the Al x6 Ga 1-x6 As the band gap of the quantum barrier layer is greater than In y1 Ga 1-y1 As is the bandgap width of the quantum well layer; more preferably, the overlap period is 1~3, 0.1≤x6≤0.4, 0.1≤y1≤0.2; most preferably, the overlap period is 1, x6=0.4, y1=0.1;

[0019] ⑥ The material of the P-type waveguide layer is Al x7 Ga 1-x7 As, where 0 ≤ x7 ≤ 0.5, is a P-type doped material with a doping concentration of 1 × 10⁻⁶. 16 ~5×10 18 atoms / cm 3 The growth thickness is 0.1 μm to 0.5 μm; more preferably, 0.1 ≤ x7 ≤ 0.4, and the doping concentration is 1 × 10⁻⁶. 16 ~2×10 17 atoms / cm 3 The growth thickness is 0.1 μm to 0.4 μm; the optimal value is x7 = 0.4, and the doping concentration is 1.5 × 10⁻⁶. 17 atoms / cm 3 The growth thickness was 0.25 μm;

[0020] ⑦ The material of the P-type confinement layer is Al. x8 Ga 1-x8 As, where 0.55≤x8≤1, is a P-type doped material with a doping concentration of 5×10⁻⁶. 17 ~5×10 18 atoms / cm 3 The growth thickness is 0.4 μm to 1.5 μm; more preferably, 0.6 ≤ x8 ≤ 0.8, and the doping concentration is 8 × 10⁻⁶. 17 ~4×10 18 atoms / cm 3 The growth thickness is 0.5 μm to 1 μm; the optimal value is x8 = 0.65, and the doping concentration is 1.7 × 10⁻⁶. 18 atoms / cm 3 The growth thickness was 0.7 μm;

[0021] ⑧ The GaAs ohmic contact layer is p-type doped with a doping concentration of 9 × 10⁻⁶. 18 ~5×10 19 atoms / cm 3 The growth thickness is 20 nm to 400 nm; more preferably, the doping concentration is 1 × 10⁻⁶. 19 ~5×10 19 atoms / cm 3 The growth thickness is 100 nm to 300 nm; the most preferred doping concentration is 2.5 × 10⁻⁶. 19 atoms / cm 3 The growth thickness is 200 nm;

[0022] ⑨ The material of the P-type ohmic electrode is any one of Ni / Au, Cr / Au, Pt / Au or Ni / Al; more preferably, the material of the P-type ohmic electrode is Ni / Au;

[0023] ⑩ The material of the N-type ohmic electrode is any one of Al / Au, Cr / Au or Ti / Al / Ti / Au; more preferably, the material of the N-type ohmic electrode is Cr / Au.

[0024] Furthermore, the growth thickness of the N-type confinement layer is 0.5 μm to 2 μm; more preferably, the growth thickness is 0.6 μm to 1 μm; most preferably, the growth thickness is 0.72 μm.

[0025] Furthermore, the growth thickness of the N-type waveguide layer is 0.4 μm to 2 μm; more preferably, the growth thickness is 0.4 μm to 1.5 μm; most preferably, the growth thickness is 0.53 μm.

[0026] Furthermore, the Al x6 Ga 1-x6 The As quantum barrier layer has a growth thickness of 1 nm to 50 nm and can be undoped, p-type doped, or n-type doped. y1 Ga 1-y1 The As quantum well layer is grown to a thickness of 1 nm to 10 nm and is undoped; more preferably, the Al... x6 Ga 1-x6 The As quantum barrier layer is grown to a thickness of 10 nm to 30 nm, without doping. y1 Ga 1-y1 The As quantum well layer is grown to a thickness of 4 nm to 10 nm; most preferably, the Al... x6 Ga 1-x6 The As quantum barrier layer has a growth thickness of 15 nm, and the In y1 Ga 1-y1 The As quantum well layer was grown to a thickness of 6 nm.

[0027] Secondly, the present invention provides a method for preparing the above-mentioned semiconductor laser having an optical field guiding layer, comprising the following steps:

[0028] S1. In a metal-organic chemical vapor deposition (MOCVD) reactor, the GaAs substrate is heated to 710~750℃ in an H2 environment for baking, and then AsH3 is introduced for high-temperature heat treatment to remove foreign matter and water and oxygen from the substrate surface.

[0029] S2. The temperature is lowered to 700~720℃, and TMAl (trimethylaluminum), TMGa (trimethylgallium) and AsH3 are introduced to grow a buffer layer on the GaAs substrate;

[0030] S3. The temperature is lowered to 640~680℃, and TMAl, TMGa and AsH3 are introduced to grow an N-type confinement layer on the buffer layer.

[0031] S4. Maintain the temperature at 640~680℃, introduce TMAl, TMGa and AsH3, and grow Al on the N-type confinement layer. x3 Ga 1- x3 As light field guiding layer;

[0032] S5. Maintain the temperature at 640~680℃, and introduce TMAl, TMGa, and AsH3, in Al... x3 Ga 1-x3 Al is grown on the light field guiding layer of As. x4 Ga 1-x4 As light field guiding layer;

[0033] S6. Maintain the temperature at 640~680℃, and introduce TMAl, TMGa, and AsH3, in Al... x4 Ga 1-x4 An N-type waveguide layer is grown on the optical field guiding layer of As;

[0034] S7. The temperature is lowered to 540~580℃, and TMAl, TMGa, and AsH3 are introduced to grow Al on the N-type waveguide layer. x6 Ga 1- x6 As a quantum barrier layer, then TMIn (trimethylindium), TMGa and AsH3 are introduced, in Al x6 Ga 1-x6 As quantum barrier layer grown In y1 Ga 1-y1 As a quantum well layer, repeat the above process, overlapping Al x6 Ga 1-x6 As quantum barrier layer and In y1 Ga 1-y1 As a quantum well layer forms an active layer;

[0035] S8. The temperature is raised to 640~680℃, and TMAl, TMGa and AsH3 are introduced to grow a P-type waveguide layer on the active layer.

[0036] S9. Maintain the temperature at 640~680℃, introduce TMAl, TMGa and AsH3, and grow a P-type confinement layer on the P-type waveguide layer.

[0037] S10, the temperature is lowered to 540~560℃, TMGa and AsH3 are introduced, and a GaAs ohmic contact layer is grown on the P-type confinement layer.

[0038] S11. A P-type ohmic electrode is deposited on the GaAs ohmic contact layer, the GaAs substrate is thinned, and an N-type ohmic electrode is deposited below the GaAs substrate.

[0039] The beneficial effects of this invention are as follows:

[0040] The semiconductor laser provided by this invention inserts Al between an N-type confinement layer and an N-type waveguide layer. x3 Ga 1-x3 As under light field guiding layer and Al x4 Ga 1-x4 As light field guiding layer, through Al x3 Ga 1-x3 As under light field guiding layer and Al x4 Ga 1-x4The gradually changing refractive index of the optical field guiding layer on As guides the optical fields of the fundamental and higher-order modes inside the device to this point, increasing the distribution range of the fundamental mode and enabling the semiconductor laser to output a small fast-axis far-field divergence angle. The optical field guiding layer can also reduce the confinement factor of higher-order modes, suppress higher-order modes, and help the semiconductor laser achieve fundamental mode lasing. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the epitaxial structure of the semiconductor laser prepared according to the present invention. In the figure, 101 represents an N-type ohmic electrode, 102 a GaAs substrate, 103 a buffer layer, 104 an N-type confinement layer, and 105 an Al layer. x3 Ga 1-x3 As light field guiding layer, 106-Al x4 Ga 1- x4 As optical field guiding layer, 107-N type waveguide layer, 108-active layer, 109-P type waveguide layer, 110-P type confinement layer, 111-GaAs ohmic contact layer, 112-P type ohmic electrode.

[0043] Figure 2 This is a diagram showing the refractive index and total optical field distribution of the semiconductor laser in Embodiment 1 of the present invention. In the diagram, the solid line represents the refractive index distribution; the dashed line represents the optical field intensity distribution; the vertical axis (left) represents the refractive index, the vertical axis (right) represents the intensity (au), and the horizontal axis represents the relative position (μm).

[0044] Figure 3 This is a diagram showing the refractive index, fundamental mode, and first-order mode optical field distribution of the semiconductor laser of Embodiment 1 of the present invention. In the diagram, the solid line represents the refractive index distribution; the dotted line represents the fundamental mode optical field intensity distribution; the dashed line represents the first-order mode optical field intensity distribution; the vertical axis (left) represents the refractive index, the vertical axis (right) represents the intensity (au), and the horizontal axis represents the relative position (μm).

[0045] Figure 4 The diagram shows the refractive index and total optical field distribution of the semiconductor laser of Comparative Example 1 of this invention. In the diagram, the solid line represents the refractive index distribution; the dashed line represents the optical field intensity distribution; the vertical axis (left) represents the refractive index, the vertical axis (right) represents the intensity (au), and the horizontal axis represents the relative position (μm).

[0046] Figure 5The diagram shows the refractive index, fundamental mode, and first-order mode optical field distribution of the semiconductor laser of Comparative Example 1 of this invention. In the diagram, the solid line represents the refractive index distribution; the dotted line represents the fundamental mode optical field intensity distribution; the dashed line represents the first-order mode optical field intensity distribution; the vertical axis (left) represents the refractive index, the vertical axis (right) represents the intensity (au), and the horizontal axis represents the relative position (μm).

[0047] Figure 6 The diagram shows the refractive index and total optical field distribution of the semiconductor laser in Comparative Example 2 of this invention. In the diagram, the solid line represents the refractive index distribution; the dashed line represents the optical field intensity distribution; the vertical axis (left) represents the refractive index, the vertical axis (right) represents the intensity (au), and the horizontal axis represents the relative position (μm).

[0048] Figure 7 The diagram shows the refractive index, fundamental mode, and first-order mode optical field distribution of the semiconductor laser of Comparative Example 2 of this invention. In the diagram, the solid line represents the refractive index distribution; the dotted line represents the fundamental mode optical field intensity distribution; the dashed line represents the first-order mode optical field intensity distribution; the vertical axis (left) represents the refractive index, the vertical axis (right) represents the intensity (au), and the horizontal axis represents the relative position (μm).

[0049] Figure 8 This is a comparison diagram of the fast axis far-field divergence angle of the semiconductor lasers of Embodiment 1 and Comparative Example 2. In the diagram, the solid line represents the semiconductor laser of Embodiment 1; the dashed line represents the semiconductor laser of Comparative Example 2; the vertical axis (left) represents intensity (au); and the horizontal axis represents angle (°). Detailed Implementation

[0050] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0051] Example 1

[0052] like Figure 1 As shown, a semiconductor laser with a light field guiding layer includes, along the epitaxial growth direction, a GaAs substrate 102, a GaAs buffer layer 103, an N-type confinement layer 104, and an Al layer 105. x3 Ga 1-x3 As lower light field guiding layer 105, Al x4 Ga 1-x4The GaAs substrate 102 comprises an optical field guiding layer 106, an N-type waveguide layer 107, an active layer 108, a P-type waveguide layer 109, a P-type confinement layer 110, and a GaAs ohmic contact layer 111; a P-type ohmic electrode 112 is disposed above the GaAs ohmic contact layer 111, and an N-type ohmic electrode 101 is disposed below the GaAs substrate 102.

[0053] A method for fabricating the above-mentioned semiconductor laser includes the following steps:

[0054] S1. In the MOCVD reactor, the GaAs substrate 102 is heated to 730°C in H2 environment for baking, and then AsH3 is introduced for high-temperature heat treatment to remove foreign matter and water oxygen from the substrate surface. The substrate angle of the GaAs substrate is 0°.

[0055] S2. The temperature is lowered to 710℃, and TMAl, TMGa, and AsH3 are introduced to grow a GaAs buffer layer 103 on the GaAs substrate 102. The GaAs buffer layer 103 is N-type doped with a doping concentration of 1×10⁻⁶. 18 atoms / cm 3 The growth thickness is 0.3 μm;

[0056] S3. The temperature is lowered to 660℃, and TMAl, TMGa, and AsH3 are introduced to grow an N-type confinement layer 104 on the GaAs buffer layer 103. The material of the N-type confinement layer 104 is Al. 0.65 Ga 0.35 As, N-type doped, with a doping concentration of 2 × 10⁻⁶ 18 atoms / cm 3 The growth thickness was 0.72 μm;

[0057] S4. Maintain the temperature at 660℃, introduce TMAl, TMGa, and AsH3, and grow Al on the N-type confinement layer 104. x3 Ga 1-x3 As the lower optical field guiding layer 105, x3 linearly decreases from 0.65 to 0.3; the lower optical field guiding layer 106 is N-type doped with a doping concentration of 1.5 × 10⁻⁶. 17 atoms / cm 3 The growth thickness was 0.26 μm;

[0058] S5. Maintain the temperature at 660℃, and introduce TMAl, TMGa, and AsH3. In Al... x3 Ga 1-x3 Al is grown on the light field guiding layer 105 under As. x4 Ga 1-x4 The optical field guiding layer 106 on As has a x4 that linearly varies from 0.3 to 0.65; the optical field guiding layer 106 is N-type doped with a doping concentration of 1.5 × 10⁻⁴.17 atoms / cm 3 The growth thickness was 0.26 μm;

[0059] S6. Maintain the temperature at 660℃, and introduce TMAl, TMGa, and AsH3, in Al... x4 Ga 1-x4 An N-type waveguide layer 107 is grown on the optical field guiding layer 206 of As; the material of the N-type waveguide layer 107 is Al. 0.4 Ga 0.6 As, N-type doped, with a doping concentration of 1.5 × 10⁻⁶. 17 atoms / cm 3 The growth thickness was 0.53 μm;

[0060] S7. The temperature is lowered to 560℃, and TMAl, TMGa, and AsH3 are introduced to grow Al on the N-type waveguide layer 107. 0.4 Ga 0.6 As a quantum barrier layer, then TMI, TMGa, and AsH3 are introduced into Al. 0.4 Ga 0.6 As quantum barrier layer grown In 0.1 Ga 0.9 As quantum well layers, with an overlap period of 1, overlapping Al 0.4 Ga 0.6 As quantum barrier layer and In 0.1 Ga 0.9 As a quantum well layer forms an active layer 108; Al 0.4 Ga 0.6 The As quantum barrier layer was grown to a thickness of 15 nm without doping; In 0.1 Ga 0.9 The As quantum well layer was grown to a thickness of 6 nm without doping; Al 0.4 Ga 0.6 As the band gap of the quantum barrier layer is greater than that of In 0.1 Ga 0.9 As the bandgap width of the quantum well layer;

[0061] S8. The temperature is raised to 660℃, and TMAl, TMGa, and AsH3 are introduced to grow a P-type waveguide layer 109 on the active layer 108; the material of the P-type waveguide layer 109 is Al. 0.4 Ga 0.6 As, p-type doped, with a doping concentration of 1.5 × 10⁻⁶. 17 atoms / cm 3 The growth thickness was 0.25 μm;

[0062] S9. Maintaining the temperature at 660℃, introduce TMAl, TMGa, and AsH3 to grow a P-type confinement layer 110 on the P-type waveguide layer 109; the material of the P-type confinement layer 110 is Al. 0.65 Ga 0.35 As, p-type doped, with a doping concentration of 1.7 × 10⁻⁶. 18 atoms / cm 3 The growth thickness was 0.7 μm;

[0063] S10. The temperature is lowered to 550℃, and TMGa and AsH3 are introduced to grow a GaAs ohmic contact layer 111 on the p-type confinement layer 110. The GaAs ohmic contact layer 111 is p-type doped with a doping concentration of 2.5 × 10⁻⁶. 19 atoms / cm 3 The growth thickness is 200 nm;

[0064] S11. A P-type ohmic electrode 112 is deposited on the GaAs ohmic contact layer 111. The material of the P-type ohmic electrode 112 is Ni / Au. The GaAs substrate 102 is thinned, and an N-type ohmic electrode 101 is deposited below the GaAs substrate 102. The material of the N-type ohmic electrode 101 is Cr / Au.

[0065] Comparative Example 1

[0066] A strong asymmetric waveguide semiconductor laser without an optical field guiding layer comprises, sequentially along the epitaxial growth direction, a GaAs substrate 102, a GaAs buffer layer 103, an N-type confinement layer 104, an N-type waveguide layer 107, an active layer 108, a P-type waveguide layer 109, a P-type confinement layer 110, and a GaAs ohmic contact layer 111; a P-type ohmic electrode 112 is disposed above the GaAs ohmic contact layer 111, and an N-type ohmic electrode 101 is disposed below the GaAs substrate 102;

[0067] The N-type waveguide layer 107 has a growth thickness of 1.05 μm;

[0068] The other steps and conditions are the same as in Example 1.

[0069] Comparative Example 2

[0070] A weak asymmetric waveguide semiconductor laser without an optical field guiding layer comprises, sequentially along the epitaxial growth direction, a GaAs substrate 102, a GaAs buffer layer 103, an N-type confinement layer 104, an N-type waveguide layer 107, an active layer 108, a P-type waveguide layer 109, a P-type confinement layer 110, and a GaAs ohmic contact layer 111; a P-type ohmic electrode 112 is disposed above the GaAs ohmic contact layer 111, and an N-type ohmic electrode 101 is disposed below the GaAs substrate 102;

[0071] The N-type confinement layer 104 has a growth thickness of 1.24 μm;

[0072] The other steps and conditions are the same as in Example 1.

[0073] Test case

[0074] The refractive index of the semiconductor lasers prepared in Examples 1, 2, and 3 were measured and modeled, respectively; the results are as follows: Figure 2-8 As shown, Figure 2 The diagram shows the refractive index and total optical field distribution of the semiconductor laser in Example 1. Figure 3 The image shows the refractive index, fundamental mode, and first-order mode optical field distribution of the semiconductor laser in Example 1, where the optical confinement factor of the fundamental mode is 0.797% and the optical confinement factor of the first-order mode is 0.329%. Figure 2 and Figure 3 It can be concluded that the optical fields of the fundamental mode and the first-order mode of the semiconductor laser in Embodiment 1 of this application are both guided into the optical field guiding layer by the optical field guiding layer. The first-order mode is guided more strongly, and the optical confinement factor is therefore smaller. The total optical field is consistent with the fundamental mode optical field, and the device exhibits fundamental mode emission.

[0075] Figure 4 The diagram shows the refractive index and total optical field distribution of the semiconductor laser in Comparative Example 1. Figure 5 The diagram shows the refractive index, fundamental mode, and first-order mode optical field distribution of the semiconductor laser in Comparative Example 1. The optical confinement factor of the fundamental mode is 0.397%, and the optical confinement factor of the first-order mode is 0.686%. Figure 4 and Figure 5 It can be concluded that, since the semiconductor laser in Comparative Example 1 has no optical field guiding layer and the waveguide layer has strong asymmetry, the optical confinement factor of the first mode is greater than that of the fundamental mode. Therefore, the device exhibits first-order mode emission, and the total optical field is consistent with the optical field of the first-order mode. The internal loss will increase sharply and the far-field divergence angle will deteriorate.

[0076] Figure 6 The diagram shows the refractive index and total optical field distribution of the semiconductor laser in Comparative Example 2. Figure 7 The diagram shows the refractive index, fundamental mode, and first-order mode optical field distribution of the semiconductor laser in Comparative Example 2. The optical confinement factor of the fundamental mode is 0.982%, and the optical confinement factor of the first-order mode is 0.512%. Figure 6 and 7 It can be concluded that, due to the weaker asymmetry of the waveguide layer in Comparative Example 2's semiconductor laser, the optical confinement factor of the fundamental mode is still greater than that of the first-order mode, therefore the device exhibits fundamental mode emission. However, by measuring the fast-axis far-field divergence angles of Example 1 and Comparative Example 2, such as... Figure 8As shown, compared to Comparative Example 2, the fast-axis far-field divergence angle of Example 1 is smaller. This is because the optical field distribution range of Comparative Example 2 is smaller, while the optical field guiding layer of Example 1 guides the optical field, changing its distribution state and expanding its distribution range. This demonstrates that the optical field guiding layer of the present invention can effectively reduce the fast-axis far-field divergence angle of a semiconductor laser and suppress the lasing of higher-order modes.

[0077] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A semiconductor laser with an optical field guiding layer, comprising, sequentially along the epitaxial growth direction, a GaAs substrate, a buffer layer, an N-type confinement layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type confinement layer, and a GaAs ohmic contact layer, wherein a P-type ohmic electrode is disposed above the GaAs ohmic contact layer, and an N-type ohmic electrode is disposed below the GaAs substrate, characterized in that, Al is inserted between the N-type confinement layer and the N-type waveguide layer. x3 Ga 1-x3 As under light field guiding layer and Al x4 Ga 1-x4 As light field guiding layer; The Al x3 Ga 1-x3 In the As light field guiding layer, 0≤x3≤0.7, x3 linearly varies from high to low within the range of 0 to 0.7, and the growth thickness is 0.1 μm to 0.5 μm. The Al x4 Ga 1-x4 An optical field guiding layer is formed on As, where 0 ≤ x4 ≤ 0.7, x4 is linearly varied in the range of 0 to 0.7, gradually increasing from a low value to a high value, and the growth thickness is 0.1 μm to 0.5 μm. The thickness of the N-type waveguide layer is 0.4 μm to 2 μm.

2. A semiconductor laser with an optical field guiding layer as described in claim 1, characterized in that, The Al x3 Ga 1-x3 In the As light field guiding layer, x3 is linearly varied from 0.65 to 0.3, and the growth thickness is 0.26 μm.

3. A semiconductor laser with an optical field guiding layer as described in claim 1, characterized in that, The Al x3 Ga 1-x3 The light field guiding layer under As is N-type doped with a doping concentration of 1×10⁻⁶. 16 ~5×10 18 atoms / cm 3 .

4. A semiconductor laser with an optical field guiding layer as described in claim 1, characterized in that, The Al x4 Ga 1-x4 In the light field guiding layer on As, x4 is linearly varied from 0.3 to 0.65, and the growth thickness is 0.26 μm.

5. A semiconductor laser with an optical field guiding layer as described in claim 1, characterized in that, The Al x4 Ga 1-x4 The optical field guiding layer on As is N-type doped with a doping concentration of 1×10⁻⁶. 16 ~5×10 18 atoms / cm 3 .

6. A semiconductor laser with an optical field guiding layer as described in claim 1, characterized in that, The semiconductor laser with an optical field guiding layer includes one or more of the following conditions: ① The GaAs substrate has an angle of 0°, 10° or 15°; ② The material of the buffer layer is Al x1 Ga 1-x1 As, where 0 ≤ x1 ≤ 0.05, is an N-type doped material with a doping concentration of 1 × 10⁻⁵. 18 ~5×10 18 atoms / cm 3 The growth thickness is 0.1 μm to 0.3 μm; ③ The material of the N-type confinement layer is Al. x2 Ga 1-x2 As, where 0.55≤x2≤1, is N-type doped with a doping concentration of 5×10⁻⁶. 17 ~5×10 18 atoms / cm 3 ; ④ The material of the N-type waveguide layer is Al. x5 Ga 1-x5 As, where 0 ≤ x5 ≤ 0.5, is an N-type doped compound with a doping concentration of 1 × 10⁻⁶. 16 ~5×10 18 atoms / cm 3 ; ⑤ The active layer is composed of Al x6 Ga 1-x6 As quantum barrier layer and In y1 Ga 1-y1 As quantum well layers are stacked, with an overlap period of 1 to 5, where 0 ≤ x6 ≤ 0.5, 0 ≤ y1 ≤ 0.5, and the Al x6 Ga 1-x6 As the band gap of the quantum barrier layer is greater than In y1 Ga 1- y1 As the bandgap width of the quantum well layer; ⑥ The material of the P-type waveguide layer is Al x7 Ga 1-x7 As, where 0 ≤ x7 ≤ 0.5, is a P-type doped material with a doping concentration of 1 × 10⁻⁶. 16 ~5×10 18 atoms / cm 3 The growth thickness was 0.25 μm; ⑦ The material of the P-type confinement layer is Al. x8 Ga 1-x8 As, where 0.55≤x8≤1, is a P-type doped material with a doping concentration of 5×10⁻⁶. 17 ~5×10 18 atoms / cm 3 The growth thickness is 0.4 μm to 1.5 μm; ⑧ The GaAs ohmic contact layer is p-type doped with a doping concentration of 9 × 10⁻⁶. 18 ~5×10 19 atoms / cm 3 The growth thickness is 20 nm to 400 nm. ⑨ The material of the P-type ohmic electrode is any one of Ni / Au, Cr / Au, Pt / Au or Ni / Al; ⑩ The material of the N-type ohmic electrode is any one of Al / Au, Cr / Au, or Ti / Al / Ti / Au.

7. A semiconductor laser with an optical field guiding layer as described in claim 6, characterized in that, The growth thickness of the N-type confinement layer is 0.5 μm to 2 μm.

8. A semiconductor laser with an optical field guiding layer as described in claim 6, characterized in that, The Al x6 Ga 1-x6 The As quantum barrier layer has a growth thickness of 1 nm to 50 nm, and the quantum barrier layer can be undoped, P-type doped, or N-type doped; the In y1 Ga 1-y1 The As quantum well layer is grown to a thickness of 1 nm to 10 nm and is undoped.

9. A method for fabricating a semiconductor laser with an optical field guiding layer as described in claim 1, characterized in that, Includes the following steps: S1. In the MOCVD reactor, the GaAs substrate is heated to 710-750°C in H2 environment for baking, and then AsH3 is introduced for high-temperature heat treatment. S2. The temperature is lowered to 700~720℃, and TMAl, TMGa and AsH3 are introduced to grow a buffer layer on the GaAs substrate. S3. The temperature is lowered to 640~680℃, and TMAl, TMGa and AsH3 are introduced to grow an N-type confinement layer on the buffer layer. S4. Maintain the temperature at 640~680℃, introduce TMAl, TMGa and AsH3, and grow Al on the N-type confinement layer. x3 Ga 1-x3 As under light field guiding layer; S5. Maintain the temperature at 640~680℃, and introduce TMAl, TMGa, and AsH3, in Al... x3 Ga 1-x3 Al is grown on the light field guiding layer of As. x4 Ga 1-x4 As light field guiding layer; S6. Maintain the temperature at 640~680℃, and introduce TMAl, TMGa, and AsH3, in Al... x4 Ga 1-x4 An N-type waveguide layer is grown on the optical field guiding layer of As; S7. The temperature is lowered to 540~580℃, and TMAl, TMGa, and AsH3 are introduced to grow Al on the N-type waveguide layer. x6 Ga 1-x6 As a quantum barrier layer, then TMI, TMGa, and AsH3 are introduced into Al. x6 Ga 1-x6 As quantum barrier layer grown In y1 Ga 1-y1 As a quantum well layer, repeat the above process, overlapping Al x6 Ga 1-x6 As quantum barrier layer and In y1 Ga 1-y1 As a quantum well layer forms an active layer; S8. The temperature is raised to 640~680℃, and TMAl, TMGa and AsH3 are introduced to grow a P-type waveguide layer on the active layer. S9. Maintain the temperature at 640~680℃, introduce TMAl, TMGa and AsH3, and grow a P-type confinement layer on the P-type waveguide layer. S10, the temperature is lowered to 540~560℃, TMGa and AsH3 are introduced, and a GaAs ohmic contact layer is grown on the P-type confinement layer. S11. A P-type ohmic electrode is deposited on the GaAs ohmic contact layer, the GaAs substrate is thinned, and an N-type ohmic electrode is deposited below the GaAs substrate.

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