A gallium nitride-based semiconductor laser

Abstract

This invention proposes a gallium nitride-based semiconductor laser, comprising, from bottom to top, a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper cladding layer. The lower waveguide layer includes a first high-coherence lower waveguide layer and a second high-coherence lower waveguide layer, with the first high-coherence lower waveguide layer located below the second high-coherence lower waveguide layer. Both the upper waveguide layer, the first high-coherence lower waveguide layer, and the second high-coherence lower waveguide layer possess electron mobility and effective electron mass characteristics. This invention improves the photon degeneracy of the laser by designing the angle and distribution of electron mobility and effective electron mass variation in the upper and lower waveguide layers of the gallium nitride-based semiconductor laser, thereby controlling the carrier transport and wavefunction distribution of the waveguide layers, reducing the intermodal variation of the laser mode number and longitudinal modes, and enhancing the temporal coherence of the laser.

Description

Technical Field

[0001] This application relates to the field of semiconductor optoelectronic devices, and more particularly to a gallium nitride-based semiconductor laser. Background Technology

[0002] Lasers are widely used in laser displays, laser TVs, laser projectors, communications, medical applications, weaponry, guidance, ranging, spectral analysis, cutting, precision welding, and high-density optical storage. There are many types of lasers, and they can be classified in various ways, mainly including solid-state, gas, liquid, semiconductor, and dye lasers. Compared with other types of lasers, all-solid-state semiconductor lasers have advantages such as small size, high efficiency, light weight, good stability, long lifespan, simple and compact structure, and miniaturization.

[0003] Lasers and nitride semiconductor light-emitting diodes (LEDs) differ significantly:

[0004] 1) Lasers are generated by stimulated emission of charge carriers. They have a small half-width at half-maximum and very high brightness. The output power of a single laser can be in the W range. In contrast, nitride semiconductor light-emitting diodes are spontaneously emitted, and the output power of a single light-emitting diode is in the mW range.

[0005] 2) The operating current density of lasers reaches KA / cm2, which is more than two orders of magnitude higher than that of nitride light-emitting diodes. This results in stronger electron leakage, more severe Auger recombination, stronger polarization effect, and more severe electron-hole mismatch, leading to more severe efficiency degradation and the Droop effect.

[0006] 3) Light-emitting diodes emit spontaneous transition radiation, which is incoherent light that transitions from a high energy level to a low energy level without external influence. In contrast, lasers emit stimulated transition radiation, where the energy of the induced photon should be equal to the energy difference of the electron transition, producing coherent light that is identical to the induced photon.

[0007] 4) Different principles: Light emission diodes emit light by electrons and holes jumping to the active layer or pn junction under the action of external voltage, generating radiative recombination. Lasers, on the other hand, require certain lasing conditions to be met before they can emit light. This requires the carriers in the active region to be reversed, the stimulated emission light to oscillate back and forth in the resonant cavity, and the propagation in the gain medium to amplify the light. When the threshold condition is met, the gain is greater than the loss, and finally, laser light is output.

[0008] Nitride semiconductor lasers have the following problems: the laser wave pattern can be divided into transverse mode and longitudinal-transverse mode; the intensity distribution of transverse mode in the cross section perpendicular to the optical axis is determined by the waveguide structure of the semiconductor laser. If the transverse mode is complex and unstable, the coherence of the output light is poor; the longitudinal mode is a standing wave distribution in the propagation direction of the resonant cavity. If many longitudinal modes are lased at the same time or there are inter-mode changes, high temporal coherence cannot be obtained, and the far-field image FFP quality is poor. Summary of the Invention

[0009] To address one of the aforementioned technical problems, the present invention provides a gallium nitride-based semiconductor laser.

[0010] This invention provides a gallium nitride-based semiconductor laser, comprising, from bottom to top, a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper cladding layer. The lower waveguide layer includes a first high-coherence lower waveguide layer and a second high-coherence lower waveguide layer, with the first high-coherence lower waveguide layer located below the second high-coherence lower waveguide layer. The upper waveguide layer, the first high-coherence lower waveguide layer, and the second high-coherence lower waveguide layer all possess electron mobility characteristics and effective electron mass characteristics.

[0011] The angle at which the valley of the electron mobility of the upper waveguide layer rises towards the active layer is α; the angle at which the peak of the electron mobility of the upper waveguide layer falls towards the upper cladding layer is β; the angle at which the peak of the electron mobility of the second high-coherence lower waveguide layer falls towards the lower cladding layer is γ; the angle at which the valley of the electron mobility of the second high-coherence lower waveguide layer rises towards the active layer is θ; and the angle at which the peak of the electron mobility of the first high-coherence lower waveguide layer falls towards the lower cladding layer is δ, where: 50°≤β≤γ≤α≤θ≤δ≤90°;

[0012] The angle at which the peak position of the effective electronic mass of the upper waveguide layer decreases towards the active layer is σ, and the angle at which the valley position of the effective electronic mass of the upper waveguide layer increases towards the upper cladding layer is σ. The angle of increase of the valley position of the effective electronic mass of the second high-coherence waveguide layer towards the lower cladding layer is ψ; the angle of decrease of the peak position of the effective electronic mass of the second high-coherence waveguide layer towards the active layer is μ; and the angle of increase of the valley position of the effective electronic mass of the first high-coherence waveguide layer towards the lower cladding layer is υ, where:

[0013] Preferably, the upper waveguide layer, the first high-coherence lower waveguide layer, and the second high-coherence lower waveguide layer all have thermal conductivity characteristics.

[0014] The angle at which the peak position of the thermal conductivity of the upper waveguide layer decreases towards the active layer is ρ; the angle at which the valley position of the thermal conductivity of the upper waveguide layer increases towards the upper cladding layer is ω; the angle at which the valley position of the thermal conductivity of the second high-coherence lower waveguide layer increases towards the lower cladding layer is ε; the angle at which the peak position of the thermal conductivity of the second high-coherence lower waveguide layer decreases towards the active layer is η; and the angle at which the valley position of the thermal conductivity of the first high-coherence lower waveguide layer increases towards the lower cladding layer is κ, where: 45°≤ω≤ε≤ρ≤η≤κ≤90°.

[0015] Preferably, the upper waveguide layer, the first high-coherence lower waveguide layer, and the second high-coherence lower waveguide layer all have elastic coefficient characteristics;

[0016] The angle at which the peak position of the elastic coefficient of the upper waveguide layer decreases towards the active layer is ζ; the angle at which the valley position of the elastic coefficient of the upper waveguide layer increases towards the upper cladding layer is χ; the angle at which the valley position of the elastic coefficient of the second high-coherence lower waveguide layer increases towards the lower cladding layer is ν; the angle at which the peak position of the elastic coefficient of the second high-coherence lower waveguide layer decreases towards the active layer is λ; and the angle at which the valley position of the elastic coefficient of the first high-coherence lower waveguide layer increases towards the lower cladding layer is τ, where: 35°≤χ≤ν≤ζ≤λ≤τ≤90°.

[0017] Preferably, the angle at which the valley of the electron mobility of the upper waveguide layer rises towards the active layer, the angle at which the peak of the electron mobility of the upper waveguide layer falls towards the upper cladding layer, the angle at which the peak of the electron mobility of the second high-coherence lower waveguide layer falls towards the lower cladding layer, the angle at which the valley of the electron mobility of the second high-coherence lower waveguide layer rises towards the active layer, the angle at which the peak of the electron mobility of the first high-coherence lower waveguide layer falls towards the lower cladding layer, and the peak values ​​of the effective electron mass, thermal conductivity, and elastic modulus of the upper waveguide layer are all considered. The following relationships exist between the descent angle towards the active layer, the descent angle of the valley positions of the effective electronic mass, thermal conductivity, and elastic modulus of the upper waveguide layer towards the upper cladding layer, the descent angle of the valley positions of the effective electronic mass, thermal conductivity, and elastic modulus of the second high-coherence lower waveguide layer towards the lower cladding layer, the descent angle of the peak positions of the effective electronic mass, thermal conductivity, and elastic modulus of the second high-coherence lower waveguide layer towards the active layer, and the descent angle of the valley positions of the effective electronic mass, thermal conductivity, and elastic modulus of the first high-coherence lower waveguide layer towards the lower cladding layer:

[0018] Preferably, the electron mobility of the upper waveguide layer has a function y1 = (a x +1) / (a x -1)(0<a<1) distribution of curves in the fourth quadrant;

[0019] The effective electron mass of the upper waveguide layer has a function y2 = (c x +1) / (c x -1)(c>1) Distribution of curves in the second quadrant;

[0020] The thermal conductivity of the upper waveguide layer has a function y3 = (f x +1) / (fx -1)(f>1) distribution of curves in the second quadrant;

[0021] The elastic coefficient of the upper waveguide layer has a function y4=(j x +1) / (j x -1)(j>1) distribution of curves in the second quadrant;

[0022] Where x is the depth of the upper waveguide layer toward the electron blocking layer, and 0 < a < 1 < j ≤ c ≤ f.

[0023] Preferably, the electron mobility of the first high-coherence lower waveguide layer has a function y5 = (e x′ +e -x′ ) / (e x′ -e -x′ The distribution of curves in the third quadrant;

[0024] The effective electronic mass of the first highly coherent lower waveguide layer has the function y6 = e -x′ / x′ 2 Second quadrant curve distribution;

[0025] The thermal conductivity of the first high-coherence lower waveguide layer has the function y7 = x'e x′ Curve distribution;

[0026] The elastic coefficient of the first high-coherence lower waveguide layer has the function y8 = x'e x′ Curve distribution;

[0027] Where x′ is the depth from the first high coherence lower waveguide layer to the second high coherence lower waveguide layer.

[0028] Preferably, the electron mobility of the second high-coherence lower waveguide layer has a function y9 = (b x” +1) / (b x” -1)(b>1) Distribution of curves in the third quadrant;

[0029] The effective electronic mass of the second highly coherent lower waveguide layer has a function y 10 =(d x” +1) / (d x "-1)(0<d<1) Second quadrant curve distribution;

[0030] The thermal conductivity of the second high-coherence lower waveguide layer has a function y 11 =(g x "+1) / (g x "-1)(0<g<1) Second quadrant curve distribution;

[0031] The elastic coefficient of the second high-coherence waveguide layer has a function y 12=(k x "+1) / (k x "-1)(0<k<1) Second quadrant curve distribution;

[0032] Where x” is the depth of the waveguide layer toward the active layer under the second high coherence condition, 0<g≤d≤k<1<b, and 0<a≤g≤d≤k<1<b≤j≤c≤f.

[0033] Preferably, the upper waveguide layer and the lower waveguide layer are any one or any combination of InGaN, GaN, InN, AlInGaN, AlInN, AlN, InGaN / GaN superlattice, InGaN / AlGaN superlattice, InGaN / AlInGaN superlattice, InGaN / AlInN superlattice, GaN / AlGaN superlattice, GaN / AlInGaN superlattice, and GaN / AlN superlattice, with a thickness of 5nm to 1000nm.

[0034] Preferably, the active layer is a quantum well structure composed of a well layer and a barrier layer;

[0035] The active layer's well layer is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond, with a thickness ranging from 10 angstroms to 150 angstroms.

[0036] The active layer barrier is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond, with a thickness of 10 angstroms to 200 angstroms.

[0037] Preferably, the lower cladding layer, electron blocking layer, and upper cladding layer are any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.

[0038] Preferably, the substrate comprises sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, graphene, sapphire / SiN x Sapphire / SiO2 / SiNx composite substrate, sapphire / SiN x Any one of the following: SiO2 composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0039] The beneficial effects of the present invention are as follows: By designing the angle and distribution of the changes in electron mobility and effective electron mass in the upper and lower waveguide layers of the gallium nitride-based semiconductor laser, the present invention regulates the carrier transport and wave function distribution of the waveguide layer, improves the photon degeneracy of the laser, reduces the intermodal variation of the laser mode and longitudinal mode, and improves the temporal coherence of the laser. Attached Figure Description

[0040] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0041] Figure 1 This is a schematic diagram of the structure of the gallium nitride-based semiconductor laser according to an embodiment of the present invention;

[0042] Figure 2 This is a SIMS secondary ion mass spectrum of the gallium nitride-based semiconductor laser described in an embodiment of the present invention;

[0043] Figure 3 This is a magnified SIMS secondary ion mass spectrum of the gallium nitride-based semiconductor laser described in an embodiment of the present invention.

[0044] Figure 4This is a transmission electron microscope (TEM) image of the lower waveguide layer of the gallium nitride-based semiconductor laser described in an embodiment of the present invention.

[0045] Figure 5 This is a transmission electron microscope (TEM) image of the active layer of the gallium nitride-based semiconductor laser described in an embodiment of the present invention.

[0046] Figure 6 This is a transmission electron microscope (TEM) image of the upper waveguide layer of the gallium nitride-based semiconductor laser described in an embodiment of the present invention.

[0047] Figure 7 This is a transmission electron microscope (TEM) image of the electron blocking layer of the gallium nitride-based semiconductor laser described in an embodiment of the present invention.

[0048] Figure 8 This is a transmission electron microscope (TEM) image of the upper cladding layer of the gallium nitride-based semiconductor laser described in an embodiment of the present invention.

[0049] Figure label:

[0050] 100. Substrate; 101. Lower cladding layer; 102. Lower waveguide layer; 103. Active layer; 104. Upper waveguide layer; 105. Electron blocking layer; 106. Upper cladding layer.

[0051] 102a, First high coherence lower waveguide layer; 102b, Second high coherence lower waveguide layer. Detailed Implementation

[0052] To make the technical solutions and advantages of the embodiments of this application clearer, the exemplary embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0053] like Figures 1 to 8 As shown, this embodiment proposes a gallium nitride-based semiconductor laser, which includes a substrate 100, a lower cladding layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, an electron blocking layer 105, and an upper cladding layer 106 arranged sequentially from bottom to top.

[0054] Specifically, in this embodiment, the gallium nitride-based semiconductor laser comprises, from bottom to top, a substrate 100, a lower cladding layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, an electron blocking layer 105, and an upper cladding layer 106. Both the lower waveguide layer 102 and the upper waveguide layer 104 exhibit high coherence; that is, the lower waveguide layer 102 is a high-coherence lower waveguide layer 102, and the upper waveguide layer 104 is a high-coherence upper waveguide layer 104. The lower waveguide layer 102 has a double-layer structure, comprising a first high-coherence lower waveguide layer 102a and a second high-coherence lower waveguide layer 102b. The first high-coherence lower waveguide layer 102a is located below the second high-coherence lower waveguide layer 102b. The high coherence of the lower waveguide layer 102 and the upper waveguide layer 104 is mainly reflected in the electron mobility and effective electron mass characteristics of the upper waveguide layer 104 and the lower waveguide layer 102. Meanwhile, the electron mobility and effective electron mass in the upper waveguide layer 104, the first high-coherence lower waveguide layer 102a, and the second high-coherence lower waveguide layer 102b also exhibit certain changing trends towards the active layer 103, the upper cladding layer 106, and the lower cladding layer 101, specifically as follows:

[0055] The location of the valley of electron mobility in the upper waveguide layer 104 shows an upward trend toward the active layer 103;

[0056] The peak position of the electron mobility of the upper waveguide layer 104 decreases towards the upper cladding layer 106;

[0057] The peak position of the electron mobility of the second high coherence waveguide layer 102b decreases towards the lower cladding layer 101.

[0058] The valley of electron mobility in waveguide layer 102b with second-highest coherence tends to increase toward active layer 103.

[0059] The peak position of the electron mobility of the first high coherence lower waveguide layer 102a decreases towards the lower cladding layer 101.

[0060] Specifically, the angle at which the peak position of the effective electronic mass of the upper waveguide layer 104 decreases towards the active layer 103 is σ, and the angle at which the valley position of the effective electronic mass of the upper waveguide layer 104 increases towards the upper cladding layer 106 is σ. The upward angle of the valley position of the effective electronic mass of the second high-coherence waveguide layer 102b towards the lower cladding layer 101 is ψ; the downward angle of the peak position of the effective electronic mass of the second high-coherence waveguide layer 102b towards the active layer 103 is μ; and the upward angle of the valley position of the effective electronic mass of the first high-coherence waveguide layer 102a towards the lower cladding layer 101 is υ, where:

[0061] The peak position of the effective electronic mass of the upper waveguide layer 104 decreases towards the active layer 103;

[0062] The valley position of the effective electronic mass of the upper waveguide layer 104 shows an upward trend towards the upper cladding layer 106;

[0063] The valley position of the effective electronic mass of the second high coherence waveguide layer 102b shows an upward trend towards the lower cladding layer 101.

[0064] The peak position of the effective electronic mass of the second high coherence waveguide layer 102b decreases towards the active layer 103.

[0065] The valley position of the effective electronic mass of the first high coherence lower waveguide layer 102a shows an upward trend towards the lower cladding layer 101.

[0066] Wherein, the angle σ is the downward angle of the peak position of the effective electronic mass of the upper waveguide layer 104 towards the active layer 103, and the angle σ is the upward angle of the valley position of the effective electronic mass of the upper waveguide layer 104 towards the upper cladding layer 106. The upward angle of the valley position of the effective electronic mass of the second high-coherence waveguide layer 102b towards the lower cladding layer 101 is ψ; the downward angle of the peak position of the effective electronic mass of the second high-coherence waveguide layer 102b towards the active layer 103 is μ; and the upward angle of the valley position of the effective electronic mass of the first high-coherence waveguide layer 102a towards the lower cladding layer 101 is υ, where:

[0067] This embodiment designs the angle and distribution of changes in electron mobility and effective electron mass in the upper waveguide layer 104 and the lower waveguide layer 102 of the gallium nitride-based semiconductor laser, thereby controlling the carrier transport and wave function distribution of the waveguide layer, improving the photon degeneracy of the laser, reducing the intermodal variation of the laser mode and longitudinal mode, and improving the temporal coherence of the laser.

[0068] In some optional embodiments, the upper waveguide layer 104, the first high-coherence lower waveguide layer 102a, and the second high-coherence lower waveguide layer 102b also possess thermal conductivity characteristics. Furthermore, the thermal conductivity of the upper waveguide layer 104, the first high-coherence lower waveguide layer 102a, and the second high-coherence lower waveguide layer 102b exhibits a certain variation trend towards the active layer 103, the upper cladding layer 106, and the lower cladding layer 101, specifically manifested as follows:

[0069] The peak position of the thermal conductivity of the upper waveguide layer 104 decreases towards the active layer 103;

[0070] The location of the lowest point of thermal conductivity in the upper waveguide layer 104 shows an upward trend towards the upper cladding layer 106;

[0071] The location of the lowest thermal conductivity value of the second high coherence waveguide layer 102b increases towards the lower cladding layer 101.

[0072] The peak position of the thermal conductivity of the second high coherence waveguide layer 102b shows a decreasing trend towards the active layer 103.

[0073] The location of the lowest thermal conductivity value of the first high coherence lower waveguide layer 102a shows an upward trend towards the lower cladding layer 101.

[0074] Specifically, the angle at which the peak position of the thermal conductivity of the upper waveguide layer 104 descends towards the active layer 103 is ρ; the angle at which the valley position of the thermal conductivity of the upper waveguide layer 104 ascends towards the upper cladding layer 106 is ω; the angle at which the valley position of the thermal conductivity of the second high coherence lower waveguide layer 102b ascends towards the lower cladding layer 101 is ε; the angle at which the peak position of the thermal conductivity of the second high coherence lower waveguide layer 102b descends towards the active layer 103 is η; and the angle at which the valley position of the thermal conductivity of the first high coherence lower waveguide layer 102a ascends towards the lower cladding layer 101 is κ, where: 45°≤ω≤ε≤ρ≤η≤κ≤90°.

[0075] In some optional embodiments, the upper waveguide layer 104, the first high-coherence lower waveguide layer 102a, and the second high-coherence lower waveguide layer 102b also possess elastic coefficient characteristics, and the elastic coefficients in the upper waveguide layer 104, the first high-coherence lower waveguide layer 102a, and the second high-coherence lower waveguide layer 102b exhibit a certain variation trend towards the active layer 103, the upper cladding layer 106, and the lower cladding layer 101, specifically manifested as follows:

[0076] The peak position of the elastic modulus of the upper waveguide layer 104 decreases towards the active layer 103;

[0077] The location of the valley of the elastic modulus of the upper waveguide layer 104 shows an upward trend towards the upper cladding layer 106;

[0078] The valley position of the elastic coefficient of the second high coherence waveguide layer 102b shows an upward trend towards the lower cladding layer 101.

[0079] The peak position of the elastic coefficient of the second high coherence waveguide layer 102b shows a decreasing trend towards the active layer 103.

[0080] The location of the valley of the elastic coefficient of the first high coherence lower waveguide layer 102a shows an upward trend towards the lower cladding layer 101.

[0081] Specifically, the angle at which the peak position of the elastic coefficient of the upper waveguide layer 104 decreases towards the active layer 103 is ζ; the angle at which the valley position of the elastic coefficient of the upper waveguide layer 104 increases towards the upper cladding layer 106 is χ; the angle at which the valley position of the elastic coefficient of the second high coherence lower waveguide layer 102b increases towards the lower cladding layer 101 is ν; the angle at which the peak position of the elastic coefficient of the second high coherence lower waveguide layer 102b decreases towards the active layer 103 is λ; and the angle at which the valley position of the elastic coefficient of the first high coherence lower waveguide layer 102a increases towards the lower cladding layer 101 is τ, where: 35°≤χ≤ν≤ζ≤λ≤τ≤90°.

[0082] More specifically, the aforementioned angular changes have a certain magnitude relationship: the upward angle of the trough position of the electron mobility of the upper waveguide layer 104 towards the active layer 103; the downward angle of the peak position of the electron mobility of the upper waveguide layer 104 towards the upper cladding layer 106; the downward angle of the peak position of the electron mobility of the second high-coherence lower waveguide layer 102b towards the lower cladding layer 101; the upward angle of the trough position of the electron mobility of the second high-coherence lower waveguide layer 102b towards the active layer 103; the downward angle of the peak position of the electron mobility of the first high-coherence lower waveguide layer 102a towards the lower cladding layer 101; and the effective electron mass of the upper waveguide layer 104... The following relationships exist between the peak positions of the electron effective mass, thermal conductivity, and elastic modulus of the upper waveguide layer 104 and the downward angle towards the active layer 103, the downward angle of the valley positions of the electron effective mass, thermal conductivity, and elastic modulus of the upper waveguide layer 104 and the upward angle of the valley positions of the electron effective mass, thermal conductivity, and elastic modulus of the second high coherence lower waveguide layer 102b and the downward angle of the valley positions of the electron effective mass, thermal conductivity, and elastic modulus of the second high coherence lower waveguide layer 102b and the downward angle of the peak positions of the electron effective mass, thermal conductivity, and elastic modulus of the first high coherence lower waveguide layer 102a and the downward angle of the valley positions of the electron effective mass, thermal conductivity, and elastic modulus of the lower waveguide layer 102a and the downward angle of the lower waveguide layer 101:

[0083] This embodiment controls the thermal and stress distribution of the laser waveguide layer by designing the change angle and distribution of the thermal conductivity and elastic coefficient of the upper waveguide layer 104 and the lower waveguide layer 102. By controlling the laser's optical field distribution through the strain field and thermal field, the longitudinal divergence angle of the main spot is increased, making the far-field spot closer to an ellipse, improving the beam quality factor, and enhancing transverse mode stability, thereby further improving the laser's coherence.

[0084] In some optional embodiments, the upper waveguide layer 104 has specific electron mobility distribution characteristics, effective electron mass distribution characteristics, thermal conductivity distribution characteristics, and elastic coefficient distribution characteristics, specifically manifested as follows:

[0085] The electron mobility of the upper waveguide layer 104 has the function y1 = (a x +1) / (a x -1)(0<a<1) distribution of curves in the fourth quadrant;

[0086] The effective electron mass of the upper waveguide layer 104 has the function y2=(c x +1) / (c x -1)(c>1) Distribution of curves in the second quadrant;

[0087] The thermal conductivity of the upper waveguide layer 104 has the function y3=(f x +1) / (f x -1)(f>1) distribution of curves in the second quadrant;

[0088] The elastic coefficient of the upper waveguide layer 104 has the function y4=(j x +1) / (j x -1)(j>1) distribution of curves in the second quadrant;

[0089] Where x is the depth of the upper waveguide layer 104 toward the electron blocking layer 105, and 0 < a < 1 < j ≤ c ≤ f.

[0090] In some optional embodiments, the first high-coherence lower waveguide layer 102a has specific electron mobility distribution characteristics, effective electron mass distribution characteristics, thermal conductivity distribution characteristics, and elastic coefficient distribution characteristics, specifically manifested as follows:

[0091] The electron mobility of the first high-coherence lower waveguide layer 102a has the function y5=(e x′ +e -x′ ) / (e x′ -e -x′ The distribution of curves in the third quadrant;

[0092] The effective electron mass of the first high-coherence lower waveguide layer 102a has the function y6 = e -x′ / x′ 2 Second quadrant curve distribution;

[0093] The thermal conductivity of the first high-coherence lower waveguide layer 102a has the function y7=x'e x′ Curve distribution;

[0094] The elastic coefficient of the first high-coherence lower waveguide layer 102a has the function y8=x'e x′ Curve distribution;

[0095] Where x′ is the depth from the first high coherence lower waveguide layer 102a toward the second high coherence lower waveguide layer 102b.

[0096] In some optional embodiments, the second high-coherence lower waveguide layer 102b has specific electron mobility distribution characteristics, effective electron mass distribution characteristics, thermal conductivity distribution characteristics, and elastic coefficient distribution characteristics, specifically manifested as follows:

[0097] The electron mobility of waveguide layer 102b with the second high coherence has the function y9=(b x "+1) / (b x "-1)(b>1) Third quadrant curve distribution;

[0098] The effective electron mass of the second high-coherence lower waveguide layer 102b has a function y 10 =(d x "+1) / (d x "-1)(0<d<1) Second quadrant curve distribution;

[0099] The thermal conductivity of the second high-coherence waveguide layer 102b has a function y 11 =(g x "+1) / (g x "-1)(0<g<1) Second quadrant curve distribution;

[0100] The elastic coefficients of the second high-coherence waveguide layer 102b have a function y 12 =(k x "+1) / (k x "-1)(0<k<1) Second quadrant curve distribution;

[0101] Where x” is the depth of the waveguide layer 102b towards the active layer 103 under the second high coherence, 0<g≤d≤k<1<b, and 0<a≤g≤d≤k<1<b≤j≤c≤f.

[0102] This embodiment further enhances the temporal coherence of lasers by specifically designing the electron mobility distribution, effective electron mass distribution, thermal conductivity distribution, and elastic coefficient distribution in the upper waveguide layer 104, the first high coherence lower waveguide layer 102a, and the second high coherence lower waveguide layer 102b.

[0103] In some optional embodiments, the upper waveguide layer 104 and the lower waveguide layer 102 are any one or any combination of InGaN, GaN, InN, AlInGaN, AlInN, AlN, InGaN / GaN superlattice, InGaN / AlGaN superlattice, InGaN / AlInGaN superlattice, InGaN / AlInN superlattice, GaN / AlGaN superlattice, GaN / AlInGaN superlattice, and GaN / AlN superlattice, with a thickness of 5 nm to 1000 nm.

[0104] In some alternative embodiments, the active layer 103 is a quantum well structure consisting of a well layer and a barrier layer.

[0105] The well layer of the active layer 103 is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond, with a thickness of 10 angstroms to 150 angstroms.

[0106] The barrier layer of the active layer 103 is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond, with a thickness of 10 angstroms to 200 angstroms.

[0107] In some optional embodiments, the lower cladding layer 101, the electron blocking layer 105, and the upper cladding layer 106 are any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.

[0108] In some alternative embodiments, the substrate 100 includes sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, graphene, and sapphire / SiN. x Sapphire / SiO2 / SiNx composite substrate, sapphire / SiN xAny one of the following: SiO2 composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0109] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A gallium nitride-based semiconductor laser, comprising, from bottom to top, a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper cladding layer, characterized in that, The lower waveguide layer includes a first high coherence lower waveguide layer and a second high coherence lower waveguide layer. The first high coherence lower waveguide layer is located below the second high coherence lower waveguide layer. The upper waveguide layer, the first high coherence lower waveguide layer, and the second high coherence lower waveguide layer all have electron mobility characteristics and electron effective mass characteristics. The angle at which the valley of the electron mobility of the upper waveguide layer rises towards the active layer is α; the angle at which the peak of the electron mobility of the upper waveguide layer falls towards the upper cladding layer is β; the angle at which the peak of the electron mobility of the second high-coherence lower waveguide layer falls towards the lower cladding layer is γ; the angle at which the valley of the electron mobility of the second high-coherence lower waveguide layer rises towards the active layer is θ; and the angle at which the peak of the electron mobility of the first high-coherence lower waveguide layer falls towards the lower cladding layer is δ, where: 50°≤β≤γ≤α≤θ≤δ≤90°; The angle at which the peak position of the effective electronic mass of the upper waveguide layer decreases towards the active layer is σ, and the angle at which the valley position of the effective electronic mass of the upper waveguide layer increases towards the upper cladding layer is σ. The angle of increase of the valley position of the effective electronic mass of the second high-coherence waveguide layer towards the lower cladding layer is ψ; the angle of decrease of the peak position of the effective electronic mass of the second high-coherence waveguide layer towards the active layer is μ; and the angle of increase of the valley position of the effective electronic mass of the first high-coherence waveguide layer towards the lower cladding layer is υ, where:

2. The gallium nitride-based semiconductor laser according to claim 1, characterized in that, The upper waveguide layer, the first high-coherence lower waveguide layer, and the second high-coherence lower waveguide layer all have thermal conductivity characteristics. The angle at which the peak position of the thermal conductivity of the upper waveguide layer decreases towards the active layer is ρ; the angle at which the valley position of the thermal conductivity of the upper waveguide layer increases towards the upper cladding layer is ω; the angle at which the valley position of the thermal conductivity of the second high-coherence lower waveguide layer increases towards the lower cladding layer is ε; the angle at which the peak position of the thermal conductivity of the second high-coherence lower waveguide layer decreases towards the active layer is η; and the angle at which the valley position of the thermal conductivity of the first high-coherence lower waveguide layer increases towards the lower cladding layer is κ, where: 45°≤ω≤ε≤ρ≤η≤κ≤90°.

3. The gallium nitride-based semiconductor laser according to claim 2, characterized in that, The upper waveguide layer, the first high-coherence lower waveguide layer, and the second high-coherence lower waveguide layer all have elastic coefficient characteristics. The angle at which the peak position of the elastic coefficient of the upper waveguide layer decreases towards the active layer is ζ; the angle at which the valley position of the elastic coefficient of the upper waveguide layer increases towards the upper cladding layer is χ; the angle at which the valley position of the elastic coefficient of the second high-coherence lower waveguide layer increases towards the lower cladding layer is ν; the angle at which the peak position of the elastic coefficient of the second high-coherence lower waveguide layer decreases towards the active layer is λ; and the angle at which the valley position of the elastic coefficient of the first high-coherence lower waveguide layer increases towards the lower cladding layer is τ, where: 35°≤χ≤ν≤ζ≤λ≤τ≤90°.

4. The gallium nitride-based semiconductor laser according to claim 3, characterized in that, The angle at which the valley of the electron mobility of the upper waveguide layer rises towards the active layer; the angle at which the peak of the electron mobility of the upper waveguide layer falls towards the upper cladding layer; the angle at which the peak of the electron mobility of the second high-coherence lower waveguide layer falls towards the lower cladding layer; the angle at which the valley of the electron mobility of the second high-coherence lower waveguide layer rises towards the active layer; the angle at which the peak of the electron mobility of the first high-coherence lower waveguide layer falls towards the lower cladding layer; the angle at which the peak of the effective electron mass, thermal conductivity, and elastic modulus of the upper waveguide layer rises towards the active layer; and the angle at which the peak of the effective electron mass, thermal conductivity, and elastic modulus of the upper waveguide layer rises towards the active layer; The following relationships exist between the descent angle in the active layer direction, the descent angle of the valley positions of the effective electronic mass, thermal conductivity, and elastic modulus of the upper waveguide layer towards the upper cladding layer, the descent angle of the valley positions of the effective electronic mass, thermal conductivity, and elastic modulus of the second high-coherence lower waveguide layer towards the lower cladding layer, the descent angle of the peak positions of the effective electronic mass, thermal conductivity, and elastic modulus of the second high-coherence lower waveguide layer towards the active layer, and the descent angle of the valley positions of the effective electronic mass, thermal conductivity, and elastic modulus of the first high-coherence lower waveguide layer towards the lower cladding layer:

5. The gallium nitride-based semiconductor laser according to claim 1, characterized in that, The electron mobility of the upper waveguide layer has a function y1 = (a x +1) / (a x -1)(0<a<1) distribution of curves in the fourth quadrant; The effective electron mass of the upper waveguide layer has a function y2 = (c x +1) / (c x -1)(c>1) Distribution of curves in the second quadrant; The thermal conductivity of the upper waveguide layer has a function y3 = (f x +1) / (f x -1)(f>1) distribution of curves in the second quadrant; The elastic coefficient of the upper waveguide layer has a function y4=(j x +1) / (j x -1)(j>1) distribution of curves in the second quadrant; Where x is the depth of the upper waveguide layer toward the electron blocking layer, and 0 < a < 1 < j ≤ c ≤ f.

6. The gallium nitride-based semiconductor laser according to claim 5, characterized in that, The electron mobility of the first high-coherence lower waveguide layer has the function y5 = (e x′ +e -x' ) / (e x′ -e -x′ The distribution of curves in the third quadrant; The effective electronic mass of the first highly coherent lower waveguide layer has the function y6 = e -x′ / x′ 2 Second quadrant curve distribution; The thermal conductivity of the first high-coherence lower waveguide layer has the function y7 = x'e x′ Curve distribution; The elastic coefficient of the first high-coherence lower waveguide layer has the function y8 = x'e x′ Curve distribution; Where x′ is the depth from the first high coherence lower waveguide layer to the second high coherence lower waveguide layer.

7. The gallium nitride-based semiconductor laser according to claim 6, characterized in that, The electron mobility of the second high-coherence lower waveguide layer has the function y9=(b x "+1) / (b x "-1)(b>1) Third quadrant curve distribution; The effective electronic mass of the second highly coherent lower waveguide layer has a function y 10 =(d x "+1) / (d x” -1)(0<d<1) distribution of curves in the second quadrant; The thermal conductivity of the second high-coherence lower waveguide layer has a function y 11 =(g x” +1) / (g x” -1)(0<g<1) distribution of curves in the second quadrant; The elastic coefficient of the second high-coherence waveguide layer has a function y 12 =(k x” +1) / (k x” -1)(0<k<1) Second quadrant curve distribution; Where x” is the depth of the waveguide layer toward the active layer under the second high coherence condition, 0<g≤d≤k<1<b, and 0<a≤g≤d≤k<1<b≤j≤c≤f.

8. The gallium nitride-based semiconductor laser according to claim 1, characterized in that, The upper and lower waveguide layers are any one or any combination of InGaN, GaN, InN, AlInGaN, AlInN, AlN, InGaN / GaN superlattice, InGaN / AlGaN superlattice, InGaN / AlInGaN superlattice, InGaN / AlInGaN superlattice, GaN / AlGaN superlattice, GaN / AlInGaN superlattice, and GaN / AlN superlattice, with a thickness of 5nm to 1000nm.

9. The gallium nitride-based semiconductor laser according to claim 1, characterized in that, The active layer is a quantum well structure composed of a well layer and a barrier layer; The active layer's well layer is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond, with a thickness ranging from 10 angstroms to 150 angstroms. The active layer barrier is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond, with a thickness of 10 angstroms to 200 angstroms.

10. The gallium nitride-based semiconductor laser according to claim 1, characterized in that, The lower cladding layer, electron blocking layer, and upper cladding layer are any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond. The substrates include sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrates, Mo, TiW, CuW, Cu, sapphire / AlN composite substrates, diamond, graphene, and sapphire / SiN. x Sapphire / SiO2 / SiNx composite substrate, sapphire / SiN x Any one of the following: SiO2 composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

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