A gallium nitride-based semiconductor laser having a graded thermal conductivity waveguide layer

Abstract

This invention proposes a gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer. By fitting the In ion intensity distribution or In atom concentration distribution, the transverse phonon velocity distribution, and the thermal conductivity distribution of the graded thermal conductivity upper and lower waveguide layers using SIMS testing, all of these curves satisfy the Stirling function or the LineMod function. The gradient of the transverse TA phonon velocity homogenizes phonon scattering in the lower waveguide layer, reduces thermally induced lattice distortion, avoids optical field mode distortion, and improves the optical field confinement factor. The gradient of the transverse phonon velocity homogenizes the temperature distribution in the upper waveguide layer, changing the thermal stress from concentrated to distributed, reducing phonon transport loss caused by interface scattering. It avoids the "bottleneck effect" of heat flow at the interface between the active region and the lower waveguide layer, further reducing the temperature coefficient of the threshold, accelerating heat flow to the substrate, and preventing thermal runaway caused by increased driving current after exceeding the threshold.

Description

Technical Field

[0001] This application relates to the field of semiconductor optoelectronic devices, and more particularly to a gallium nitride-based semiconductor laser with a gradient thermal conductivity waveguide layer. 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 generated by spontaneous emission. 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 to generate radiative recombination, while lasers 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 suffer from the following problems: Traditional uniform waveguide layers, due to their constant phonon velocity / thermal conductivity, exhibit issues such as concentrated heat flux, high interfacial thermal resistance, and heat accumulation in the active region. Lasers operate with high current, resulting in significant heat generation due to high current density. Poor heat dissipation and temperature characteristics exacerbate thermal mismatch between the semiconductor epitaxial layers, leading to increased threshold current, decreased output power, and reduced slope efficiency. The active region of the laser chip experiences non-radiative recombination losses and free carrier absorption, generating substantial heat. Furthermore, the resistance of the epitaxial and chip materials under current injection results in Joule heat loss and carrier absorption losses. The low thermal conductivity of the chip material further hinders heat dissipation, leading to increased active layer temperature and resulting in problems such as redshift of the lasing wavelength, decreased quantum efficiency, reduced power, increased threshold current, shorter lifetime, and decreased reliability. Thermal losses: Stokes shift loss caused by the photon energy difference between the pump light and the oscillating light is converted into heat, as is energy loss due to the non-uniform coupling ratio from the pump level to the upper laser level. Both contribute to a large amount of waste heat, resulting in uneven temperature distribution in the laser, causing thermal expansion and uneven thermal stress distribution, leading to temperature quenching, laser breakage, thermal lensing, and stress birefringence. The transverse mode stability of the GaN laser determines the beam quality of the output light. Heat accumulation causes distortion of the refractive index distribution in the waveguide layer (thermally induced refractive index gradient), which in turn induces transverse mode jumps and increases the beam divergence angle. Thermal lensing produces lens-like phenomena in space, while stress birefringence alters the polarization state of the incident light, causing depolarization and distortion of the laser beam. The active region of a laser chip contains nonradiative recombination loss and free carrier absorption, which generate a large amount of heat. At the same time, the resistance of the epitaxial layer and the chip material generates Joule heat loss and carrier absorption loss under current injection. Furthermore, the low thermal conductivity of the chip material results in poor heat dissipation performance, leading to an increase in the temperature of the active layer. This causes problems such as redshift of the lasing wavelength, decreased quantum efficiency, reduced power, increased threshold current, shorter lifetime, and decreased reliability. Summary of the Invention

[0009] To address one of the aforementioned technical problems, this invention provides a gallium nitride-based semiconductor laser with a gradient thermal conductivity waveguide layer.

[0010] This invention provides a gallium nitride-based semiconductor laser with a gradient thermal conductivity waveguide layer, comprising, from bottom to top, a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, a first upper confinement layer, an electron blocking layer, a second upper confinement layer, and a contact layer. The lower waveguide layer includes a first lower waveguide layer and a second lower waveguide layer, with the first lower waveguide layer located below the second lower waveguide layer. The first lower waveguide layer is a constant thermal conductivity lower waveguide layer, and the second lower waveguide layer is a gradient thermal conductivity lower waveguide layer. The upper waveguide layer includes a first upper waveguide layer and a second upper waveguide layer, with the first upper waveguide layer located below the second upper waveguide layer. The first upper waveguide layer is a gradient thermal conductivity upper waveguide layer, and the second upper waveguide layer is a constant thermal conductivity upper waveguide layer. The gradient thermal conductivity lower waveguide layer and the gradient thermal conductivity upper waveguide layer on both sides of the active layer constitute a gradient thermal conductivity waveguide layer.

[0011] The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the transverse phonon velocity distribution, and the fitting curve of the thermal conductivity distribution of the waveguide layer with the gradient thermal conductivity all satisfy the Stirling function or the LineMod function.

[0012] The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the transverse phonon velocity distribution, and the fitting curve of the thermal conductivity distribution of the waveguide layer under the gradient thermal conductivity all satisfy the Stirling function or the LineMod function.

[0013] Preferably, when the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer with gradient thermal conductivity measured by SIMS satisfies the Stirling function, the Stirling function is y1=a+b*(exp(k*x1)-1) / k, where y1 is the In ion intensity or In atom concentration of the waveguide layer with gradient thermal conductivity measured by SIMS, x1 is the thickness of the waveguide layer with gradient thermal conductivity, a is the background constant or initial base value, b is the amplitude coefficient or growth scaling factor, and k is the rate constant or exponential growth coefficient, wherein: -7E25≤a≤0, 1E15≤b≤1E26, 0.003≤k≤300;

[0014] When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer with gradient thermal conductivity measured by SIMS satisfies the LineMod function, the LineMod function is y2=c*(x1-d), where y2 is the In ion intensity or In atom concentration of the waveguide layer with gradient thermal conductivity measured by SIMS, x1 is the thickness of the waveguide layer with gradient thermal conductivity, c is the linear proportionality coefficient or rate of change, and d is the independent variable threshold or critical value, where: 2E15≤c≤2E26, 0.004≤d≤400.

[0015] Preferably, when the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the graded thermal conductivity SIMS test satisfies the Stirling function, the Stirling function is y3=f+g*(exp(h*x2)-1) / h, where y3 is the In ion intensity or In atom concentration of the waveguide layer under the graded thermal conductivity SIMS test, x2 is the thickness of the waveguide layer under the graded thermal conductivity, f is the background constant or initial base value, g is the amplitude coefficient or growth scaling factor, and h is the rate constant or exponential growth coefficient, wherein: 2E15≤f≤2E26, -3E25≤g≤0, -500≤h≤0;

[0016] When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the graded thermal conductivity SIMS test satisfies the LineMod function, the LineMod function is y4=j*(x2-m), where y4 is the In ion intensity or In atom concentration of the waveguide layer under the graded thermal conductivity SIMS test, x2 is the thickness of the waveguide layer under the graded thermal conductivity, j is the linear proportionality coefficient or rate of change, and k is the independent variable threshold or critical value, where: -2E26≤j≤0, 0.008≤m≤800.

[0017] Preferably, when the fitting curve of the transverse phonon velocity distribution of the waveguide layer with the graded thermal conductivity satisfies the Stirling function, the Stirling function is y5=n+p*(exp(q*x1)-1) / q, where y5 is the transverse phonon velocity of the waveguide layer with the graded thermal conductivity, x1 is the thickness of the waveguide layer with the graded thermal conductivity, n is the background constant or initial base value, p is the amplitude coefficient or growth scaling factor, and q is the rate constant or exponential growth coefficient, wherein: 2500≤n≤2500000000, -2000000≤p≤0, 0.0003≤q≤300;

[0018] When the fitting curve of the transverse phonon velocity distribution of the waveguide layer under the graded thermal conductivity satisfies the Stirling function, the Stirling function is y6=t+u*(exp(v*x2)-1) / v, where y6 is the transverse phonon velocity of the waveguide layer under the graded thermal conductivity, x2 is the thickness of the waveguide layer under the graded thermal conductivity, t is the background constant or initial base value, u is the amplitude coefficient or growth scaling factor, and v is the rate constant or exponential growth coefficient, where: 250≤t≤2500000000, 20≤u≤30000000, -50000≤v≤500.

[0019] Preferably, when the fitting curve of the transverse phonon velocity distribution of the waveguide layer with the gradient thermal conductivity satisfies the LineMod function, the LineMod function is y7=r*(x1-s), where y7 is the transverse phonon velocity of the waveguide layer with the gradient thermal conductivity, x1 is the thickness of the waveguide layer with the gradient thermal conductivity, r is the linear proportionality coefficient or rate of change, and s is the independent variable threshold or critical value, wherein: -20000000≤r≤0, 0.01≤s≤10000;

[0020] When the fitting curve of the transverse phonon velocity distribution of the waveguide layer under the gradient thermal conductivity satisfies the LineMod function, the LineMod function is y8=w*(x2-z), where y6 is the transverse phonon velocity of the waveguide layer under the gradient thermal conductivity, x2 is the thickness of the waveguide layer under the gradient thermal conductivity, w is the linear proportionality coefficient or rate of change, and z is the independent variable threshold or critical value, where: 200≤w≤200000000, -100000≤z≤100.

[0021] Preferably, when the fitting curve of the thermal conductivity distribution of the waveguide layer with the gradient thermal conductivity satisfies the Stirling function, the Stirling function is y9=A+B*(exp(K*x1)-1) / K, where y9 is the thermal conductivity of the waveguide layer with the gradient thermal conductivity, x1 is the thickness of the waveguide layer with the gradient thermal conductivity, A is the background constant or initial base value, B is the amplitude coefficient or growth scaling factor, and K is the rate constant or exponential growth coefficient, wherein: 0.002≤A≤2000, -2000≤B≤200, 0.003≤K≤300;

[0022] When the fitted curve of the thermal conductivity distribution of the waveguide layer under the gradient thermal conductivity satisfies the Stirling function, the Stirling function is y 10 =C+D*(exp(F*x2)-1) / F,y 10 x2 is the thermal conductivity of the waveguide layer under graded thermal conductivity, C is the background constant or initial base value, D is the amplitude coefficient or growth scaling factor, and F is the rate constant or exponential growth coefficient, where: 0.00004≤C≤400, 0.00002≤D≤200, and -5000≤F≤500.

[0023] Preferably, when the fitting curve of the thermal conductivity distribution of the waveguide layer with the gradually varying thermal conductivity satisfies the LineMod function, the LineMod function is y 11 =G*(x1-H), y 11 Let x1 be the thermal conductivity of the waveguide layer with the gradient thermal conductivity, G be the linear proportionality coefficient or rate of change, and H be the independent variable threshold or critical value, where: -10000≤G≤100, 0.0001≤H≤1000;

[0024] When the fitted curve of the thermal conductivity distribution of the waveguide layer under the gradient thermal conductivity satisfies the LineMod function, the LineMod function is y 12 =J*(x2-M), y 12 x2 is the thermal conductivity of the waveguide layer under the graded thermal conductivity, J is the linear proportionality coefficient or rate of change, and M is the threshold or critical value of the independent variable, where: 0.0001≤J≤100, -20000≤H≤200.

[0025] Preferably, the substrate is a GaN single crystal substrate;

[0026] The lower waveguide layer is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, or GaN.

[0027] The active layer is an InGaN / GaN quantum well;

[0028] The upper waveguide layer is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, or GaN.

[0029] The electron blocking layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN.

[0030] The lower confinement layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0031] The first upper confinement layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0032] The second upper confinement layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0033] The contact layer is any one or any combination of GaN, AlGaN, InGaN, and AlInGaN.

[0034] Preferably, the lower waveguide layer is a combination of GaN / InGaN;

[0035] The upper waveguide layer is an InGaN / GaN combination;

[0036] The upper confinement layer is an AlGaN / AlGaN combination;

[0037] The electron blocking layer is AlGaN;

[0038] The lower confinement layer is a combination of AlGaN / InGaN / AlGaN;

[0039] The first upper confinement layer is AlGaN;

[0040] The second upper confinement layer is an AlGaN / GaN combination;

[0041] The contact layer is a GaN / InGaN combination.

[0042] Preferably, the thickness of the lower waveguide layer is 300 angstroms to 8000 angstroms;

[0043] The thickness of the upper waveguide layer is 300 angstroms to 8000 angstroms;

[0044] The thickness of the upper confinement layer is 500 angstroms to 9000 angstroms;

[0045] The thickness of the electron blocking layer is from 5 angstroms to 800 angstroms;

[0046] The thickness of the lower confinement layer is from 500 angstroms to 80,000 angstroms;

[0047] The thickness of the first upper confinement layer is from 100 angstroms to 50,000 angstroms;

[0048] The thickness of the second upper confinement layer is from 100 angstroms to 50,000 angstroms;

[0049] The thickness of the contact layer is from 5 angstroms to 500 angstroms.

[0050] The beneficial effects of the present invention are as follows: The lower waveguide layer of the gallium nitride-based semiconductor laser in the present invention includes a first lower waveguide layer and a second lower waveguide layer, wherein the first lower waveguide layer is a constant thermal conductivity lower waveguide layer and the second lower waveguide layer is a graded thermal conductivity lower waveguide layer. The upper waveguide layer includes a first upper waveguide layer and a second upper waveguide layer, wherein the first upper waveguide layer is a graded thermal conductivity upper waveguide layer and the second upper waveguide layer is a constant thermal conductivity upper waveguide layer. The graded thermal conductivity lower waveguide layer and the graded thermal conductivity upper waveguide layer on both sides of the active layer constitute a graded thermal conductivity waveguide layer. This invention achieves this by ensuring that the fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curves of the transverse phonon velocity distribution, and the fitting curves of the thermal conductivity distribution obtained from SIMS testing of the waveguide layer with gradient thermal conductivity all satisfy the Stirling function or the LineMod function. Similarly, the fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curves of the transverse phonon velocity distribution, and the fitting curves of the thermal conductivity distribution obtained from SIMS testing of the waveguide layer with gradient thermal conductivity all satisfy the Stirling function or the LineMod function. This results in: a gradual change in the transverse TA phonon velocity, which homogenizes phonon scattering in the lower waveguide layer, reduces thermally induced lattice distortion, avoids optical field mode distortion, and improves the optical field confinement factor; a gradual change in the transverse phonon velocity, which homogenizes the temperature distribution in the upper waveguide layer, changing the thermal stress from concentrated to distributed, and reducing the maximum thermal stress from 1.2 GPa to 0.6~0.8 GPa (lower than the fracture strength of GaN, 1.0 GPa); simultaneously, the interface binding energy of the gradient structure is improved, reducing phonon transport loss caused by interface scattering; and the microcrack incidence rate in the upper waveguide layer is reduced by 90%. The above significantly improves the mechanical stability and environmental adaptability of the device, providing structural protection for high-power, long-life operation. Simultaneously, it avoids the "bottleneck effect" of heat flow at the interface between the active region and the lower waveguide layer, lowering the steady-state temperature of the active region. The gradient design reduces thermally induced carrier leakage, further reducing the temperature coefficient of the threshold, accelerating heat transport to the substrate, and preventing thermal runaway caused by increased drive current after exceeding the threshold. At the same time, it reduces the temperature coefficient of heat transport, and the gradual reduction in thermal conductivity lowers the active region temperature, suppressing thermally induced nonradiative recombination and improving internal quantum efficiency. The thermal conductivity gradient in the upper waveguide layer decreases from the active region to the electrode, forming a thermally resistive isolation layer. The Joule heat generated by the electrode is confined to the low thermal conductivity region near the electrode, reducing heat backpropagation efficiency by 70%–80%. Simultaneously, the decrease in transverse phonon velocity enhances phonon scattering in the low thermal conductivity region, further suppressing heat transport. Attached Figure Description

[0051] 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:

[0052] Figure 1This is a schematic diagram of the structure of a gallium nitride-based semiconductor laser with a gradient thermal conductivity waveguide layer according to an embodiment of the present invention;

[0053] Figure 2 This is a SIMS secondary ion mass spectrum and a schematic diagram of x and y coordinates of a gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer as described in an embodiment of the present invention.

[0054] Figure 3 The image shows the SIMS secondary ion mass spectrum of the upper waveguide layer with graded thermal conductivity of the gallium nitride-based semiconductor laser with graded thermal conductivity waveguide layer according to the embodiments of the present invention, and its Stirling function fitting curve.

[0055] Figure 4 The image shows the SIMS secondary ion mass spectrum of the upper waveguide layer with graded thermal conductivity of the gallium nitride-based semiconductor laser with graded thermal conductivity waveguide layer according to the embodiments of the present invention, and its LineMod function fitting curve.

[0056] Figure 5 The image shows the SIMS secondary ion mass spectrum of the waveguide layer with graded thermal conductivity and its Stirling function fitting curve for the gallium nitride-based semiconductor laser with graded thermal conductivity waveguide layer described in the embodiments of the present invention.

[0057] Figure 6 The image shows the SIMS secondary ion mass spectrum of the waveguide layer with graded thermal conductivity and its LineMod function fitting curve for the gallium nitride-based semiconductor laser with graded thermal conductivity waveguide layer described in the embodiments of the present invention.

[0058] Figure label:

[0059] 100. Substrate; 101. Lower confinement layer; 102. Lower waveguide layer; 103. Active layer; 104. Upper waveguide layer; 105. Electron blocking layer; 106. Upper confinement layer; 107. Contact layer.

[0060] 102a, First lower waveguide layer; 102b, Second lower waveguide layer;

[0061] 104a, First upper waveguide layer; 104b, Second upper waveguide layer;

[0062] 106a, First upper confinement layer; 106b, Second upper confinement layer. Detailed Implementation

[0063] 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.

[0064] like Figure 1 and Figure 2 As shown, this embodiment proposes a gallium nitride-based semiconductor laser with a gradient thermal conductivity waveguide layer, including a substrate 100, a lower confinement layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, an electron blocking layer 105, an upper confinement layer 106, and a contact layer 107 arranged sequentially from bottom to top.

[0065] Specifically, in this embodiment, the gallium nitride-based semiconductor laser with a gradient thermal conductivity waveguide layer is provided from bottom to top with a substrate 100, a lower confinement layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, an electron blocking layer 105, an upper confinement layer 106, and a contact layer 107. The upper confinement layer 106 includes a first upper confinement layer 106a and a second upper confinement layer 106b, which are located below and above the electron blocking layer 105, respectively.

[0066] In this embodiment, the lower waveguide layer 102 includes a first lower waveguide layer 102a and a second lower waveguide layer 102b, with the first lower waveguide layer 102a located below the second lower waveguide layer 102b. The first lower waveguide layer 102a is a constant thermal conductivity lower waveguide layer, and the second lower waveguide layer 102b is a graded thermal conductivity lower waveguide layer. The upper waveguide layer 104 includes a first upper waveguide layer 104a and a second upper waveguide layer 104b, with the first upper waveguide layer 104a located below the second upper waveguide layer 104b. The first upper waveguide layer 104a is a graded thermal conductivity upper waveguide layer, and the second upper waveguide layer 104b is a constant thermal conductivity upper waveguide layer. The graded thermal conductivity lower waveguide layer and the graded thermal conductivity upper waveguide layer located on both sides of the active layer 103 constitute a graded thermal conductivity waveguide layer.

[0067] Both the lower and upper waveguide layers with this graded thermal conductivity exhibit the In ion intensity distribution or In atom concentration distribution characteristics, transverse phonon velocity characteristics, and thermal conductivity distribution characteristics as measured by SIMS. Specifically, they are as follows:

[0068] The fitting curves of In ion intensity distribution or In atom concentration distribution, transverse phonon velocity distribution and thermal conductivity distribution of the SIMS test of the waveguide layer with graded thermal conductivity all satisfy the Stirling function or the LineMod function.

[0069] The fitting curves of In ion intensity distribution or In atom concentration distribution, transverse phonon velocity distribution and thermal conductivity distribution of the waveguide layer under graded thermal conductivity all satisfy the Stirling function or the LineMod function.

[0070] The exponential extension of the Stirling function (also known as the Stirling exponential growth model) is a standardized model used in scientific data fitting for data with slow growth under low independent variables and exponential saturation / accelerated growth under high independent variables. It is primarily adapted to fit physical processes that change gradually in the initial stage and exhibit an exponential trend in the later stage. In GaN-based optoelectronic device research, it can be used to model processes such as carrier injection, optical power enhancement, and defect evolution.

[0071] The LineMod function is the core expression of the Linear Modified Model. It is a modified intercept offset of a basic linear function. By introducing an offset parameter d, it achieves a horizontal axis shift in the linear relationship. It is suitable for fitting characteristic data where "physical quantities only exhibit linear changes after the independent variable reaches a threshold d". In GaN-based optoelectronic device research, it perfectly matches the physical processes of "threshold-type linear response" (such as laser threshold current, device threshold voltage, carrier threshold injection, etc.). It is a standardized and simple model for handling threshold linear relationships in scientific research.

[0072] The transverse direction of a GaN-based laser, perpendicular to the c-axis, is the primary heat transport direction from the waveguide layer to the substrate 100 and heat sink. Thermal conductivity is dominated by transverse acoustic (TA) phonons (TA phonons account for over 80% of GaN's transverse thermal conductivity). The transverse TA phonon velocity is the core parameter determining thermal conductivity, and their quantitative correlation forms the theoretical basis for the graded design of GaN waveguide layers. The upper waveguide layer 104 and lower waveguide layer 102 of the GaN-based laser are the core structures for optical field confinement, carrier transport, and lattice heat transport. Traditional uniform waveguide layers, due to their constant phonon velocity and thermal conductivity, suffer from problems such as concentrated heat flow, high interfacial thermal resistance, and heat accumulation in the active region. Graded thermal conductivity waveguide layers achieve spatially graded distributions of transverse phonon velocity (mainly transverse acoustic phonons) and thermal conductivity by controlling the material element distribution and microstructure distribution. This optimizes heat dissipation in the active region from the source of heat transport, reducing heat flow resistance and preventing heat accumulation in the active region. The gradual variation of transverse phonon velocity and thermal conductivity achieves synergistic matching, homogenizing the temperature distribution of the waveguide layer and reducing thermally induced refractive index distortion by 60%–70%. Simultaneously, the gradual thermal conductivity reduces lattice thermal stress, preventing light scattering caused by microcracks in the waveguide layer. Furthermore, it balances light field and carrier confinement characteristics, ultimately achieving a comprehensive improvement in core laser performance such as threshold current, slope efficiency, high-temperature stability, and lifetime. The threshold power of transverse mode switching is increased by 50%–80%, and the beam quality factor M² of the output light is closer to 1. This gradual design optimizes thermal accumulation in the active region from the source, achieving reduced threshold current, improved slope efficiency, improved high-temperature performance, enhanced mode stability, and significantly extended lifetime. It is a core technology for designing high-power, long-lifetime, and high-reliability GaN lasers.

[0073] Specifically, in this embodiment, the fitting curve of the In ion intensity distribution or In atom concentration distribution for the SIMS test of the waveguide layer with graded thermal conductivity can be specifically represented as follows:

[0074] When the fitted curves of the In ion intensity distribution or In atom concentration distribution obtained by SIMS testing of a waveguide layer with graded thermal conductivity satisfy the Stirling function, the Stirling function is y1=a+b*(exp(k*x1)-1) / k, where y1 is the In ion intensity or In atom concentration obtained by SIMS testing of the waveguide layer with graded thermal conductivity, x1 is the thickness of the waveguide layer with graded thermal conductivity, a is the background constant or initial base value, b is the amplitude coefficient or growth scaling factor, which determines the overall amplitude of exponential growth, and k is the rate constant or exponential growth coefficient, where: -7E25≤a≤0, 1E15≤b≤1E26, 0.003≤k≤300. Figure 3As shown, when the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer with gradient thermal conductivity in SIMS test satisfies the Stirling function, the Stirling function can be y1=(-7.38842E20)+1.74386E21*(exp(0.35322*x1)-1) / 0.35322.

[0075] When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer with graded thermal conductivity obtained by SIMS testing satisfies the LineMod function, the LineMod function is y2=c*(x1-d), where y2 is the In ion intensity or In atom concentration of the waveguide layer with graded thermal conductivity obtained by SIMS testing, x1 is the thickness of the waveguide layer with graded thermal conductivity, c is the linear proportionality coefficient or rate of change, and d is the independent variable threshold or critical value, where: 2E15≤c≤2E26, 0.004≤d≤400. Figure 4 As shown, when the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer with gradient thermal conductivity in SIMS test satisfies the LineMod function, the LineMod function can be y2=2.07161E21*(x1-0.39582).

[0076] The fitting curves for the In ion intensity distribution or In atom concentration distribution of the waveguide layer under graded thermal conductivity in SIMS testing can be specifically represented as follows:

[0077] When the fitted curves of the In ion intensity distribution or In atom concentration distribution of a waveguide layer under graded thermal conductivity according to SIMS testing satisfy the Stirling function, the Stirling function is y3=f+g*(exp(h*x2)-1) / h, where y3 is the In ion intensity or In atom concentration of the waveguide layer under graded thermal conductivity according to SIMS testing, x2 is the thickness of the waveguide layer under graded thermal conductivity, f is the background constant or initial base value, g is the amplitude coefficient or growth scaling factor, and h is the rate constant or exponential growth coefficient, where: 2E15≤f≤2E26, -3E25≤g≤0, -500≤h≤0. Figure 5 As shown, when the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the graded thermal conductivity satisfies the Stirling function, the Stirling function can be y3=2.07431E21+(-3.20097E21)*(exp((-0.52444)*x2)-1) / (-0.52444).

[0078] When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under graded thermal conductivity according to SIMS testing satisfies the LineMod function, the LineMod function is y4=j*(x2-m), where y4 is the In ion intensity or In atom concentration of the waveguide layer under graded thermal conductivity according to SIMS testing, x2 is the thickness of the waveguide layer under graded thermal conductivity, j is the linear proportionality coefficient or rate of change, and k is the independent variable threshold or critical value, where: -2E26≤j≤0, 0.008≤m≤800. Figure 6 As shown, when the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test satisfies the LineMod function, the LineMod function can be y4=(-2.22176E21)*(x2-0.7903).

[0079] The fitted curves for the transverse phonon velocity distributions of the upper and lower waveguide layers with graded thermal conductivity are as follows:

[0080] When the fitted curve of the transverse phonon velocity distribution of a waveguide layer with graded thermal conductivity satisfies the Stirling function, the Stirling function is y5=n+p*(exp(q*x1)-1) / q, where y5 is the transverse phonon velocity of the waveguide layer with graded thermal conductivity, x1 is the thickness of the waveguide layer with graded thermal conductivity, n is the background constant or initial base value, p is the amplitude coefficient or growth scaling factor, and q is the rate constant or exponential growth coefficient, where: 2500≤n≤2500000000, -2000000≤p≤0, 0.0003≤q≤300. Specifically, the Stirling function can be expressed as y5=275605.1576+(-17950.12029)*(exp(0.35322*x1)-1) / 0.35322.

[0081] When the fitted curve of the transverse phonon velocity distribution of a waveguide layer under graded thermal conductivity satisfies the Stirling function, the Stirling function is y6=t+u*(exp(v*x2)-1) / v, where y6 is the transverse phonon velocity of the waveguide layer under graded thermal conductivity, x2 is the thickness of the waveguide layer under graded thermal conductivity, t is the background constant or initial base value, u is the amplitude coefficient or growth scaling factor, and v is the rate constant or exponential growth coefficient, where: 250≤t≤2500000000, 20≤u≤30000000, -50000≤v≤500. Specifically, the Stirling function can be expressed as y6=248881.82053+29502.28813*(exp((-0.52444)*x2)-1) / (-0.52444).

[0082] When the fitted curve of the transverse phonon velocity distribution of a waveguide layer with graded thermal conductivity satisfies the LineMod function, the LineMod function is y7=r*(x1-s), where y7 is the transverse phonon velocity of the waveguide layer with graded thermal conductivity, x1 is the thickness of the waveguide layer with graded thermal conductivity, r is the linear proportionality coefficient or rate of change, and s is the independent variable threshold or critical value, where: -20000000≤r≤0, 0.01≤s≤10000. Specifically, the LineMod function can be expressed as y7=(-21323.802)*(x1-12.96394).

[0083] When the fitted curve of the transverse phonon velocity distribution of a waveguide layer under graded thermal conductivity satisfies the LineMod function, the LineMod function is y8=w*(x2-z), where y6 is the transverse phonon velocity of the waveguide layer under graded thermal conductivity, x2 is the thickness of the waveguide layer under graded thermal conductivity, w is the linear proportionality coefficient or rate of change, and z is the independent variable threshold or critical value, where: 200≤w≤200000000, -100000≤z≤100. Specifically, the LineMod function can be y8=20477.25109*(x2+12.29739).

[0084] The fitted curves for the thermal conductivity distributions of the upper and lower waveguide layers with graded thermal conductivity are as follows:

[0085] When the fitted curve of the thermal conductivity distribution of a waveguide layer with graded thermal conductivity satisfies the Stirling function, the Stirling function is y9=A+B*(exp(K*x1)-1) / K, where y9 is the thermal conductivity of the waveguide layer with graded thermal conductivity, x1 is the thickness of the waveguide layer with graded thermal conductivity, A is the background constant or initial base value, B is the amplitude coefficient or growth scaling factor, and K is the rate constant or exponential growth coefficient, where: 0.002≤A≤2000, -2000≤B≤200, 0.003≤K≤300. Specifically, the Stirling function can be expressed as y9=1.79726+(-1.17366)*(exp(0.35322*x1)-1) / 0.35322.

[0086] When the fitted curve of the thermal conductivity distribution of a waveguide layer with graded thermal conductivity satisfies the Stirling function, the Stirling function is y. 10 =C+D*(exp(F*x2)-1) / F,y 10Let be the thermal conductivity of the waveguide layer under graded thermal conductivity, x2 be the thickness of the waveguide layer under graded thermal conductivity, C be the background constant or initial base value, D be the amplitude coefficient or growth scaling factor, and F be the rate constant or exponential growth coefficient, where: 0.00004≤C≤400, 0.00002≤D≤200, -5000≤F≤500. The Stirling function can be specifically defined as y 10 =0.04997+1.929*(exp((-0.52444)*x2)-1) / (-0.52444).

[0087] When the fitted curve of the thermal conductivity distribution of a waveguide layer with graded thermal conductivity satisfies the LineMod function, the LineMod function is y. 11 =G*(x1-H), y 11 Let x1 be the thermal conductivity of the waveguide layer with a gradually increasing thermal conductivity, G be the linear proportionality coefficient or rate of change, and H be the threshold or critical value of the independent variable, where -10000 ≤ G ≤ 100 and 0.0001 ≤ H ≤ 1000. The LineMod function can be specifically defined as y 11 =-1.39425*(x1-1.32823).

[0088] When the fitted curve of the thermal conductivity distribution of a waveguide layer with graded thermal conductivity satisfies the LineMod function, the LineMod function is y. 12 =J*(x2-M), y 12 Let be the thermal conductivity of the waveguide layer under graded thermal conductivity, x2 be the thickness of the waveguide layer under graded thermal conductivity, J be the linear proportionality coefficient or rate of change, and M be the independent variable threshold or critical value, where: 0.0001≤J≤100, -20000≤H≤200. This LineMod function can be specifically defined as y 12 =1.3389*(x2+0.18065).

[0089] In some alternative embodiments, the substrate 100 is a GaN single crystal substrate 100;

[0090] The lower waveguide layer 102 is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, or GaN;

[0091] The active layer 103 is an InGaN / GaN quantum well;

[0092] The upper waveguide layer 104 is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, or GaN.

[0093] The electron blocking layer 105 is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0094] The lower confinement layer 101 is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0095] The first upper confinement layer 106a is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0096] The second upper confinement layer 106b is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0097] The contact layer 107 is any one or any combination of GaN, AlGaN, InGaN, and AlInGaN.

[0098] In some alternative embodiments, the lower waveguide layer 102 is a combination of GaN / InGaN;

[0099] The upper waveguide layer 104 is an InGaN / GaN combination;

[0100] The upper confinement layer 106 is an AlGaN / AlGaN combination;

[0101] Electron blocking layer 105 is AlGaN;

[0102] The lower confinement layer 101 is an AlGaN / InGaN / AlGaN combination;

[0103] The first upper confinement layer 106a and the upper confinement layer 106 are AlGaN;

[0104] The second upper confinement layer 106b is an AlGaN / GaN combination;

[0105] The contact layer 107 is a GaN / InGaN combination.

[0106] In some alternative embodiments, the thickness of the lower waveguide layer 102 is from 300 angstroms to 8000 angstroms;

[0107] The thickness of the upper waveguide layer 104 is 300 angstroms to 8000 angstroms;

[0108] The thickness of the upper confinement layer 106 is 500 angstroms to 9000 angstroms;

[0109] The thickness of the electron blocking layer 105 ranges from 5 angstroms to 800 angstroms;

[0110] The thickness of the lower confinement layer 101 is 500 angstroms to 80,000 angstroms;

[0111] The thickness of the first upper confinement layer 106a is 100 angstroms to 50,000 angstroms;

[0112] The thickness of the second upper confinement layer 106b is 100 angstroms to 50,000 angstroms;

[0113] The thickness of the contact layer 107 is from 5 angstroms to 500 angstroms.

[0114] The table below compares the performance of the gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer proposed in this embodiment with that of a conventional laser. The comparison is mainly based on several aspects, including threshold current, slope efficiency, maximum output power at room temperature, temperature coefficient, slope efficiency at 100°C, slow-axis divergence angle, light extraction efficiency, and long-term operating life.

[0115] Traditional lasers Laser in this embodiment Performance improvement <![CDATA[Threshold current I th (mA)]]> 60 50-52 Reduced by 13%-17% <![CDATA[Slope efficiency η slope (W / A)]]> 0.5 0.6-0.65 Increase by 20%-30% <![CDATA[Maximum output power P at room temperature max (mW)]]> 80 120-140 Increase by 50%-75% <![CDATA[Temperature coefficient T0 (K)]]> 120 150-180 Increase by 25%-50% Slope efficiency at 100℃ (W / A) 0.35 0.5-0.55 Increase by 43%-57% Slow-axis divergence angle (°) 30 24-26 Reduce by 13%-20% Light extraction efficiency 32 38-40 Increase by 19%-25% 50mW output lifespan at room temperature (h) <![CDATA[10 4 ]]> <![CDATA[5*10 4 -10 5 ]]> Increase by 400%-900%

[0116] As can be seen from the table above, the gallium nitride-based semiconductor laser with a gradient thermal conductivity waveguide layer proposed in this embodiment improves the slope efficiency, maximum output power at room temperature, temperature coefficient, slope efficiency at 100℃, light extraction efficiency, and long-term working life compared to traditional lasers. It also reduces the threshold current and decreases the slow-axis divergence angle, and its performance is significantly better than that of traditional lasers.

[0117] 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 with a gradient thermal conductivity waveguide layer, comprising, from bottom to top, a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, a first upper confinement layer, an electron blocking layer, a second upper confinement layer, and a contact layer, characterized in that, The lower waveguide layer includes a first lower waveguide layer and a second lower waveguide layer. The first lower waveguide layer is located below the second lower waveguide layer. The first lower waveguide layer is a constant thermal conductivity lower waveguide layer, and the second lower waveguide layer is a graded thermal conductivity lower waveguide layer. The upper waveguide layer includes a first upper waveguide layer and a second upper waveguide layer. The first upper waveguide layer is located below the second upper waveguide layer. The first upper waveguide layer is a graded thermal conductivity upper waveguide layer, and the second upper waveguide layer is a constant thermal conductivity upper waveguide layer. The graded thermal conductivity lower waveguide layer and the graded thermal conductivity upper waveguide layer on both sides of the active layer constitute a graded thermal conductivity waveguide layer. The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the transverse phonon velocity distribution, and the fitting curve of the thermal conductivity distribution of the waveguide layer with the gradient thermal conductivity all satisfy the Stirling function or the LineMod function. The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the transverse phonon velocity distribution, and the fitting curve of the thermal conductivity distribution of the waveguide layer under the gradient thermal conductivity all satisfy the Stirling function or the LineMod function.

2. The gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer according to claim 1, characterized in that, When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer with gradient thermal conductivity measured by SIMS satisfies the Stirling function, the Stirling function is y1=a+b*(exp(k*x1)-1) / k, where y1 is the In ion intensity or In atom concentration of the waveguide layer with gradient thermal conductivity measured by SIMS, x1 is the thickness of the waveguide layer with gradient thermal conductivity, a is the background constant or initial base value, b is the amplitude coefficient or growth scaling factor, and k is the rate constant or exponential growth coefficient, where: -7E25≤a≤0, 1E15≤b≤1E26, 0.003≤k≤300; When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer with gradient thermal conductivity measured by SIMS satisfies the LineMod function, the LineMod function is y2=c*(x1-d), where y2 is the In ion intensity or In atom concentration of the waveguide layer with gradient thermal conductivity measured by SIMS, x1 is the thickness of the waveguide layer with gradient thermal conductivity, c is the linear proportionality coefficient or rate of change, and d is the independent variable threshold or critical value, where: 2E15≤c≤2E26, 0.004≤d≤400.

3. The gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer according to claim 1, characterized in that, When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the graded thermal conductivity SIMS test satisfies the Stirling function, the Stirling function is y3=f+g*(exp(h*x2)-1) / h, where y3 is the In ion intensity or In atom concentration of the waveguide layer under the graded thermal conductivity SIMS test, x2 is the thickness of the waveguide layer under the graded thermal conductivity, f is the background constant or initial base value, g is the amplitude coefficient or growth scaling factor, and h is the rate constant or exponential growth coefficient, where: 2E15≤f≤2E26, -3E25≤g≤0, -500≤h≤0; When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the graded thermal conductivity SIMS test satisfies the LineMod function, the LineMod function is y4=j*(x2-m), where y4 is the In ion intensity or In atom concentration of the waveguide layer under the graded thermal conductivity SIMS test, x2 is the thickness of the waveguide layer under the graded thermal conductivity, j is the linear proportionality coefficient or rate of change, and k is the independent variable threshold or critical value, where: -2E26≤j≤0, 0.008≤m≤800.

4. The gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer according to claim 1, characterized in that, When the fitting curve of the transverse phonon velocity distribution of the waveguide layer with the gradient thermal conductivity satisfies the Stirling function, the Stirling function is y5=n+p*(exp(q*x1)-1) / q, where y5 is the transverse phonon velocity of the waveguide layer with the gradient thermal conductivity, x1 is the thickness of the waveguide layer with the gradient thermal conductivity, n is the background constant or initial base value, p is the amplitude coefficient or growth scaling factor, and q is the rate constant or exponential growth coefficient, where: 2500≤n≤2500000000, -2000000≤p≤0, 0.0003≤q≤300; When the fitting curve of the transverse phonon velocity distribution of the waveguide layer under the graded thermal conductivity satisfies the Stirling function, the Stirling function is y6=t+u*(exp(v*x2)-1) / v, where y6 is the transverse phonon velocity of the waveguide layer under the graded thermal conductivity, x2 is the thickness of the waveguide layer under the graded thermal conductivity, t is the background constant or initial base value, u is the amplitude coefficient or growth scaling factor, and v is the rate constant or exponential growth coefficient, where: 250≤t≤2500000000, 20≤u≤30000000, -50000≤v≤500.

5. The gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer according to claim 1, characterized in that, When the fitting curve of the transverse phonon velocity distribution of the waveguide layer with the gradient thermal conductivity satisfies the LineMod function, the LineMod function is y7=r*(x1-s), where y7 is the transverse phonon velocity of the waveguide layer with the gradient thermal conductivity, x1 is the thickness of the waveguide layer with the gradient thermal conductivity, r is the linear proportionality coefficient or rate of change, and s is the independent variable threshold or critical value, where: -20000000≤r≤0, 0.01≤s≤10000; When the fitting curve of the transverse phonon velocity distribution of the waveguide layer under the gradient thermal conductivity satisfies the LineMod function, the LineMod function is y8=w*(x2-z), where y6 is the transverse phonon velocity of the waveguide layer under the gradient thermal conductivity, x2 is the thickness of the waveguide layer under the gradient thermal conductivity, w is the linear proportionality coefficient or rate of change, and z is the independent variable threshold or critical value, where: 200≤w≤200000000, -100000≤z≤100.

6. The gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer according to claim 1, characterized in that, When the fitting curve of the thermal conductivity distribution of the waveguide layer with the gradient thermal conductivity satisfies the Stirling function, the Stirling function is y9=A+B*(exp(K*x1)-1) / K, where y9 is the thermal conductivity of the waveguide layer with the gradient thermal conductivity, x1 is the thickness of the waveguide layer with the gradient thermal conductivity, A is the background constant or initial base value, B is the amplitude coefficient or growth scaling factor, and K is the rate constant or exponential growth coefficient, where: 0.002≤A≤2000, -2000≤B≤200, 0.003≤K≤300; When the fitted curve of the thermal conductivity distribution of the waveguide layer under the gradient thermal conductivity satisfies the Stirling function, the Stirling function is y 10 =C+D*(exp(F*x2)-1) / F,y 10 x2 is the thermal conductivity of the waveguide layer under graded thermal conductivity, C is the background constant or initial base value, D is the amplitude coefficient or growth scaling factor, and F is the rate constant or exponential growth coefficient, where: 0.00004≤C≤400, 0.00002≤D≤200, and -5000≤F≤500.

7. The gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer according to claim 1, characterized in that, When the fitted curve of the thermal conductivity distribution of the waveguide layer with the gradient thermal conductivity satisfies the LineMod function, the LineMod function is y 11 =G*(x1-H), y 11 Let x1 be the thermal conductivity of the waveguide layer with the gradient thermal conductivity, G be the linear proportionality coefficient or rate of change, and H be the independent variable threshold or critical value, where: -10000≤G≤100, 0.0001≤H≤1000; When the fitted curve of the thermal conductivity distribution of the waveguide layer under the gradient thermal conductivity satisfies the LineMod function, the LineMod function is y 12 =J*(x2-M), y 12 x2 is the thermal conductivity of the waveguide layer under the graded thermal conductivity, J is the linear proportionality coefficient or rate of change, and M is the threshold or critical value of the independent variable, where: 0.0001≤J≤100, -20000≤H≤200.

8. The gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer according to claim 1, characterized in that, The substrate is a GaN single crystal substrate; The lower waveguide layer is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, or GaN. The active layer is an InGaN / GaN quantum well; The upper waveguide layer is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, or GaN. The electron blocking layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN. The lower confinement layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN; The first upper confinement layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN; The second upper confinement layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN; The contact layer is any one or any combination of GaN, AlGaN, InGaN, and AlInGaN.

9. The gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer according to claim 1, characterized in that, The lower waveguide layer is a combination of GaN / InGaN; The upper waveguide layer is an InGaN / GaN combination; The upper confinement layer is an AlGaN / AlGaN combination; The electron blocking layer is AlGaN; The lower confinement layer is a combination of AlGaN / InGaN / AlGaN; The first upper confinement layer is AlGaN; The second upper confinement layer is an AlGaN / GaN combination; The contact layer is a GaN / InGaN combination.

10. The gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer according to claim 1, characterized in that, The thickness of the lower waveguide layer is 300 angstroms to 8000 angstroms; The thickness of the upper waveguide layer is 300 angstroms to 8000 angstroms; The thickness of the upper confinement layer is 500 angstroms to 9000 angstroms; The thickness of the electron blocking layer is from 5 angstroms to 800 angstroms; The thickness of the lower confinement layer is from 500 angstroms to 80,000 angstroms; The thickness of the first upper confinement layer is from 100 angstroms to 50,000 angstroms; The thickness of the second upper confinement layer is from 100 angstroms to 50,000 angstroms; The thickness of the contact layer is from 5 angstroms to 500 angstroms.

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