Gallium nitride semiconductor laser element with low fast axis divergence angle lower waveguide layer

Abstract

The invention discloses a gallium nitride semiconductor laser element with a low fast axis divergence angle lower waveguide layer, which sequentially comprises a substrate, a lower coating layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, an upper coating layer and a contact layer from bottom to top, and is characterized in that the lower waveguide layer is the low fast axis divergence angle lower waveguide layer; the low fast axis divergence angle lower waveguide layer comprises a first low fast axis divergence angle lower waveguide layer and a second low fast axis divergence angle lower waveguide layer; the thickness of the lower waveguide layer with the low fast axis divergence angle is 5-1000 nm. According to the invention, the hole mobility and electron mobility change angle and change curve of the lower waveguide layer regulate and control the quasi Fermi level pinning degree of holes and electrons of the active layer and the lower waveguide layer after laser lasing, and reduce the abrupt change probability of the symmetry breaking of the active layer and the lower waveguide layer away from the equilibrium state at the threshold. And the IV curve Kink problem and the fast axis divergence angle jump problem are inhibited.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor optoelectronic devices, and in particular to a gallium nitride semiconductor laser element with a lower waveguide layer having a low fast axis divergence angle. Background Art

[0002] Lasers are widely used in laser display, laser TV, laser projector, communication, medical treatment, weapons, guidance, ranging, spectral analysis, cutting, precision welding, high-density optical storage and other fields. There are many types of lasers, and the classification methods are also diverse, mainly including solid, gas, liquid, semiconductor and dye types of lasers; compared with other types of lasers, all-solid-state semiconductor ultraviolet lasers have the advantages of small size, high efficiency, light weight, good stability, long life, simple and compact structure, and miniaturization.

[0003] There are significant differences between lasers and nitride semiconductor light-emitting diodes. 1) Lasers are generated by stimulated radiation from carriers, with a small half-width spectrum and high brightness. The output power of a single laser can be in the W level, while nitride semiconductor light-emitting diodes emit spontaneous radiation, and the output power of a single light-emitting diode is in the mW level. 2) The current density of the laser is as high as KA / cm 2 , which is more than 2 orders of magnitude higher than that of nitride light-emitting diodes, resulting in stronger electron leakage, more serious Auger recombination, stronger polarization effect, more serious electron-hole mismatch, and more serious efficiency attenuation Droop effect; 3) The light-emitting diode spontaneously radiates, without external influence, and is incoherent light that transitions from high energy level to low energy level, while the laser is stimulated transition radiation, and the energy of the induced photon should be equal to the difference in energy levels of the electron transition, generating photons and induced photons with identical coherent light; 4) The principles are different: the light-emitting diode is under the action of external voltage, and the electron-hole transition to the active layer or pn junction generates radiation recombination and luminescence, while the laser needs the lasing conditions to be met before it can be lased, and the carrier inversion distribution in the active area must be met. The stimulated radiation light oscillates back and forth in the resonant cavity, and the propagation in the gain medium amplifies the light, and the threshold condition is met so that the gain is greater than the loss, and finally the laser is output.

[0004] Nitride semiconductor ultraviolet lasers have the following problems: after the laser emits stable laser saturation, the quasi-Fermi levels of holes and electrons are pinned, the injected carriers are completely converted into photon output, the optical gain reaches saturation, the junction voltage also reaches saturation, and the carrier concentration in the cavity does not change with the current. The symmetry breaking corresponding to the phase transition of the active layer away from the equilibrium state causes the laser to be discontinuous or sudden at the threshold, such as the Kink problem of the IV curve and the jump of the fast axis divergence angle. The quantum well confinement factor is small, and the light field diffuses longitudinally, resulting in problems such as a large fast axis divergence angle. Summary of the invention

[0005] The present invention provides a gallium nitride semiconductor laser element with a lower waveguide layer with a low fast axis divergence angle, a hole mobility and an electron mobility change angle and a change curve of the lower waveguide layer, and regulates the quasi-Fermi level pinning degree of holes and electrons in the active layer and the lower waveguide layer after laser lasing, reduces the mutation probability of symmetry breaking far from the equilibrium state of the active layer and the lower waveguide layer at the threshold, and suppresses the Kink problem of the IV curve and the jump problem of the fast axis divergence angle.

[0006] The present invention provides a gallium nitride semiconductor laser element with a low fast axis divergence angle lower waveguide layer, which comprises, 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, an upper cladding layer and a contact layer, wherein the lower waveguide layer is a low fast axis divergence angle lower waveguide layer; the low fast axis divergence angle lower waveguide layer comprises a first low fast axis divergence angle lower waveguide layer and a second low fast axis divergence angle lower waveguide layer; the low fast axis divergence angle lower waveguide layer is 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, and has a thickness of 5 to 1000 nm.

[0007] Preferably, the peak position of the hole mobility of the waveguide layer at the first low fast axis divergence angle has a descending angle α toward the cladding layer, the peak position of the electron mobility of the waveguide layer at the first low fast axis divergence angle has a descending angle β toward the cladding layer, the valley position of the covalent bond energy of the waveguide layer at the first low fast axis divergence angle has a rising angle γ toward the cladding layer, and the valley position of the light hole effective mass of the waveguide layer at the first low fast axis divergence angle has a rising angle θ toward the cladding layer, wherein: 45°≤γ≤θ≤α≤β≤90°;

[0008] Preferably, the peak position of the hole mobility of the waveguide layer at the second low fast axis divergence angle has a descending angle of δ toward the cladding layer, the peak position of the electron mobility of the waveguide layer at the second low fast axis divergence angle has a descending angle of σ toward the cladding layer, the valley position of the covalent bond energy of the waveguide layer at the second low fast axis divergence angle has a rising angle of φ toward the cladding layer, and the valley position of the light hole effective mass of the waveguide layer at the second low fast axis divergence angle has a rising angle of ψ toward the cladding layer, wherein: 50°≤ψ≤φ≤σ≤δ≤90°;

[0009] Preferably, the rising angle of the valley position of the hole mobility of the waveguide layer at the second low fast axis divergence angle toward the active layer is ω, the rising angle of the valley position of the electron mobility of the waveguide layer at the second low fast axis divergence angle toward the active layer is ε, the descending angle of the peak position of the covalent bond energy of the waveguide layer at the second low fast axis divergence angle toward the active layer is η, and the descending angle of the peak position of the light hole effective mass of the waveguide layer at the second low fast axis divergence angle toward the active layer is κ, wherein: 55°≤κ≤η≤ε≤ω≤90°.

[0010] Preferably, the descending angle of the peak position of the hole mobility and the electron mobility of the waveguide layer at the first low fast axis divergence angle toward the lower cladding layer, the rising angle of the covalent bond energy and the valley position of the light hole effective mass of the waveguide layer at the first low fast axis divergence angle toward the lower cladding layer, the descending angle of the peak position of the hole mobility and the electron mobility of the waveguide layer at the second low fast axis divergence angle toward the lower cladding layer, the rising angle of the covalent bond energy and the valley position of the light hole effective mass of the waveguide layer at the second low fast axis divergence angle toward the lower cladding layer, the rising angle of the valley position of the hole mobility and the electron mobility of the waveguide layer at the second low fast axis divergence angle toward the active layer, and the descending angle of the peak position of the covalent bond energy and the light hole effective mass of the waveguide layer at the second low fast axis divergence angle toward the active layer have the following relationship: 45°≤γ≤ψ≤φ≤κ≤η≤θ≤α≤σ≤ε≤δ≤ω≤β≤90°.

[0011] Preferably, the hole mobility distribution at the interface between the waveguide layer and the lower cladding layer at the first low fast axis divergence angle has a function y=D+E*sinx / x 2 The first quadrant curve distribution; the electron mobility distribution at the interface between the waveguide layer and the lower cladding layer under the first low fast axis divergence angle has a function y=F+G*x -A (A>1 odd number) first quadrant curve distribution; the covalent bond energy distribution of the interface between the waveguide layer and the lower cladding layer under the first low fast axis divergence angle has a function y=H+J*lnx+x curve distribution; the light hole effective mass distribution of the interface between the waveguide layer and the lower cladding layer under the first low fast axis divergence angle has a function y=K+L*lnx+e x Curve distribution; where: K≤H≤D≤F.

[0012] Preferably, the hole mobility distribution of the second low fast axis divergence angle waveguide layer and the first low fast axis divergence angle waveguide layer has a function y=M+Q*e x / lnx fourth quadrant curve distribution; the electron mobility distribution of the waveguide layer under the second low fast axis divergence angle and the waveguide layer under the first low fast axis divergence angle has the function y=N+R*x / lnx fourth quadrant curve distribution; the covalent bond energy distribution of the waveguide layer under the second low fast axis divergence angle and the waveguide layer under the first low fast axis divergence angle has the function y=P+x+S*lnx curve distribution; the light hole effective mass distribution of the waveguide layer under the second low fast axis divergence angle and the waveguide layer under the first low fast axis divergence angle has the function y=T+U*e x lnx curve distribution; where T≤P≤M≤N.

[0013] Preferably, the upper waveguide layer is 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, and has a thickness of 5 to 1000 nm.

[0014] Preferably, the well layer of the active 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, and has a thickness of 10 to 100 μm. angstroms, and the barrier layer of the active 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 of 10 to 200 angstroms.

[0015] 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.

[0016] 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 / SiN x Composite substrate, sapphire / SiN x Any one of a / SiO2 composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0017] Compared with the prior art, the gallium nitride semiconductor laser element with a lower waveguide layer with a low fast-axis divergence angle provided by an embodiment of the present invention has the following beneficial effects: the hole mobility and electron mobility change angle and change curve of the lower waveguide layer regulate the quasi-Fermi level pinning degree of holes and electrons in the active layer and the lower waveguide layer after laser lasing, reduce the mutation probability of symmetry breaking far from the equilibrium state of the active layer and the lower waveguide layer at the threshold, and suppress the Kink problem of the IV curve and the fast-axis divergence angle jump problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of a gallium nitride semiconductor laser element with a lower waveguide layer with a low fast axis divergence angle according to an embodiment of the present invention;

[0019] Figure 2 This is a structural SIMS secondary ion mass spectrum of a gallium nitride semiconductor laser element with a lower waveguide layer with a low fast axis divergence angle according to an embodiment of the present invention;

[0020] Figure 3 This is a SIMS secondary ion mass spectrum of the structure of a gallium nitride semiconductor laser element with a lower waveguide layer with a low fast axis divergence angle according to an embodiment of the present invention (partially enlarged view);

[0021] Figure 4This is a TEM lens electron microscope image of a gallium nitride semiconductor laser element having a waveguide layer with a low fast axis divergence angle according to an embodiment of the present invention;

[0022] Figure 5 This is a TEM lens electron microscope image (partial magnified image) of a gallium nitride semiconductor laser element with a waveguide layer having a low fast axis divergence angle according to an embodiment of the present invention;

[0023] Figure 6 This is a TEM lens electron microscope image (partial magnified image) of a gallium nitride semiconductor laser element with a waveguide layer having a low fast axis divergence angle according to an embodiment of the present invention;

[0024] Reference numerals: 100: substrate; 101: lower cladding layer; 102: lower waveguide layer; 102a: first low fast axis divergence angle lower waveguide layer; 102b: second low fast axis divergence angle lower waveguide layer; 103: active layer; 104: upper waveguide layer, 105: electron blocking layer, 106: upper cladding layer, 107: contact layer. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to solve the above problems, a gallium nitride semiconductor laser element with a lower waveguide layer with a low fast axis divergence angle provided in an embodiment of the present application will be introduced and described in detail through the following specific embodiments.

[0027] Reference Figure 1-6The present invention provides a gallium nitride semiconductor laser element with a low fast axis divergence angle lower waveguide layer, which 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, an upper cladding layer 106 and a contact layer 107, wherein the lower waveguide layer 102 is a low fast axis divergence angle lower waveguide layer; the low fast axis divergence angle lower waveguide layer comprises a first low fast axis divergence angle lower waveguide layer 102a and a second low fast axis divergence angle lower waveguide layer 10 2b; The waveguide layer at the low fast axis divergence angle is 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, and has a thickness of 5 to 1000 nm.

[0028] The peak position of the hole mobility of the waveguide layer 102a at the first low fast axis divergence angle has a descending angle α toward the cladding layer 101, the peak position of the electron mobility of the waveguide layer 102a at the first low fast axis divergence angle has a descending angle β toward the cladding layer 101, the valley position of the covalent bond energy of the waveguide layer 102a at the first low fast axis divergence angle has a rising angle γ toward the cladding layer 101, and the valley position of the light hole effective mass of the waveguide layer 102a at the first low fast axis divergence angle has a rising angle θ toward the cladding layer 101, wherein: 45°≤γ≤θ≤α≤β≤90°;

[0029] The descending angle of the peak position of the hole mobility of the waveguide layer 102b at the second low fast axis divergence angle toward the cladding layer 101 is δ, the descending angle of the peak position of the electron mobility of the waveguide layer 102b at the second low fast axis divergence angle toward the cladding layer 101 is σ, the rising angle of the valley position of the covalent bond energy of the waveguide layer 102b at the second low fast axis divergence angle toward the cladding layer 101 is φ, and the rising angle of the valley position of the light hole effective mass of the waveguide layer 102b at the second low fast axis divergence angle toward the cladding layer 101 is ψ, wherein: 50°≤ψ≤φ≤σ≤δ≤90°;

[0030] The rising angle of the valley position of the hole mobility of the waveguide layer 102b at the second low fast axis divergence angle toward the active layer 103 is ω, the rising angle of the valley position of the electron mobility of the waveguide layer 102b at the second low fast axis divergence angle toward the active layer 103 is ε, the descending angle of the peak position of the covalent bond energy of the waveguide layer 102b at the second low fast axis divergence angle toward the active layer 103 is η, and the descending angle of the peak position of the light hole effective mass of the waveguide layer 102b at the second low fast axis divergence angle toward the active layer 103 is κ, wherein: 55°≤κ≤η≤ε≤ω≤90°.

[0031] In summary, the peak positions of the hole mobility and electron mobility of the waveguide layer 102a at the first low fast axis divergence angle are decreased at an angle toward the cladding layer 101, the valley positions of the covalent bond energy and light hole effective mass of the waveguide layer 102a at the first low fast axis divergence angle are increased at an angle toward the cladding layer 101, the peak positions of the hole mobility and electron mobility of the waveguide layer 102b at the second low fast axis divergence angle are decreased at an angle toward the cladding layer 101, and the valley positions of the covalent bond energy and light hole effective mass of the waveguide layer 102a at the first low fast axis divergence angle are increased at an angle toward the cladding layer 101, and the valley positions of the covalent bond energy and light hole effective mass of the waveguide layer 102b at the second low fast axis divergence angle are decreased at an angle toward the cladding layer 101. The rising angle of the valley position of the covalent bond energy and light hole effective mass of waveguide layer 102b towards the lower cladding layer 101, the rising angle of the valley position of the hole mobility and electron mobility of the waveguide layer 102b at the second low fast axis divergence angle towards the active layer 103, and the descending angle of the peak position of the covalent bond energy and light hole effective mass of the waveguide layer 102b at the second low fast axis divergence angle towards the active layer 103 have the following relationship: 45°≤γ≤ψ≤φ≤κ≤η≤θ≤α≤σ≤ε≤δ≤ω≤β≤90°.

[0032] The hole mobility distribution at the interface between the first low fast axis divergence angle waveguide layer 102a and the lower cladding layer 101 has a function y=D+E*sinx / x 2 The first quadrant curve distribution; the electron mobility distribution at the interface between the waveguide layer 102a and the lower cladding layer 101 under the first low fast axis divergence angle has a function y=F+G*x -A (A>1 odd number) first quadrant curve distribution; the covalent bond energy distribution at the interface between the waveguide layer 102a and the lower cladding layer 101 under the first low fast axis divergence angle has a function y=H+J*lnx+x curve distribution; the light hole effective mass distribution at the interface between the waveguide layer 102a and the lower cladding layer 101 under the first low fast axis divergence angle has a function y=K+L*lnx+e x Curve distribution; where: K≤H≤D≤F.

[0033] The hole mobility distribution of the second low fast axis divergence angle waveguide layer 102b and the first low fast axis divergence angle waveguide layer 102a has a function y=M+Q*e x / lnx fourth quadrant curve distribution; the electron mobility distribution of the waveguide layer 102b at the second low fast axis divergence angle and the waveguide layer 102a at the first low fast axis divergence angle has a function y=N+R*x / lnx fourth quadrant curve distribution; the covalent bond energy distribution of the waveguide layer 102b at the second low fast axis divergence angle and the waveguide layer 102a at the first low fast axis divergence angle has a function y=P+x+S*lnx curve distribution; the light hole effective mass distribution of the waveguide layer 102b at the second low fast axis divergence angle and the waveguide layer 102a at the first low fast axis divergence angle has a function y=T+U*e x lnx curve distribution; where T≤P≤M≤N.

[0034] In summary, the hole mobility and electron mobility change angles and change curves of the lower waveguide layer in the present invention regulate the quasi-Fermi level pinning degree of holes and electrons in the active layer and the lower waveguide layer after laser lasing, reduce the mutation probability of symmetry breaking far from equilibrium state of the active layer and the lower waveguide layer at the threshold, and suppress the Kink problem of IV curve and the jump problem of fast axis divergence angle; at the same time, the change angles and change curves of the covalent bond energy and light hole effective mass of the lower waveguide layer are designed, the doping concentration change and refractive index change of the lower waveguide layer are regulated, the effective confinement effect of photons is improved, the longitudinal diffusion of the light field is suppressed, and the fast axis divergence angle is reduced, and the fast axis divergence angle is reduced from 65 to 80° to 30 to 65°.

[0035] In the present invention, the upper waveguide layer 104 is 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, and has a thickness of 5 to 1000 nm.

[0036] In the present invention, 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, and the thickness is 10 to 10 0 angstroms, and 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 to 200 angstroms.

[0037] In the present invention, 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.

[0038] In the present invention, 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, sapphire / SiN x , Sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of a / SiO2 composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A gallium nitride semiconductor laser element having a lower waveguide layer with a low fast axis divergence angle, comprising, 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), an upper cladding layer (106) and a contact layer (107), characterized in that: The lower waveguide layer (102) is a low fast axis divergence angle lower waveguide layer; the low fast axis divergence angle lower waveguide layer comprises a first low fast axis divergence angle lower waveguide layer (102a) and a second low fast axis divergence angle lower waveguide layer (102b); the low fast axis divergence angle lower waveguide layer is 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, and has a thickness of 5 to 1000 nm.

2. The gallium nitride semiconductor laser element with a waveguide layer having a low fast axis divergence angle according to claim 1, characterized in that: The peak position of the hole mobility of the waveguide layer (102a) at the first low fast axis divergence angle has a descending angle α toward the lower cladding layer (101), the peak position of the electron mobility of the waveguide layer (102a) at the first low fast axis divergence angle has a descending angle β toward the lower cladding layer (101), the valley position of the covalent bond energy of the waveguide layer (102a) at the first low fast axis divergence angle has a rising angle γ toward the lower cladding layer (101), and the valley position of the light hole effective mass of the waveguide layer (102a) at the first low fast axis divergence angle has a rising angle θ toward the lower cladding layer (101), wherein: 45°≤γ≤θ≤α≤β≤90°; The peak position of the hole mobility of the waveguide layer (102b) at the second low fast axis divergence angle has a descending angle of δ toward the lower cladding layer (101), the peak position of the electron mobility of the waveguide layer (102b) at the second low fast axis divergence angle has a descending angle of σ toward the lower cladding layer (101), the valley position of the covalent bond energy of the waveguide layer (102b) at the second low fast axis divergence angle has a rising angle of φ toward the lower cladding layer (101), and the valley position of the light hole effective mass of the waveguide layer (102b) at the second low fast axis divergence angle has a rising angle of ψ toward the lower cladding layer (101), wherein: 50°≤ψ≤φ≤σ≤δ≤90°; The rising angle of the valley position of the hole mobility of the waveguide layer (102b) at the second low fast axis divergence angle toward the active layer (103) is ω, the rising angle of the valley position of the electron mobility of the waveguide layer (102b) at the second low fast axis divergence angle toward the active layer (103) is ε, the falling angle of the peak position of the covalent bond energy of the waveguide layer (102b) at the second low fast axis divergence angle toward the active layer (103) is η, and the falling angle of the peak position of the light hole effective mass of the waveguide layer (102b) at the second low fast axis divergence angle toward the active layer (103) is κ, wherein: 55°≤κ≤η≤ε≤ω≤90°.

3. The gallium nitride semiconductor laser element with a lower waveguide layer with a low fast axis divergence angle according to claim 2, characterized in that: The peak positions of the hole mobility and the electron mobility of the waveguide layer (102a) at the first low fast axis divergence angle are decreased toward the cladding layer (101); the valley positions of the covalent bond energy and the light hole effective mass of the waveguide layer (102a) at the first low fast axis divergence angle are increased toward the cladding layer (101); the peak positions of the hole mobility and the electron mobility of the waveguide layer (102b) at the second low fast axis divergence angle are decreased toward the cladding layer (101); the peak positions of the hole mobility and the electron mobility of the waveguide layer (102b) at the second low fast axis divergence angle are decreased toward the cladding layer (101); the peak positions of the covalent bond energy and the light hole effective mass of the waveguide layer (102a) at the first low fast axis divergence angle are increased toward the cladding layer (101); b), the rising angle of the valley position of the covalent bond energy and the light hole effective mass of the waveguide layer (102b) toward the lower cladding layer (101), the rising angle of the valley position of the hole mobility and the electron mobility of the waveguide layer (102b) at the second low fast axis divergence angle toward the active layer (103), and the descending angle of the peak position of the covalent bond energy and the light hole effective mass of the waveguide layer (102b) at the second low fast axis divergence angle toward the active layer (103) have the following relationship: 45°≤γ≤ψ≤φ≤κ≤η≤θ≤α≤σ≤ε≤δ≤ω≤β≤90°.

4. The gallium nitride semiconductor laser element with a lower waveguide layer with a low fast axis divergence angle according to claim 1, characterized in that: The hole mobility distribution at the interface between the first low fast axis divergence angle waveguide layer (102a) and the lower cladding layer (101) has a function y=D+E*sinx / x 2 The first quadrant curve distribution; the electron mobility distribution at the interface of the waveguide layer (102a) and the lower cladding layer (101) under the first low fast axis divergence angle has a function y=F+G*x -A (A>1 odd number) first quadrant curve distribution; the covalent bond energy distribution at the interface between the waveguide layer (102a) and the lower cladding layer (101) at the first low fast axis divergence angle has a function y=H+J*lnx+x curve distribution; the light hole effective mass distribution at the interface between the waveguide layer (102a) and the lower cladding layer (101) at the first low fast axis divergence angle has a function y=K+L*lnx+e x Curve distribution; where: K≤H≤D≤F.

5. The gallium nitride semiconductor laser device with a lower waveguide layer with a low fast axis divergence angle according to claim 1, characterized in that: The hole mobility distribution of the second low fast axis divergence angle waveguide layer (102b) and the first low fast axis divergence angle waveguide layer (102a) has a function y=M+Q*e x / lnx fourth quadrant curve distribution; the electron mobility distribution of the waveguide layer (102b) at the second low fast axis divergence angle and the waveguide layer (102a) at the first low fast axis divergence angle has a function y=N+R*x / lnx fourth quadrant curve distribution; the covalent bond energy distribution of the waveguide layer (102b) at the second low fast axis divergence angle and the waveguide layer (102a) at the first low fast axis divergence angle has a function y=P+x+S*lnx curve distribution; the light hole effective mass distribution of the waveguide layer (102b) at the second low fast axis divergence angle and the waveguide layer (102a) at the first low fast axis divergence angle has a function y=T+U*e x lnx curve distribution; where T≤P≤M≤N.

6. The gallium nitride semiconductor laser device with a lower waveguide layer with a low fast axis divergence angle according to claim 1, characterized in that: The upper waveguide layer (104) is 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, and has a thickness of 5 to 1000 nm.

7. The gallium nitride semiconductor laser device with a lower waveguide layer with a low fast axis divergence angle according to claim 1, characterized in that: 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, and has a thickness of 10 to 100 angstroms. 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, and has a thickness of 10 to 200 angstroms.

8. The gallium nitride semiconductor laser device with a lower waveguide layer with a low fast axis divergence angle according to claim 1, characterized in that: 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.

9. The gallium nitride semiconductor laser device with a lower waveguide layer with a low fast axis divergence angle according to claim 1, characterized in that: 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, sapphire / SiN x , Sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of a / SiO2 composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

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