CN115548877A - Laser radar-oriented 1550nm waveband high-power semiconductor laser epitaxial structure and method - Google Patents
Laser radar-oriented 1550nm waveband high-power semiconductor laser epitaxial structure and method Download PDFInfo
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Abstract
The invention discloses a 1550nm waveband high-power semiconductor laser epitaxial structure and a method facing a laser radar, wherein the epitaxial structure comprises an n-type substrate layer, and an n-type mode extension waveguide layer, a non-doping lower limiting layer, a barrier layer, a quantum well layer, a non-doping upper limiting layer, a p-type etching stop layer, a p-type buffer layer, a p-type grating layer, a p-type cladding layer, a p-type energy band transition layer and a p-type ohmic contact layer which are epitaxially grown on the n-type substrate layer in sequence; the multi-quantum well layer and the multi-barrier layer form a multi-quantum well layer as an active region, and the gain peak value is positioned at 1550nm waveband; the p-type ohmic contact layer, the p-type energy band transition layer, the p-type cladding layer, the p-type grating layer and the p-type buffer layer are etched onto the p-type etching stop layer to form a ridge waveguide structure for regulating and controlling lateral light field distribution; and the n-type mode extension waveguide layer is used for extending the near-field optical field. The invention can obtain 1550nm waveband high-power continuous wave and high-beam quality laser.
Description
Technical Field
The invention belongs to the technical field of laser radars, and particularly relates to a 1550nm waveband high-power semiconductor laser epitaxial structure and a method for a laser radar.
Background
Currently, with the rise of automatic driving technology, the market demand for low-cost LiDAR (LiDAR) is more and more vigorous. Because there is no waveguide effect in the atmosphere, there is no restriction ability to the light beam, consider various losses and distortions that meteorological conditions brought at the same time, in order to guarantee that the receiving end has high enough laser energy density, the transmitting end needs to adopt the high power light source, therefore the laser radar field needs the single wavelength high power light source with high beam quality, especially in optical phase control (OPA) array laser radar and Frequency Modulation Continuous Wave (FMCW) laser radar, needs the high power semiconductor laser even more.
Generally, the wavelength of the laser radar which is mainstream in the industry is 905nm, which is close to the visible wavelength (380 nm-760 nm) of human eyes, so that the 905nm laser can be easily focused into a point on the retina of the human eyes, and the optical power upper limit of the 905nm laser radar is generally lower for protecting the safety of the human eyes.
In consideration of the power limitation caused by the human eye injury of the 905nm laser light source, the 1550nm band laser is more dominant in the long term, and will become the main light source band in the future industry. On the one hand, the 1550nm wave band is located in an atmospheric window right, meanwhile, laser of the wave band cannot be focused into a point on retina of human eyes, most of the laser of the wave band can be absorbed by water in an eyeball process, and safety of the 1550nm wave band laser to the human eyes under the same power is more than 10 ten thousand times of that of the 905nm wave band laser. Therefore, the laser can be allowed to output higher power, the upper limit of the safe power is 40 times of the 905nm wave band, the loss of the laser in the atmosphere is compensated, the farther detection distance is realized, and the detection distance can be increased to 250 meters or even more than 300 meters. On the other hand, 1550nm wave band laser interference killing feature is strong, the light beam collimation degree is better, light source luminance is high, and these several advantages let the transmission of laser and accept more high-efficient, can realize more meticulous object identification. In addition, the light spot of the 1550nm wave band laser is very small, the diameter of the light spot is only one fourth of the 905nm wave band outside 100 meters, and when a pedestrian is detected at 100 meters, 4 horizontal rows of pulses and 7 vertical rows of pulses can be received, so that the posture of the pedestrian can be clearly detected.
Semiconductor lasers include internal absorption losses and cavity surface losses, which are mainly caused by large optical dispersion due to internal carrier absorption in the epitaxial material, waveguide scattering losses, etc., and especially around the 1550nm band, the absorption of free carriers in the p-type region is quite high, resulting in large optical losses. Thus, it is difficult to increase the optical power of the 1550nm band semiconductor laser. Because the design of a waveguide region in semiconductor epitaxy cannot limit transverse and lateral modes, the quality of a light beam of emergent light is low, and the coherence and the optical power density of the light beam are reduced due to the coexistence of multiple modes.
However, in view of the need of a single-wavelength high-power light source with high beam quality in the field of laser radar, especially in optical phase control (OPA) array laser radar and Frequency Modulated Continuous Wave (FMCW) laser radar, how to obtain a 1550nm band high-power and high-beam-quality semiconductor laser for laser radar is an urgent problem to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to solve the technical problem of providing a 1550nm waveband high-power semiconductor laser epitaxial structure and a method for a laser radar, aiming at the defects of the prior art.
In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:
the 1550nm waveband high-power semiconductor laser epitaxial structure facing the laser radar comprises an n-type substrate layer, and an n-type mode extension waveguide layer, a non-doped lower limiting layer, a barrier layer, a quantum well layer, a non-doped upper limiting layer, a p-type etching stop layer, a p-type buffer layer, a p-type grating layer, a p-type cladding layer, a p-type energy band transition layer and a p-type ohmic contact layer which are epitaxially grown on the n-type substrate layer in sequence;
the barrier layer and the quantum well layer are both multilayer, the multilayer quantum well layer and the multilayer barrier layer form a multi-quantum well layer as an active region, and the gain peak value is located at 1550nm waveband;
the p-type ohmic contact layer, the p-type energy band transition layer, the p-type cladding layer, the p-type grating layer and the p-type buffer layer are etched onto the p-type etching stop layer to form a ridge waveguide structure, so that the lateral limitation of light in the semiconductor laser epitaxial structure is enhanced, and the lateral light field distribution is regulated and controlled;
the n-type mode extension waveguide layer is used for extending a near-field optical field, increasing the distribution of photons in an n-type region, reducing the overlapping of the optical field with an active region and a p-type region, reducing the absorption loss of photons in a laser cavity and reducing a transverse divergence angle.
In order to optimize the technical scheme, the specific measures adopted further comprise:
the materials of each layer are formed by adopting metal organic compound chemical vapor deposition.
The n-type substrate is InP material with doping concentration of 1-3 × 10 18 cm-3 of Si;
the n-type mode extension waveguide layer adopts In (1-x) Ga (x) As (y) P (1-y) Quaternary compound material lattice matched with InP substrate, 3-5 micron thick and doped in 0.5-2X 10 concentration 17 cm-3 of Si;
the non-doped lower limiting layer adopts In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The thickness of the As quaternary compound material is 50-130nm, and the As quaternary compound material is matched with the InP substrate in a lattice mode.
The barrier layer adopts tensile strain In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The thickness of the As quaternary compound material is 0-20nm, and compared with an InP substrate material, the tensile strain is 0-4000ppm;
the quantum well layer adopts compressive strain In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The thickness of the As quaternary compound material is 0-20nm, and compared with an InP substrate material, the compressive strain is 8000-12000ppm.
The number of layers of the quantum well layer is 1-5, the number of layers of the barrier layer is 2-6, and the formed multiple quantum well adopts the following materials:
quantum well layer: in (1-x) Ga (x) As (y) P (1-y) Barrier layer: in (1-x) Ga (x) As (y) P (1-y) ；
Or
Quantum well layer: al (Al) (x) Ga (y) In (1-x-y) As, barrier layer: al (Al) (x) Ga (y) In (1-x-y) As。
The non-doped upper limiting layer adopts In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The As quaternary compound material is 50-130nm thick and is matched with the InP substrate in lattice mode;
the p-type etching stop layer adopts In (1-x) Ga (x) As (y) P (1-y) The thickness of the quaternary compound material is 0-20nm, the quaternary compound material is matched with the InP substrate in lattice mode, and the doping concentration is 2-5 multiplied by 10 17 cm-3 of Zn;
the p-type buffer layer is made of InP material, has a thickness of 20-40nm and a doping concentration of 2-5 × 10 17 cm-3 of Zn;
the p-type grating layer adopts In (1-x) Ga (x) As (y) P (1-y) The thickness of the quaternary compound material is 0-70nm, the quaternary compound material is matched with the lattice of the InP substrate, and the doping concentration is 5-8 multiplied by 10 17 cm-3 of Zn.
When the thickness of the p-type grating layer is 0, a Fabry-Perot resonant cavity semiconductor laser is formed;
when the thickness of the p-type grating layer is not 0, a distributed feedback semiconductor laser is formed, the grating structure can adopt a uniform grating, the grating period is 243nm, and a central lambda/4 phase-shift grating or a non-central lambda/4 multi-phase-shift grating can also be adopted.
The p-type cladding layer is made of InP material with thickness of 1-2.5 μm and doping concentration of 0.5-2.5 × 10 18 cm-3 of Zn;
the p-type energy band transition layer adopts In (1-x) Ga (x) As (y) P (1-y) The thickness of the quaternary compound material is 50-100nm, the quaternary compound material is matched with the InP substrate in a lattice mode, and the doping concentration is 3-5 multiplied by 10 18 cm-3 of Zn;
the p-type ohmic contact layer adopts In (1-x) Ga (x) As ternaryThe compound material has a thickness of 100-200nm, is lattice-matched with InP substrate, and has a doping concentration of 20-60 × 10 18 cm-3 of Zn.
The epitaxial growth method of the 1550nm waveband high-power semiconductor laser epitaxial structure facing the laser radar comprises the following steps:
the sequential growth is shown on n-type InP substrates: the n-type mode extension waveguide layer, the undoped lower limiting layer, the barrier layer, the quantum well layer, the undoped upper limiting layer, the p-type etching stop layer, the p-type buffer layer and the p-type grating layer;
step 4, after the second epitaxial growth is completed, etching the epitaxial layer obtained by the second epitaxial growth to the position above the p-type etching stop layer by utilizing photoetching and etching processes to form a ridge waveguide structure;
and 5, arranging a deposition insulation SiO2 layer for the ridge waveguide structure, etching and windowing the deposition insulation SiO2 layer above the ridge waveguide structure, evaporating a front electrode above the ridge waveguide structure, thinning the n-type InP substrate, and evaporating a back electrode on the thinned n-type InP substrate.
The n-type InP substrate is thinned to 100 μm in step 5 above.
The invention has the following beneficial effects:
the invention designs a laser radar oriented semiconductor laser epitaxial structure with excellent performance and a method thereof, which can obtain 1550nm waveband high-power continuous wave and high-beam-quality laser.
The design of the n-type mode extension waveguide layer can increase the distribution of a transverse optical field in an n-type region, reduce the overlapping of photons with an active region and a p-type region, reduce the internal absorption loss of the photons in a laser cavity, improve the light emitting power of a semiconductor laser, reduce a transverse divergence angle and improve the beam quality;
the design of the ridge waveguide structure strengthens the transverse limitation of the optical field, regulates and controls the lateral optical field distribution and further improves the beam quality.
Drawings
Fig. 1 is a schematic structural diagram of an epitaxial structure of a 1550nm waveband high-power semiconductor laser facing a laser radar in an embodiment of the present invention.
FIG. 2 is a schematic view of an epitaxial structure made in accordance with an embodiment of the present invention;
the figures have been labelled: the light-emitting diode comprises a 1-n type substrate layer, a 2-n type mode extension waveguide layer, a 3-undoped lower limiting layer, a 4-barrier layer, a 5-quantum well layer, a 6-undoped upper limiting layer, a 7-p type etching stopping layer, an 8-p type buffer layer, a 9-p type grating layer, a 10-p type cladding layer, an 11-p type energy band transition layer and a 12-p type ohmic contact layer.
Detailed Description
Embodiments of the present invention are described in further detail below with reference to the accompanying drawings.
As shown in fig. 1, the 1550nm waveband high-power semiconductor laser epitaxial structure facing to the laser radar of the present invention includes an n-type substrate layer 1, and an n-type mode extension waveguide layer 2, an undoped lower limiting layer 3, a barrier layer 4, a quantum well layer 5, an undoped upper limiting layer 6, a p-type etching stop layer 7, a p-type buffer layer 8, a p-type grating layer 9, a p-type cladding layer 10, a p-type energy band transition layer 11 and a p-type ohmic contact layer 12 which are epitaxially grown on the n-type substrate layer 1 in sequence;
the barrier layer 4 and the quantum well layer 5 are both multilayer, the multilayer quantum well layer 5 and the multilayer barrier layer 4 form a multi-quantum well layer as an active region, and the gain peak value is positioned at 1550nm waveband;
the p-type ohmic contact layer 12, the p-type energy band transition layer 11, the p-type cladding layer 10, the p-type grating layer 9 and the p-type buffer layer 8 are etched onto the p-type etching stop layer 7 to form a ridge waveguide structure, so that the lateral limitation of light in the epitaxial structure of the semiconductor laser is enhanced, and the lateral light field distribution is regulated;
the n-type mode extension waveguide layer 2 extends a near-field optical field, increases the distribution of the optical field in an n-type region, reduces the overlapping of the optical field with an active region and a p-type region, reduces the absorption loss of photons in a laser cavity, and reduces a transverse divergence angle.
In example 1, the materials of the layers were formed using metal organic chemical vapor deposition MOCVD deposition.
The n-type substrate 1 is InP material with doping concentration of 1-3 × 10 18 cm -3 Si of (2);
the n-type mode extension waveguide layer 2 adopts In (1-x) Ga (x) As (y) P (1-y) Quaternary compound material lattice matched with InP substrate, 3-5 micron thick and doped in 0.5-2X 10 concentration 17 cm -3 Si of (2);
the undoped lower limiting layer 3 adopts In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The thickness of the As quaternary compound material is 50-130nm, and the As quaternary compound material is matched with the InP substrate in a lattice mode.
The barrier layer 4 adopts tensile strain In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) As quaternary compound material with thickness of 0-20nm and tensile strain amount of 0-4000ppm compared with InP substrate material;
the quantum well layer 5 adopts compressive strain In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) As quaternary compound material with thickness of 0-20nm and pressure strain amount of 8000-12000ppm compared with InP substrate material.
The number of the 5 quantum well layers is 1-5;
the number of the barrier layers 4 is 2-6;
the multi-quantum well formed by the method adopts the following material compositions:
quantum well layer 5: in (1-x) Ga (x) As (y) P (1-y) Barrier layer 4: in (1-x) Ga (x) As (y) P (1-y) ；
Or
Quantum well layer 5: al (Al) (x) Ga (y) In (1-x-y) As, barrier layer 4: al (Al) (x) Ga (y) In (1-x-y) As。
The undoped upper limiting layer 6 adopts In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The As quaternary compound material is 50-130nm thick and is matched with the InP substrate in lattice mode;
the p-type etching stop layer 7 adopts In (1-x) Ga (x) As (y) P (1-y) The thickness of the quaternary compound material is 0-20nm, the quaternary compound material is matched with the InP substrate in lattice mode, and the doping concentration is 2-5 multiplied by 10 17 cm -3 Zn of (2);
the p-type buffer layer 8 is made of InP material, has a thickness of 20-40nm and a doping concentration of 2-5 × 10 17 cm -3 Zn of (2);
the p-type grating layer 9 adopts In (1-x) Ga (x) As (y) P (1-y) The thickness of the quaternary compound material is 0-70nm, the quaternary compound material is matched with the InP substrate in lattice mode, and the doping concentration is 5-8 multiplied by 10 17 cm -3 Zn (2) in (2).
When the thickness of the p-type grating layer 9 is 0, a Fabry-Perot FP resonant cavity semiconductor laser is formed;
when the thickness of the p-type grating layer 9 is not 0, a distributed feedback DFB semiconductor laser is formed, the grating structure can adopt a uniform grating, the grating period is about 243nm, and a central lambda/4 phase-shift grating or a non-central lambda/4 multi-phase-shift grating can also be adopted.
The p-type cladding layer 10 is made of InP material, has a thickness of 1-2.5 μm and a doping concentration of 0.5-2.5 × 10 18 cm -3 Zn of (2);
the p-type energy band transition layer 11 adopts In (1-x) Ga (x) As (y) P (1-y) The thickness of the quaternary compound material is 50-100nm, the quaternary compound material is matched with the InP substrate in a lattice mode, and the doping concentration is 3-5 multiplied by 10 18 cm -3 Zn of (1);
the p-type ohmic contact layer 12 adopts In (1-x) Ga (x) As ternary compound material with thickness of 100-200nm and InP substrateLattice matching, doping concentration of 20-60 × 10 18 cm -3 Zn (1) in the presence of a base.
The epitaxial growth method of the 1550nm waveband high-power semiconductor laser epitaxial structure facing the laser radar comprises the following steps:
the sequential growth is shown on n-type InP substrates: the n-type mode extension waveguide layer 2, the undoped lower limiting layer 3, the barrier layer 4, the quantum well layer 5, the undoped upper limiting layer 6, the p-type etching stop layer 7, the p-type buffer layer 8 and the p-type grating layer 9; epitaxially growing a protective layer to the p-type grating layer 9 for the first time;
the n-type mode extension waveguide layer 2 is epitaxially grown on the n-type InP substrate by using In (1-x) Ga (x) As (y) P (1-y) The quaternary compound material comprises the components which are designed to be matched with an InP substrate in a lattice mode, the thickness of the quaternary compound material is 4 mu m, si with gradually changed concentration is doped, and the concentration is changed from bottom to top from 2 multiplied by 10 17 Gradation to 0.5X 10 17 cm-3；
The undoped lower limiting layer 3 is epitaxially grown on the n-type mode extension waveguide layer and made of Al (x) Ga (y) In (1-x-y) The component of the As quaternary compound material is designed to be matched with the lattice of the InP substrate, and the thickness of the As quaternary compound material is 120nm;
the barrier layer 4 is epitaxially grown on the undoped lower limiting layer and made of Al (x) Ga (y) In (1-x-y) The As quaternary compound material comprises the components which are designed to have the tensile strain of 3000ppm and the thickness of 10nm compared with the InP substrate material;
the quantum well layer 5 is epitaxially grown on the barrier layer, using Al in consideration of excellent carrier confinement and high temperature characteristics (x) Ga (y) In (1-x-y) The As quaternary compound material comprises 9000ppm of compressive strain and 6nm of thickness compared with an InP substrate material;
the active region part comprises 3 layers of Al (x) Ga (y) In (1-x-y) As quantum well layer and 4 layers of Al (x) Ga (y) In (1-x-y) The gain peak value of the multi-quantum well layer of the As barrier layer is positioned at 1550nm wave band;
the non-doped upper limit layer 6 is epitaxially grown on the barrier layer above the multiple quantum layers and made of Al (x) Ga (y) In (1-x-y) The component of the As quaternary compound material is designed to be matched with the crystal lattice of the InP substrate, and the thickness of the As quaternary compound material is 60nm;
a p-type etch stop layer 7 epitaxially grown on the undoped upper confinement layer using In (1-x) Ga (x) As (y) P (1-y) The quaternary compound material has the components designed to be lattice matched with the InP substrate, the thickness of 10 mu m and the doping concentration of 5 multiplied by 10 17 Zn of (1);
the p-type buffer layer 8 is epitaxially grown on the p-type etching stop layer, and is made of InP material with a thickness of 30nm and a doping concentration of 5 × 10 17 Zn of (2);
the p-type grating layer 9 is epitaxially grown on the p-type buffer layer by using In (1-x) Ga (x) As (y) P (1-y) The components of the quaternary compound material are designed to be matched with the lattice of the InP substrate; the thickness is 0-70nm, and the thickness of the grating layer is selected under the condition of selecting the laser cavity long strip to ensure that the value of the grating coupling coefficient kappa L is 1.5; the doping concentration is 8X 10 17 cm-3 of Zn;
the p-type grating layer structure adopts a central lambda/4 phase-shift grating to ensure the characteristic of a single longitudinal mode, and the grating period is about 243nm;
a p-type cladding layer 10 epitaxially grown on the p-type grating layer and made of InP material with a thickness of 1.5 μm and a doping concentration of 2 × 10 18 cm-3 of Zn;
a p-type energy band transition layer 11 is epitaxially grown on the p-type cladding layer 10 using In (1-x) Ga (x) As (y) P (1-y) Quaternary compound material with the components designed to be matched with the InP substrateLattice matching, thickness of 100nm, doping Zn with gradient concentration from bottom to top, concentration of 3 × 10 18 Gradation to 5 × 10 18 cm-3；
A p-type ohmic contact layer 12 epitaxially grown on the p-type energy band transition layer 11 with heavily doped In 0.53 Ga 0.47 As ternary compound material with thickness of 150nm and doping concentration of 50 × 10 18 cm-3 of Zn;
step 4, after the second epitaxial growth is completed, etching the epitaxial layer to the position above the p-type etching stop layer 7 by utilizing photoetching and etching processes to form a ridge waveguide structure;
The above are only preferred embodiments of the present invention, and the scope of the present invention is not limited to the above examples, and all technical solutions that fall under the spirit of the present invention belong to the scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.
Claims (10)
1. Towards 1550nm wave band high power semiconductor laser epitaxial structure of laser radar, including n type substrate layer (1), and on n type substrate layer (1) epitaxial growth's n type mode extension waveguide layer (2) in proper order, limiting layer (3) under the non-doping, barrier layer (4), quantum well layer (5), limiting layer (6) on the non-doping, p type sculpture stops layer (7), p type buffer layer (8), p type grating layer (9), p type cladding (10), p type energy band transition layer (11) and p type ohmic contact layer (12), its characterized in that:
the barrier layer (4) and the quantum well layer (5) are both multilayer, the multilayer quantum well layer (5) and the multilayer barrier (4) layer form a multi-quantum well layer as an active region, and the gain peak value is located at 1550nm waveband;
the p-type ohmic contact layer (12), the p-type energy band transition layer (11), the p-type cladding layer (10), the p-type grating layer (9) and the p-type buffer layer (8) are etched onto the p-type etching stop layer (7) to form a ridge waveguide structure, so that the lateral limitation of light in the semiconductor laser epitaxial structure is enhanced, and the lateral light field distribution is regulated;
the n-type mode extension waveguide layer (2) is used for extending a near-field optical field, increasing the distribution of photons in an n-type region, reducing the overlapping of the optical field with an active region and a p-type region, reducing the absorption loss of the photons in a laser cavity and reducing a transverse divergence angle.
2. The epitaxial structure of a 1550nm band high power semiconductor laser facing to a lidar according to claim 1, wherein the materials of the layers are formed by chemical vapor deposition of metal organic compounds.
3. The 1550nm band high power semiconductor laser epitaxial structure according to claim 1, characterized in that the n-type substrate (1) is of InP material with doping concentration of 1-3 x 10 18 cm -3 Si of (2);
the n-type mode extension waveguide layer (2) adopts In (1-x) Ga (x) As (y) P (1-y) A quaternary compound material lattice-matched with the n-type InP substrate (1), with a thickness of 3-5 μm and a doping concentration of 0.5-2 × 10 17 cm -3 Si of (2);
the undoped lower limiting layer (3) adopts In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The thickness of the As quaternary compound material is 50-130nm, and the As quaternary compound material is in lattice match with the n-type InP substrate (1).
4. The 1550nm band high power semiconductor laser epitaxial structure according to claim 3, characterized In that the barrier layer (4) adopts tensile strain In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The thickness of the As quaternary compound material is 0-20nm, and compared with the material of the n-type InP substrate (1), the tensile strain quantity is 0-4000ppm；
The quantum well layer (5) is compressively strained In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The thickness of the As quaternary compound material is 0-20nm, and the compressive strain quantity is 8000-12000ppm compared with the material of the n-type InP substrate (1).
5. The epitaxial structure of the 1550nm band high-power semiconductor laser facing to the lidar according to claim 1 or 4, wherein the number of layers of the quantum well layer (5) is 1-5, the number of layers of the barrier layer (4) is 2-6, and the formed multiple quantum wells are made of the following materials:
quantum well layer (5): in (In) (1-x) Ga (x) As (y) P (1-y) Barrier layer (4): in (1-x) Ga (x) As (y) P (1-y) ；
Or
Quantum well layer (5): al (Al) (x) Ga (y) In (1-x-y) As, barrier layer (4): al (Al) (x) Ga (y) In (1-x-y) As。
6. The epitaxial structure of a 1550nm band high power semiconductor laser facing laser radars according to claim 4, characterized In that the undoped upper confinement layer (6) employs In (1-x) Ga (x) As (y) P (1-y) Or Al (x) Ga (y) In (1-x-y) The As quaternary compound material is 50-130nm thick and is in lattice matching with the n-type InP substrate (1);
the p-type etching stop layer (7) adopts In (1-x) Ga (x) As (y) P (1-y) The thickness of the quaternary compound material is 0-20nm, the quaternary compound material is matched with the InP substrate in lattice mode, and the doping concentration is 2-5 multiplied by 10 17 cm -3 Zn of (1);
the p-type buffer layer (8) is made of InP material, the thickness is 20-40nm, and the doping concentration is 2-5 multiplied by 10 17 cm -3 Zn of (1);
the p-type grating layer (9) adopts In (1-x) Ga (x) As (y) P (1-y) The thickness of the quaternary compound material is 0-70nm, the quaternary compound material is matched with the lattice of the InP substrate, and the doping concentration is 5-8 multiplied by 10 17 cm -3 Zn (1) in the presence of a base.
7. The structure of the 1550nm band high power semiconductor laser epitaxy according to claim 1 or 6, wherein the p-type grating layer (9) has a no grating structure when the thickness is 0, and the laser type is a fabry-perot resonant cavity semiconductor laser;
the p-type grating layer (9) has a grating structure when the thickness is not 0, the laser is a distributed feedback semiconductor laser, the grating structure can adopt a uniform grating, the grating period is 243nm, and a central lambda/4 phase-shift grating or a non-central lambda/4 multi-phase-shift grating can also be adopted.
8. The 1550nm band high power semiconductor laser epitaxial structure according to claim 6, characterized in that the p-type cladding layer (10) is made of InP material, has a thickness of 1-2.5 μm, and is doped at a concentration of 0.5-2.5 x 10 18 cm -3 Zn of (2);
the p-type energy band transition layer (11) adopts In (1-x) Ga (x) As (y) P (1-y) The thickness of the quaternary compound material is 50-100nm, the quaternary compound material is in lattice match with the n-type InP substrate (1), and the doping concentration is 3-5 multiplied by 10 18 cm -3 Zn of (1);
the p-type ohmic contact layer (12) adopts In (1-x) Ga (x) The As ternary compound material has the thickness of 100-200nm, is in lattice match with the n-type InP substrate (1), and has the doping concentration of 20-60 multiplied by 10 18 cm -3 Zn (1) in the presence of a base.
9. A method for epitaxial growth of an epitaxial structure for a 1550nm band high power semiconductor laser facing a lidar according to any one of claims 1 to 8, wherein the method comprises the steps of:
step 1, placing an n-type InP substrate (1) in MOCVD equipment for first epitaxial growth;
sequential growth is shown on an n-type InP substrate: the n-type mode extension waveguide layer (2), the undoped lower limiting layer (3), the barrier layer (4), the quantum well layer (5), the undoped upper limiting layer (6), the p-type etching stop layer (7), the p-type buffer layer (8) and the p-type grating layer (9);
step 2, taking out the epitaxial wafer obtained in the step 1, and manufacturing a grating structure on the surface of the epitaxial wafer through a photoetching process;
step 3, putting the primary epitaxial wafer with the manufactured grating structure into MOCVD equipment again for secondary epitaxial growth, and growing a p-type cladding layer (10), a p-type energy band transition layer (11) and a p-type ohmic contact layer (12) on the upper surface of the p-type grating layer (9) in sequence;
step 4, after the second epitaxial growth is completed, etching the epitaxial layer obtained by the second epitaxial growth to the position above the p-type etching stop layer (7) by utilizing photoetching and etching processes to form a ridge waveguide structure;
and 5, arranging a deposited insulating SiO2 layer for the ridge waveguide structure, etching and windowing the deposited insulating SiO2 layer above the ridge waveguide structure, evaporating a front electrode above the ridge waveguide structure, thinning the n-type InP substrate (1), and evaporating a back electrode at the bottom of the thinned n-type InP substrate (1).
10. The method for epitaxial growth of epitaxial structures of 1550nm band high power semiconductor lasers facing towards lidar according to claim 9, characterized in that step 5 thins the n-type InP substrate (1) to 100 μ ι η.
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