84 results about "Threshold current" patented technology

The invention relates to the technical field of aging test, and discloses a laser chip accelerated aging test method, which comprises the following steps: synchronously measuring the optical power, the threshold current, the slope efficiency and the emergent wavelength of a laser chip in an accelerated aging environment to obtain a time sequence data matrix; performing double sparse dictionary decomposition on the time series data matrix to obtain a normal feature coefficient and a degradation feature coefficient; calculating a target characteristic value of the time-varying covariance matrix based on the degradation characteristic coefficient, and generating a dynamic characteristic value sequence and a corresponding degradation stage identifier according to the target characteristic value; and based on the degradation stage identifier, inputting the dynamic characteristic value sequence into a life prediction model for life prediction, and obtaining the remaining service life. The method can accurately capture the nonlinear characteristic and the time evolution mode of the laser chip degradation process, automatically identify the time period characteristic which contributes to life prediction, and improve the service life of the laser chip. And the accelerated aging test accuracy of the laser chip is improved.

The invention relates to the technical field of semiconductor lasers, in particular to a laser based on a bimetallic Bragg grating and a top surface HR reflecting film, which comprises a gain chip, a first high-reflection HR film is plated on the left end surface of the gain chip, and a first anti-reflection AR film is plated on the right end surface of the gain chip. A metal Bragg grating waveguide is arranged on the right side of the gain chip, an annular resonance optical waveguide is arranged on the front side of the ridge optical waveguide, the right end face of the gain chip and the left end face of the metal Bragg grating waveguide are aligned and attached to form an outer cavity structure, and the left end face of the metal Bragg grating waveguide is plated with a second anti-reflection AR film. The right end face of the metal Bragg grating waveguide is plated with a third anti-reflection AR film. Performance test is carried out on the laser provided by the invention, and test results show that the line width is 0.6 kHz, the SMSR is 63dB, and the threshold current is 22mA, thereby verifying the effectiveness of the laser provided by the invention.

The embodiment of the application provides a test method, network equipment and an optical module, relates to the technical field of optical communication, and improves the influence caused by the failure problem of the optical module. The specific scheme is as follows: the network equipment obtains threshold currents of the optical module at different time points in sequence, whenever a threshold current is obtained, the network equipment obtains the aging rate at the current time point based on the obtained threshold current and the aging rate at the previous time point, and the network equipment obtains the life margin of the optical module at the current time point based on the initial threshold current, the obtained threshold current and the aging rate at the current time point, wherein the initial threshold current is obtained according to the temperature at the initial time point of the current test of the optical module and a mapping relationship. The embodiment of the application is used for the process of predicting the life margin of the optical module by the network equipment.

This invention relates to a dual-comb control system for a terahertz quantum cascade laser, comprising a first terahertz quantum cascade laser, a second terahertz quantum cascade laser, a first T-type biaser, and a second T-type biaser. The first terahertz quantum cascade laser operates in optical frequency comb mode, while the second terahertz quantum cascade laser operates above a threshold current. The first and second terahertz quantum cascade lasers emit terahertz light from each other. The first terahertz quantum cascade laser also functions as a detector to detect a mixing signal. The state of the mixing signal is switched by changing the power of the radio frequency signal generated by the radio frequency source. This invention enables the switching of the mixing signal between chaotic, unstable, and dual-comb states under high drive current, significantly improving the spectral width and application scenarios of the dual-comb system based on the quantum cascade laser.

The invention belongs to the technical field of control circuits, and particularly relates to a threshold current control circuit for a PSI5 interface. According to the circuit, the positive input end of an operational amplifier is connected with the drain electrode of an NMOS tube M1 and one end of a resistor R2, the negative input end of the operational amplifier is connected with one end of a resistor R1, and the output end of the operational amplifier is connected with the grid electrode of the NMOS tube M1; the source electrode of the NMOS tube M1 is connected with the drain electrode of the NMOS tube M2, the grid electrode of the NMOS tube M2 and one end of the resistor R4, and the source electrode of the NMOS tube M2 is grounded; the other end of the resistor R4 is connected with one end of a capacitor C1 and a grid electrode of the NMOS tube M3, and the other end of the capacitor C1 is grounded; the drain electrode of the NMOS tube M3 is connected with one end of the resistor R3, and the source electrode of the NMOS tube M3 is grounded; the other ends of the resistors R1, R2 and R3 are connected with a power supply; according to the invention, the threshold current control of the PSI5 interface is realized without depending on the feedback control of a digital circuit.

The application discloses a nano-ampere current source with process voltage temperature compensation capability and a design method, comprising a current bias circuit and an adaptive constant current bias voltage generating circuit; the current bias circuit is used for realizing nano-ampere sub-threshold current bias; the bias voltage generating circuit is used for extracting the characteristics of a target circuit under different processes, power supply voltages and temperature conditions, so as to obtain a corresponding bias voltage variation characteristic curve and guide the construction of the current bias circuit. The nano-ampere current source with process voltage temperature compensation capability can not only provide accurate current bias for a sub-threshold circuit, but also has the ability to resist process, power supply voltage and temperature fluctuations, and can avoid the use of large-size current mirror MOS tubes, thereby saving the layout area.

According to the gallium nitride-based semiconductor laser with the gradually-changed polarized optical phonon energy waveguide layer, a fitting curve of In ion strength distribution or In atom concentration distribution of an upper waveguide layer and a lower waveguide layer is tested through SIMS, and a fitting curve of polarized optical phonon energy distribution meets any function distribution of Log3P1, Lop2P2 and Biphase. The spatial continuous regulation and control of the phonon energy of the optical field are realized, so that the LO phonon energy is continuously and gradually changed along the propagation direction, the phonon energy gradient is formed, the LO phonon scattering is improved, the inelastic scattering and energy relaxation of carriers and LO phonons are inhibited, the carrier transportation and phonon scattering are optimized, the service life of the carriers and the gain retention time are prolonged, and the optical field performance is improved. According to the invention, the threshold current density is reduced, the thermal stability of the laser is improved, the use power and the use temperature of the laser are improved, meanwhile, the phonon energy valley value is matched with the quantum well gain peak, the scattering loss is inhibited, additional scattering caused by phonon energy mutation is avoided, the light field limitation is enhanced, and the slope efficiency is improved.

The invention relates to the technical field of semiconductor lasers. The number of quantum wells of the strained quantum well active region structure is limited by strain accumulation, the total thickness needs to be smaller than the critical thickness, implementation is achieved by increasing the number of the quantum wells, but the excessive number of the quantum wells can cause increase of threshold current; according to the high-speed multi-junction cascaded wafer fusion type vertical cavity surface emitting laser and the preparation method thereof, the active regions are connected in series in the same resonant cavity by using the tunnel junctions, so that the threshold carrier density is effectively reduced, the differential gain of the laser is improved, the threshold current is reduced, and the performance of the laser is improved. And the output power and the small signal modulation bandwidth of the laser are remarkably improved while the resistance and the absorption loss are not multiplied.

A laser display system 100 is configured to increase the dynamic range of a laser diode by modulating an operating current applied to the laser diode based on a desired sequence of brightness levels and a temperature of the laser diode. In some embodiments, a measuring circuit measures a voltage of the laser diode at a given current, which indirectly indicates the temperature of the laser diode, thus obviating the need for a direct measurement of temperature. In addition, in some embodiments, the measuring circuit identifies a threshold current of the laser diode based on a range of current values at which values of the current multiplied by the derivative of the voltage against the current vary relatively rapidly. By compensating for temperature effects and identifying the threshold current, a driver of the laser diode more precisely controls light output of the laser diode across an increased dynamic range.

The invention relates to the technical field of semiconductor lasers, in particular to a laser based on a bimetallic Bragg grating and a top surface HR reflecting film, which comprises a gain chip, a first high-reflection HR film is plated on the left end surface of the gain chip, and a first anti-reflection AR film is plated on the right end surface of the gain chip. A metal Bragg grating waveguide is arranged on the right side of the gain chip, the right end face of the gain chip and the left end face of the metal Bragg grating waveguide are aligned and attached to form an outer cavity structure, and the left end face of the metal Bragg grating waveguide is plated with a second anti-reflection AR film. The right end face of the metal Bragg grating waveguide is plated with a third anti-reflection AR film. Performance test is carried out on the laser provided by the invention, and test results show that the line width is 0.6 kHz, the SMSR is 63dB, and the threshold current is 22mA, thereby verifying the effectiveness of the laser provided by the invention.

The invention relates to an array type methane detection method and device based on TDLAS, and belongs to the technical field of laser methane detection. The method comprises the following steps: adopting a plurality of lasers, and screening the lasers; arranging the screened lasers on a substrate to form a laser array, and sealing the laser array; sequentially driving each laser light source, and for each laser, carrying out linear scanning in a process of increasing a light-emitting initial threshold current to a full-scale current to obtain laser array absorption spectral line data; and carrying out harmonic demodulation on the light intensity data corresponding to each laser light source, and taking the data corresponding to the laser light source with the maximum absorption degree as the current detection data. The problem that a single laser needs temperature control to keep methane absorption peaks within a scanning range is solved, a plurality of light sources are adopted to form a light source array, the overall light emitting wavelength range within the working temperature is increased, heating and refrigerating devices are omitted, and power consumption is reduced.

The application discloses an anti-interface rough scattering quantum cascade laser active region and a preparation method thereof. The application forms a topological interface state protected by chiral symmetry as a lasing upper energy level at the butt joint interface between a first superlattice region and a second superlattice region, the wave function of the topological interface state is strictly zero in the thick barrier center and the interface, thereby the non-radiation loss caused by the interface roughness scattering is inhibited from the root, and the upper energy level carrier lifetime is significantly prolonged. Based on this, the threshold current density of the quantum cascade laser is greatly reduced, and high-efficiency lasing of 10 μm wavelength can be realized at room temperature. Meanwhile, a mixed epitaxy process combining molecular beam epitaxy and metal organic chemical vapor deposition is adopted, the nanometer precision energy band design of the core active region is ensured, and the efficient growth of the thick film waveguide layer is realized, which is beneficial to the practicalization and large-scale preparation of the device.

The invention provides a gallium nitride-based semiconductor laser with a gradient radiation recombination coefficient waveguide layer, which is characterized in that a lower waveguide layer and an upper waveguide layer are respectively a gradient radiation recombination coefficient lower waveguide layer and a gradient radiation recombination coefficient upper waveguide layer; and a fitting curve of In ion strength distribution or In atom concentration distribution and a fitting curve of radiation recombination coefficient distribution of the waveguide layer on the gradient radiation recombination coefficient both meet any function distribution of GaussAmp, InvsPoly and Hill in an SIMS test. A fitting curve of In ion strength distribution or In atom concentration distribution and a fitting curve of radiation recombination coefficient distribution of the waveguide layer under the gradient radiation recombination coefficient both meet BiDoseResp function distribution in an SIMS test. According to the invention, carriers, quantum recombination and a light field are efficiently localized, the laser gain is improved, the carriers and the light field are efficiently localized in an active layer (quantum well), meanwhile, non-radiative recombination and absorption loss of a waveguide region are inhibited, and the threshold current, slope efficiency and reliability are further improved.

The application relates to the technical field of semiconductor lasers, in particular to a laser based on a double-metal Bragg grating and a top SiO2 waveguide layer, which comprises a gain chip, the left end face of the gain chip is coated with a first high-reflection (HR) film, and the right end face of the gain chip is coated with a first antireflection (AR) film; a metal Bragg grating waveguide is arranged on the right side of the gain chip, the right end face of the gain chip is aligned and attached to the left end face of the metal Bragg grating waveguide to form an external cavity structure, the left end face of the metal Bragg grating waveguide is coated with a second antireflection (AR) film, and the right end face of the metal Bragg grating waveguide is coated with a third antireflection (AR) film. The application is subjected to a temperature change test, wavelength drift is controlled within the range of -40 DEG C to 85 DEG C, and is controlled within the range of -40 DEG C to 85 DEG C; performance test results show that the line width is 0.6 kHz, the SMSR is 65 dB, and the threshold current is 22 mA.

The present invention relates to a photonic circuit for generating squeezed light, comprising: an electron-pumping source (SPS) that pumps electrons at a constant rate, a distributed optical-feedback quantum dot laser component (QDL), the laser component being electrically coupled to the silent pump and integrated into a semiconductor substrate, the laser component having a predefined threshold current. The silent pump is configured to inject, into the laser component, a supply current with an intensity proportional to the intensity of the predefined threshold current by a factor between 1 and 5, so as to make the laser component generate a phase-squeezed or amplitude-squeezed light beam.

The application relates to the technical field of semiconductor lasers, in particular to a gallium nitride-based laser with high electric injection efficiency and a preparation method and device thereof. The laser comprises a substrate, an n-type gallium nitride layer, an n-type light confinement layer, an n-type spin-polarized injection layer, an n-type optical waveguide layer, a multi-quantum well active layer, a p-type optical waveguide layer, a p-type spin-polarized injection layer, a p-type light confinement layer and a p-type gallium nitride layer which are sequentially stacked on the substrate; and an n-electrode and a p-electrode are respectively arranged on the n-type gallium nitride layer and the p-type gallium nitride layer. The n-type spin-polarized injection layer is arranged between the n-type light confinement layer and the n-type optical waveguide layer, and the p-type spin-polarized injection layer is arranged between the p-type optical waveguide layer and the p-type light confinement layer, thereby forming a symmetrical double spin-polarized injection layer structure, realizing directional transmission and spin recombination of spin-polarized carriers, improving the electric injection efficiency of the laser, effectively reducing the threshold current of the gallium nitride-based laser and improving the efficiency and stability of the gallium nitride-based laser.

The invention relates to the technical field of semiconductor lasers, in particular to a laser based on a bimetallic Bragg grating and a top SiO2 waveguide layer, which comprises a gain chip, the left end face of the gain chip is plated with a first high-reflection HR film, and the right end face of the gain chip is plated with a first anti-reflection AR film; a metal Bragg grating waveguide and an annular resonance optical waveguide are arranged on the right side of the gain chip, the right end face of the gain chip and the left end face of the metal Bragg grating waveguide are aligned and attached to form an outer cavity structure, and the left end face of the metal Bragg grating waveguide is plated with a second anti-reflection AR film. The right end face of the metal Bragg grating waveguide is plated with a third anti-reflection AR film. According to the invention, a temperature change test is carried out, and the wavelength drift is controlled to be + / -0.002 nm in a range of-40 DEG C to 85 DEG C; performance test results show that the line width is 0.6 kHz, the SMSR is 65 dB, and the threshold current is 22 mA.

Light-emitting device configured to emit radiation, comprising: a substrate (50); an epitaxic structure (20) comprising in succession a first DBR stack (21), a light-emitting stack (22), a second DBR stack (23) and several discrete first and second contact regions (241), wherein the light-emitting device emits coherent light having a far-field angle of less than 15 degrees, at a forward current between a laser threshold current and a saturation current therein, and incoherent light at a forward current less than the laser threshold current, wherein the epitaxial structure (20) is arranged on the substrate (50) and further comprises: several first radiation-emitting areas in a first column; and several second radiation-emitting areas in a second column; a conductive layer (60) on the epitaxial structure (20); wherein the contact areas (241) are arranged in a two-dimensional field and are configured to direct a spatially limited current in the light-emitting device to the several first radiation-emitting areas and the several second radiation-emitting areas; and wherein one of the several first contact areas includes a first latitude (w3') and one of the several second contact areas includes a second latitude (w3) that differs from the first latitude (w3').

The application discloses a semiconductor laser with an exciton polaron topological layer, which comprises, from bottom to top, a substrate, a lower confining layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper confining layer in sequence, and has the exciton polaron topological layer; the exciton polaron topological layer comprises a first exciton polaron topological layer, a second exciton polaron topological layer and a third exciton polaron topological layer, the first exciton polaron topological layer is located between the lower confining layer and the substrate, the second exciton polaron topological layer is located in the lower confining layer, and the third exciton polaron topological layer is located between the lower confining layer and the lower waveguide layer. The application uses exciton polaron as a medium for population inversion, enhances the stability of exciton polaron quasi-particles, enhances the laser oscillation of the laser, reduces the threshold current of the energy level particle number inversion of the laser, and improves the capture effect of the depletion region, the deep energy level trap and the insulating interface layer.

The application discloses a display driving method, a readable storage medium and a scanning display device. The method is applied to the scanning display device, the scanning display device comprises a light source and a scanning display device, and the scanning display device is used for scanning and emitting light emitted by the light source. The method comprises the following steps: acquiring effective scanning time and invalid scanning time of the scanning display device; selecting a performance mode to drive the light source in the effective scanning time; selecting an energy-saving mode to drive the light source in the invalid scanning time; wherein the initial current of the light source in the performance mode is greater than the initial current of the light source in the energy-saving mode. Since the initial current of the light source is different in different time periods, the technical problem that the driving current of the LD is always above the threshold current, which causes the standby power consumption of the LD to be always maintained and the energy utilization rate to be low can be solved.

The invention discloses a low-dropout linear voltage regulator, which relates to the technical field of electronic circuits and is characterized in that bias currents of a main error amplifier and a buffer are dynamically adjusted according to load conditions, and meanwhile, a non-dominant pole in the low-dropout linear voltage regulator is pushed to high frequency and drives a main power tube through the buffer. The auxiliary error amplifier and the secondary power tube are added, when load current is small, output current is provided only through the main error amplifier, the main power tube and the auxiliary path, when the load current is larger than threshold current, the low dropout linear regulator can be converted into a three-level structure, and the secondary power tube can rapidly provide most current. Feedforward zero compensation based on the auxiliary path can be combined with conventional Miller compensation for application, the compensation capacitance can be greatly reduced, and the system bandwidth is improved. The low-dropout linear regulator has larger bandwidth and stronger transient charging and discharging capability, and low power consumption, high stability and excellent transient response performance are considered in a full-load range.

The invention discloses a method, a system, equipment and a medium for reducing signal flash of a hot metal detector at an outlet of a rolling mill, and belongs to the technical field of signal detection of the hot metal detector. The method comprises the following steps: acquiring historical current data of the rolling mill in a no-load state, and setting a threshold current value based on the historical current data; monitoring rolling mill current in real time, comparing the rolling mill current with a threshold current value, and judging whether a rolling mill steel signal exists or not; collecting a detection signal of a hot metal detector arranged at an outlet of the rolling mill; when the steel signal of the rolling mill and the detection signal of the hot metal detector exist at the same time, a self-inspection command output signal is generated, and the hot metal detector is triggered to execute a self-inspection function through the self-inspection command output signal; and the hot metal detector continuously feeds back a detection signal to the rolling automatic control system in a self-detection state, and cancels a self-detection command output signal when a steel signal of the rolling mill disappears. The signal flash of the hot metal detector at the outlet of the rolling mill is reduced.

The invention provides a laser operation method and device adaptive to a low-temperature scene, and the method comprises the steps: stripping residual pumping power under a low-temperature condition through a high-stripping-ratio CPS, and enabling the residual pumping power to be higher than the residual pumping power under a low-temperature condition through the high-stripping-ratio CPS by changing the thickness of a corrosive agent, the corrosion time and the corrosion length. And the packaging length is increased. And calculating the influence of the current application on heat accumulation, determining a threshold current based on a calculation result, and applying the threshold current to the pump source to preheat the pump source. A large amount of cladding light which is not absorbed at a low temperature is stripped through the CPS with a high stripping ratio, a threshold current is provided for the pumping source at the low temperature, the pumping source is pre-heated in advance, and damage to the pumping source caused by thermal shock is prevented.

The invention discloses a vertical-cavity surface-emitting laser structure and a preparation method thereof, and relates to the technical field of semiconductor optoelectronic devices, and the vertical-cavity surface-emitting laser structure comprises a substrate, a first distributed Bragg reflector, an n-type layer, a multi-quantum well layer, an electron blocking layer, a p-type layer, an n-type semiconductor limiting layer, an insulation current limiting layer, and a current expansion layer. A second distributed Bragg reflector and an electrode; according to the invention, the n-type semiconductor limiting layer with a larger forbidden bandwidth is introduced into the p-type layer below the insulating current limiting layer, and a heterojunction barrier and a built-in electric field formed by the n-type semiconductor limiting layer and the p-type layer are utilized to prevent transverse leakage of carriers, so that the loss of the carriers in a non-active region is reduced; therefore, the output light power of the laser is improved and the threshold current is reduced.

The invention provides a tunnel junction type vertical cavity surface emitting laser structure and a forming method thereof, the tunnel junction type vertical cavity surface emitting laser structure comprises a substrate on which a first distributed Bragg reflector layer, an active layer and an etching stop layer which are sequentially stacked from bottom to top are formed, and the etching stop layer contains arsenic element; the first tunnel junction layer is formed on the etching stop layer and exposes part of the top surface of the etching stop layer, the second tunnel junction layer is formed on the first tunnel junction layer, and the second tunnel junction layer contains phosphorus; the second distributed Bragg reflector layer covers the second tunnel junction layer and extends to cover the exposed top surface of the etch stop layer. Because the second tunnel junction layer contains phosphorus, the light absorption of the second tunnel junction layer to the working wavelength can be reduced, thereby improving the output power of the device and reducing the threshold current. In addition, since the etching stop layer contains the arsenic element, the film layer quality of the second distributed Bragg reflector layer can be improved.

The invention discloses an epitaxial structure of a strain compensation type VCSEL (Vertical Cavity Surface Emitting Laser) based on AsH3 flow regulation and control and a preparation method thereof. The epitaxial structure comprises a substrate, and a buffer layer, an N-type DBR (Distributed Bragg Reflector) layer, an active layer, a P-type oxidation limiting layer, a P-type DBR layer and a surface highly-doped GaAs layer are sequentially arranged on the substrate; the N-type DBR layer comprises an N-type high-Al component layer, an Al component transition layer and a low-Al component layer, the P-type DBR layer comprises a P-type high-Al component layer, an Al component transition layer and a low-Al component layer, the active layer comprises a quantum well layer and a quantum barrier layer, the quantum well layer and the quantum barrier layer periodically grow to form the active layer, the quantum well layer is a quantum well layer with compressive strain, and the quantum barrier layer is a quantum well layer with compressive strain. The quantum barrier layer is a tensile strain layer for realizing strain compensation, and the quantum well layer and the quantum barrier layer are alternately arranged to form a periodic structure; the As / P proportion can be accurately controlled to achieve dynamic strain compensation, the As component of the barrier layer is progressively increased to form gradient tensile strain, well layer compression strain is offset, atom mutual diffusion is restrained, P atoms are restrained from diffusing to the well layer, threshold current is reduced, slope efficiency is improved, and characteristic temperature is improved.

The utility model discloses a relay. The relay comprises a shell, an internal component and an exciter, the shell is provided with a through hole, and the through hole penetrates through the inner wall surface and the outer wall surface of the shell; the internal component is movably arranged in the shell and is configured to switch the state of the relay from a closed state to an open state and from the open state to the closed state in response to an input signal; the exciter is arranged on the outer wall surface of the shell and seals the through hole; the exciter is configured to be activated to generate gas impact force when threshold current passes through the internal part, and the gas impact force can drive the internal part to move so that the relay can be switched from the closed state to the open state.

The application discloses a single-photon avalanche diode modeling method based on Verilog-A, which comprises the following steps: model parameter definition and initialization; judging the state of the single-photon avalanche diode, if the avalanche is closed, performing statistical model calculation, judging whether the avalanche state is opened according to the statistical model calculation result, if the avalanche is opened, performing electrical model calculation, updating the avalanche state according to the electrical model calculation result and the quenching threshold current based on Gaussian distribution, and outputting each current; the statistical model calculation comprises calculating the photon detection event time, the dark count event occurrence time and the post-pulse trigger time; the electrical model calculation comprises calculating the leakage current and the segmented avalanche current, and calculating the junction charge of the SPAD cathode-anode, the parasitic capacitance charge of the SPAD cathode-substrate and the parasitic capacitance charge of the SPAD anode-substrate, so as to calculate the corresponding current according to the charge-current relationship. The application can comprehensively reflect the working characteristics of the device.

Embodiments of the present disclosure provide techniques for optimizing quiescent current in an amplifier. The amplifier may include an output stage associated with a quiescent current; a set of NMOS transistors comprising a first NMOS transistor and a second NMOS transistor connected together. The first NMOS transistor may have a first bias current. The amplifier may further include a first set of PMOS transistors comprising a first PMOS transistor and a second PMOS transistor. The first PMOS transistor may have a second bias current. The amplifier may further include an optimization circuit. The optimization circuit may include a current steering circuit that is driven by a threshold current. The optimization circuit may further include a level shifting device connected to the current steering circuit. The current steering circuit may be configured to adjust the first bias current based on the threshold current.

The invention discloses an InAs quantum dot laser and an InAs quantum dot laser preparation method, and belongs to the technical field of semiconductor lasers. The energy band and the waveguide of the epitaxial structure are jointly designed, the epitaxial structure adopts the multi-layer stacked lower gradient waveguide layer and the multi-layer stacked upper gradient waveguide layer, and the refractive indexes of the gradient waveguide layers are distributed in a gradient manner, so that continuous and convergent deflection can be performed on light rays in the gradient waveguide layers, and the light rays can be continuously deflected in the gradient waveguide layers. Light emitted from the end face of the gradient waveguide layer has a velocity component closer to the normal direction, so that the divergence angle of a light beam is reduced; and meanwhile, the epitaxial structure adopts the multi-layer stacked InAs quantum dot active region, so that the density of the quantum dots is multiplied, and the energy band of the InAs quantum dot active region is optimized, thereby increasing the optical gain volume and reducing the threshold current density. And only the epitaxial structure is designed, and the method can be compatible with the existing process, so that the process complexity and cost are reduced.