Automatic device and method for light emitting and power optimization of 2-micron solid laser

Abstract

The invention provides an automatic device and method for light emitting and power optimization of 2-micron solid laser. The automatic device comprises a laser pumping source, a plano-convex lens group, a gain medium, a confocal resonant cavity, an output coupling mirror, a five-degree-of-freedom electric displacement table and a regulation and control system. Automatic optimization and stable output of laser power are realized through the design of an asymmetric confocal resonant cavity and micron-order adjustment of a high-precision five-degree-of-freedom electric displacement table in combination with a tolerance optimization algorithm and a gradient descent spiral search algorithm. A thulium-doped CYA disordered crystal is adopted as a gain medium, and the angle of the thulium-doped CYA disordered crystal is adjustable so as to excite a high-order vortex The transmittance of the output coupling mirror is dynamically adjusted according to the working mode, and the intra-cavity power density and the light-to-light conversion efficiency are ensured. The invention has the advantages of high efficiency and stability, strong universality, low cost, diversified output and the like, is suitable for the fields of space communication, quantum optics, laser processing and the like, and obviously improves the performance and application range of the laser.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state lasers, and in particular to an automatic device and method for emitting light and optimizing power of a 2-micron solid-state laser. Background Art

[0002] In the field of space laser communications, 2-micron band lasers have become the core light source supporting high-speed intersatellite data transmission (rate > 10Gbps) and deep space exploration communications due to their low atmospheric transmission loss (about 0.1dB / km) and high match with the response spectrum of indium gallium arsenide detectors. Their light output stability and power optimization accuracy directly affect the link bit error rate and communication distance. However, the complex disturbances of the space environment pose multiple technical barriers to laser control: the pulse jet of the satellite platform's attitude control engine (frequency 50Hz, amplitude ±5μm) and the flexible vibration of the solar wing cause the coaxial deviation of the resonant cavity mirror to reach ±3μm. The positioning accuracy of the traditional stepper motor-driven translation stage is only ±5μm, which cannot achieve submicron calibration. As a result, the mode purity is less than 90%, the maximum output power is attenuated by 25%, and the power recovery time is as long as 3.5 seconds under simulated vibration environment, and the fluctuation amplitude exceeds 5%, far exceeding the stability threshold of ±1.5% for communication systems. The periodic temperature drift in orbital space (alternating between -100℃ and +150℃, with a cycle period of 90 minutes) triggers the birefringence effect of the 4at.%Tm:CYA crystal (Δn=0.022) and the difference in thermal expansion coefficient of the ceramic medium (10×10 -6 / ℃vs 5×10 -6 / ℃), causing the equivalent cavity length of the resonant cavity to drift by ±8 microns. The existing fixed cavity length design relies on a single PID algorithm for compensation, and it takes more than 2 seconds to complete gain matching when switching media. In addition, due to the uncoupled birefringence effect compensation model, the power overshoot reaches 130% of the rated power, posing a risk of detector damage. The TDMA protocol of low-orbit satellite networking requires the laser to complete mode switching and stabilize the power output within 1 second. However, the traditional solution is limited by open-loop control, and the mode switching time is as long as 2.3 seconds. In addition, when the beam deflects rapidly by ±10°, the lack of five-degree-of-freedom calibration causes the spot offset to exceed 30% of the detector's receiving field of view (±50 microradians), increasing the probability of link interruption by 15%. Moreover, due to the lack of joint compensation for cavity mirror offset and thermal distortion, the power drift accumulates to ±3% after 24 hours of continuous operation, exceeding the allowable range for intersatellite space communications. Existing technologies have significant deficiencies in vibration calibration accuracy (±5 microns vs. the required ±1 micron), temperature drift compensation speed (3.5 seconds vs. the required <1 second) and multi-disturbance joint compensation capabilities. There is an urgent need for a laser generating device that combines high-precision coaxial calibration with high-precision displacement control and intelligent algorithms to achieve rapid power recovery after disturbances and wide-range stable regulation capabilities, in order to meet the core requirements of space laser communications for 2-micron lasers: "rapid response after disturbances and efficient output in complex scenarios." Summary of the Invention

[0003] In response to the above-mentioned technical deficiencies, the purpose of the present invention is to provide an automatic device and method for 2-micron solid-state laser light emission and power optimization, which can easily, conveniently and at low cost generate vortex, vector and vector vortex ring ultrafast lasers, and realize the acquisition of multi-dimensional ultrafast ring laser beams in the 2-micron band.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] An automatic device for 2-micron solid-state laser light extraction and power optimization, comprising:

[0006] A laser pump source, used to provide pump light;

[0007] Plano-convex mirror group, arranged at the laser pump source, used to accurately focus the pump light;

[0008] The gain medium uses a C-cut Tm:CYA crystal to receive the pump light focused by the plano-convex mirror group, and the angle between the normal vector of its light-passing plane and the laser propagation direction can be adjusted in the range of 0°-20°;

[0009] The first plano-concave mirror and the second plano-concave mirror are respectively located on both sides of the gain medium and together constitute a confocal resonant cavity for receiving the gain laser generated by the gain medium; the first plano-concave mirror is arranged between the plano-convex mirror group and the gain medium, and the second plano-concave mirror is slidably arranged on the other side of the gain medium;

[0010] An output coupling mirror is located at the folding angle of the second plano-concave mirror and is used to output a small portion of the stable laser in the cavity;

[0011] A five-degree-of-freedom electric translation stage is slidably arranged at the folding angle of the first plano-concave mirror and is arranged to adjust the xyz displacement and the pitch angle and deflection angle, and is used to receive the laser beam reflected by the first plano-concave mirror and adjust the laser beam to reflect it back into the cavity;

[0012] The control system monitors the output power and efficiency of the laser pump source in real time, and dynamically adjusts the operating parameters in combination with a patient optimization algorithm to achieve automatic optimization. When the output power is lower than expected, the control system automatically adjusts the current or temperature of the laser pump source to increase the power; it automatically adjusts the working mode according to different working conditions to achieve optimal power output.

[0013] Preferably, when the confocal resonator formed by the first plano-concave mirror and the second plano-concave mirror is an asymmetric confocal resonator, the ratio of the distance d3 between the second plano-concave mirror and the output coupling mirror to the distance d4 between the first plano-concave mirror and the five-degree-of-freedom electric displacement stage is [3, 6):6; the stable region of the confocal resonator is divided into a first stable region and a second stable region, and the distance between the two is 2 mm - 4 mm; when the second plano-concave mirror is moved to the front edge of the second stable region by the electric displacement stage, the threshold power for triggering the soft-aperture Kerr-lens mode locking is reduced to 60% - 70% of the fundamental-mode mode-locking threshold.

[0014] Preferably, the five-degree-of-freedom electric displacement stage has micron-level regulation in six degrees of freedom, with XYZ travel of ±25 mm and a resolution of 0.25 μm; θx / θy of ±15° and a resolution of 0.001°, integrating the function of a mirror; the laser pump source is a 30W single-mode fiber laser at 1620 nm.

[0015] Preferably, the transmittance of the output coupling mirror is 0.2% - 1%, which is specifically optimized according to the cavity loss:

[0016] When using soft-aperture Kerr mode locking, the transmittance is set to 0.5% - 1% to ensure that the intracavity power density ≥ 10 6 W / cm 2 , triggering a non-linear refractive index change Δn ≥ 1×10 -6 ;

[0017] When operating in the continuous-wave mode, the transmittance is optimized to 0.2% - 0.5% to balance the intracavity gain and output efficiency and achieve an optical-optical conversion efficiency > 25%.

[0018] Preferably, the plano-convex mirror group includes a first plano-convex mirror and a second plano-convex mirror arranged in sequence along the propagation direction of the pump light; the focal length of the first plano-convex mirror is f1, which is used to collimate the pump light output by the laser pump source to reduce the divergence angle of the pump light; the focal length of the second plano-convex mirror is f2, and f2 < f1, which is used to focus the collimated pump light by the first plano-convex mirror into the gain medium to form a focused spot with a diameter of d in the gain medium; among them, the mirror surfaces of the first plano-convex mirror and the second plano-convex mirror are both coated with an antireflection film for the pump light wavelength, and the transmittance of the antireflection film at the pump light wavelength is not less than 99% to reduce the loss of the pump light at the plano-convex mirror group; at the same time, the optical axes of the first plano-convex mirror and the second plano-convex mirror coincide with the optical axis of the pump light output by the laser pump source to ensure the collimation and focusing effect of the pump light.

[0019] Preferably, the electric translation stage automatically finds light using a gradient descent algorithm and a spiral search algorithm. A spiral search path is generated with the current parameters as the center. The power error ΔP is calculated in each iteration. The search step size and direction are adjusted according to ΔP until the convergence condition is met. The automatic light finding algorithm adopts a hybrid strategy combining gradient descent and spiral search. The specific steps are as follows:

[0020] a. Parameter initialization: With the current position of the electric translation stage as the center, set the initial search step δ0 = 5 μm, the angle step θ0 = 0.1°, the attenuation factor α = 0.8, and the safety margin ±5°;

[0021] b. Spiral path generation: In the polar coordinate system, the displacement increment of the nth iteration is:

[0022] Δx n =δ0·α n-1 ·cos(n·15°);

[0023] Δy n =δ0·α n-1 ·sin(n·15°);

[0024] c. Power error calculation: Real-time measurement of output power P n , calculate the target power P target The difference ΔP=|P n -P target |

[0025] d. Dynamic step size adjustment: If ΔP≤0.1W, the step size is attenuated by δ n =δ n-1 α; if ΔP>0.1W, the step size is restored to δ n =δ n-1 ·1 / α.

[0026] Preferably, the steps of implementing the patience optimization algorithm include:

[0027] Set initial parameters: P n_max =c, initial maximum power threshold; N n_max =4, number of patience window iterations;

[0028] Initialize counter: N n =0, power iteration value: P n =0;

[0029] Power monitoring: Get laser power P in real time n+1 ;

[0030] P n Update: If P n+1 <P n , execute P n =Pn-1 +1; if P n+1 >P n , reset P n =0;

[0031] Judgment and Update: When P n <P n-max , counter N n+1 =N n +1; when P n >P n_max , the counter is reset N n+1 =0;

[0032] Trigger cutoff condition: N n =N n_max , which is considered as the power optimum.

[0033] Preferably, the gain medium is a 4% thulium-doped c-cut yttrium garnet (CYA) disordered crystal, the end face of which is coated with a 1900nm-2100nm band anti-reflection film, the crystal size is 3mm×3mm×6.1mm, and the optical axis direction is adjustable at 5°-15° to the laser propagation direction.

[0034] A method for operating an automatic device for emitting and optimizing 2-micron solid-state laser light and power, comprising the following steps:

[0035] a. Arrange the laser pump source, plano-convex mirror group, first plano-concave mirror, gain medium, second plano-concave mirror, output coupling mirror, and electric translation stage in the xoy plane;

[0036] The pump light output by the laser pump source is collimated and focused onto the C-cut gain medium. The positions of the first plano-concave mirror, the gain medium, the second plano-concave mirror, and the electric translation stage are adjusted to allow the laser to resonate in the cavity. The output coupling mirror stably outputs fundamental mode continuous laser light in the mid-infrared 2-micron band.

[0037] b. Adjust the pitch angle of the plane mirror in the yoz plane and perform non-collinear pumping. The high-order transverse mode gain is greater and thus selected, while the fundamental transverse mode gain is small and thus suppressed, and an ultrafast vortex ring beam in the mid-infrared micrometer band is obtained in the cavity.

[0038] c. Dynamically adjust and control the position of the five-degree-of-freedom electric translation stage and switch the gain medium from C to C-cut. At this time, the birefringence effect of the C-cut gain medium is utilized to obtain an ultrafast vector ring beam, including radially polarized beams and angularly polarized beams;

[0039] d. Adjust the position of the motorized translation stage, including the distance L between the motorized translation stage and the second plano-concave mirror, and the pitch angle of the plane mirror, to obtain an ultrafast vector vortex ring beam in the mid-infrared 2-micron band.

[0040] e. Through patient optimization algorithms, the electric translation stage is electrically controlled to maximize the optical power, achieve optimal power output, and improve efficiency and effect.

[0041] Preferably, in step e, the measurement of the laser pulse covers multiple dimensions of key parameters: a spot analyzer with an accuracy of ±1% is used to obtain the spot intensity distribution, an autocorrelator with a femtosecond pulse width accuracy of ±0.1fs / picosecond level of ±1ps is used to measure the time domain characteristics of the pulse width range of 10fs-100ps, a frequency-resolved optical gate with a phase accuracy of ±0.01π and FROG is used to monitor the phase characteristics, a frequency counter with an accuracy of ±0.001% is used to verify the repetition frequency of 1kHz-100GHz, and a spectrum analyzer with an accuracy of ±0.1dB is used to evaluate the 10dB-100dB signal-to-noise ratio; the measurement data is fed back to the control system in real time for dynamic optimization of the position of the electric translation stage and the cavity mirror parameters to ensure that the spot pattern purity of the output pulse is greater than 98% and the phase error is less than 0.1π;

[0042] After triggering the soft-aperture Kerr lens mode locking, the output laser pulse has excellent time-domain characteristics, with a pulse width in the range of 90fs-150fs. The spectral width is 30nm-70nm, with a central wavelength of 2000nm, FWHM, monitored by a spectrometer with a resolution of 0.1nm. The phase characteristics of the laser pulse are monitored in real time using a frequency-resolved optical gate (FROG) with an accuracy of 0.01π. When a phase error greater than 0.1π is detected, the control system adjusts the position of the second plano-concave mirror in 0.1μm steps to achieve phase compensation. The repetition frequency of the mode-locked pulse is 78MHz±0.1%, verified by a spectrum analyzer with a resolution of 1Hz. The single pulse energy is 15nJ-20nJ, the optical-to-optical conversion efficiency is greater than 25%, and the damage threshold is greater than 10GW / cm. 2 , to meet the needs of high-power applications; when the pulse width is greater than 150fs, the control system will automatically adjust the second plano-concave mirror to the front edge of the second stable zone at a position of 76.2mm±0.1mm to compress the pulse width to below 143fs.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. High efficiency and stability of light output and power optimization: The asymmetric confocal resonant cavity design and the dynamic matching of the gain medium significantly improve the efficiency and stability of the laser output. Using a high-brightness 793nm laser diode or a 1620nm single-mode fiber laser pump source, combined with a collimating and focusing system of a plano-convex mirror group, the pump light energy conversion efficiency is increased to more than 65%, and the heat loss is reduced by 30%, avoiding the problem of insufficient signal-to-noise ratio caused by wide spectral noise in traditional quasi-continuous light sources. The gain medium uses anisotropic c-cut crystals or isotropic ceramics, and its gain spectrum width covers 1900-2100nm, supporting efficient energy extraction in the 2-micron band. The single-mode continuous output power can reach 10W level, and the beam quality factor (M 2 ) is stable below 1.2, and the long-term power fluctuation is less than ±1%, far exceeding the performance limitations of traditional C+L band light sources.

[0045] In addition, the precise adjustment function of the five-degree-of-freedom electric displacement stage effectively suppresses the mode detuning caused by environmental vibration, ensuring that the power drift within 8 hours of continuous operation is less than 0.5%, and the reliability is significantly better than traditional mechanical tuning solutions.

[0046] 2. Universality of the method: The device is simple, no complicated adjustment device is required, and it is easy to mass produce

[0047] This technical solution breaks through the dependence of traditional multi-dimensional laser production on complex auxiliary devices through an innovative full-cavity control mechanism. Its core lies in the synergistic effect of the anisotropic properties of the gain medium and the adjustment of the spatial parameters of the resonant cavity to directly generate an ultrafast ring beam with specific phase and polarization characteristics. Compared with the traditional solution, this method abandons the intracavity annular aperture, active mode-locking devices (such as SESAM) and extracavity beam shaping devices (including complex optical elements such as spatial light modulators, q-wave plates, cylindrical lenses, etc.). Only by jointly controlling the tangential angle of the gain medium and the spatial position of the cavity mirror, it can achieve synchronous control of high-order vortex mode excitation, vector polarization separation and ultrafast mode locking. This highly integrated design reduces the number of system components by 40%, and the assembly tolerance requirements are relaxed to 1 / 3 of the traditional solution (for example, the optical path collimation angle tolerance is increased from ±0.1° to ±0.5°), which significantly reduces the difficulty of the production process. The key adjustment steps can be achieved through an automated electric translation stage control system, combined with standardized crystal cutting processing (C-cut crystal angle error <0.1°), shortening the equipment production cycle.

[0048] 3. Low cost of the method: The device is simple and uses a precision electric translation stage assembled based on 3D printing technology, which effectively avoids high costs. The entire device system has no additional active modulation devices and is suitable for mid-infrared high-power applications.

[0049] The present invention uses 3D printing technology to build all structures except electronic components, overcoming the problems of traditional electric translation stages such as heavy weight and difficulty in direct reading. At the same time, it has strong plasticity, wide applicability, low cost and easy promotion.

[0050] 4. Diversity of effects: Customized models can be achieved and widely used in scientific research, processing, medical treatment and other fields.

[0051] By precisely adjusting the crystal orientation of the gain medium and the spatial configuration of the resonant cavity mirrors through a motorized translation stage, the system can achieve multi-degree-of-freedom coordinated control of high-order annular light fields, radial polarization, and angular polarization states. The output laser beam not only has the orbital angular momentum characteristics brought by the spiral phase distribution, but also exhibits a unique electromagnetic field configuration of radial / angular vector polarization. Combined with the "donut" spatial characteristics of the annular light intensity distribution, it forms a light field system with the synergistic effect of multi-dimensional physical parameters. This composite control capability not only provides a new dimension of multi-dimensional multiplexing for optical communication systems (theoretical channel capacity is increased by 2 orders of magnitude), but also shows breakthrough application potential in cutting-edge fields such as quantum optical entangled state preparation, ultrafast nonlinear dynamics research, sub-wavelength precision laser micro-nano processing, and selective photothermal therapy of biological tissues. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a structural schematic diagram of the present invention;

[0053] Figure 2 Schematic diagram of the power optimization process;

[0054] Figure 3 This is a flowchart of the patience optimization algorithm operation in Example 2 of the present invention.

[0055] in:

[0056] 1. Laser pump source; 2. First plano-convex mirror; 3. Second plano-convex mirror; 4. First plano-concave mirror; 5. Gain medium; 6. Second plano-concave mirror; 7. Output coupling mirror; 8. Five-degree-of-freedom electric displacement stage. DETAILED DESCRIPTION

[0057] The present invention will be further described below with reference to the accompanying drawings.

[0058] like Figures 1 to 3 As shown, an automatic device for emitting and optimizing the power of a 2-micron solid-state laser comprises:

[0059] A laser pump source 1, used for providing pump light;

[0060] A plano-convex mirror group is arranged at the laser pump source 1 and is used to accurately focus the pump light;

[0061] Gain medium 5, using a C-cut Tm:CYA crystal, is used to receive the pump light focused by the plano-convex mirror group, and the angle between the normal vector of its light-passing plane and the laser propagation direction can be adjusted in the range of 0°-20°;

[0062] The first plano-concave mirror 4 and the second plano-concave mirror 6 are respectively located on both sides of the gain medium 5 to form a confocal resonant cavity for receiving the gain laser generated by the gain medium 5; the first plano-concave mirror 4 is arranged between the plano-convex mirror group and the gain medium 5, and the second plano-concave mirror 6 is slidably arranged on the other side of the gain medium 5;

[0063] Output coupling mirror 7, located at the folding angle of the second plano-concave mirror 6, used to output a small portion of the stable laser in the cavity;

[0064] A five-degree-of-freedom electric displacement stage 8 is slidably arranged at the folding angle of the first plano-concave mirror 4 and is arranged to adjust the xyz displacement and the pitch angle and deflection angle, and is used to receive the laser beam reflected by the first plano-concave mirror 4 and adjust it to reflect back into the cavity;

[0065] The control system monitors the output power and efficiency of the laser pump source 1 in real time, and dynamically adjusts the working parameters in combination with the patient optimization algorithm to achieve automatic optimization. When the output power is lower than expected, the control system automatically adjusts the current or temperature of the laser pump source 1 to increase the power; it automatically adjusts the working mode according to different working conditions to achieve optimal power output.

[0066] The laser pump source 1 utilizes a fiber-coupled semiconductor laser with an output wavelength of 793 nm, a maximum power of 30 W, a fiber core diameter of 105 μm, and a numerical aperture of 0.22 NA. The pump light is collimated and focused by a plano-convex mirror assembly, forming a 60 μm diameter spot on the surface of the gain medium 5. The plano-convex mirror assembly consists of two plano-convex mirrors with a focal length of 100 mm. The second plano-convex mirror 3 is 100 mm away from the pump source, and the two plano-convex mirrors are 50 mm apart, ensuring a collimated and focused pump light accuracy error of less than 2 μm.

[0067] Gain medium 5 utilizes an anisotropic c-cut Tm:CYA crystal with a 6 at.% doping concentration and dimensions of 3mm × 3mm × 6.1mm. Its light-transmitting surface is coated with a 1900-2100nm antireflection coating. The crystal's tilt angle can be adjusted from 0° to 20° using a rotating bracket equipped with an angle encoder with an adjustment resolution of 0.1°. The plane mirror is replaced with a high-precision motorized translation stage control system, consisting of a three-dimensional linear displacement platform (±10mm travel, 0.1μm resolution) and a two-axis rotation platform (±5° angular range, 0.01° resolution). Multi-parameter linkage control is achieved through LabVIEW programming.

[0068] In this embodiment, when the confocal resonant cavity jointly constituted by the first plano-concave mirror 4 and the second plano-concave mirror 6 is an asymmetric confocal resonant cavity, the ratio of the distance d3 between the second plano-concave mirror 6 and the output coupling mirror 7 to the distance d4 between the first plano-concave mirror 4 and the five-degree-of-freedom electric displacement stage 8 is [3, 6): 6; the stable zone of the confocal resonant cavity includes a first stable zone and a second stable zone, and the distance between the two is 2mm-4mm; when the second plano-concave mirror 6 is moved to the front edge of the second stable zone through the electric displacement stage, the threshold power for triggering the soft aperture Kerr lens locking is reduced to 60%-70% of the fundamental mode locking threshold.

[0069] The resonant cavity structure adopts an asymmetric confocal design. The first plano-concave mirror 4 has a curvature radius of 100mm, the second plano-concave mirror 6 has a curvature radius of 150mm, and the two mirrors are separated by 200mm, forming the basic cavity type. The output coupling mirror 7 has a transmittance of 0.5% and is separated from the second plano-concave mirror 6 by 50mm. The plane reflector is separated from the second plano-concave mirror 6 by 75mm. The position of the plane reflector is precisely adjusted using a translation stage. When it deviates from the yoz plane by 2.5°±0.2°, a phase vortex ring beam is formed in the cavity with a topological charge l=±1. At this time, the beam radius at the gain medium 5 is 45μm. Zemax simulation verifies that the mode purity reaches 98.7%.

[0070] Mode locking is achieved through precise control of a motorized translation stage. The motorized translation stage moves the second plano-concave mirror 6 to a position 576.2 mm from the gain medium (the front edge of the second stable region), at which point the output power drops from 1.5 W to 200 mW. The motorized translation stage's rapid perturbation mode (speed > 5 mm / s) triggers the power to surge to 1.2 W within 0.2 seconds, shrinking the spot radius from 45 μm to 31 μm and completing soft-aperture Kerr lens mode locking. The mode-locked pulse parameters are: pulse width 143 ± 5 fs, spectral width 50 nm (central wavelength 2000 nm), repetition rate 78 MHz, single-pulse energy 15 nJ, and FROG measurements show a nonlinear phase distortion of less than 0.1 π.

[0071] The control system includes a multi-dimensional analysis module: a 12GHz bandwidth high-speed oscilloscope and autocorrelator are used to measure time-domain characteristics; a spectrometer records the evolution of the spectrum from 200 to 2400nm; a spectrum analyzer monitors the stability of the repetition frequency (jitter <50fs); a Mach-Zehnder interferometer combined with a cooled infrared CCD analyzes the spot intensity distribution with a spatial resolution of 3.5μm; and a rotatable polarization beam splitter and focusing lens form a polarization detection module with an angular positioning accuracy of 0.5°.

[0072] The system integrates closed-loop feedback control. It collects data from the power meter and beam analyzer in real time through the NIPXIe-8840 controller, combines it with the encoder signal of the motorized displacement stage, and establishes a mode stability prediction model. Experiments show that the success rate of automatic control mode switching has increased from 82% in manual operation to 99.6%, the polarization purity has increased from 92% to 98%, the mode switching time has been shortened from the minute level to the second level, and the power fluctuation of the system during continuous operation for 8 hours is less than 1.5%.

[0073] In this embodiment, the five-degree-of-freedom electric displacement stage 8 has micron-level regulation in six degrees of freedom, with an XYZ travel of ±25 mm and a resolution of 0.25 μm; θx / θy of ±15° and a resolution of 0.001°, integrating the function of a mirror; the laser pump source 1 is a 30W 1620nm single-mode fiber laser.

[0074] In this embodiment, the transmittance of the output coupling mirror 7 is 0.2% - 1%, which is specifically determined according to cavity loss optimization:

[0075] When using a soft-aperture Kerr mode-locking, the transmittance is set to 0.5% - 1% to ensure that the intracavity power density ≥ 10 6 W / cm 2 , triggering a non-linear refractive index change Δn ≥ 1×10 -6 ;

[0076] When operating in the continuous-wave mode, the transmittance is optimized to 0.2% - 0.5% to balance the intracavity gain and output efficiency, achieving an optical-to-optical conversion efficiency > 25%.

[0077] In this embodiment, the plano-convex lens group includes a first plano-convex lens 2 and a second plano-convex lens 3 arranged in sequence along the propagation direction of the pump light; the focal length of the first plano-convex lens 2 is f1, which is used to collimate the pump light output by the laser pump source 1 to reduce the divergence angle of the pump light; the focal length of the second plano-convex lens 3 is f2, and f2 < f1, which is used to focus the collimated pump light by the first plano-convex lens 2 into the gain medium 5, so that a focused spot with a diameter of d is formed in the gain medium 5; among them, the mirror surfaces of the first plano-convex lens 2 and the second plano-convex lens 3 are both coated with an antireflection film for the pump light wavelength, and the transmittance of the antireflection film at the pump light wavelength is not less than 99% to reduce the loss of the pump light at the plano-convex lens group; at the same time, the optical axes of the first plano-convex lens 2 and the second plano-convex lens 3 coincide with the optical axis of the pump light output by the laser pump source 1 to ensure the collimation and focusing effects of the pump light.

[0078] In this embodiment, the motorized translation stage automatically finds light using a gradient descent algorithm and a spiral search algorithm. A spiral search path is generated with the current parameters as the center. The power error ΔP is calculated in each iteration, and the search step size and direction are adjusted according to ΔP until the convergence condition is met. The automatic light finding algorithm adopts a hybrid strategy combining gradient descent and spiral search. The specific steps are as follows:

[0079] a. Parameter initialization: With the current motorized stage position as the center, set the initial search step size δ0 = 5 μm, the angle step size θ0 = 0.1°, the attenuation factor α = 0.8, and the safety margin ±5°;

[0080] b. Spiral path generation: In the polar coordinate system, the displacement increment of the nth iteration is:

[0081] Δx n =δ0·α n-1 ·cos(n·15°);

[0082] Δy n =δ0·α n-1 ·sin(n·15°);

[0083] c. Power error calculation: Real-time measurement of output power P n , calculate the target power P target The difference ΔP=|P n -P target |

[0084] d. Dynamic step size adjustment: If ΔP≤0.1W, the step size is attenuated by δ n =δ n-1 α; if ΔP>0.1W, the step size is restored to δ n =δ n-1 ·1 / α.

[0085] In this embodiment, the gain medium 5 is a disordered crystal of c-cut yttrium garnet (CYA) doped with 4% thulium, the end face of which is coated with a 1900nm-2100nm band anti-reflection film. The crystal size is 3mm×3mm×6.1mm, and the optical axis direction is adjustable at 5°-15° to the laser propagation direction.

[0086] A method for operating an automatic device for emitting and optimizing 2-micron solid-state laser light and power, comprising the following steps:

[0087] a. Arrange the laser pump source 1, the plano-convex mirror group, the first plano-concave mirror 4, the gain medium 5, the second plano-concave mirror 6, the output coupling mirror 7, and the electric translation stage in the xoy plane;

[0088] The pump light output by the laser pump source 1 is collimated and focused onto the C-cut gain medium 5. The positions of the first plano-concave mirror 4, the gain medium 5, the second plano-concave mirror 6 and the electric translation stage are adjusted to make the laser resonate in the cavity. The output coupling mirror 7 stably outputs the fundamental mode continuous laser in the mid-infrared 2 micron band.

[0089] b. Adjust the pitch angle of the plane mirror in the yoz plane and perform non-collinear pumping. The high-order transverse mode gain is greater and thus selected, while the fundamental transverse mode gain is small and thus suppressed, and an ultrafast vortex ring beam in the mid-infrared micrometer band is obtained in the cavity.

[0090] c. Dynamically adjust and control the position of the five-degree-of-freedom electric displacement stage 8 and switch the gain medium 5 from c to c-cut. At this time, the birefringence effect of the c-cut gain medium 5 is used to obtain an ultrafast vector ring beam, including a radially polarized beam and an angularly polarized beam;

[0091] d. Adjust the position of the motorized translation stage: including the distance L between the motorized translation stage and the second plano-concave mirror 6, and the pitch angle of the plane mirror, to obtain an ultrafast vector vortex annular beam in the mid-infrared 2-micron band;

[0092] e. Through patient optimization algorithms, the electric translation stage is electrically controlled to maximize the optical power, achieve optimal power output, and improve efficiency and effect.

[0093] In this embodiment, in step e, the measurement of the laser pulse covers multiple key parameters: a spot analyzer with an accuracy of ±1% is used to obtain the spot intensity distribution, an autocorrelator with a femtosecond pulse width accuracy of ±0.1fs / picosecond level of ±1ps is used to measure the time domain characteristics of the pulse width range of 10fs-100ps, a frequency-resolved optical gate with a phase accuracy of ±0.01π and a FROG is used to monitor the phase characteristics, a frequency counter with an accuracy of ±0.001% is used to verify the repetition frequency of 1kHz-100GHz, and a spectrum analyzer with an accuracy of ±0.1dB is used to evaluate the 10dB-100dB signal-to-noise ratio; the measurement data is fed back to the control system in real time for dynamic optimization of the position of the motorized translation stage and the cavity mirror parameters to ensure that the spot pattern purity of the output pulse is greater than 98% and the phase error is less than 0.1π;

[0094] After triggering the soft-aperture Kerr lens mode locking, the output laser pulse has excellent time-domain characteristics, with a pulse width in the range of 90fs-150fs. The spectral width is 30nm-70nm, with a central wavelength of 2000nm, FWHM, monitored by a spectrometer with a resolution of 0.1nm. The phase characteristics of the laser pulse are monitored in real time using FROG, a frequency-resolved optical gate with an accuracy of 0.01π. When a phase error greater than 0.1π is detected, the control system adjusts the position of the second plano-concave mirror 6 in 0.1μm steps to achieve phase compensation. The repetition frequency of the mode-locked pulse is 78MHz±0.1%, verified by a spectrum analyzer with a resolution of 1Hz. The single pulse energy is 15nJ-20nJ, the optical-to-optical conversion efficiency is greater than 25%, and the damage threshold is greater than 10GW / cm 2 , meeting the needs of high-power applications; when the pulse width is greater than 150fs, the control system will automatically adjust the second plano-concave mirror 6 to the front edge of the second stable zone at a position of 76.2mm±0.1mm to compress the pulse width to below 143fs.

[0095] In terms of special process treatment, the end face of the gain medium 5 adopts ion beam polishing technology (roughness < 0.2nm), combined with anti-damage coating technology (damage threshold > 5GW / cm 2 The cavity mirrors are assembled using a six-dimensional automated alignment platform (accuracy ±0.5μrad), coupled with a He-Ne calibration laser to achieve an optical path alignment error of less than 5μm / m. The temperature control system maintains a constant temperature of 20±0.1°C and humidity of 45±2% RH, ensuring that the crystal thermal lens effect changes by less than 0.05D.

[0096] After 200 hours of continuous testing, the device achieved an output power stability standard deviation of 0.8% and a mode purity decay rate of less than 0.1% per 100 hours, verifying the reliability of the technical solution. By setting a combination of motorized translation stage motion parameters for high-precision control, the device has achieved controllable output of 12 annular beam modes (including four topological charges, three polarization states, and their combinations), providing a flexible light source solution for multi-dimensional optical communication systems.

[0097] The present invention will be further described below in conjunction with embodiment:

[0098] Example 1

[0099] The laser pump source 1 is a commercial fiber-coupled semiconductor laser with an output wavelength of 793 nm, a maximum output power of 30 W, a fiber core diameter of 105 μm, and a fiber numerical aperture of 0.22 NA. It provides pump excitation for the gain medium 55 and generates laser output in the mid-infrared 2 μm band.

[0100] A plano-convex mirror assembly, comprising a first plano-convex mirror 2 and a second plano-convex mirror 3, wherein the focal length is 100 mm, the distance between the second plano-convex mirror 3 and the output end of the laser pump source 1 is 100 mm, and the distance between the second plano-convex mirror 3 and the first plano-convex mirror 2 is 50 mm;

[0101] The gain medium 5 is a thulium-doped anisotropic c-cut yttrium aluminum garnet (CYA) disordered crystal that can be switched to an anisotropic c-cut CYA disordered crystal. Its doping concentration is 4%, and its dimensions are 3 mm × 3 mm × 6.1 mm. The crystal end faces are coated with an antireflection coating for the 1900 nm-2100 nm band. The distance between the gain medium 5 and the second plano-convex mirror 33 is 105 mm. Its main functions are to provide gain to generate laser light in the mid-infrared 2-micron band and to provide intracavity nonlinearity.

[0102] The first plano-concave mirror 4 and the second plano-concave mirror 6 have a curvature radius of 100 mm and a size of 1 inch. The mirror surface is coated with an optical film that is highly reflective in the 1900nm-2100nm band and highly transparent in the 780nm-980nm band.

[0103] The first plano-concave mirror 44 is located on the left side of the gain medium 5, with a distance of 50 mm between them. The second plano-concave mirror 6 is located on the right side of the gain medium 5, with a distance of 50 mm between them. The folding angles of the first plano-concave mirror 4 and the second plano-concave mirror 6 are both less than 8°. The plano-concave mirror group forms a confocal cavity, which allows the laser to resonate stably in the resonant cavity.

[0104] Five-degree-of-freedom electric translation stage 8, motion dimensions: X / Y / Z linear + θx / θy / θz angle;

[0105] Travel range: linear axis: ±25mm, angular axis: ±15°;

[0106] Resolution: linear axis: 1nm (closed loop), angular axis: 0.001°;

[0107] Repeat positioning accuracy: linear axis: ±0.05μm, angular axis: ±0.0005°;

[0108] Load capacity: 500g;

[0109] Trajectory control: supports linear / circular interpolation, with runout ≤5μm;

[0110] The output coupling mirror 7 is a 1-inch plane mirror coated with a highly reflective optical film in the 1900nm-2100nm band. It has a transmittance of 2% and is 398mm away from the second plano-concave mirror 6. Its main function is to output a small portion of the laser light in the resonant cavity.

[0111] The positions and folding angles of each cavity mirror meet the conditions for stable laser resonance. A commercial fiber-coupled laser diode is used as the pump source to pump a thulium-doped anisotropic c-cut CYA disordered crystal, thereby generating laser output in the mid-infrared 2-micron band. The five-degree-of-freedom electric displacement stage 8 is used to adjust the XYZ angles with high precision to achieve the output of different vortex lasers. The second plano-concave mirror 6 is then adjusted by the five-degree-of-freedom electric displacement stage 8 to quickly perturb the output coupling mirror 7, achieving soft-aperture Kerr lens mode locking of the vortex light, thereby realizing the direct output of the ultrafast vortex beam.

[0112] like Figure 1 As shown, the laser pump source 1 uses a high-power fiber-coupled laser diode with a wavelength of 793 nm. The pump light emitted by it passes through the first lens and the second lens in sequence, and is collimated and focused in the gain medium 5. The pump spot radius is 30 μm.

[0113] The gain medium 5 absorbs the 793nm pump light, achieving population inversion. The stimulated radiated photons resonate back and forth in the laser cavity, ultimately forming a stable resonance in the first plano-concave mirror 4, the gain medium 5, the second plano-concave mirror 6, the five-degree-of-freedom electric displacement stage 8, and the output coupling mirror 7. Continuous laser light in the mid-infrared 2-micron band is then output from the output coupling mirror 7.

[0114] The vortex beam generation is achieved by step-by-step control of the angle and resonant cavity parameters through the five-degree-of-freedom electric displacement stage 8: at low pump power (15-20W), spatial non-collinear pumping (oblique incidence angle 2°) is formed through three-dimensional angle adjustment (horizontally 1°, vertically 1°), and a first-order vortex beam with a ring radius of 40μm is generated in the gain medium 5 (thulium-doped YAG ceramic); when the pump power is increased to 50-60W, the second plano-concave mirror 6 (R2=50mm) is moved outward by 300μm to the critical position of the second stable zone (g1g2=0.98), and the first-order vortex beam with a ring radius of 40μm is generated in the gain medium 5 (thulium-doped YAG ceramic). 8±5° pulse perturbation of the translation stage or micro-displacement of the output coupling mirror by 7° triggers soft-aperture Kerr lens mode locking, abruptly reducing the spot radius to 20μm, achieving a mode-locked pulse output with a central wavelength of 2000nm, a spectral width of 34nm, and a pulse width of 96fs. Further increasing the angle control (horizontally by 2° and vertically by 3°) induces a second-order vortex beam (ring radius of 45μm). Repeating the aforementioned cavity length adjustment (ΔL = +350μm, g1g2 = 0.97) and perturbation excitation, the spot radius is compressed to 25μm, resulting in a second-order mode-locked pulse with a spectral width of 70.4nm. This method selectively excites high-order transverse modes through non-collinear pumping, combined with stable region boundary mode locking, to directly generate an ultrafast ring beam carrying orbital angular momentum within the cavity.

[0115] Example 2

[0116] Hardware composition Laser power sensor: used to monitor the laser output power in real time with an accuracy of ±0.1W. Control execution unit: including pump current regulator, cavity mirror angle adjustment device, etc., with a response time of <50ms. Data processing module: equipped with a processor with patient optimization algorithm to realize power data calculation and optimization instruction output. Software architecture algorithm layer: integrated with the core logic of the patient optimization algorithm, based on formula N n+1 、P n Variables such as , etc. are used to implement iterative judgment.

[0117] Patience optimization algorithm implementation steps:

[0118] Set initial parameters: P n_max =c initial maximum power threshold), N n_max = 4 (number of patience window iterations);

[0119] Initialize counter N n =0, power iteration value P n =0;

[0120] Power monitoring: Get laser power P in real time n+1 .

[0121] P n Update: If P n+1 <P n , execute P n =P n-1 +1; if P n+1 >P n , reset P n =0.

[0122] Judgment and Update: When P n <P n-max , counter N n+1 =N n +1; when P n >P n_max , the counter is reset N n+1 =0.

[0123] Trigger cutoff condition: When N n <N n_max , which is considered as the power optimum.

[0124] The power optimization time is 27 seconds (taking mechanical movement into account).

[0125] Automatic optimization is achieved by real-time monitoring of laser output power and efficiency, combined with a patient optimization algorithm to dynamically adjust operating parameters. When output power falls below expectations, the system automatically adjusts the pump source current or temperature to increase power. It also automatically adjusts operating modes based on different operating conditions to achieve optimal power output, improving efficiency and effectiveness.

Claims

1. An automatic device for 2-micron solid-state laser light emission and power optimization, characterized in that: include: A laser pump source (1) for providing pump light; A plano-convex mirror assembly is arranged at the laser pump source (1) and is used for precisely focusing the pump light; The gain medium (5) is a C-cut Tm:CYA crystal, which is used to receive the pump light focused by the plano-convex mirror group, and the angle between the normal vector of the light-passing plane and the laser propagation direction can be adjusted in the range of 0°-20°; A first plano-concave mirror (4) and a second plano-concave mirror (6) are respectively located on both sides of a gain medium (5) and together constitute a confocal resonant cavity for receiving a gain laser generated by the gain medium (5); the first plano-concave mirror (4) is arranged between the plano-convex mirror group and the gain medium (5), and the second plano-concave mirror (6) is slidably arranged on the other side of the gain medium (5); An output coupling mirror (7), located at the folding angle of the second plano-concave mirror (6), and used for outputting a small portion of the stable laser light in the cavity; A five-degree-of-freedom electric displacement stage (8) is slidably arranged at the folding angle of the first plano-concave mirror (4) and performs xyz displacement adjustment and pitch angle and deflection angle adjustment, and is used for receiving the laser beam reflected by the first plano-concave mirror (4) and adjusting and reflecting it back into the cavity; The control system monitors the output power and efficiency of the laser pump source (1) in real time, dynamically adjusts the working parameters in combination with the patient optimization algorithm, and realizes automatic optimization. When the output power is lower than expected, the control system automatically adjusts the current or temperature of the laser pump source (1) to increase the power; and automatically adjusts the working mode according to different working conditions to achieve the best power output.

2. The automatic device for 2-micron solid-state laser light emission and power optimization according to claim 1, characterized in that: When the confocal resonant cavity formed by the first concave mirror (4) and the second concave mirror (6) is an asymmetric confocal resonant cavity, the ratio of the distance d3 between the second concave mirror (6) and the output coupling mirror (7) to the distance d4 between the first concave mirror (4) and the five-degree-of-freedom electric displacement stage (8) is [3, 6): 6; the stable zone of the confocal resonant cavity includes a first stable zone and a second stable zone, and the distance between the two is 2 mm to 4 mm; when the second concave mirror (6) is moved to the front edge of the second stable zone through the electric displacement stage, the threshold power for triggering the soft aperture Kerr lens mode locking is reduced to 60% to 70% of the fundamental mode mode locking threshold.

3. The automatic device for emitting and optimizing 2-micron solid-state laser light as claimed in claim 1, characterized in that: The five-degree-of-freedom electric displacement stage (8) has micron-level control in six degrees of freedom, XYZ travel ±25mm, resolution 0.25μm; θx / θy ±15°, resolution 0.001°, and integrated reflector function; the laser pump source (1) is a 1620nm single-mode fiber laser with a power of 30W.

4. The automatic device for 2-micron solid-state laser light emission and power optimization according to claim 1, characterized in that: The transmittance of the output coupling mirror (7) is 0.2%-1%, which is specifically determined according to the cavity loss optimization: When soft aperture Kerr mode locking is used, the transmittance is set to 0.5%-1% to ensure that the intracavity power density is ≥10 6 W / cm 2 , triggering a nonlinear refractive index change Δn ≥ 1×10 -6 ; When operating in continuous wave mode, the transmittance is optimized to 0.2%-0.5%, balancing the intracavity gain and output efficiency to achieve a light-to-light conversion efficiency greater than 25%.

5. The automatic device for emitting and optimizing 2-micron solid-state laser light as claimed in claim 1, characterized in that: The plano-convex lens group includes a first plano-convex lens (2) and a second plano-convex lens (3) arranged in sequence along the propagation direction of the pump light; the focal length of the first plano-convex lens (2) is f1, which is used to collimate the pump light output by the laser pump source (1) to reduce the divergence angle of the pump light; the focal length of the second plano-convex lens (3) is f2, and f2 < f1, which is used to focus the pump light collimated by the first plano-convex lens (2) into the gain medium (5) so that a focused light spot with a diameter of d is formed in the gain medium (5); wherein, the mirror surfaces of the first plano-convex lens (2) and the second plano-convex lens (3) are both coated with an antireflection film for the wavelength of the pump light, and the transmittance of the antireflection film at the wavelength of the pump light is not less than 99% to reduce the loss of the pump light at the plano-convex lens group; at the same time, the optical axes of the first plano-convex lens (2) and the second plano-convex lens (3) coincide with the optical axis of the pump light output by the laser pump source (1) to ensure the collimation and focusing effects of the pump light.

6. The automatic device for emitting and optimizing 2-micron solid-state laser light as claimed in claim 1, characterized in that: The electric displacement stage performs automatic light search through a gradient descent algorithm and a spiral search algorithm, generates a spiral search path centered on the current parameters, calculates the power error ΔP in each iteration, and adjusts the search step size and direction according to ΔP until the convergence condition is met; the automatic light search algorithm adopts a hybrid strategy combining gradient descent and spiral search, and the specific steps are as follows: a. Parameter initialization: Centered on the current position of the electric displacement stage, set the initial search step size δ0 = 5μm, the angular step size θ0 = 0.1°, the attenuation factor α = 0.8, and the safety boundary ±5°. b. Spiral path generation: In the polar coordinate system, the displacement increment in the nth iteration is: Δx n =δ0·a n-1 ·cos(n·15°); Δy n =δ0·a n-1 ·sin(n·15°); c. Power error calculation: Real-time measurement of output power P n , calculate the target power P target The difference ΔP=|P n -P target | d. Dynamic step size adjustment: If ΔP≤0.1W, the step size is attenuated by δ n =δ n-1 α; if ΔP>0.1W, the step size is restored to δ n =δ n-1 ·1 / α.

7. The automatic device for emitting and optimizing 2-micron solid-state laser light as claimed in claim 1, characterized in that: The implementation steps of the patience optimization algorithm include: Set initial parameters: P n_max =c, initial maximum power threshold; N n_max =4, number of patience window iterations; Initialize counter: N n =0, power iteration value: P n =0; Power monitoring: Get laser power P in real time n+1 ; P n Update: If P n+1 <P n , execute P n =P n-1 +1; if P n+1 >P n , reset P n =0; Judgment and Update: When P n <P n-max , counter N n+1 =N n +1; when P n >P n_max , the counter is reset N n+1 =0; Trigger cutoff condition: When N n =N n_max , which is considered as the power optimum.

8. The automatic device for emitting and optimizing 2-micron solid-state laser light as claimed in claim 1, characterized in that: The gain medium (5) is a disordered crystal of c-cut yttrium garnet (CYA) doped with 4% thulium. Its end faces are coated with an antireflection film in the 1900nm - 2100nm band. The crystal size is 3mm × 3mm × 6.1mm, and the optical axis direction is adjustable at 5° - 15° with respect to the laser propagation direction.

9. A method for operating an automatic device for 2-micron solid-state laser light emission and power optimization, characterized in that: It includes the following steps: a. Arrange the laser pump source (1), the plano-convex lens group, the first plano-concave lens (4), the gain medium (5), the second plano-concave lens (6), the output coupling mirror (7), and the electric displacement stage in the x-o-y plane; Make the pump light output by the laser pump source (1) pass through collimation and focus on the c-cut gain medium (5), and adjust the positions of the first plano-concave lens (4), the gain medium (5), the second plano-concave lens (6), and the electric displacement stage to make the laser resonate in the cavity, and the output coupling mirror (7) stably outputs a fundamental mode continuous laser in the mid-infrared 2-micron band; b. Adjust the pitch angle of the plane mirror in the y-o-z plane to perform non-collinear pumping, select the higher-order transverse mode with a larger gain and suppress the fundamental-order transverse mode with a smaller gain, and obtain an ultrafast vortex ring beam in the mid-infrared micron band in the cavity; c. Dynamically adjust and control the position of the five-degree-of-freedom electric displacement stage (8), and switch the gain medium (5) from c to c-cut. At this time, utilize the birefringence effect of the c-cut gain medium (5) to obtain an ultrafast vector ring beam, including a radially polarized beam and an azimuthally polarized beam; d. Adjusting the position of the electric translation stage: including the distance L between the electric translation stage and the second plano-concave mirror (6), and the pitch angle of the plane mirror to obtain an ultrafast vector vortex annular beam in the mid-infrared 2-micron band; e. Through patient optimization algorithms, the electric translation stage is electrically controlled to maximize the optical power, achieve optimal power output, and improve efficiency and effect.

10. The method for operating the automatic device for emitting and optimizing the power of a 2-micron solid-state laser according to claim 9, characterized in that: In step e, the measurement of laser pulses covers multiple critical parameters: a spot analyzer with an accuracy of ±1% is used to obtain the spot intensity distribution, an autocorrelator with a pulse width accuracy of ±0.1fs at the femtosecond level and ±1ps at the picosecond level is used to measure the time domain characteristics of the pulse width range of 10fs-100ps, a frequency-resolved optical gate with a phase accuracy of ±0.01π and a FROG is used to monitor the phase characteristics, a frequency counter with an accuracy of ±0.001% is used to verify the repetition frequency of 1kHz-100GHz, and a spectrum analyzer with an accuracy of ±0.1dB is used to evaluate the 10dB-100dB signal-to-noise ratio. The measurement data is fed back to the control system in real time to dynamically optimize the position of the motorized translation stage and the cavity mirror parameters to ensure that the spot pattern purity of the output pulse is greater than 98% and the phase error is less than 0.1π. After the soft aperture Kerr lens mode locking is triggered, the output laser pulse has excellent time domain characteristics, and its pulse width is in the range of 90fs-150fs; the spectral width is 30nm-70nm, the central wavelength is 2000nm, FWHM, and is monitored by a spectrometer with a resolution of 0.1nm; the phase characteristics of the laser pulse are monitored in real time using FROG, a frequency-resolved optical gate with an accuracy of 0.01π. When the phase error is detected to be greater than 0.1π, the control system adjusts the position of the second plano-concave mirror (6) with an adjustment step of 0.1μm to achieve phase compensation; the repetition frequency of the mode-locked pulse is 78MHz±0.1%, which is verified by a spectrum analyzer with a resolution of 1Hz; the single pulse energy is 15nJ-20nJ, the optical-to-optical conversion efficiency is greater than 25%, and the damage threshold is greater than 10GW / cm 2 , to meet the needs of high power applications; When the pulse width is greater than 150 fs, the control system will automatically adjust the second plano-concave mirror (6) to the front edge of the second stable zone at a position of 76.2 mm ± 0.1 mm to compress the pulse width to below 143 fs.

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