High-power multimode fiber laser amplifier based on wavefront shaping

Abstract

The invention provides a high-power multimode fiber laser amplifier based on wavefront shaping. The high-power multimode fiber laser amplifier comprises a seed light wavefront control unit, a multimode gain fiber amplification unit and an output light spot detection and feedback unit, the seed light wavefront control unit is used for carrying out wavefront modulation on the seed light output by the polarization seed laser by using a spatial light modulator loaded with a phase diagram; the multimode gain optical fiber amplification unit is used for performing power amplification on the seed light which is output by the seed light wavefront control system and is subjected to output wavefront modulation; and the output light spot detection and feedback unit is used for outputting the laser of most power of the multimode gain fiber amplification system, collecting the rest laser of a small part of power for far-field light spot information detection, calculating the corresponding far-field barrel medium power based on the detected far-field light spot information, and outputting the far-field barrel medium power. And the power in the far-field barrel is used as an evaluation function to operate an optimization algorithm to generate an optimal phase diagram, and the optimal phase diagram is loaded on the spatial light modulator to realize closed-loop feedback control.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber lasers, and in particular relates to a high-power multi-mode optical fiber laser amplifier based on wavefront shaping. Background Art

[0002] High-power fiber laser amplifiers have a wide range of application needs in advanced manufacturing, national defense and military industries. The key challenges of high-power fiber amplifiers are nonlinear optical effects and transverse mode instability effects. In order to maintain good beam quality, the current technology for suppressing nonlinear and transverse mode instability effects is basically limited to the use of single-mode or few-mode gain fibers, including bent fibers, partially gain-doped fibers, specially designed refractive index profile fibers, 3C fibers, etc. The main idea is to suppress the transmission in high-order mode fibers by increasing high-order mode loss or reducing high-order mode gain, so as to achieve laser transmission and amplification in the fundamental mode in few-mode fibers with large mode field areas. Multimode gain fibers have more modes and larger mode field areas. Larger mode field areas can significantly increase the threshold of nonlinear effects. At the same time, recent theoretical studies have shown that exciting multiple transverse modes in highly multimode fibers, multi-transverse mode transmission and amplification can increase the threshold of transverse mode modulation instability and stimulated Brillouin scattering by at least one order of magnitude, which makes it a promising development direction for high-power fiber laser amplifiers in the future. However, due to the random coupling between transverse modes and inter-mode interference in multimode fibers, the multimode laser transmission and amplification process becomes complicated, and the output laser beam quality is poor. Therefore, it is challenging to achieve high-power and high-beam-quality amplification of fiber lasers using multimode optical fibers, which has become a problem faced by high-power fiber lasers.

[0003] Using a gain fiber with a small numerical aperture to limit the excitation of high-order modes and designing the fiber structure to increase the loss of high-order modes can both suppress the generation of high-order modes and ensure the amplification and output of high-quality laser spots. However, these two methods have high requirements for the design and drawing process of the optical fiber, which reduces the universality and economy of the system. In addition, a large number of current research results show that these methods are difficult to increase the output power of single-fiber high-beam quality fiber lasers by an order of magnitude. The scattered light focusing technology based on wavefront shaping provides a way to solve the above problems.

[0004] At present, the main optical focusing technologies based on wavefront shaping include the transmission matrix method, the optical phase conjugation method and the feedback iterative optimization method. The transmission matrix method provides a theoretical tool for studying the light transmission and focusing mechanism in scattering media, but the increase in the order of the transmission matrix leads to an exponential increase in the number of measurements, which requires a lot of measurement time. The phase conjugation method requires precise phase measurement and has high requirements for system stability. The feedback iterative optimization method can adapt to complex optimization scenarios and dynamic scattering media, has strong resistance to environmental interference, and can adapt to different shaping requirements through different optimization algorithms and feedback signals. Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a high-power multi-mode fiber laser amplifier based on wavefront shaping.

[0006] In order to achieve the above technical objectives, the specific technical solutions adopted by the present invention are as follows: The present invention provides a high-power multimode fiber laser amplifier based on wavefront shaping, comprising a seed light wavefront control unit, a multimode gain fiber amplification unit, and an output light spot detection and feedback unit; The seed light wavefront control unit comprises a polarization seed laser and a spatial light modulator, and uses the spatial light modulator loaded with a phase diagram to perform wavefront modulation on the seed light output by the polarization seed laser, and outputs the seed light after wavefront modulation; The multi-mode gain fiber amplification unit is used to amplify the power of the seed light after the output wavefront modulation output by the seed light wavefront control system; The output light spot detection and feedback unit is used to output most of the laser power of the multi-mode gain fiber amplification system, and at the same time collect the remaining small part of the laser power for far-field light spot information detection, calculate the corresponding far-field bucket power based on the detected far-field light spot information, and use the far-field bucket power as an evaluation function to run an optimization algorithm to generate an optimal phase diagram, and load it on the spatial light modulator to achieve closed-loop feedback control.

[0007] Further, the seed light wavefront control unit includes a seed laser, a spatial light modulator, a third lens, a polarization beam splitter, a first reflector, a second reflector, a dichroic mirror, and a fourth lens; The seed light output by the polarization seed laser is incident on the polarization beam splitter through the third lens. The seed light output by the polarization beam splitter is incident on the spatial light modulator after adjusting the optical path through the first reflector. The seed light after wavefront modulation output by the spatial light modulator is incident on the dichroic mirror after adjusting the optical path through the second reflector. The seed light after forward residual light is filtered out by the dichroic mirror is coupled into the multi-mode gain fiber amplification system through the fourth lens.

[0008] Furthermore, the multimode gain fiber amplification unit comprises a multimode passive fiber, a multimode gain fiber, a pump signal combiner, and a pump source; each pump source is connected to a pump arm of the pump signal combiner, and the pump light output by the pump source enters the multimode gain fiber through the pump signal combiner; The seed light output by the seed light wavefront control unit is coupled into the multimode passive optical fiber, the seed light enters the multimode gain optical fiber through the multimode passive optical fiber to achieve power amplification, and the pump signal combiner outputs the laser after power amplification.

[0009] Furthermore, the output light spot detection and feedback unit includes a first lens, a second lens, an adjustable attenuator, a large fraction beam splitter, an optical power meter, a camera, an adjustable aperture, and a computer; The laser output by the multi-mode gain fiber amplifier unit is incident on the first lens, and the output light beam of the first lens passes through the adjustable aperture and is incident on the large fraction beam splitter, which splits the incident light into two parts, wherein the large fraction beam splitter outputs most of the power beam of the incident light as the amplifier output beam, and the power of the output beam is measured by an optical power meter; the remaining small part of the power laser is output to the adjustable attenuator, and after further power attenuation by the adjustable attenuator, it is incident on the camera through the second lens for far-field light spot information detection, and the camera transmits the detected far-field light spot information to the computer to realize closed-loop feedback control.

[0010] Furthermore, the first lens and the second lens have different focal lengths, so that the light beam forms an equally-proportionally magnified intensity distribution of the optical fiber output end face on the camera.

[0011] Furthermore, the closed-loop feedback control implementation specifically includes: S1, turning on the polarization seed laser and the pump source to make the high-power multimode fiber laser amplifier based on wavefront shaping at the target output power; S2, the computer randomly generates multiple phase images as all individuals in the first generation of the optimization algorithm; S3, the spatial light modulator sequentially loads the phase map corresponding to each individual of the current generation, uses the camera to detect the far-field spot information corresponding to each phase map, calculates the far-field bucket power corresponding to each phase map based on each far-field spot information, uses the far-field bucket power as an evaluation function, and finds the best evaluation function among all individuals of the current generation; S4, evaluate whether the best evaluation function among all individuals in the current generation meets the evaluation criteria, if the best evaluation function among all individuals in the current generation meets the evaluation criteria, then go to S6, if the best evaluation function among all individuals in the current generation does not meet the evaluation criteria, then go to S5; S5, select the phase diagrams corresponding to some individuals from all individuals of the current generation, perform interleaving and mutation, and use them as the phase diagrams corresponding to the new generation of individuals, and go to S3; S6. The computer loads the phase map corresponding to the optimal evaluation function into the spatial light modulator.

[0012] Furthermore, the optimization algorithm includes a genetic algorithm, a simulated annealing algorithm, a particle swarm optimization algorithm, and an ant colony algorithm.

[0013] Furthermore, in S3, the best evaluation function among all individuals in the current generation is found, including: The evaluation functions of all individuals in the current generation are sorted by size, and the largest evaluation function among the evaluation functions of all individuals in the current generation is selected as the best evaluation function among all individuals in the current generation.

[0014] Further, in S4, whether the best evaluation function among all individuals in the current generation meets the evaluation criteria is evaluated, and the method includes: Set the evaluation function reference value; The best evaluation function among all individuals in the current generation is compared with the evaluation function reference value. If the best evaluation function among all individuals in the current generation is higher than the evaluation function reference value, it is determined that the evaluation criteria are met; if the best evaluation function among all individuals in the current generation is lower than the evaluation function reference value, it is determined that the evaluation criteria are not met.

[0015] Furthermore, in S5, the method of selecting phase diagrams corresponding to some individuals from all individuals of the current generation includes: The evaluation functions of all individuals in the current generation are sorted by size, and the evaluation functions ranked in the top a% of the evaluation functions of all individuals in the current generation are selected. The phase maps corresponding to the top a% of the evaluation functions are used as the phase maps corresponding to some individuals; the value range of a% is 20%~50%.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The high-power multimode fiber laser amplifier based on wavefront shaping provided by the present invention allows high-order modes to be transmitted and amplified in the gain fiber. Under the premise of ensuring laser amplification efficiency and high output power, the wavefront shaping technology is used to regulate the output light field of the multimode fiber, thereby significantly improving the beam quality of the output high-power laser and solving the problem of limited output power of high-quality beam fiber laser.

[0017] The present invention has a simple structure. The camera and the spatial light modulator are connected by a computer to form a closed-loop control, and the camera is kept running continuously, so that it continuously monitors the far-field spot information and the corresponding evaluation function is calculated by the computer, and the optimization algorithm is automatically started for optimization when the evaluation function is lower than the set value; and the present invention uses the power in the far-field bucket as the evaluation function, so that the present invention can accurately evaluate the quality of the light beam with background interference. Therefore, the present invention can adapt to complex dynamic environments and has strong anti-environmental interference capabilities; moreover, the present invention can adapt to different needs through different optimization algorithms, feedback methods and evaluation functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of a high-power multimode fiber laser amplifier based on wavefront shaping provided by an embodiment; Figure 2 A schematic diagram of a closed-loop feedback control process provided by an embodiment.

[0020] Figure annotation: 1. Polarization seed laser; 2. Third lens; 3. Polarization beam splitter; 401. First reflector; 402. Second reflector; 5. Dichroic mirror; 6. Fourth lens; 7. 48 / 400 multimode passive fiber; 8. 48 / 400 multimode gain fiber; 9. Pump signal combiner; 10. Semiconductor laser pump source; 11. First lens; 12. Adjustable attenuator; 13. Large fraction beam splitter; 14. Optical power meter; 15. Second lens; 16. Camera; 17. Computer; 18. Spatial light modulator; 19. Adjustable aperture. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Reference Figure 1 , In one embodiment, a high-power multimode fiber laser amplifier based on wavefront shaping is provided, including a seed light wavefront control unit, a multimode gain fiber amplification unit, an output light spot detection and feedback unit; The seed light wavefront control unit uses a spatial light modulator loaded with a phase diagram to perform wavefront modulation on the seed light output by the polarization seed laser, and outputs the seed light after wavefront modulation, including a polarization seed laser 1, a spatial light modulator 18, a third lens 2, a polarization beam splitter 3, a first reflector 401, a second reflector 402, a dichroic mirror 5, and a fourth lens 6; The polarized seed laser 1 outputs seed light which is incident on the polarization beam splitter 3 through the third lens 2. The seed light output from the polarization beam splitter 3 is incident on the spatial light modulator 18 after adjusting the optical path through the first reflector 401. The seed light after wavefront modulation output from the spatial light modulator 18 is incident on the dichroic mirror 5 after adjusting the optical path through the second reflector 402. The seed light after forward residual light is filtered out from the dichroic mirror 5 is coupled into the multimode passive optical fiber 7 through the fourth lens 6. The multimode gain fiber amplifier unit is used to power amplify the seed light after the output wavefront modulation output by the seed light wavefront control system, and comprises a multimode passive fiber 7, a multimode gain fiber 8, a pump signal combiner 9, and a pump source 10; each pump source 10 is connected to the pump arm of the pump signal combiner 9, and the pump light output by the pump source 10 enters the multimode gain fiber 8 through the pump signal combiner 9; The seed light output by the seed light wavefront control unit is coupled into the multimode passive optical fiber 7, and the seed light enters the multimode gain optical fiber 8 through the multimode passive optical fiber 7 to achieve power amplification, and the pump signal combiner 9 outputs the laser after power amplification.

[0023] The output light spot detection and feedback unit is used to output the laser of most of the power of the multi-mode gain fiber amplification system, and collect the remaining small part of the power of the laser for far-field light spot information detection, calculate the corresponding far-field bucket power based on the detected far-field light spot information, and use the far-field bucket power as an evaluation function to run the optimization algorithm to generate an optimal phase diagram, and load it on the spatial light modulator to realize closed-loop feedback control, including a first lens 11, a second lens 15, an adjustable attenuator 12, a large fractional beam splitter 13, an optical power meter 14, a camera 16, an adjustable aperture 19, and a computer 17; The laser output by the multi-mode gain fiber amplifier unit is incident on the first lens 11, and the output light beam of the first lens 11 passes through the adjustable aperture 19 and is incident on the large fraction beam splitter 13, and the large fraction beam splitter 13 divides the incident light into two parts, wherein the large fraction beam splitter 13 outputs most of the power beam of the incident light as the amplifier output beam, and the power of the output beam is measured by the optical power meter 14; the remaining small part of the power laser is output to the adjustable attenuator 12, and after further power attenuation by the adjustable attenuator 12, it is incident on the camera 16 through the second lens 15 for far-field spot information detection, and the camera 16 transmits the detected far-field spot information to the computer 17 to realize closed-loop feedback control.

[0024] The multimode passive optical fiber and the multimode gain optical fiber are both optical fibers whose core supports more than 10 modes.

[0025] In this embodiment, the polarization seed laser 1 is a linearly polarized single-mode laser with a line width of 0.1 nm; the multimode passive optical fiber 7 is a 48 / 400 multimode passive optical fiber; the multimode gain optical fiber 8 is a 48 / 400 multimode gain optical fiber; and the camera 16 is a near-infrared camera.

[0026] The first lens 11 and the second lens 15 have different focal lengths, so that the light beam forms an equally-proportionally magnified intensity distribution of the optical fiber output end face on the camera.

[0027] The optimization algorithms include genetic algorithm, simulated annealing algorithm, particle swarm optimization algorithm and ant colony algorithm.

[0028] Reference Figure 2 In one embodiment, the closed-loop feedback control implementation specifically includes: S1, turning on the polarization seed laser and the pump source to make the high-power multimode fiber laser amplifier based on wavefront shaping at the target output power; S2, the computer randomly generates multiple phase images as all individuals in the first generation of the optimization algorithm; S3, the spatial light modulator sequentially loads the phase map corresponding to each individual of the current generation, uses the camera to detect the far-field spot information corresponding to each phase map, calculates the far-field bucket power corresponding to each phase map based on each far-field spot information, uses the far-field bucket power as an evaluation function, and finds the best evaluation function among all individuals of the current generation; S4, evaluate whether the best evaluation function among all individuals in the current generation meets the evaluation criteria, if the best evaluation function among all individuals in the current generation meets the evaluation criteria, then go to S6, if the best evaluation function among all individuals in the current generation does not meet the evaluation criteria, then go to S5; S5, select the phase diagrams corresponding to some individuals from all individuals of the current generation, perform interleaving and mutation, and use them as the phase diagrams corresponding to the new generation of individuals, and go to S3; S6. The computer loads the phase map corresponding to the optimal evaluation function into the spatial light modulator.

[0029] In this embodiment, the optimization algorithm adopts a genetic algorithm.

[0030] In S3, the best evaluation function among all individuals in the current generation is found, including: The evaluation functions of all individuals in the current generation are sorted by size, and the largest evaluation function among the evaluation functions of all individuals in the current generation is selected as the best evaluation function among all individuals in the current generation.

[0031] In S4, whether the best evaluation function among all individuals in the current generation meets the evaluation criteria is evaluated, and the method includes: Set the evaluation function reference value; The best evaluation function among all individuals in the current generation is compared with the evaluation function reference value. If the best evaluation function among all individuals in the current generation is higher than the evaluation function reference value, it is determined that the evaluation criteria are met; if the best evaluation function among all individuals in the current generation is lower than the evaluation function reference value, it is determined that the evaluation criteria are not met.

[0032] In S5, the method of selecting phase diagrams corresponding to some individuals from all individuals of the current generation includes: The evaluation functions of all individuals in the current generation are sorted by size, and the evaluation functions ranked in the top a% of the evaluation functions of all individuals in the current generation are selected. The phase maps corresponding to the top a% of the evaluation functions are used as the phase maps corresponding to some individuals; the value range of a% is 20%~50%.

[0033] Since the optomechanical components in the seed light wavefront control system may drift over time, the camera is always in working condition during the operation of the high-power multimode fiber laser amplifier based on wavefront shaping. After the initial optimization is completed and the optimal phase diagram is found, it is also necessary to monitor the evaluation function at certain time intervals; when the evaluation function is lower than the optimal value by a certain proportion due to external disturbances, the optimization algorithm is restarted for optimization; at this time, the genetic algorithm mutation probability is small, the spot is relatively stable during the phase diagram iteration process, and the high-power multimode fiber laser amplifier based on wavefront shaping can be continuously in use.

[0034] A person skilled in the art can select a method for calculating the power in the far-field barrel based on the prior art. It is not general. The present invention calculates the power in the far-field barrel corresponding to each phase diagram based on the information of each far-field light spot. The power in the far-field barrel corresponding to each phase diagram can be calculated using the detected far-field light spot information and the pre-calibrated barrel diameter, wherein the barrel diameter is obtained by calibration, and the specific calibration method is not limited.

[0035] In one embodiment, a calibration method for a far-field barrel power mid-barrel diameter of a high-power multimode fiber laser amplifier based on wavefront shaping as an evaluation function is as follows: Turning on the polarization seed laser 1 and the pump source 10 to make the high-power multimode fiber laser amplifier based on wavefront shaping at a lower output power; Align the center of the variable iris 19 to the center of the output beam, and continue to reduce the variable iris 19 until the power reading of the optical power meter 14 drops to 98.5% of the maximum power. Record the aperture diameter of the adjustable iris 19 at this time as the near-field diameter of the beam. D ; According to the focal length of the second lens 15 f And the measured near-field beam diameter D , calculate the corresponding diffraction-limited spot diameter according to the following formula D m ,

[0036] in, is the wavelength of the light beam; Diffraction-limited spot diameter D m The barrel diameter as a function of the power in the far-field barrel.

[0037] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0038] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-power multimode fiber laser amplifier based on wavefront shaping, characterized in that: It includes a seed light wavefront control unit, a multi-mode gain fiber amplification unit, and an output light spot detection and feedback unit; The seed light wavefront control unit comprises a polarization seed laser and a spatial light modulator, and uses the spatial light modulator loaded with a phase diagram to perform wavefront modulation on the seed light output by the polarization seed laser, and outputs the seed light after wavefront modulation; The multi-mode gain fiber amplification unit is used to amplify the power of the seed light after the output wavefront modulation output by the seed light wavefront control system; The output light spot detection and feedback unit is used to output most of the laser power of the multi-mode gain fiber amplification system, and at the same time collect the remaining small part of the laser power for far-field light spot information detection, calculate the corresponding far-field bucket power based on the detected far-field light spot information, and use the far-field bucket power as an evaluation function to run an optimization algorithm to generate an optimal phase diagram, and load it on the spatial light modulator to achieve closed-loop feedback control.

2. The high-power multimode fiber laser amplifier based on wavefront shaping according to claim 1, characterized in that: The seed light wavefront control unit includes a seed laser, a spatial light modulator, a third lens, a polarization beam splitter, a first reflector, a second reflector, a dichroic mirror, and a fourth lens; The seed light output by the polarization seed laser is incident on the polarization beam splitter through the third lens. The seed light output by the polarization beam splitter is incident on the spatial light modulator after adjusting the optical path through the first reflector. The seed light after wavefront modulation output by the spatial light modulator is incident on the dichroic mirror after adjusting the optical path through the second reflector. The seed light after forward residual light is filtered out by the dichroic mirror is coupled into the multi-mode gain fiber amplification system through the fourth lens.

3. The high-power multimode fiber laser amplifier based on wavefront shaping according to claim 1, characterized in that: The multimode gain fiber amplification unit comprises a multimode passive fiber, a multimode gain fiber, a pump signal combiner, and a pump source; each pump source is connected to a pump arm of the pump signal combiner, and the pump light output by the pump source enters the multimode gain fiber through the pump signal combiner; The seed light output by the seed light wavefront control unit is coupled into the multimode passive optical fiber, the seed light enters the multimode gain optical fiber through the multimode passive optical fiber to achieve power amplification, and the pump signal combiner outputs the laser after power amplification.

4. The high-power multimode fiber laser amplifier based on wavefront shaping according to any one of claims 1 to 3, characterized in that: The output light spot detection and feedback unit includes a first lens, a second lens, an adjustable attenuator, a large fraction beam splitter, an optical power meter, a camera, an adjustable aperture, and a computer; The laser output by the multi-mode gain fiber amplifier unit is incident on the first lens, and the output light beam of the first lens passes through the adjustable aperture and is incident on the large fraction beam splitter, which splits the incident light into two parts, wherein the large fraction beam splitter outputs most of the power beam of the incident light as the amplifier output beam, and the power of the output beam is measured by an optical power meter; the remaining small part of the power laser is output to the adjustable attenuator, and after further power attenuation by the adjustable attenuator, it is incident on the camera through the second lens for far-field light spot information detection, and the camera transmits the detected far-field light spot information to the computer to realize closed-loop feedback control.

5. The high-power multimode fiber laser amplifier based on wavefront shaping according to claim 4, characterized in that: The first lens and the second lens have different focal lengths, so that the light beam forms an equally-proportionally magnified intensity distribution of the optical fiber output end face on the camera.

6. The high-power multimode fiber laser amplifier based on wavefront shaping according to claim 4, characterized in that: The closed-loop feedback control implementation specifically includes: S1, turning on the polarization seed laser and the pump source to make the high-power multimode fiber laser amplifier based on wavefront shaping at the target output power; S2, the computer randomly generates multiple phase images as all individuals in the first generation of the optimization algorithm; S3, the spatial light modulator sequentially loads the phase map corresponding to each individual of the current generation, uses the camera to detect the far-field spot information corresponding to each phase map, calculates the far-field bucket power corresponding to each phase map based on each far-field spot information, uses the far-field bucket power as an evaluation function, and finds the best evaluation function among all individuals of the current generation; S4, evaluate whether the best evaluation function among all individuals in the current generation meets the evaluation criteria, if the best evaluation function among all individuals in the current generation meets the evaluation criteria, then go to S6, if the best evaluation function among all individuals in the current generation does not meet the evaluation criteria, then go to S5; S5, select the phase diagrams corresponding to some individuals from all individuals of the current generation, perform interleaving and mutation, and use them as the phase diagrams corresponding to the new generation of individuals, and go to S3; S6. The computer loads the phase map corresponding to the optimal evaluation function into the spatial light modulator.

7. The high-power multimode fiber laser amplifier based on wavefront shaping according to claim 6, characterized in that: The optimization algorithms include genetic algorithm, simulated annealing algorithm, particle swarm optimization algorithm and ant colony algorithm.

8. The high-power multimode fiber laser amplifier based on wavefront shaping according to claim 6, characterized in that: In S3, the best evaluation function among all individuals in the current generation is found, including: The evaluation functions of all individuals in the current generation are sorted by size, and the largest evaluation function among the evaluation functions of all individuals in the current generation is selected as the best evaluation function among all individuals in the current generation.

9. The high-power multimode fiber laser amplifier based on wavefront shaping according to claim 6, characterized in that: In S4, whether the best evaluation function among all individuals in the current generation meets the evaluation criteria is evaluated, and the method includes: Set the evaluation function reference value; The best evaluation function among all individuals in the current generation is compared with the evaluation function reference value. If the best evaluation function among all individuals in the current generation is higher than the evaluation function reference value, it is determined that the evaluation criteria are met; if the best evaluation function among all individuals in the current generation is lower than the evaluation function reference value, it is determined that the evaluation criteria are not met.

10. The high-power multimode fiber laser amplifier based on wavefront shaping according to claim 6, characterized in that: In S5, the method of selecting phase diagrams corresponding to some individuals from all individuals of the current generation includes: The evaluation functions of all individuals in the current generation are sorted by size, and the evaluation functions ranked in the top a% of the evaluation functions of all individuals in the current generation are selected. The phase maps corresponding to the top a% of the evaluation functions are used as the phase maps corresponding to some individuals; the value range of a% is 20%~50%.

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