Optical path differential time-sharing measurement and control device and method for fiber laser coherent combining system

Abstract

A time-division measurement and control device and method for optical path difference in a fiber laser coherent combining system includes a phase modulator, a high-speed fiber delay line, a wavelength division multiplexer, an amplifier, and a fiber collimator, all provided on the transmission optical path of each sub-laser channel. A dynamic optical path difference control module is connected between the high-speed fiber delay line and the wavelength division multiplexer corresponding to each sub-laser channel. The dynamic optical path difference control module emits a probe laser, which is reflected by the end face of the fiber collimator corresponding to each laser channel. The probe laser is injected into the currently selected sub-laser optical path through time division multiplexing technology, and the probe laser reflected back from the end face of the fiber collimator corresponding to the currently selected sub-laser optical path is detected. The corresponding optical path is calculated and compensated in real time, thereby achieving real-time control of the optical path difference of each sub-laser channel. The present invention realizes optical path measurement and control of multiple laser channels through a set of optical path measurement and control devices.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of optical coherent combining, and in particular to an optical path differential time-sharing measurement and control device and method for a fiber laser coherent combining system. Background Art

[0002] The spatial coherence length of a fiber laser decreases as the spectral linewidth of the laser increases. When the optical path difference between the two laser beams is greater than the spatial coherence length, the coherence between the two beams decreases, and they are transmitted independently during transmission without interference. The spectral linewidth of a fiber laser is related to the stimulated Brillouin scattering threshold, and the higher the stimulated Brillouin scattering threshold, the higher the output power of the fiber laser. When the spectral linewidth is wide, the stimulated Brillouin scattering threshold is high, so the seed light source of a fiber laser is often spectrally broadened to increase the output power.

[0003] In high-power fiber laser coherent combining, multiple narrow-linewidth fiber lasers with a certain spectral linewidth can be used as sub-unit beams. Therefore, it is necessary to control the optical path difference between each sub-unit. The traditional optical path difference compensation method can achieve static compensation of the optical path difference of the array laser by compensating the length of the energy transmission fiber and using a mechanical delay line. However, when the output power of the fiber laser is increased, the optical path in the fiber laser changes in real time due to factors such as thermal effects, causing the coherence between the sub-beams to deteriorate, requiring further real-time measurement and compensation. At the same time, the optical path measurement of multi-channel lasers requires multiple sets of optical path measurement devices, which makes the optical path measurement complex and costly. Summary of the Invention

[0004] In view of the technical problems existing in the prior art, the present invention proposes an optical path differential time-sharing measurement and control device and method for a fiber laser coherent combining system.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] On the one hand, the present invention provides an optical path difference time-sharing measurement and control device for a fiber laser coherent combining system, comprising a fiber laser coherent combining system and a dynamic optical path difference control module;

[0007] The transmission optical path of each laser in the laser coherent combining system is provided with a phase modulator, a high-speed optical fiber delay line, a wavelength division multiplexer, an amplifier and an optical fiber collimator;

[0008] The high-speed optical fiber delay line is used to compensate for the dynamic optical path difference in real time. A dynamic optical path difference control module is connected between the high-speed optical fiber delay line corresponding to each laser path and the wavelength division multiplexer. The dynamic optical path difference control module emits a detection laser, and the fiber collimator end face corresponding to each laser path can reflect the detection laser. The detection laser is injected into the currently selected sub-laser optical path through time division multiplexing technology, and the detection laser reflected back from the fiber collimator end face corresponding to the currently selected sub-laser optical path is detected, and the corresponding optical path is calculated and compensated in real time, thereby realizing real-time control of the optical path difference of each sub-laser path.

[0009] Furthermore, the laser coherent combining system of the present invention includes 1 seed laser, 1 1×N laser beam splitter, N phase modulators, N high-speed optical fiber delay lines, N wavelength division multiplexers, N amplifiers and N optical fiber collimators and 1 closed-loop phase control module;

[0010] The seed laser with a wavelength of λ1 is used to output a seed laser with a wavelength of λ1;

[0011] The 1×N laser beam splitter is used to split the seed laser into N sub-lasers;

[0012] The N optical fiber collimators are arranged in a certain array to form an optical fiber collimator array, which is used to combine and collimate the laser beams of each path for output;

[0013] The closed-loop phase control module collects a small portion of the power of the combined and collimated laser output and inputs it into the closed-loop phase control module, and uses the closed-loop phase control module to achieve phase control of each path of laser light and thus achieve coherent synthesis.

[0014] Furthermore, a long-range optical fiber delay line is provided on the transmission optical path of each laser in the laser coherent combining system of the present invention, and the long-range optical fiber delay line is used to compensate for the static optical path difference of each laser.

[0015] Furthermore, the dynamic optical path difference control module of the present invention includes a detection laser with a wavelength of λ2, a Mazur-Zehn modulator, a three-port optical circulator, an optical switch module, a high-speed photodetector and an optical path controller;

[0016] The detection laser is optically connected to the Markov modulator, which is optically connected to port 1 of the three-port circulator; port 2 of the three-port optical circulator is optically connected to port 1 of the optical switch module; port 3 of the three-port optical circulator is optically connected to a high-speed photodetector, and the output end of the high-speed photodetector is electrically connected to input ends 2 of an optical path controller; output end 1 of the optical path controller is electrically connected to the Markov modulator for applying radio frequency signal modulation; output end 3 of the optical path controller is electrically connected to the optical switch module for selecting different sub-laser optical paths; output end i+3 of the optical path controller is electrically connected to the i-th high-speed optical fiber delay line, where i=1, 2, ..., N; the laser input to port 1 of the three-port optical circulator can only be output from port 2 of the three-port optical circulator, and the output end of the three-port optical circulator can only be output from port 2 of the three-port optical circulator. Laser light input from port 2 can only be output from port 3 of the three-port optical circulator. The Marzon modulator is used to amplitude modulate the detection laser seed. The optical switch module is used to select the optical path. Laser light input from port 1 of the optical switch module can only be output from the currently selected sub-laser optical path, and laser light input from the currently selected sub-laser optical path is output from port 1 of the optical switch module. The high-speed photodetector is used to detect the intensity of the detection light with a wavelength of λ2 returned from the end face of the optical fiber collimator array and convert it into an electrical signal. The optical path controller uses time division multiplexing technology to select different sub-laser optical paths through the optical switch module, demodulates the absolute optical path value of the currently selected sub-laser optical path in real time, and calculates the optical path change, thereby obtaining the delay increment and realizing real-time control of the optical path difference of each sub-laser.

[0017] Furthermore, the closed-loop phase control module of the present invention includes a sampling mirror, a focusing lens, a photodetector and a phase controller; the laser output by the optical fiber collimator array is incident on the sampling mirror, and the sampling mirror collects a small portion of the power of the combined and collimated laser output, which is focused by the focusing lens and then incident on the photodetector; the photodetector converts the light intensity signal into an electrical signal, and the output end of the photodetector is electrically connected to the input end of the phase controller, and each output end of the phase controller is electrically connected to the electrical input end of the phase modulator on the transmission optical path of each laser path, and the phase controller is used to compensate for the phase error existing in the system to achieve phase consistency of each laser path.

[0018] Furthermore, the sampling mirror of the present invention is a high-reflection mirror. The laser beams output by the optical fiber collimator array are incident on the high-reflection mirror. Most of the laser power is reflected to the free space by the high-reflection mirror, and the remaining small portion of the laser power is transmitted to the focusing lens by the high-reflection mirror.

[0019] Furthermore, the sampling mirror of the present invention is a high lens, and the laser output by the fiber collimator array is incident on the high lens. Most of the laser power is transmitted to the free space through the high lens, and the remaining small part of the laser power is reflected to the focusing lens through the high lens.

[0020] On the one hand, the present invention provides an optical path differential time-sharing measurement and control method for a fiber laser coherent combining system, that is, an optical path differential time-sharing measurement and control device based on any of the above-mentioned fiber laser coherent combining systems realizes the optical path differential time-sharing measurement and control of the fiber laser coherent combining system.

[0021] Compared with the prior art, the present invention can produce the following technical effects:

[0022] Through the all-fiber structure, a detection laser is injected into the transmission optical path of each laser channel. The fiber collimator end face corresponding to each laser channel can reflect the detection laser. By detecting the detection laser reflected back from the fiber collimator end face corresponding to each laser channel, the corresponding optical path is calculated and compensated in real time, thereby improving the coherence between the sub-beams of fiber laser coherent synthesis when operating at high output power. The use of time division multiplexing technology can achieve hardware resource optimization, and the optical path measurement of each laser channel can be achieved through a set of optical path measurement devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0024] Figure 1 This is a schematic structural diagram of an optical path difference time-sharing measurement and control device for a fiber laser coherent combining system provided by an embodiment;

[0025] Numbers in the figure:

[0026] 1. Seed laser; 2. Pre-amplifier; 3. Laser beam splitter; 4. Phase modulator; 5. Large-range fiber delay line; 6. High-speed fiber delay line; 7. Wavelength division multiplexer; 8. Fiber amplifier; 9. Fiber collimator; 10. Sampling mirror; 11. Focusing lens; 12. Photodetector; 13. Phase controller; 14. Detection laser; 15. Mazur-Zehn modulator; 16. Three-port optical circulator; 17. Optical switch module; 18. High-speed photodetector; 19. Optical path controller. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] In one embodiment, an optical path difference time-sharing measurement and control device for a fiber laser coherent combining system is provided, comprising a fiber laser coherent combining system and a dynamic optical path difference control module;

[0029] The transmission optical path of each laser in the laser coherent combining system is provided with a phase modulator, a high-speed optical fiber delay line, a wavelength division multiplexer, an amplifier and an optical fiber collimator;

[0030] The high-speed optical fiber delay line is used to compensate for the dynamic optical path difference in real time. A dynamic optical path difference control module is connected between the high-speed optical fiber delay line corresponding to each laser path and the wavelength division multiplexer. The dynamic optical path difference control module emits a detection laser, and the end face of the optical fiber collimator corresponding to each laser path can reflect the detection laser. By detecting the detection laser reflected back from the end face of the optical fiber collimator corresponding to each laser path, the corresponding optical path is calculated and compensated in real time.

[0031] Reference Figure 1 One embodiment provides an optical path difference time-sharing measurement and control device for a fiber laser coherent combining system, including a fiber laser coherent combining system and a dynamic optical path difference control module. The fiber laser coherent combining system includes a seed laser 1, a preamplifier 2, a 1×N laser beam splitter 3, N phase modulators 4, N high-speed fiber delay lines 6, N wavelength division multiplexers 7, N amplifiers 8, N fiber collimators 9, and a closed-loop phase control module.

[0032] The seed laser 1 has a wavelength of λ1 and is connected to the input port of the preamplifier 2. The output port of the preamplifier 2 is connected to the first port of the 1×N laser beam splitter 3. The wavelength λ1 of the seed laser 1 can be selected from 1080 nm, 1064 nm, 1030 nm, etc. without loss of generality.

[0033] The seed laser 1 with a wavelength of λ1 is used to output a seed laser with a wavelength of λ1.

[0034] The seed laser 1 is connected to a pre-amplifier 2 , which is used to amplify the power of the seed laser with a wavelength λ1 output by the seed laser 1 .

[0035] The 1×N laser beam splitter 3 has N+1 ports. When laser light is input from the first port of the 1×N laser beam splitter 3, the seed laser light, after power amplification by the pre-amplifier 2, is split into N laser beams by the 1×N laser beam splitter 3 and output from the second port to the N+1 port of the 1×N laser beam splitter 3, respectively.

[0036] The output laser port (i+1) of the 1×N laser beam splitter 3 is optically connected to the i-th phase modulator 4, where i=1, 2, . . . , N.

[0037] The phase modulator 4 is used to change the piston phase of each laser beam. The i-th phase modulator 4 is optically connected to the i-th long-range optical fiber delay line 5, which is optically connected to the i-th high-speed optical fiber delay line 6, which is optically connected to the i-th wavelength division multiplexer 7, which is optically connected to the i-th optical fiber amplifier 8, where i = 1, 2, ..., N.

[0038] The long-range optical fiber delay line 5 is used to compensate for the static optical path difference of each laser path. The high-speed optical fiber delay line 6 is used to compensate for the dynamic optical path difference of each laser path in real time.

[0039] The wavelength division multiplexer 7 is used to combine two light beams of different wavelengths into one beam, or to separate one light beam according to different wavelength components.

[0040] The optical fiber amplifier 8 is used to amplify the power of the laser.

[0041] The fiber amplifiers corresponding to the sub-lasers of each path are optically connected to the corresponding fiber collimators 9. The N fiber collimators 9 are arranged in a certain array to form a fiber collimator array, which is used to combine and collimate the laser beams of each path for output.

[0042] The dynamic optical path difference control module includes a detection laser 14 with a wavelength of λ2, a Mazda-Zehnder modulator 15, a three-port optical circulator 16, an optical switch module 17, a high-speed photodetector 18, and an optical path controller 19. λ2 is the laser wavelength used to detect the optical path. The selection of λ2 should avoid the absorption and emission peaks of the dopant particles in the gain fiber of the subsequent optical fiber amplifier, while also ensuring minimal loss when passing through the laser link. Without loss of generality, λ2 can be selected as a sensing wavelength such as 1330 nm or 1550 nm.

[0043] The detection laser 14 is optically connected to the Markov modulator 15, and the Markov modulator 15 is optically connected to port 1 of the three-port circulator 16; port 2 of the three-port optical circulator 16 is optically connected to port 1 of the optical switch module 17; port 3 of the three-port optical circulator 16 is optically connected to the high-speed photodetector 18, and the output end of the high-speed photodetector 18 is electrically connected to input end 2 of the optical path controller 19; output end 1 of the optical path controller 19 is electrically connected to the Markov modulator 15 for applying radio frequency signal modulation; output end 3 of the optical path controller 19 is electrically connected to the optical switch module 17 for selecting different sub-laser optical paths; output end i+3 of the optical path controller 17 is electrically connected to the i-th high-speed optical fiber delay line 6, i=1, 2, ..., N; the laser input to port 1 of the three-port optical circulator 16 can only be output from port 2 of the three-port optical circulator 16 The laser light input from the second port of the three-port optical circulator 16 can only be output from the third port of the three-port optical circulator 16. The Ma-Zeng modulator 15 is used to perform amplitude modulation on the detection laser seed. The optical switch module 17 is used to select the optical path. The laser light input from the first port of the optical switch module 17 can only be output from the currently selected sub-laser optical path. The laser light input from the currently selected sub-laser optical path is output from the first port of the optical switch module 17. The high-speed photodetector 18 is used to detect the intensity of the detection light with a wavelength of λ2 returned from the end face of the optical fiber collimator array and convert it into an electrical signal. The optical path controller 19 uses time division multiplexing technology to select different sub-laser optical paths through the optical switch module, demodulates the absolute optical path value of the currently selected sub-laser optical path in real time, and calculates the optical path change, thereby obtaining the delay increment and realizing real-time control of the optical path difference of each sub-laser.

[0044] The closed-loop phase control module collects a small portion of the power of the combined and collimated laser output and inputs it into the closed-loop phase control module, and uses the closed-loop phase control module to achieve phase control of each laser path and thus achieve coherent synthesis. The closed-loop phase control module includes a sampling mirror 10, a focusing lens 11, a photodetector 12 and a phase controller 13; the laser output of the combined and collimated laser of the fiber collimator array is incident on the sampling mirror 10, and the sampling mirror 10 collects a small portion of the power of the combined and collimated laser output and focuses it through the focusing lens 11 and then incident on the photodetector 12 (preferably, a photodetector with a pinhole); the photodetector 12 converts the light intensity signal into an electrical signal, and the output end of the photodetector 12 is electrically connected to the input end of the phase controller 13, and each output end of the phase controller 13 is electrically connected to the electrical input end of the phase modulator 4 on the transmission optical path of each laser path. The phase controller 13 is used to compensate for the phase error in the system to achieve phase consistency of each laser path.

[0045] Figure 1In the illustrated embodiment, the sampling mirror is a high lens, and the laser light output by the fiber collimator array is incident on the high lens. Most of the laser light power is transmitted to the free space through the high lens, and the remaining small portion of the laser light power is reflected by the high lens to the focusing lens.

[0046] It can be understood that the sampling mirror can also be a high-reflection mirror. The laser output by the fiber collimator array is incident on the high-reflection mirror. Most of the laser power is reflected to the free space by the high-reflection mirror, and the remaining small part of the laser power is transmitted to the focusing lens through the high-reflection mirror.

[0047] One embodiment provides a method for real-time measurement and control of optical path difference of a fiber laser coherent combining system. Based on the above-mentioned real-time measurement and control device for optical path difference of a fiber laser coherent combining system, real-time measurement and control of the optical path difference of each sub-laser optical path is achieved.

[0048] Specifically, in one embodiment, a real-time measurement and control method for the optical path difference of the optical fiber laser coherent combining system based on the optical path difference time-sharing measurement and control device of the optical fiber laser coherent combining system is as follows:

[0049] (1) The optical path controller 19 outputs a control signal to the Markov-Zehnder modulator 15, which amplitude-modulates the detection laser light output by the detection laser 14;

[0050] The modulated detection laser intensity E(t) is:

[0051] E(t)=E(1+Dcosω m t)expj(ω c t) (1)

[0052] Where E is the amplitude, D is the modulation depth, ω m is the modulation signal angular frequency, ω c is the light frequency, t is the time;

[0053] (2) The optical path controller 19 selects the optical switch module 17 and selects the currently selected sub-laser optical path. At this time, it is considered that the optical path change is mainly caused by the thermal effect in the optical amplifier, and the optical path change in other optical fibers is negligible.

[0054] (3) The modulated detection laser passes through the three-port optical circulator 16 and the optical switch module 17, and then passes through the wavelength division multiplexer 7 to enter the current gated sub-laser optical path. The detection laser is reflected back from the end face of the fiber collimator 9 of the current gated sub-laser optical path and returns to the three-port optical circulator 16 along the original path. It is output from the third port of the three-port optical circulator 16 and collected by the high-speed photodetector 18. The light intensity signal collected by the high-speed photodetector 18 is as follows:

[0055]

[0056] Where η is the photodetector responsivity, τ is the transmission delay, β2 is the group velocity dispersion coefficient of the detection laser, and L is the optical path length of the current gated sub-laser.

[0057] (5) The light intensity signal collected by the high-speed photodetector 18 is input into the optical path controller 19. The optical path controller 19 performs phase detection processing on the modulation signal input to the Ma-Zehnder modulator 15 and the light intensity signal collected by the high-speed photodetector 18 to obtain a phase difference. Based on the phase difference, the optical path delay of the currently selected sub-laser optical path is obtained.

[0058] Specifically, the modulation signal input to the Mazda-Zehnder modulator 15 and the light intensity signal collected by the high-speed photodetector 18 are subjected to phase detection processing, and the phase difference obtained is:

[0059]

[0060] Since the phase detector output range is from 0 to 2π, the phase needs to be unwound to obtain:

[0061]

[0062] Among them, N m is a non-negative integer, θ(ω m ) is the measured phase value.

[0063] Combining formulas (3) and (4), we can obtain the optical path delay of the current gated sub-laser optical path as:

[0064]

[0065] Among them, T m =2π / ω m .

[0066] By sweeping the modulation frequency, the phase after unwinding is measured at different frequencies. According to the phase and frequency curve, a straight line with an intercept of N1 and a slope of k can be fitted. At this time, N m It can be expressed as k / T m , and then estimate the delay of the pre-gated sub-laser optical path according to formula (5).

[0067] (5) Based on the optical path delay of the currently selected sub-laser optical path at the current moment and the previous moment, the delay increment is calculated, and the delay line of the currently selected sub-laser optical path is then controlled. At the same time, the currently selected sub-laser optical path is updated, and the process returns to step (2) to achieve real-time measurement and control of the optical path difference of each sub-laser optical path. In this way, the optical path controller records the delay in the sub-laser optical path of each channel and repeatedly measures it.

[0068] Matters not covered by the present invention are known technologies.

[0069] The technical features of the above embodiments can 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.

[0070] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

[0071] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An optical path difference time-sharing measurement and control device for a fiber laser coherent combining system, characterized in that: Including fiber laser coherent combining system and dynamic optical path difference control module; The transmission optical path of each laser in the laser coherent combining system is provided with a phase modulator, a high-speed optical fiber delay line, a wavelength division multiplexer, an amplifier and an optical fiber collimator; The high-speed fiber delay line is used to compensate for the dynamic optical path difference in real time. A dynamic optical path difference control module is connected between the high-speed fiber delay line corresponding to each laser path and the wavelength division multiplexer. The dynamic optical path difference control module emits a detection laser, and the fiber collimator end face corresponding to each laser path can reflect the detection laser. The detection laser is injected into the currently selected sub-laser optical path through time division multiplexing technology, and the detection laser reflected back from the fiber collimator end face corresponding to the currently selected sub-laser optical path is detected. The corresponding optical path is calculated and compensated in real time, thereby realizing real-time control of the optical path difference of each sub-laser path; The dynamic optical path difference control module includes a detection laser with a wavelength of λ2, a Markov-Zehn modulator, a three-port optical circulator, an optical switch module, a high-speed photodetector and an optical path controller; the detection laser is optically connected to the Markov-Zehn modulator, the Markov-Zehn modulator is optically connected to port 1 of the three-port circulator; port 2 of the three-port optical circulator is optically connected to port 1 of the optical switch module; port 3 of the three-port optical circulator is optically connected to the high-speed photodetector, and the output end of the high-speed photodetector is electrically connected to input 2 of the optical path controller; output end 1 of the optical path controller is electrically connected to the Markov-Zehn modulator for applying radio frequency signal modulation; output end 3 of the optical path controller is electrically connected to the optical switch module for selecting different sub-laser optical paths; output end i+3 of the optical path controller is electrically connected to the i-th high-speed optical fiber delay line, i=1, 2, ..., N; input end 1 of the three-port optical circulator is electrically connected to the high-speed photodetector, and the output end of the high-speed photodetector is electrically connected to input end ... The laser light input from the second port of the three-port optical circulator can only be output from the second port of the three-port optical circulator, and the laser light input from the second port of the three-port optical circulator can only be output from the third port of the three-port optical circulator. The Ma-Zeng modulator is used to perform amplitude modulation on the detection laser seed. The optical switch module is used to select the optical path. The laser light input from the first port of the optical switch module can only be output from the currently selected sub-laser optical path, and the laser light input from the currently selected sub-laser optical path is output from the first port of the optical switch module. The high-speed photodetector is used to detect the light intensity of the detection light with a wavelength of λ2 returned from the end face of the optical fiber collimator array and convert it into an electrical signal. The optical path controller uses time division multiplexing technology to select different sub-laser optical paths through the optical switch module, demodulates the absolute optical path value of the currently selected sub-laser optical path in real time, and calculates the optical path change, thereby obtaining the delay increment and realizing real-time control of the optical path difference of each sub-laser.

2. The optical path difference time-sharing measurement and control device for the fiber laser coherent combining system according to claim 1, characterized in that: The laser coherent combining system includes 1 seed laser, 1 1×N laser beam splitter, N phase modulators, N high-speed optical fiber delay lines, N wavelength division multiplexers, N amplifiers, N optical fiber collimators and 1 closed-loop phase control module; The seed laser with a wavelength of λ1 is used to output a seed laser with a wavelength of λ1; The 1×N laser beam splitter is used to split the seed laser into N sub-lasers; The N optical fiber collimators are arranged in a certain array to form an optical fiber collimator array, which is used to combine and collimate the laser beams of each path for output; The closed-loop phase control module collects a small portion of the power of the combined and collimated laser output and inputs it into the closed-loop phase control module, and uses the closed-loop phase control module to achieve phase control of each path of laser light and thus achieve coherent synthesis.

3. The optical path difference time-sharing measurement and control device for the fiber laser coherent combining system according to claim 1 or 2, characterized in that: A long-range optical fiber delay line is provided on the transmission optical path of each laser channel in the laser coherent combining system, and the long-range optical fiber delay line is used to compensate for the static optical path difference of each laser channel.

4. The optical path difference time-sharing measurement and control device for the fiber laser coherent combining system according to claim 2, characterized in that: The closed-loop phase control module includes a sampling mirror, a focusing lens, a photodetector and a phase controller; the laser output from the combined and collimated beam of the fiber collimator array is incident on the sampling mirror, and the sampling mirror collects a small portion of the power of the combined and collimated laser output, which is focused by the focusing lens and then incident on the photodetector; the photodetector converts the light intensity signal into an electrical signal, and the output end of the photodetector is electrically connected to the input end of the phase controller, and each output end of the phase controller is electrically connected to the electrical input end of the phase modulator on the transmission optical path of each laser path. The phase controller is used to compensate for the phase error in the system to achieve phase consistency of each laser path.

5. The optical path difference time-sharing measurement and control device for the fiber laser coherent combining system according to claim 4, characterized in that: The sampling mirror is a high-reflection mirror. The laser beam output by the optical fiber collimator array is incident on the high-reflection mirror. Most of the laser power is reflected to the free space by the high-reflection mirror, and the remaining small part of the laser power is transmitted to the focusing lens by the high-reflection mirror.

6. The optical path difference time-sharing measurement and control device for the fiber laser coherent combining system according to claim 4, characterized in that: The sampling mirror is a high lens. The laser beams output by the optical fiber collimator array are incident on the high lens. Most of the laser power is transmitted to the free space through the high lens, and the remaining small part of the laser power is reflected by the high lens to the focusing lens.

7. A method for optical path difference time-sharing measurement and control of a fiber laser coherent combining system, characterized in that: The optical path difference time-sharing measurement and control device of the optical fiber laser coherent combining system as claimed in claim 1 realizes the optical path difference time-sharing measurement and control of the optical fiber laser coherent combining system.

8. The optical path difference time-sharing measurement and control method for a fiber laser coherent combining system according to claim 7, characterized in that: include: (1) The optical path controller outputs a control signal to the Markov-Zehn modulator, which then amplitude-modulates the detection laser output by the detection laser. (2) The optical path controller selects the optical switch module and selects the current selected sub-laser optical path; (3) The modulated detection laser passes through the three-port optical circulator, the optical switch module, and then enters the current gated sub-laser optical path through the wavelength division multiplexer. The detection laser is reflected back from the end face of the fiber collimator of the current gated sub-laser optical path and returns to the three-port optical circulator along the original path. It is output from the third port of the three-port optical circulator and collected by a high-speed photodetector. (4) The light intensity signal collected by the high-speed photodetector is input into the optical path controller, and the optical path controller performs phase detection processing on the modulation signal input to the Ma-Zehnder modulator and the light intensity signal collected by the high-speed photodetector to obtain a phase difference, and the optical path delay of the current gated sub-laser optical path is obtained based on the phase difference; (5) Based on the optical path delay of the currently selected sub-laser optical path at the current moment and the previous moment, the delay increment is calculated, and then the delay line of the currently selected sub-laser optical path is controlled; at the same time, the currently selected sub-laser optical path is updated, and the process returns to step (2) to achieve real-time measurement and control of the optical path difference of each sub-laser optical path.

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