Single-step coherent combination phase locking system and method based on single detection signal, and medium

Abstract

The invention discloses a single-step coherent combination phase locking system and method based on a single detection signal, and a medium, and relates to the technical field of laser coherent combination. The system comprises a laser module, a synthesis module, a detection module and a control module, the laser module is used for splitting laser into a plurality of sub-beams and a reference beam; the synthesis module is used for synthesizing the multiple sub-light beams into a second light beam; the detection module is used for separating the second light beam into a third light beam and the first light beam, and detecting the third light beam and the reference light beam to obtain a detection signal; the control module is used for acquiring the detection signal, determining the phase difference of each sub-beam relative to the reference beam according to the detection signal, and compensating the phase of each sub-beam based on the phase difference. By adopting the system provided by the invention, single-step phase locking can be realized, the control bandwidth is remarkably improved, and the optical structure is simple.

Description

Technical Field

[0001] This application relates to the technical field of laser coherent combination, and particularly to a single-step coherent combination phase-locked system and method, and a medium based on a single detection signal. Background Art

[0002] Laser coherent combination is a technology that realizes high-power output and maintains high beam quality by synchronously superposing parameters such as the phase and polarization of multiple laser beams. Affected by factors such as thermal effects, mechanical vibrations, air flow disturbances, and power supply noise, the phases of multiple laser beams are constantly changing.

[0003] Currently, related technologies mainly use methods such as the stochastic parallel gradient descent method, the multi-dither method, and the heterodyne method for active phase locking. However, the heterodyne method requires each beam to undergo heterodyne interference with the same reference beam, and multiple detectors are used to obtain heterodyne signals. The optical structure is complex, and high requirements are imposed on beam collimation, etc. At the same time, it is difficult to be used in a common-aperture combination system with complete near-field overlap, while other methods require multiple iterations to converge, and the control bandwidth is limited. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the related technologies, it is desirable to provide a single-step coherent combination phase-locked system and method, and a medium based on a single detection signal, which can improve the control bandwidth and have a simple optical structure.

[0005] In a first aspect, this application provides a single-step coherent combination phase-locked system based on a single detection signal. The system includes a laser module, a combination module, a detection module, and a control module. The first end of the combination module is connected to the first end of the laser module, the second end of the combination module is connected to the first end of the detection module, the second end of the detection module is connected to the second end of the laser module, the third end of the detection module emits a first beam, the fourth end of the detection module is connected to the first end of the control module, the second end of the control module is connected to the third end of the laser module, and the third end of the control module is connected to the fourth end of the laser module; The laser module is used to split the laser into multiple sub-beams and a reference beam; the combination module is used to combine the multiple sub-beams into a second beam; the detection module is used to separate the second beam into a third beam and the first beam, and detect the third beam and the reference beam to obtain a detection signal; the control module is used to acquire the detection signal, determine the phase difference between each sub-beam and the reference beam according to the detection signal, and compensate the phase of each sub-beam based on the phase difference.

[0006] Optionally, in some embodiments of the present application, the detection module includes a sampling mirror, a beam splitter, a focusing lens, and a photodetector that are sequentially distributed along the emission direction of the second beam. The sampling mirror and the beam splitter are arranged in parallel; The sampling mirror is used to separate the second beam to obtain the first beam and the third beam. The beam splitter is used to combine the third beam and the reference beam into a fourth beam and incident it on the focusing lens. The photodetector is used to collect the detection signal and transmit it to the control module.

[0007] Optionally, in some embodiments of the present application, the control module includes a controller, a phase modulator, and an acousto-optic modulator. The phase modulator is provided on each branch corresponding to each sub-beam, and the acousto-optic modulator is provided on the branch corresponding to the reference beam; The first end of the controller is connected to the fourth end of the detection module. The second end of the controller is connected to the phase modulator. The third end of the controller is connected to the acousto-optic modulator. The controller is used to adjust the operating voltage of the phase modulator according to the phase difference.

[0008] Optionally, in some embodiments of the present application, the laser module includes a seed laser source, a first amplifier, a beam splitter, a second amplifier, and a collimator that are sequentially distributed. The seed laser source is used to emit the laser. The beam splitter is used to split the laser into multiple sub-beams and one reference beam.

[0009] Optionally, in some embodiments of the present application, the synthesis module is a sub-aperture coherent synthesis module or a common-aperture coherent synthesis module.

[0010] In a second aspect, the present application provides a single-step coherent synthesis and phase-locking method based on a single detection signal. The method is used for the control module of the system according to any one of the first aspects. The method includes: Obtain the detection signal obtained by the detection module detecting the third beam and the reference beam, and determine the phase difference between each sub-beam and the reference beam according to the detection signal, where each sub-beam and the reference beam are obtained by splitting the laser of the laser module. The third beam is obtained by the detection module separating the second beam, and the second beam is obtained by the synthesis module synthesizing each sub-beam; Compensate the phases of each sub-beam based on the phase difference.

[0011] Optionally, in some embodiments of the present application, the detection signal is obtained by the following formula: = ; In the above formula, represents the voltage conversion coefficient of the detection module; represents the air refractive index, represents the vacuum permittivity, represents the speed of light; represents the combined optical field corresponding to the second light beam, represents taking the conjugate of the combined optical field; represents the detection area of the detection module; represents the power of the reference light beam irradiating on the detection surface of the detection module, represents the number of sub-light beams, represents the phase of the reference light beam, represents the modulation depth, represents the acousto-optic modulation angular frequency, represents time; represents the th sub-light beam of the third light beam irradiating on the detection surface of the detection module, represents the th sub-light beam of the third light beam, represents the th sub-light beam of the third light beam; represents the th sub-light beam of the third light beam irradiating on the detection surface of the detection module, represents the th sub-light beam of the third light beam, represents the th sub-light beam of the third light beam;

[0012] Optionally, in some embodiments of the present application, the phase difference is obtained by the following formula: ; ; ; In the above formula, represents the integration time, represents the first kind of Bessel function of the first order, represents the imaginary unit.

[0013] Optionally, in some embodiments of the present application, the combined optical field is obtained by the following formula: ; In the above formula, represents the amplitude of the reference light beam, represents the laser central angular frequency of the laser module, represents the The amplitude of the path sub-beam.

[0014] In a third aspect, the present application provides a computer-readable storage medium storing one or more programs, which can be executed by one or more processors to implement the steps of the method according to any one of the second aspect.

[0015] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages: The embodiments of the present application provide a single-step coherent synthesis phase-locked system, method and medium based on a single detection signal. By separating a first beam and a third beam from the second beam synthesized by multiple path sub-beams, the first beam is emitted, that is, a small part of the power is taken out to obtain the third beam, without affecting the phase change. Furthermore, only one sampling of the third beam and the reference beam is required to obtain the detection signal, and the optical structure is simple. Moreover, the reference beam and the multiple path sub-beams are derived from the same laser. Therefore, the phase difference between each sub-beam and the reference beam can be determined according to the detection signal, and the phases of each sub-beam can be accurately compensated based on the phase difference to achieve single-step phase locking, significantly improving the control bandwidth. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a structural block diagram of a single-step coherent synthesis phase-locked system based on a single detection signal provided by an embodiment of the present application; Figure 2 It is a specific example of a single-step coherent synthesis phase-locked system based on a single detection signal provided by an embodiment of the present application; Figure 3 It is a schematic flowchart of a single-step coherent synthesis phase-locked method based on a single detection signal provided by an embodiment of the present application; Figure 4 It is a schematic diagram of the comparison test results between a single-step coherent synthesis phase-locked method based on a single detection signal provided by an embodiment of the present application and the multi-dither method.

[0018] Reference Signs: 10 - Single - step coherent synthesis phase - locked system based on single detection signal, 101 - Laser module, 1011 - Seed laser source, 1012 - First amplifier, 1013 - Beam splitter, 1014 - Second amplifier, 1015 - Collimator, 102 - Synthesis module, 103 - Detection module, 1031 - Sampling mirror, 1032 - Beam splitter mirror, 1033 - Focusing lens, 1034 - Photoelectric detector, 104 - Control module, 1041 - Controller, 1042 - Phase modulator, 1043 - Acousto - optic modulator, a - First light beam, b - Second light beam, c - Third light beam, d - Fourth light beam. Detailed implementation mode

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without making creative efforts belong to the scope of protection of the present application.

[0020] To make the above - mentioned objects, features and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the drawings and specific implementation modes.

[0021] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following will Figures 1 to 4 elaborate in detail on the single - step coherent synthesis phase - locked system, method and medium based on single detection signal provided by the embodiments of the present application.

[0022] Please refer to Figure 1 , which is a structural block diagram of a single - step coherent synthesis phase - locked system based on single detection signal provided by the embodiments of the present application. The single - step coherent synthesis phase - locked system 10 includes a laser module 101, a synthesis module 102, a detection module 103 and a control module 104. The first end of the synthesis module 102 is connected to the first end of the laser module 101, the second end of the synthesis module 102 is connected to the first end of the detection module 103, the second end of the detection module 103 is connected to the second end of the laser module 101, the first light beam a is emitted from the third end of the detection module 103, the fourth end of the detection module 103 is connected to the first end of the control module 104, the second end of the control module 104 is connected to the third end of the laser module 101, and the third end of the control module 104 is connected to the fourth end of the laser module 101.

[0023] In actual use, as shown in Figure 2 , the laser module 101 can split the laser into multiple sub - light beams and one reference light beam. For example, the number of sub - light beams is , ≥1, the combining module 102 can combine multiple sub-beams into the second beam b. The detection module 103 can separate the second beam b into the third beam c and the first beam a, and detect the third beam c and the reference beam to obtain a detection signal. Furthermore, the control module 104 can acquire the detection signal, determine the phase difference of each sub-beam relative to the reference beam according to the detection signal, and precisely compensate the phase of each sub-beam based on the phase difference, realizing single-step phase locking.

[0024] In some embodiments of the present application, for example, the laser module 101 may include, but is not limited to, a seed laser source 1011, a first amplifier 1012, a beam splitter 1013, a second amplifier 1014, and a collimator 1015 distributed in sequence, etc. The seed laser source 1011 can emit laser light, and the beam splitter 1013 can split the laser light into multiple sub-beams and a reference beam. Again, the combining module 102 can be a sub-aperture coherent combining module or a common-aperture coherent combining module, which is more versatile and meets diverse usage requirements.

[0025] In some embodiments of the present application, for example, the detection module 103 may include, but is not limited to, a sampling mirror 1031, a beam splitter 1032, a focusing lens 1033, a photodetector 1034, etc., which are sequentially distributed along the emission direction of the second beam b. Among them, the sampling mirror 1031 and the beam splitter 1032 are arranged in parallel. The sampling mirror 1031 can separate the second beam b to obtain a first beam a and a third beam c. The beam splitter 1032 can combine the third beam c and the reference beam into a fourth beam d and incident it on the focusing lens 1033, while the photodetector 1034 can collect the detection signal and transmit it to the control module 104. Another example is that the control module 104 may include, but is not limited to, a controller 1041, a phase modulator 1042, an acousto-optic modulator 1043, etc. Phase modulators 1042 are provided on the branches corresponding to each sub-beam, and an acousto-optic modulator 1043 is provided on the branch corresponding to the reference beam. That is, different frequency modulation signals are applied to each beam. The first end of the controller 1041 is connected to the fourth end of the detection module 103, the second end of the controller 1041 is connected to the phase modulator 1042, and the third end of the controller 1041 is connected to the acousto-optic modulator 1043. The controller 1041 can adjust the operating voltage of the phase modulator 1042 according to the phase difference. It should be noted that in the embodiments of the present application, the modulation angular frequency of the phase modulator 1042 and the modulation angular frequency of the acousto-optic modulator 1043 are both set values. That is to say, in addition to applying different frequency modulation signals to each sub-beam, the phase modulator 1042 also needs to superimpose the operating potential given by the controller 1041, which is related to the working mechanism of the phase modulator 1042. Thus, the phase compensation of each sub-beam is achieved, and the acousto-optic modulator 1043 only needs to complete the acousto-optic modulation of the reference beam. In addition, the detection optical path of the detection module 103 in the embodiments of the present application can also adopt a fiber structure, as long as it is ensured that the sampled third beam c can be coherently synthesized with the frequency-shifted reference beam and detected.

[0026] The single-step coherent synthesis and phase-locked system based on a single detection signal provided by the embodiments of the present application separates a first beam and a third beam from the second beam synthesized by multiple sub-beams. The first beam is emitted, that is, a small part of the power is taken out to obtain the third beam, which does not affect the phase change. Furthermore, only one sampling of the third beam and the reference beam is required to obtain the detection signal. The optical structure is simple, and the reference beam and the multiple sub-beams are derived from the same laser. Thus, the phase difference between each sub-beam and the reference beam can be determined according to the detection signal, and the phases of each sub-beam can be accurately compensated based on the phase difference to achieve single-step phase locking, significantly improving the control bandwidth.

[0027] Based on the foregoing embodiments, the embodiments of the present application provide a single-step coherent synthesis and phase-locking method based on a single detection signal. The single-step coherent synthesis and phase-locking method based on a single detection signal can be used for Figures 1 to 2The control module 104 of the single-step coherent synthesis phase-locked system 10 based on a single detection signal in the corresponding embodiment. Please refer to Figure 3 , which is a schematic flow chart of a single-step coherent synthesis phase-locked method based on a single detection signal provided by an embodiment of the present application. The single-step coherent synthesis phase-locked method based on a single detection signal specifically includes the following steps: S101, obtain the detection signal obtained by the detection module detecting the third beam and the reference beam, and determine the phase difference between each sub-beam and the reference beam according to the detection signal, where each sub-beam and the reference beam are obtained by splitting the laser of the laser module, the third beam is obtained by the detection module separating the second beam, and the second beam is obtained by the synthesis module synthesizing each sub-beam.

[0028] In some embodiments of the present application, the detection signal can be obtained by formula (1), that is: = (1) In formula (1), represents the voltage conversion coefficient of the detection module; represents the air refractive index, represents the vacuum permittivity, represents the speed of light; represents the combined optical field corresponding to the second beam, represents taking the conjugate of the combined optical field; represents the detection area of the detection module; represents the power of the reference beam irradiating on the detection surface of the detection module, represents the number of sub-beams, represents the phase of the reference beam, represents the modulation depth, represents the acousto-optic modulation angular frequency, represents time; represents the power of the th sub-beam in the third beam irradiating on the detection surface of the detection module, represents the th sub-beam in the third beam, represents the th sub-beam in the third beam, represents the th sub-beam in the third beam irradiating on the detection surface of the detection module, Indicates the phase of the path sub - beam in the third light beam, Indicates the phase - modulation angular frequency of the path sub - beam in the third light beam, and can be equal or not equal. Among them, the power , represents the amplitude corresponding to each light beam.

[0029] And the synthesized optical field can be obtained by Equation (2), that is: (2) In Equation (2), represents the amplitude of the reference light beam, represents the laser central angular frequency of the laser module, Indicates the amplitude of the path sub - beam in the third light beam.

[0030] Furthermore, the phase difference can be obtained by Equation (3), that is: (3) In Equation (3), represents the integration time, represents the first - order Bessel function of the first kind, represents the imaginary unit. In addition, the difference - frequency modulation signals and of each light beam can also be and , that is to say, the angular frequency is .

[0031] S102, compensate the phase of each sub - beam based on the phase difference.

[0032] In some embodiments of the present application, taking the coherent combination of 4 - path sub - beams with a common aperture as an example, that is, N = 4, the acousto - optic modulation angular frequency is 80 MHz, and the phase - modulation angular frequencies of each path sub - beam are 1 MHz, 2 MHz, 3 MHz, and 4 MHz respectively, and the integration time is 1 , that is, one - step control requires 1 , and the test results are as Figure 4 shown. The black dashed line represents the corresponding result of the multi - dithering method, and the gray solid line represents the method of the present application. The horizontal - axis time unit is . From Figure 4It can be seen that the multi-dithering method requires three steps of control to complete locking, while the synthesis efficiency of the method of the present application has increased from less than 10% initially to more than 99% in one step, achieving single-step phase locking.

[0033] It should be noted that the descriptions of the same steps and the same content in this embodiment and other embodiments can be referred to the descriptions in other embodiments, and will not be repeated here.

[0034] The single-step coherent synthesis phase-locking method based on a single detection signal provided by the embodiment of the present application separates the first light beam and the third light beam from the second light beam synthesized by multiple sub-light beams. The first light beam is emitted, that is, a small part of the power is taken out to obtain the third light beam, which does not affect the phase change. Furthermore, only one sampling of the third light beam and the reference light beam is required to obtain the detection signal. The optical structure is simple, and the reference light beam and the multiple sub-light beams are derived from the same laser. Therefore, the phase difference between each sub-light beam and the reference light beam can be determined according to the detection signal, and the phase of each sub-light beam can be accurately compensated based on the phase difference to achieve single-step phase locking, significantly improving the control bandwidth.

[0035] As another aspect, the embodiment of the present application provides a computer-readable storage medium for storing program codes, and the program codes are used to execute any implementation manner of the single-step coherent synthesis phase-locking method based on a single detection signal in the foregoing Figure 3 corresponding embodiments.

[0036] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described systems, devices, and modules can refer to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0037] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules is only a logical function division, and there can be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some interfaces, and the indirect coupling or communication connection of devices or modules can be in electrical, mechanical, or other forms. The modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0038] In addition, each functional module in the various embodiments of the present application may be integrated in a processing unit, may exist physically as individual modules, or two or more units may be integrated in one module. The above integrated unit may be implemented in the form of hardware or in the form of a software functional unit. When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it may be stored in a computer-readable storage medium.

[0039] Based on such understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, may be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the single-step coherent synthesis phase-locking method based on a single detection signal in the various embodiments of the present application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs that can store program codes.

[0040] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, 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, it should be considered to be within the scope described in this specification.

[0041] Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A single-step coherent synthesis phase-locked system based on a single detection signal, characterized in that The system includes a laser module, a synthesis module, a detection module, and a control module. The first end of the synthesis module is connected to the first end of the laser module. The second end of the synthesis module is connected to the first end of the detection module. The second end of the detection module is connected to the second end of the laser module. The first beam is emitted from the third end of the detection module. The fourth end of the detection module is connected to the first end of the control module. The second end of the control module is connected to the third end of the laser module. The third end of the control module is connected to the fourth end of the laser module; The laser module is used to split the laser into multiple sub-beams and one reference beam; the synthesis module is used to synthesize the multiple sub-beams into a second beam; the detection module is used to separate the second beam into a third beam and the first beam, and detect the third beam and the reference beam to obtain a detection signal; the control module is used to obtain the detection signal, determine the phase difference between each sub-beam and the reference beam according to the detection signal, and compensate the phase of each sub-beam based on the phase difference.

2. The system according to claim 1, wherein The detection module includes a sampling mirror, a beam splitter, a focusing lens, and a photodetector that are sequentially distributed along the emission direction of the second beam. The sampling mirror and the beam splitter are arranged in parallel; The sampling mirror is used to separate the second beam to obtain the first beam and the third beam. The beam splitter is used to synthesize the third beam and the reference beam into a fourth beam and make it incident on the focusing lens. The photodetector is used to collect the detection signal and transmit it to the control module.

3. The system according to claim 1, wherein The control module includes a controller, a phase modulator, and an acousto-optic modulator. The phase modulator is provided on the branch corresponding to each sub-beam, and the acousto-optic modulator is provided on the branch corresponding to the reference beam; The first end of the controller is connected to the fourth end of the detection module. The second end of the controller is connected to the phase modulator. The third end of the controller is connected to the acousto-optic modulator. The controller is used to adjust the operating voltage of the phase modulator according to the phase difference.

4. The system according to any one of claims 1 to 3, characterized in that, The laser module includes a seed laser source, a first amplifier, a beam splitter, a second amplifier, and a collimator that are sequentially distributed. The seed laser source is used to emit the laser. The beam splitter is used to split the laser into multiple sub-beams and one reference beam.

5. The system according to claim 4, wherein The synthesis module is a sub-aperture coherent synthesis module or a common-aperture coherent synthesis module.

6. A single-step coherent synthesis phase-locking method based on a single detection signal, characterized in that, The method is used for the control module of the system according to any one of claims 1 to 5. The method includes: Obtaining the detection signal obtained by the detection module detecting the third beam and the reference beam, and determining the phase difference between each sub-beam and the reference beam according to the detection signal, where each sub-beam and the reference beam are obtained by splitting the laser of the laser module, the third beam is obtained by the detection module separating the second beam, and the second beam is obtained by the synthesis module synthesizing each sub-beam; Compensating the phase of each sub-beam based on the phase difference.

7. The method according to claim 6, wherein The detection signal is obtained by the following formula: = ； In the above formula, represents the voltage conversion coefficient of the detection module; represents the air refractive index, represents the vacuum permittivity, represents the speed of light; represents the composite optical field corresponding to the second light beam, represents taking the conjugate of the composite optical field; represents the detection area of the detection module; represents the power of the reference light beam irradiating on the detection surface of the detection module, represents the number of sub-light beams, represents the phase of the reference light beam, represents the modulation depth, represents the acousto-optic modulation angular frequency, represents time; represents the th sub-light beam of the third light beam irradiating on the detection surface of the detection module, represents the th sub-light beam of the third light beam, represents the th sub-light beam of the third light beam; represents the th sub-light beam of the third light beam irradiating on the detection surface of the detection module, represents the th sub-light beam of the third light beam, represents the th sub-light beam of the third light beam; 8. The method according to claim 7, wherein The phase difference is obtained by the following formula: ； ； ； In the above formula, represents the integration time, represents the first kind of Bessel function of the first order, represents the imaginary unit.

9. The method according to any one of claims 7 to 8, characterized in that The synthesized light field is obtained by the following formula: ； In the above formula, represents the amplitude of the reference beam, represents the laser central angular frequency of the laser module, represents the amplitude of the 10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps of the method according to any one of claims 6 to 9.

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