Laser coherent array phase calibration and control method
By building a laser coherent array and using a combination of coherent synthesis technology and phase controller, the problem of laser phase and polarization regulation in high-power laser arrays is solved, and flexible and simple regulation effect is achieved.
Patent Information
- Application Number
- CN202210230640.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-03-09
- Publication Date
- 2025-03-11
- Estimated Expiration
- 2042-03-09
AI Technical Summary
The prior art is difficult to achieve flexible and simple regulation of laser phase and polarization in high-power laser arrays, especially under high-power conditions.
By building a laser coherent array, the system phase error calibration is completed using coherent synthesis technology, and the phase locking and regulation of each laser channel is achieved using a high-speed phase controller and a low-speed phase controller respectively, and the polarization direction of the laser is adjusted through a half-wave plate.
It realizes flexible regulation of the phase and polarization of various lasers in high-power laser arrays, with simple calibration process and easy phase control.
Smart Images
Figure CN114628979B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of laser light field control, and in particular to a laser array phase and polarization control method. Background Art
[0002] Laser arrays can be widely used in laser communications, laser radar, and directed energy technology. Laser arrays based on master oscillator power amplifiers (MOPA) can achieve coherent synthesis of multiple lasers, increasing the total power while maintaining the beam quality of the array laser. If the piston phase of each laser can be flexibly controlled through light field control, array beams with special transmission characteristics such as vortex beams can also be obtained.
[0003] In order to realize the phase detection and regulation of each laser, the phase of each laser can be calibrated by using the interference fringe detection method. However, the above method is difficult to realize the flexible and simple regulation of the phase and polarization of each laser in a high-power laser array. Summary of the invention
[0004] The present invention provides a laser array phase and polarization control method, which can realize flexible control of the phase and polarization of each laser in a high-power laser array, and the phase and polarization calibration process is simple and the phase control is easy to realize.
[0005] To achieve the above object, the technical solution adopted by the present invention is:
[0006] On the one hand, the present invention provides a laser coherent array phase calibration method, comprising:
[0007] Build a laser coherent array: In the laser coherent array, N beams of sub-lasers are respectively input into the corresponding first beam splitter for splitting after passing through a phase modulator, a laser amplifier, and a laser collimator, wherein most of the laser power is output through the first output optical path of the first beam splitter, and the remaining small part of the laser power is output through the second output optical path of the first beam splitter; the laser output from the first output optical path of each first beam splitter is transmitted to the first laser beam combiner through a half-wave plate, and the first laser beam combiner is combined to output an array light beam, wherein the half-wave plate is used to change the polarization direction of each laser beam; the laser output from the second output optical path of each first beam splitter is transmitted to the second laser beam combiner through a spatial light phase modulator, and the second phase controller is connected to each spatial light phase modulator; the array light beam output by the second laser beam combiner reaches the first photodetector after passing through the first lens and the first pinhole, and the first photodetector is connected to the first phase controller, which is used to convert the detected optical signal into an electrical signal and transmit it to the first phase controller, and the first phase controller is connected to each phase modulator;
[0008] A second beam splitter is arranged on the output optical path of the first laser beam combiner, and a small portion of the array light beam is collected by the second beam splitter to the second lens and reaches the second photodetector after passing through the second small hole. The second photodetector is connected to the second phase controller and is used to convert the detected light signal into an electrical signal and transmit it to the second phase controller;
[0009] The phase difference between the combined output array beam of the first laser beam combiner and the combined output array beam of the second laser beam combiner is calibrated: firstly, the first phase controller is turned on, the phase control algorithm loaded on the first phase controller is run, and the voltage value output to each phase modulator is changed until the power in the bucket detected by the first photodetector maintains the maximum value; then the second phase controller is turned on, the phase control algorithm loaded on the second phase controller is run, and the voltage value output to each spatial light phase modulator is changed until the power in the bucket detected by the second photodetector reaches the maximum value, and the voltage value V output to each spatial light phase modulator when the power in the bucket detected by the second photodetector reaches the maximum value is recorded. i , i=1,2,…,N, and the calibration is completed.
[0010] After the phase calibration of the laser coherent array is completed by the above method, a laser coherent array phase control method is provided, comprising:
[0011] removing the second beam splitter, the second lens, the second pinhole and the second photodetector;
[0012] First, turn on the first phase controller, run the phase control algorithm loaded on the first phase controller, change the voltage value output to each phase modulator, until the power in the bucket detected by the first photodetector remains at the maximum value; then turn on the second phase controller, and directly output the voltage value to the i-th spatial optical phase modulator is the phase of the i-th laser in the array beam output from the first laser combiner, V π is the half-wave voltage of the spatial optical phase modulator.
[0013] In the present invention, the implementation method of N sub-lasers in the present invention is not limited. Preferably, the laser coherent array includes a seed laser and a laser beam splitter, and the seed laser is connected to the laser beam splitter to evenly divide the seed laser output by the seed laser into N sub-lasers, N≥2.
[0014] The present invention builds a laser coherent array and completes the system phase error calibration through coherent synthesis technology. The calibration process will not introduce new system errors and the calibration accuracy is high. The first phase controller is a high-speed phase controller, which uses a mature phase control algorithm to achieve phase locking of each laser. During the normal phase control process after the second phase controller completes the phase calibration of the laser coherent array, its direct output voltage value realizes the phase control of each laser.
[0015] In addition, the present invention can realize polarization control of each laser by directly adjusting each half-wave plate, and by individually setting the polarization direction of each laser, the array laser can form radial polarization distribution, circular polarization distribution, spiral polarization distribution, etc.
[0016] The present invention can realize flexible regulation of the phase and polarization of each laser in a high-power laser array, and the phase and polarization calibration process is simple and the phase control is easy to realize. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] 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 prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without creative work.
[0018] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention;
[0019] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention;
[0020] Numbers in the figure:
[0021] 1. Seed laser; 2. Laser beam splitter; 3. Phase modulator; 4. Laser amplifier; 5. Laser collimator; 6. First beam splitter; 7. Half-wave plate; 8. First laser beam combiner; 9. Spatial light phase modulator; 10. Second laser beam combiner; 11. First lens; 12. First pinhole; 13. First photodetector; 14. First phase controller; 15. Second phase controller; 16. Second beam splitter; 17. Second lens; 18. Second pinhole; 19. Second photodetector. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention more clearly understood, the following will be used with drawings and detailed descriptions to clearly illustrate the spirit of the contents disclosed by the present invention. After understanding the embodiments of the contents of the present invention, any person skilled in the art can change and modify the techniques taught by the contents of the present invention without departing from the spirit and scope of the contents of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.
[0023] Reference Figure 1, a laser coherent array provided in one embodiment includes a seed laser 1, a laser beam splitter 2, N phase modulators 3, N laser amplifiers 4, N laser collimators 5, N first beam splitters 6, N half-wave plates 7, a first laser beam combiner 8, N spatial light phase modulators 9, a second laser beam combiner 10, a first lens 11, a first aperture 12, a first photodetector 13, a first phase controller 14 and a second phase controller 15. The first phase controller 14 is a high-speed phase controller, and relative to the first phase controller 14, the second phase controller 15 adopts a low-speed phase controller. N is an integer and N≥2.
[0024] The seed laser 1 is connected to the input end of the laser beam splitter 2 , and the seed laser output by the seed laser 1 is evenly divided into N beams of sub-lasers by the laser beam splitter 2 .
[0025] The laser beam splitter 2 has N output ends, and the i-th output end is optically connected to the i-th phase modulator 3, where i=1, ..., N.
[0026] The phase modulator 3 is used to change the piston phase of each path of laser. The i-th phase modulator 3 is optically connected to the i-th laser amplifier 4, i=1, 2, ..., N.
[0027] The laser amplifier 4 is used to amplify the power of the sub-laser. The i-th laser amplifier 4 is optically connected to the i-th laser collimator 5, i=1, 2, ..., N.
[0028] The laser collimator 5 is used to collimate the laser output from the laser amplifier 4. The laser output from the laser collimator 5 is a linearly polarized laser with the same polarization direction. The output laser from the i-th laser collimator 5 is incident on the i-th first beam splitter 6, i=1, 2, ..., N.
[0029] The i-th first beam splitter 6 is used to split the output laser energy of the i-th laser collimator 5, wherein >99% of the laser energy is output through the first output optical path of the i-th first beam splitter 6, and the remaining <1% of the laser energy is output through the second output optical path of the i-th first beam splitter 6. A half-wave plate 7 is arranged on the first output optical path of each first beam splitter 6, and a spatial light phase modulator 9 is arranged on the second output optical path of each first beam splitter 6. The second phase controller 15 is connected to each spatial light phase modulator 9.
[0030] The half-wave plate 7 is used to change the polarization direction of each sub-laser by an angle θ i, i = 1, 2, ..., N. Each sub-laser outputted by each half-wave plate 7 is incident on the first laser beam combiner 8, and the first laser beam combiner 8 combines and outputs an array beam. The first laser beam combiner 8 can reduce the spacing between the incident sub-lasers of each path to form a tightly arranged array laser output.
[0031] The spatial light phase modulator 9 is used to change the piston phase of each laser. Each sub-laser output by each spatial light phase modulator 9 is incident on the second laser beam combiner 10, and the second laser beam combiner 10 combines and outputs an array beam. The second laser beam combiner 10 can also reduce the spacing between the incident sub-lasers of each path to form a tightly arranged array laser output.
[0032] The array light beam output by the second laser beam combiner 10 reaches the first photodetector 13 after passing through the first lens 11 and the first pinhole 12. The first photodetector 13 is connected to the first phase controller 14, which is used to convert the detected light signal into an electrical signal and transmit it to each first phase controller 14. The first phase controller 14 is connected to each phase modulator 3.
[0033] Build Figure 1 After the laser coherent array is shown, the present invention provides a calibration method for the laser coherent array, comprising:
[0034] Build a calibration device for laser coherent arrays,
[0035] like Figure 2 As shown, a second beam splitter 16 is arranged on the output optical path of the first laser beam combiner 8. The second beam splitter 16 collects a small part of the array light beam to the second lens 17 and reaches the second photodetector 19 after passing through the second small hole 18. The second photodetector 19 is connected to the second phase controller 15, and is used for converting the detected optical signal into an electrical signal and transmitting it to the second phase controller 15.
[0036] The phase difference between the array beam output by the first laser beam combiner 8 and the array beam output by the second laser beam combiner 10 is calibrated: first, the first phase controller 14 is turned on, and the phase control algorithm loaded on the first phase controller 14 is run to change the voltage value output to each phase modulator 3 until the power in the barrel detected by the first photodetector 13 maintains the maximum value; then the second phase controller 15 is turned on, and the phase control algorithm loaded on the second phase controller 15 is run to change the voltage value output to each spatial light phase modulator 9 until the power in the barrel detected by the second photodetector 19 reaches the maximum value, and the voltage value V output to each spatial light phase modulator 9 when the power in the barrel detected by the second photodetector 19 reaches the maximum value is recorded. i , i=1,2,…,N, and the calibration is completed.
[0037] The first lens 11, the first pinhole 12 and the first photodetector 13 are used to detect the barrel power of the far-field spot of the incident array light beam. Similarly, the second lens 17, the second pinhole 18 and the second photodetector 19 are used to detect the barrel power of the far-field spot of the incident array light beam.
[0038] The first phase controller 14 is used to correct the phase noise of each laser. Its input port is connected to the first photodetector 13, and the i-th output port is connected to the i-th phase modulator 3, i=1, 2, ..., N. The first phase controller 14 is a high-speed phase controller, which is pre-loaded with a phase control algorithm. By running the phase control algorithm, the voltage value output to each phase modulator 3 is changed so that the power in the barrel detected by the first photodetector 13 remains at the maximum value.
[0039] The second phase controller 15 is used to calibrate the phase difference between the array beams output by the first laser beam combiner 8 and the second laser beam combiner 10, and to adjust the phase of the array beam output by the first laser beam combiner 8. The i-th output port of the second phase controller 15 is connected to the i-th spatial optical phase modulator 9. During the calibration of the laser coherent array, its input port is connected to the second photodetector 19, and by running the phase control algorithm loaded thereon, the power in the barrel detected by the second photodetector 19 reaches the maximum value, and the voltage value V output to the i-th spatial optical phase modulator 9 is recorded. i After the calibration of the laser coherent array is completed, during the normal operation phase of the laser coherent array, the second phase controller 15 directly outputs a voltage value to the i-th spatial optical phase modulator 9. is the phase of the i-th laser beam output from the first laser beam combiner 8, V π is the half-wave voltage of the spatial optical phase modulator 9.
[0040] Specifically, an embodiment provides a laser coherent array phase control method, including:
[0041] Build as Figure 2 The phase calibration system of the laser coherent array shown in the figure adopts the laser coherent array phase calibration method provided in the above embodiment to complete the phase calibration of the laser coherent array, and then removes the second beam splitter 16, the second lens 17, the second aperture 18 and the second photodetector 19;
[0042] First, the first phase controller 14 is turned on, and the phase control algorithm loaded on the first phase controller 14 is run to change the voltage value output to each phase modulator 3 until the power in the bucket detected by the first photodetector 13 remains at the maximum value; then the second phase controller 15 is turned on to directly output the voltage value to the i-th spatial optical phase modulator 9 is the phase of the i-th laser beam in the array beam output from the first laser beam combiner 8, V π is the half-wave voltage of the spatial optical phase modulator 9.
[0043] The phase control algorithm in the present invention is not limited and may be a parallel gradient random descent algorithm, a single dithering algorithm or a multi-dithering algorithm.
[0044] In the present invention, the polarization direction of each laser path is individually adjusted by the half-wave plate corresponding to each laser path, so that the first laser beam combiner combines and outputs array beams with different polarization distributions. The specific polarization distribution method is not limited, including but not limited to separately adjusting the polarization direction of each laser path by the half-wave plate corresponding to each laser path, so that the first laser beam combiner combines and outputs array beams with radial polarization distribution, circular polarization distribution, or spiral polarization distribution.
[0045] 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.
[0046] The above-mentioned 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 patent. It should be pointed out that, for a person of ordinary skill in the art, several variations 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 patent of the present application shall be subject to the attached claims.
Claims
1. A laser coherent array phase calibration method, characterized in that: include: A laser coherent array is constructed, in which N sub-laser beams are respectively input into the corresponding first beam splitter for splitting after passing through a phase modulator, a laser amplifier, and a laser collimator, wherein most of the laser power is output through the first output optical path of the first beam splitter, and the remaining small part of the laser power is output through the second output optical path of the first beam splitter; the laser output from the first output optical path of each first beam splitter is transmitted to the first laser beam combiner through a half-wave plate, and the first laser beam combiner combines the laser beams to output an array light beam, wherein the half-wave plate is used to change the polarization direction of each laser beam; the laser output from the second output optical path of each first beam splitter is transmitted to the second laser beam combiner through a spatial light phase modulator, and the second phase controller is connected to each spatial light phase modulator; The array light beam output by the second laser beam combiner reaches the first photodetector after passing through the first lens and the first pinhole. The first photodetector is connected to the first phase controller, which is used to convert the detected light signal into an electrical signal and transmit it to the first phase controller. The first phase controller is connected to each phase modulator. A second beam splitter is arranged on the output optical path of the first laser beam combiner, and a small portion of the array light beam is collected by the second beam splitter to the second lens and reaches the second photodetector after passing through the second small hole. The second photodetector is connected to the second phase controller and is used to convert the detected light signal into an electrical signal and transmit it to the second phase controller; The phase difference between the array beam output by the first laser beam combiner and the array beam output by the second laser beam combiner is calibrated: first, the first phase controller is turned on, the phase control algorithm loaded on the first phase controller is run, and the voltage value output to each phase modulator is changed until the power in the bucket detected by the first photodetector remains at a maximum value; then the second phase controller is turned on, the phase control algorithm loaded on the second phase controller is run, and the voltage value output to each spatial light phase modulator is changed until the power in the bucket detected by the second photodetector reaches a maximum value, and the voltage value output to each spatial light phase modulator is recorded when the power in the bucket detected by the second photodetector reaches a maximum value. , , the calibration is now completed.
2. The laser coherent array phase calibration method according to claim 1, characterized in that: The laser coherent array comprises a seed laser and a laser beam splitter, wherein the seed laser is connected to the laser beam splitter to divide the seed laser outputted by the seed laser into Beam laser, .
3. The laser coherent array phase calibration method according to claim 1, characterized in that: The phase control algorithm is a parallel gradient random descent algorithm, a single dithering algorithm or a multi-dithering algorithm.
4. The laser coherent array phase calibration method according to claim 1, characterized in that: The polarization direction of each laser path is individually adjusted through the half-wave plate corresponding to each laser path, so that the first laser beam combiner combines the laser beams to output array light beams with different polarization distributions.
5. The laser coherent array phase calibration method according to claim 4, characterized in that: The polarization direction of each laser path is individually adjusted through the half-wave plate corresponding to each laser path, so that the first laser beam combiner combines the lasers to output an array beam with radial polarization distribution, circular polarization distribution or spiral polarization distribution.
6. A laser coherent array phase control method, characterized in that: include: After completing the phase calibration of the laser coherent array by the method as claimed in claim 1, removing the second beam splitter, the second lens, the second pinhole and the second photodetector; First, turn on the first phase controller, run the phase control algorithm loaded on the first phase controller, change the voltage value output to each phase modulator, until the power in the bucket detected by the first photodetector remains at the maximum value; then turn on the second phase controller, directly to the first phase controller. The output voltage of the spatial optical phase modulator , is the first laser beam output from the first laser beam combiner. The phase of the laser path, is the half-wave voltage of the spatial optical phase modulator.
7. The laser coherent array phase control method according to claim 6, characterized in that: The laser coherent array comprises a seed laser and a laser beam splitter, wherein the seed laser is connected to the laser beam splitter to divide the seed laser outputted by the seed laser into Beam laser, .
8. The laser coherent array phase control method according to claim 6 or 7, characterized in that: The phase control algorithm is a parallel gradient random descent algorithm, a single dithering algorithm or a multi-dithering algorithm.
9. The laser coherent array phase control method according to claim 8, characterized in that: The polarization direction of each laser path is individually adjusted through the half-wave plate corresponding to each laser path, so that the first laser beam combiner combines the laser beams to output array light beams with different polarization distributions.
10. The laser coherent array phase control method according to claim 8, characterized in that: The polarization direction of each laser path is individually adjusted through the half-wave plate corresponding to each laser path, so that the first laser beam combiner combines the lasers to output an array beam with radial polarization distribution, circular polarization distribution or spiral polarization distribution.