阅读说明：本技术 一种激光相干阵列分布式相位控制系统及控制方法 (Laser coherent array distributed phase control system and control method ) 是由 粟荣涛 龙金虎 靳凯凯 侯天悦 常琦 马阎星 马鹏飞 周朴 司磊 许晓军 陈金宝 于 2021-07-21 设计创作，主要内容包括：本申请涉及一种激光相干阵列分布式相位控制系统及控制方法。所述系统包括：激光相干阵列输出模块和分布式相位控制模块；分布式相位控制模块包括小透镜阵列、多个二级相位调制器、多个光纤耦合器、1个光纤端帽、多个光电探测器、一级相位控制系统、二级相位控制系统。二级相位控制器可有效控制阵列激光的波前信息,实现阵列激光的相干合成效果的实时控制；光纤耦合器将阵列光束的相位信息进行两两耦合探测,无需对整个阵列光束的相位信息进行统一探测,提高系统相位控制带宽；该系统具有全光纤化的特点,降低了热管理方面的压力,并提高了系统结构的紧凑性和可操作性。(The application relates to a laser coherent array distributed phase control system and a control method. The system comprises: the system comprises a laser coherent array output module and a distributed phase control module; the distributed phase control module comprises a lenslet array, a plurality of secondary phase modulators, a plurality of fiber couplers, 1 fiber end cap, a plurality of photodetectors, a primary phase control system and a secondary phase control system. The secondary phase controller can effectively control the wave front information of the array laser and realize the real-time control of the coherent combination effect of the array laser; the optical fiber coupler performs pairwise coupling detection on the phase information of the array light beam, so that the phase information of the whole array light beam does not need to be uniformly detected, and the phase control bandwidth of a system is improved; the system has the characteristic of full optical fiber, reduces the pressure in the aspect of thermal management, and improves the compactness and operability of the system structure.)

1. A laser coherent array distributed phase control system, the system comprising: the system comprises a laser coherent array output module and a distributed phase control module; the distributed phase control module comprises a small lens array, a plurality of secondary phase modulators, a plurality of optical fiber couplers, 1 optical fiber end cap, a plurality of photoelectric detectors, a primary phase control system and a secondary phase control system;

the laser coherent array output module outputs a laser coherent array and a plurality of paths of control laser beams for phase control, and inputs the plurality of paths of control laser beams into corresponding small lenses of the small lens array;

the lenslets of the lenslet array are connected with optical paths corresponding to the secondary phase modulators, one group of two secondary phase modulators is connected with an optical path of a first-stage optical fiber coupler, one group of two first-stage optical fiber couplers is connected with an optical path of a second-stage optical fiber coupler, the last optical fiber coupler is obtained when the number of the optical fiber couplers is 1, and the optical end cap is connected with the last optical fiber coupler; the secondary phase modulator applies piston phase shift to the laser beam output by the small lens according to a specific voltage value applied by a secondary phase control system;

the photoelectric detector is used for detecting laser energy output by the optical fiber coupler, converting an optical signal into a digital signal through photoelectric conversion, and transmitting the digital signal to the primary phase control system;

the primary phase control system is used for carrying out operation processing on the digital signal, outputting a control signal according to a preset phase control algorithm, inputting the control signal into the laser coherent array output module to control the laser phase, and enabling the laser coherent array output module to output a laser coherent array;

the secondary phase control system applies a specific voltage value to each secondary phase modulator to change the piston phase of each sub-beam, so as to control the coherent combination effect of the array beams in a far field.

2. The system of claim 1, wherein the laser coherent array output module comprises: a first phase modulator;

the mode of the system for phase control is as follows: after the primary phase modulator corrects the system phase noise according to the control signal output by the primary phase control system, the secondary phase modulator applies piston phase shift to each sub-beam passing through, and changes the piston phase of the emitted beam when the phase is locked next time, so that the piston phase after the phase change is conjugated with the piston phase applied by the secondary phase modulator, and the secondary phase modulator constructs the wave front of the emitted beam and controls the far field coherent synthesis effect.

3. The system of claim 1, wherein the fiber coupler is a2 x 2 fiber coupler or other similar fiber coupler; the optical fiber coupler is used for coupling and outputting the laser energy of the two sub-beams, and the proportion of the two output laser energy can be effectively changed by controlling the phase of the optical fiber coupler, so that a rear-end phase control system can conveniently perform phase control.

4. The system of claim 2, wherein the primary phase modulator and the secondary phase modulator are each LiNbO₃A phase modulator.

5. The system of claim 1, wherein the lenslet array is configured to focus each of the beamlets to concentrate a substantial portion of the laser energy at a small spot to facilitate coupling the substantial portion of the laser energy into the optical fiber.

6. A laser coherent array distributed phase control method, which is used for performing phase control on the laser coherent array distributed phase control system according to any one of claims 1 to 5; wherein; the number of the secondary phase modulators and the number of the photoelectric detectors are N, and the number of the optical fiber couplers are N-1; the method comprises the following steps:

the multi-channel control laser beam for phase control output by the laser coherent array output module is incident into a corresponding small lens of the small lens array, and the laser beam is coupled into an optical fiber;

applying piston phase shift to the coupled laser beam by using a secondary phase modulator to obtain a secondary phase modulation laser beam;

coupling the secondary phase modulation laser beams into the optical fiber coupler in pairs, detecting laser energy output by the optical fiber coupler by using a photoelectric detector, and converting the laser energy into digital signals to obtain N-1 paths of digital signals;

the N-1 paths of digital signals are used as feedback signals of phase control to be transmitted to a primary phase control system, and the digital signals are subjected to operation processing in the primary phase control system to obtain N paths of control signals;

inputting N paths of control signals into a primary phase modulator in a laser coherent array output module, changing the piston phase of each path of light beam, and acquiring feedback signals again for iterative control until the feedback signals are optimal, thereby realizing the same-phase output of the array laser;

when the system realizes phase locking, a secondary phase control system is operated, and a specific voltage signal is applied to the N secondary phase modulators, so that the piston phase of each sub-beam is changed, the equivalent wave front information of the emitted array laser is changed, and the coherent combination effect of the emitted array laser in a far field is controlled.

7. The method of claim 6, wherein when the system achieves phase locking, operating the secondary phase control system, and applying specific voltage signals to the N secondary phase modulators to change the piston phase of each sub-beam, so as to change the equivalent wavefront information of the emitted array laser and control the coherent combining effect in the far field, comprises:

sequentially applying phases to the N-way two-stage phase modulator Corresponding voltage makes the two-stage phase modulator sequentially generate the phase from the 1 st path to the Nth path WhereinWherein L represents the number of topological charges generated by coherent synthesis in the far field;

the piston phase distribution of the emitted array laser is obtained by controlling the secondary phase modulator to ensure that the phase of the emitted array laser becomes conjugate with the phase applied by the secondary phase modulator when the next algorithm is operated

Enabling the array laser to have spiral phase wave fronts in step distribution according to the piston phase distribution of the emitted array laser, and performing coherent synthesis in a far field to generate vortex beams with topological charge number L;

after changing the applied phase again, a vortex beam of another topological charge number can be generated in the far field.

Technical Field

The present application relates to the field of optical coherent combining technologies, and in particular, to a distributed phase control system and a distributed phase control method for a laser coherent array.

Background

The fiber laser coherent array based on Master Oscillator Power Amplifier (MOPA) is widely applied to the fields of active imaging and detection, directional energy and laser communication, and the like, because the fiber laser coherent array can realize synthetic aperture emission, increase the emission aperture of the system and reduce the transmission divergence angle of laser (see patents: CA2278071a1, CN103513428A, CN106451055B, CN103346470B and CN 110729628B).

Fig. 1 is a schematic structural diagram of a coherent array phase control system in the prior art. The system comprises a laser coherent array output module and a phase control module, wherein the laser alignment output module mainly comprises a laser seed source 101, a laser beam splitter 102, N phase modulators 103, N laser amplifiers 104, N collimators 105, N beam splitters 106 and N laser beam expanders 107; the phase control module mainly includes N spatial optical path adjusters 108, a laser beam combiner 109, a phase detection module 110, and a phase control circuit 111. Laser output by the laser seed source 101 is divided into N sub-beams by the laser beam splitter 102 and output, and each sub-beam enters the phase modulator 103. Each phase modulator 103 is optically connected to each corresponding laser amplifier 104. The laser amplifiers 104 are in turn optically connected to collimators 105, respectively. The N laser beams output from the collimator 105 are divided into two parts by N beam splitters 106 connected in the optical path: the laser power of the major part respectively enters the N laser beam expanders 107 to form array laser output; a small portion of the laser power is directed through the beam splitter 106 for phase control. Before the laser enters the phase detection module 110, N spatial optical path adjusters 108 are required to be arranged on the optical path to adjust the optical path of each path of laser, so that the array has high coherence to meet the condition of phase control, and then the array laser enters the laser beam combiner 109 to compress the distance between the array lasers, and finally is detected by the phase detection module 110, and a feedback signal is transmitted to the phase control circuit 111, so as to control the phase modulator 103 and correct the phase noise of the system.

Because the energy of the central main lobe is coherently synthesized by the far field of the array light beam as an evaluation function, as shown in fig. 1, the iteration time of the algorithm of the phase control is approximately proportional to the half power of the number of the arrays, and along with the increase of the number of the arrays, the iteration time of the algorithm seriously limits the rate of the phase control, reduces the bandwidth of the phase control and further reduces the coherent synthesis effect; meanwhile, the phase control is carried out by adopting the spatial light path structure, so that not only is the spatial light path adjuster 108 required to adjust the light path of each laser, but also the laser beam combiner 109 is required to reduce the beam of the array light beam and focus the light beam on the same pinhole detector, the weight and the volume of the system are increased by too many devices, the compactness of the system structure is reduced, and the pressure in the practical application aspects of thermal management and the like in high-power application is increased.

Disclosure of Invention

In order to overcome the defects of a phase control scheme in the prior art, a laser coherent array distributed phase control system and a control method are provided.

A laser coherent array distributed phase control system, the system comprising: the system comprises a laser coherent array output module and a distributed phase control module; the distributed phase control module comprises a small lens array, a plurality of secondary phase modulators, a plurality of optical fiber couplers, 1 optical fiber end cap, a plurality of photoelectric detectors, a primary phase control system and a secondary phase control system.

The laser coherent array output module outputs a laser coherent array and a plurality of paths of control laser beams for phase control, and inputs the plurality of paths of control laser beams into corresponding small lenses of the small lens array;

the lenslets of the lenslet array are connected with optical paths corresponding to the secondary phase modulators, one group of two secondary phase modulators is connected with an optical path of a first-stage optical fiber coupler, one group of two first-stage optical fiber couplers is connected with an optical path of a second-stage optical fiber coupler, the last optical fiber coupler is obtained when the number of the optical fiber couplers is 1, and the optical end cap is connected with the last optical fiber coupler; the secondary phase modulator applies a piston phase shift to the laser beam output by the lenslets according to a specific voltage value applied by the secondary phase control system.

The photoelectric detector is used for detecting laser energy output by the optical fiber coupler, converting an optical signal into a digital signal through photoelectric conversion, and transmitting the digital signal to the primary phase control system.

And the primary phase control system performs operation processing on the digital signal, outputs a control signal according to a preset phase control algorithm, and inputs the control signal into the laser coherent array output module to control the laser phase so that the laser coherent array output module outputs a laser coherent array.

The secondary phase control system applies a specific voltage value to each secondary phase modulator to change the piston phase of each sub-beam, so as to control the coherent combination effect of the array beams in a far field.

In one embodiment, the laser coherent array output module comprises: a first phase modulator; the mode of the system for phase control is as follows: after the primary phase modulator corrects the system phase noise according to the control signal output by the primary phase control system, the secondary phase modulator applies piston phase shift to each sub-beam passing through, and changes the piston phase of the emitted beam when the phase is locked next time, so that the piston phase after the phase change is conjugated with the piston phase applied by the secondary phase modulator, and the secondary phase modulator constructs the wave front of the emitted beam and controls the far field coherent synthesis effect.

In one embodiment, the optical fiber coupler is a2 × 2 optical fiber coupler or other similar optical fiber coupler; the optical fiber coupler is used for coupling and outputting the laser energy of the two sub-beams, and the proportion of the two output laser energy can be effectively changed by controlling the phase of the optical fiber coupler, so that a rear-end phase control system can conveniently perform phase control.

In one embodiment, the primary phase modulator and the secondary phase modulator are LiNbO₃A phase modulator.

In one embodiment, the lenslet array is used to focus each beamlet to concentrate a substantial portion of the laser energy at a small spot, facilitating coupling of the substantial portion of the laser energy into the fiber.

A laser coherent array distributed phase control method is used for carrying out phase control on any one laser coherent array distributed phase control system; wherein; the number of the secondary phase modulators is N, and the number of the optical fiber couplers and the number of the photoelectric detectors are N-1; the method comprises the following steps:

and the multipath control laser beams for phase control output by the laser coherent array output module are incident into corresponding lenslets of the lenslet array, and the laser beams are coupled into the optical fiber.

And applying piston phase shift to the coupled laser beam by adopting a secondary phase modulator to obtain a secondary phase modulation laser beam.

And coupling the secondary phase modulation laser beams into the optical fiber coupler in pairs, detecting laser energy output by the optical fiber coupler by using a photoelectric detector, and converting the laser energy into digital signals to obtain N-1 paths of digital signals.

And (3) taking the N-1 paths of digital signals as feedback signals of phase control, transmitting the feedback signals to a primary phase control system, and performing operation processing on the digital signals in the primary phase control system to obtain N paths of control signals.

And inputting the N paths of control signals into a primary phase modulator in a laser coherent array output module, changing the piston phase of each path of light beam, and acquiring the feedback signals again for iterative control until the feedback signals reach the optimal value, thereby realizing the same-phase output of the array laser.

When the system realizes phase locking, a secondary phase control system is operated, and specific voltage signals are applied to a plurality of secondary phase modulators, so that the piston phase of each sub-beam is changed, the equivalent wave front information of the emitted array laser is changed, and the coherent combination effect of the emitted array laser in a far field is controlled.

In one embodiment, after the system achieves phase locking, the secondary phase control system is operated to apply a specific voltage signal to the N secondary phase modulators, so that the piston phase of each sub-beam is changed, thereby changing equivalent wavefront information of the emitted array laser, and further controlling the coherent combining effect in the far field, including:

sequentially applying phases to the N-way two-stage phase modulatorCorresponding voltage makes the two-stage phase modulator sequentially generate the phase from the 1 st path to the Nth path WhereinWhere L represents the number of topological charges generated by coherent synthesis in the far field.

The piston phase distribution of the emitted array laser is obtained by controlling the secondary phase modulator to ensure that the phase of the emitted array laser becomes conjugate with the phase applied by the secondary phase modulator when the next algorithm is operated

According to the piston phase distribution of the emitted array laser, the array laser has spiral phase wave fronts in step distribution, and the spiral phase wave fronts are coherently synthesized in a far field to generate vortex beams with topological charge number L.

After changing the applied phase again, a vortex beam of another topological charge number can be generated in the far field.

The above laser coherent array distributed phase control system and control method, the system includes: the system comprises a laser coherent array output module and a distributed phase control module; the distributed phase control module comprises a lenslet array, a plurality of secondary phase modulators, a plurality of fiber couplers, 1 fiber end cap, a plurality of photodetectors, a primary phase control system and a secondary phase control system. The secondary phase controller can effectively control the wave front information of the array laser, so that the coherent combination effect of the array laser can be controlled in real time; the optical fiber coupler carries out pairwise coupling detection on the phase information of the array light beam, and the grouped detection mode is adopted without carrying out unified detection on the phase information of the whole array light beam, so that the algorithm iteration time is reduced, the phase control bandwidth of the system is improved, the defect that the phase control bandwidth of the existing coherent array is greatly reduced along with the increase of the number of arrays is overcome, and the feasibility of the path number expansion of the system is improved; meanwhile, the phase control module has the characteristic of full optical fiber, overcomes the defect that a laser beam combiner, a spatial optical path adjusting device and other complex devices are needed in a spatial optical path, is convenient to operate, reduces the pressure in the aspect of thermal management, and further improves the compactness and operability of the system structure.

Drawings

FIG. 1 is a schematic block diagram of a distributed phase control system of a prior art laser coherent array;

FIG. 2 is a block diagram illustrating a distributed phase control system for a coherent laser array in accordance with an embodiment;

fig. 3 is a schematic flow chart of a laser coherent array distributed phase control method in another embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In one embodiment, as shown in fig. 2, there is provided a laser coherent array distributed phase control system, comprising: the system comprises a laser coherent array output module and a distributed phase control module; the distributed phase control module includes: a lenslet array 208, a plurality of secondary phase modulators 209, a plurality of fiber couplers 210, 1 fiber end cap 212, a plurality of photodetectors 211, a primary phase control system 213, and a secondary phase control system 214.

Preferably, the laser coherent array output module includes: the laser seed source 201, the laser beam splitter 202 and more than 2 optical paths; the optical path includes a first-stage phase modulator 203, a laser cascade amplifier 204, a laser collimator 205, a beam splitter 206, and a laser beam expander 207, which are connected in turn. The laser seed source 201, the laser beam splitter 202 and the optical path are connected in sequence by optical paths. The laser beam splitter 202 splits the input laser beam generated by the laser seed source 201 into laser beams corresponding to the number of optical paths.

The primary phase modulator 203 is used to correct the system phase noise according to the control signal output by the primary phase control system 213. The laser beam expander 207 expands the high-power laser output by the beam splitter array 206 to obtain large-aperture emission and a small transmission divergence angle; on the other hand, the coherent array is constructed into a sub-aperture emission mode, and the arrangement form of the laser is set according to the requirement.

99.99% of the laser energy split by the beam splitter 206 is transmitted to the laser beam expander 207, and 0.01% of the laser energy is incident on the corresponding lenslets of the lenslet array 208 in the distributed phase control module.

The lenslets of the lenslet array 208 are optically connected with corresponding secondary phase modulators 209, one set of two secondary phase modulators 208 is optically connected with a first-stage optical fiber coupler 210, one set of two first-stage optical fiber couplers 210 is optically connected with a second-stage optical fiber coupler 210, until the number of the optical fiber couplers 210 is 1, the last optical fiber coupler 210 is obtained, and the optical fiber end cap 212 is connected with the last optical fiber coupler 210; the secondary phase modulator 209 applies a piston phase shift to the laser beam output by the lenslets according to a particular voltage level applied by the secondary phase control system 214.

The number of the two-stage phase modulators 209 corresponds to the number of optical paths in the laser coherent array output module.

And the optical fiber end cap 212 is used for blocking one path of laser light output by the last optical fiber coupler 210 and preventing the laser light from leaking into the space.

And the photodetector 211 is configured to detect laser energy output by the fiber coupler 210, convert an optical signal into a digital signal through photoelectric conversion, and transmit the electrical signal to the primary phase control system 213.

The number of photodetectors 211 corresponds to the number of fiber couplers 210, the number of fiber couplers 210 being one less than the number of secondary phase modulators 209.

The first-stage phase control system 213 performs operation processing on the digital signal, outputs a control signal according to a predetermined phase control algorithm, and inputs the control signal into the laser coherent array output module 203 to control the laser phase so that the laser coherent array output module outputs a laser coherent array meeting the requirement.

And the secondary phase control system 214 is used for controlling the secondary phase modulators 209, and applying a specific voltage value to each secondary phase modulator 209 to change the piston phase of each sub-beam so as to control the coherent combination effect of the array beams in the far field.

In the above laser coherent array distributed phase control system, the system includes: the system comprises a laser coherent array output module and a distributed phase control module; the distributed phase control module comprises a lenslet array, a plurality of secondary phase modulators, a plurality of fiber couplers, 1 fiber end cap, a plurality of photodetectors, a primary phase control system and a secondary phase control system. The secondary phase controller can effectively control the wave front information of the array laser, so that the coherent combination effect of the array laser can be controlled in real time; the optical fiber coupler carries out pairwise coupling detection on the phase information of the array light beam, and the grouped detection mode is adopted without carrying out unified detection on the phase information of the whole array light beam, so that the algorithm iteration time is reduced, the phase control bandwidth of the system is improved, the defect that the phase control bandwidth of the existing coherent array is greatly reduced along with the increase of the number of arrays is overcome, and the feasibility of the path number expansion of the system is improved; meanwhile, the phase control module has the characteristic of full optical fiber, overcomes the defect that a laser beam combiner, a spatial optical path adjusting device and other complex devices are needed in a spatial optical path, is convenient to operate, reduces the pressure in the aspect of thermal management, and further improves the compactness and operability of the system structure.

In one embodiment, the laser coherent array output module comprises: a first phase modulator; the system is used for phase control in the following modes: after the primary phase modulator corrects the system phase noise according to the control signal output by the primary phase control system, the secondary phase modulator applies piston phase shift to each sub-beam passing through, and changes the piston phase of the emitted beam when the phase is locked next time, so that the piston phase after the phase change is conjugated with the piston phase applied by the secondary phase modulator, and the wavefront of the emitted beam is constructed by the secondary phase modulator to control the far field coherent synthesis effect.

In one embodiment, the fiber coupler is a2 × 2 fiber coupler or other similar fiber coupler; the optical fiber coupler is used for coupling and outputting the laser energy of the two sub-beams, and the proportion of the two output laser energy can be effectively changed by controlling the phase of the optical fiber coupler, so that a rear-end phase control system can conveniently perform phase control.

In one embodiment, the primary phase modulator and the secondary phase modulator are both LiNbO₃A phase modulator.

In one embodiment, the lenslet array is used to focus each beamlet to concentrate a substantial portion of the laser energy at a small spot, facilitating coupling of the substantial portion of the laser energy into the fiber.

In one embodiment, as shown in fig. 3, a laser coherent array distributed phase control method is provided, which is used for performing phase control on any one of the laser coherent array distributed phase control systems; wherein; the number of the secondary phase modulators and the number of the photoelectric detectors are N, and the number of the optical fiber couplers are N-1; the method comprises the following steps:

step 300: and the multipath control laser beams for phase control output by the laser coherent array output module are incident into corresponding lenslets of the lenslet array, and the laser beams are coupled into the optical fiber.

Step 302: and applying piston phase shift to the coupled laser beam by adopting a secondary phase modulator to obtain a secondary phase modulation laser beam.

Step 304: and coupling the secondary phase modulation laser beams into the optical fiber coupler in pairs, detecting laser energy output by the optical fiber coupler by using a photoelectric detector, and converting the laser energy into digital signals to obtain N-1 paths of digital signals.

Step 306: and (3) taking the N-1 paths of digital signals as feedback signals of phase control, transmitting the feedback signals to a primary phase control system, and carrying out operation processing on the digital signals in the primary phase control system to obtain N paths of control signals.

Step 308: and inputting the N paths of control signals into a primary phase modulator in a laser coherent array output module, changing the piston phase of each path of light beam, and acquiring the feedback signals again for iterative control until the feedback signals reach the optimal value, thereby realizing the same-phase output of the array laser.

Step 310: when the system realizes phase locking, a secondary phase control system is operated, and a specific voltage signal is applied to the N secondary phase modulators, so that the piston phase of each sub-beam is changed, the equivalent wave front information of the emitted array laser is changed, and the coherent combination effect of the emitted array laser in a far field is controlled.

According to the laser coherent array distributed phase control method, the wavefront information of the array laser can be effectively controlled by controlling the secondary phase modulator, so that the coherent combination effect of the array laser can be controlled in real time; the phase information of the array light beams is subjected to pairwise coupling detection through the optical fiber coupler, the phase information of the whole array light beams does not need to be uniformly detected in a grouping detection mode, the algorithm iteration time is effectively reduced, the phase control bandwidth of the system is favorably improved, the defect that the phase control bandwidth of the existing coherent array is greatly reduced along with the increase of the number of the arrays is overcome, and the feasibility of the path number expansion of the system is improved; meanwhile, the phase control module has the characteristic of full optical fiber, overcomes the defect that complex devices such as the laser beam combiner 109 and the spatial optical path adjusting device 108 are needed in a spatial optical path, is convenient to operate, reduces the pressure in the aspect of thermal management, and further improves the compactness and operability of the system structure.

In one embodiment, step 310 further comprises: sequentially applying phases to the N-way two-stage phase modulatorCorresponding voltage makes the two-stage phase modulator sequentially generate the phase from the 1 st path to the Nth pathWhereinWherein L represents the number of topological charges generated by coherent synthesis in the far field; the piston phase distribution of the emitted array laser is obtained by controlling the secondary phase modulator to ensure that the phase of the emitted array laser becomes conjugate with the phase applied by the secondary phase modulator when the next algorithm is operated Enabling the array laser to have spiral phase wave fronts in step distribution according to the piston phase distribution of the emitted array laser, and performing coherent synthesis in a far field to generate vortex beams with topological charge number L; after changing the applied phase again, a vortex beam of another topological charge number can be generated in the far field.

It should be understood that, although the steps in the flowchart of fig. 3 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 3 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

In one embodiment, a laser coherent array distributed phase control system is controlled to generate structured light such as a high-power vortex beam. A vortex light beam mode high-speed switching method is provided, and comprises the following steps:

firstly, seed laser 201 is divided into N paths of laser output by a laser beam splitter 202, then each path of laser realizes high-power laser output after a primary phase modulator 203 and a cascade amplifier 204, then the array laser is divided into two parts by a collimator 205 and a beam splitter array 206, 99.99% of laser energy is emitted into corresponding N laser beam expanders 207, and the N paths of laser beams are arranged into a specific array laser emission form after being expanded and output; 0.01% of the laser energy is transmitted through beam splitter array 206 and used for phase control.

Secondly, 0.01% of laser energy is coupled into the optical fiber after passing through the lenslet array 208, is coupled into the optical fiber coupler 210 after passing through the secondary phase modulator 209, and finally is detected by the photodetector 211 and converted into a digital signal, which is transmitted to the primary phase control system 213 as a feedback signal for phase control; and through the processing operation of the primary phase control system 213, N paths of control signals are generated, the primary phase modulator 203 is respectively controlled, the piston phase of each path of light beam is changed, and then the feedback signals are acquired again for iterative control until the feedback signals reach the optimal value, so that the same-phase output of the array laser is realized.

Finally, when the system isAfter the system achieves phase locking, the secondary phase control system 214 operates to apply a specific voltage signal to the N secondary phase modulators 209, the signal level of which is equal to LiNbO₃The voltage phase shift curves of the phase modulators correspond; in order to obtain a vortex light beam with topological charge number L, sequentially applying voltage with corresponding phases from L multiplied by 2 pi/N to L multiplied by 2 pi to the N paths of secondary phase modulators 209, so that the secondary phase modulators 209 sequentially generate the vortex light beams with the phases of L multiplied by 2 pi/N, 2 multiplied by 2 pi/N, … … and L multiplied by 2 pi from the 1 st path to the N path; so that the phase of the emitted array laser becomes conjugate with the phase applied by the secondary phase modulator 209 when the algorithm of the next step is run, and the piston phase distribution of the emitted array laser is-lx 2 pi/N, -2 xl x 2 pi/N, … …, -lx 2 pi; therefore, the array laser has spiral phase wave fronts in step distribution, and finally generates vortex beams with topological charge number L in a far field through coherent synthesis; after changing the applied phase again, a vortex beam of another topological charge number can be generated in the far field.

Therefore, by controlling the secondary phase modulator 209, the phase wavefront of the emitted array laser can be effectively controlled, so that the array laser has a spiral phase wavefront with a certain number of topological charge, and further generates a vortex light beam by coherent synthesis in a far field; and the first-stage phase modulator 203 and the second-stage phase modulator 209 are both LiNbO₃The phase modulator has response frequency up to several GHz and precision up to one thousandth of wavelength, so that the mode of the vortex light beam generated by the method has high-speed switching capacity, compared with the vortex light beam generated by the liquid crystal space optical phase modulator, the switching speed of the vortex light beam can be increased from the KHz magnitude to the MHz or GHz magnitude, and a novel method is provided for more application requirements of the vortex light beam.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.