CN113937609B - Active phase locking method for fiber laser coherent synthesis based on Dammann vortex grating and fiber laser coherent synthesis system - Google Patents

Active phase locking method for fiber laser coherent synthesis based on Dammann vortex grating and fiber laser coherent synthesis system Download PDF

Info

Publication number
CN113937609B
CN113937609B CN202111201308.9A CN202111201308A CN113937609B CN 113937609 B CN113937609 B CN 113937609B CN 202111201308 A CN202111201308 A CN 202111201308A CN 113937609 B CN113937609 B CN 113937609B
Authority
CN
China
Prior art keywords
vortex
light beam
light
oam mode
fiber laser
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202111201308.9A
Other languages
Chinese (zh)
Other versions
CN113937609A (en
Inventor
夏辉
于涛
谢文科
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wuhan Moguang Technology Co.,Ltd.
Original Assignee
Central South University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Central South University filed Critical Central South University
Priority to CN202111201308.9A priority Critical patent/CN113937609B/en
Publication of CN113937609A publication Critical patent/CN113937609A/en
Application granted granted Critical
Publication of CN113937609B publication Critical patent/CN113937609B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/23—Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
    • G02B27/0938—Using specific optical elements
    • G02B27/0944—Diffractive optical elements, e.g. gratings, holograms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/10053—Phase control

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

The invention discloses an active phase locking method and a fiber laser coherent synthesis system based on fiber laser coherent synthesis of Dammann vortex grating, wherein the method comprises the following steps: splitting the currently output vortex light beam, wherein the low-power part is used as the vortex light beam to be detected; generating a vortex light beam array with known OAM mode distribution by utilizing a Dammann vortex grating; performing coaxial interference on the vortex light beam to be detected and each vortex light beam in the vortex light beam array, and detecting and calculating the light intensity of a target OAM mode corresponding to the solid light spot in the interference field; and selecting the light intensity of the solid light spot corresponding to the specified target OAM mode in the interference field as an evaluation function of an SPGD algorithm, calculating the phase control signal of each sub-beam in the next optical fiber laser array by using the SPGD algorithm, applying the phase control signal to a phase modulation module, and iterating for multiple times to realize the output of the vortex light beam with the adjustable OAM mode. The invention can realize high-power vortex light beam output and has the potential of outputting OAM mode diversity.

Description

Active phase locking method for fiber laser coherent synthesis based on Dammann vortex grating and fiber laser coherent synthesis system
Technical Field
The invention belongs to the field of fiber laser coherent synthesis and the field of light field regulation and control, and particularly relates to an active phase locking method and a fiber laser coherent synthesis system for fiber laser coherent synthesis based on Dammann vortex gratings.
Background
Theoretically, the Angular quantum number of the vortex light beam can be infinite and the carried Orbital Angular Momentum (OAM) modes are mutually orthogonal, so that the vortex light beam has a great application prospect in the fields of optical communication, optical storage, optical micro-control and the like. Especially in the remote application fields such as remote space optical communication and remote sensing speed measurement, higher requirements are provided for the power of vortex beams and the diversity of OAM modes.
The optical fiber laser coherent combining technology divides a seed laser light source into a plurality of paths of sub light sources, respectively amplifies the power of the plurality of paths of sub light sources to form a coherent array, realizes the coherent output of array light beams by controlling the phase synchronization among the light beams of each sub unit, and realizes the high-power laser output while keeping the high light beam quality. The independent regulation and control of parameters such as the phase, polarization, amplitude and the like of each path of sub-beams can be realized by adopting a sub-aperture coherent synthesis mode. Therefore, the fiber laser array coherent combination technology provides an effective technical approach for obtaining the high-power vortex beam required by practical application.
In practical application, since the influence of external environment and the thermal effect of a gain medium can introduce fiber laser phase noise, the phase noise can seriously influence the beam quality and the output power of a coherent-synthesized output beam, and the real-time control of the output beam phase of each laser unit is required to be realized by an active phase-locking method in order to realize the active coherent synthesis of a fiber laser array.
In the prior art, the Power In Bucket (PIB) is generally chosen as an evaluation function for the phase lock control, which is defined as the percentage of the total Power of the laser Power enclosed in a "Bucket" of a given size in the far field, which characterizes the energy concentration of the beam. The active phase-locking system of the traditional fiber laser coherent synthesis technology mainly comprises a light beam detection module and a phase control module. The beam detection module has the function of extracting PIB of signal light as an evaluation function of the active phase-locking system, and the phase control module converts the PIB into an electric signal and outputs the electric signal to the phase control system to realize closed-loop control of the system. However, the vortex light beam is a hollow annular light field, and effective light beam quality evaluation on the vortex light beam cannot be realized by selecting the PIB as an evaluation function of phase-locked control, so that the traditional phase-locked method is not suitable for generating the vortex light beam.
Therefore, in order to output a high-quality vortex beam, it is necessary to provide a new active phase-locking method for coherent combination of fiber lasers.
Disclosure of Invention
The invention aims to provide an active phase locking method and an optical fiber laser coherent synthesis system for optical fiber laser coherent synthesis based on a Dammann vortex grating.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
an active phase locking method for coherent synthesis of a coherent fiber laser array based on a Dammann vortex grating comprises the following steps:
splitting the currently output vortex light beam, wherein the low-power part is used as the vortex light beam to be detected and is used for active phase control;
generating a vortex light beam array by using a Dammann vortex grating, wherein each vortex light beam in the vortex light beam array corresponds to a known OAM mode, and all vortex light beams correspond to different OAM modes;
performing coaxial interference on the vortex light beam to be detected and each vortex light beam in the vortex light beam array, detecting an OAM mode component in the vortex light beam to be detected according to the fact whether the vortex light beam in the interference field has a solid light spot or not, and detecting and calculating the light intensity of a target OAM mode in the interference field corresponding to the solid light spot;
selecting the light intensity of a solid light spot corresponding to a specified target OAM mode in an interference field as an evaluation function of an SPGD algorithm, calculating a phase control signal of each sub-beam of the next optical fiber laser array by using the SPGD algorithm, applying the phase control signal to a phase modulator module, and performing iteration for multiple times until the algorithm is converged and the evaluation function value is not changed any more, wherein the target OAM mode intensity in the vortex light beam to be detected is stably converged to the maximum value, and the output of the vortex light beam with the adjustable OAM mode is realized.
Further, the method for detecting the OAM mode component in the vortex optical beam to be detected according to whether the vortex optical beam in the interference field has a solid light spot as a criterion comprises the following steps: and if the light spot is a solid light spot, an OAM mode opposite to the vortex light beam corresponding to the solid light spot exists in the vortex light beam to be detected.
Further, the method for detecting and calculating the light intensity of the solid light spot corresponding to the target OAM mode comprises the following steps: and acquiring images of the interference field by using a CCD camera, processing the acquired images and extracting information to obtain the light intensity of any one or more target OAM modes corresponding to the solid light spots in the images.
Further, the method for detecting and calculating the solid light spot light intensity corresponding to the target OAM mode comprises the following steps: and a photoelectric detector is adopted to collect the light intensity of the solid light spot corresponding to the target OAM mode in the light field.
Furthermore, the vortex light beam arrays are arranged at 5x5, and the OAM mode range covered by the vortex light beam arrays is-12.
Further, a lithium niobate phase modulator is adopted to perform phase-locked control on the corresponding sub-beams according to the phase control signal.
Fiber laser coherent synthesis system based on Dammann vortex grating includes: the device comprises a coherent fiber laser array module, a light beam processing module, a light beam detection module and a phase control module;
the coherent fiber laser array module is used for: amplifying, splitting, phase modulating and cascade amplifying the seed laser in sequence to obtain vortex light beam output;
the beam splitting processing module comprises a high reflector, a beam splitter, a Dammann vortex grating and a spatial light modulator;
the high reflector reflects the high-power part in the vortex optical rotation beam output by the coherent fiber laser array module, and the reflected part is used for practical application and transmits the low-power part;
the beam splitter splits the transmitted portion of the high-reflectivity mirror, the beam splitter being 50: 50 beam splitters, wherein one part of light beams are focused and converged on a CCD camera positioned on a focal plane through a lens, and the other part of light beams are incident to a spatial light modulator as vortex light beams to be detected;
the Dammann vortex grating is used for generating a vortex light beam array, wherein each vortex light beam in the vortex light beam array corresponds to a known OAM mode, and all vortex light beams correspond to different OAM modes;
the spatial light modulator is configured to: performing coaxial interference on the vortex light beam to be detected and each vortex light beam in the vortex light beam array;
the beam detection module is used for: detecting and calculating the light intensity of a target OAM mode in the vortex optical beam to be detected corresponding to the solid light spot;
the phase control module is configured to: selecting the light intensity of a solid light spot corresponding to a specified target OAM mode in an interference field as an evaluation function of an SPGD algorithm, calculating a phase control signal of each sub-beam in the next optical fiber laser array by using the SPGD algorithm, applying the phase control signal to a phase modulator, performing multiple iterations until the algorithm converges and the evaluation function value does not change any more, and then stably converging the target OAM mode intensity in the vortex light beam to be detected to the maximum value to realize the output of the vortex light beam with the adjustable OAM mode.
Furthermore, the light beam detection module adopts a CCD camera to collect images of the interference field, and adopts a processor to process and extract information of the collected images, so as to obtain the light intensity of any one or more target OAM modes corresponding to the solid light spots in the images.
Furthermore, the light beam detection module adopts a photoelectric detector to directly collect the light intensity of the solid light spot corresponding to the target OAM mode in the light field.
Has the advantages that: compared with the active phase locking scheme of the existing fiber laser array, the fiber laser array based on the active phase locking of the Dammann vortex grating can realize the output of high-power vortex beams, has the potential of realizing the diversity of output OAM modes, and accordingly expands the application scene of the vortex beams.
Drawings
FIG. 1 is a schematic structural diagram of a fiber laser coherent combining system generating vortex beams based on Dammann vortex grating
FIG. 2 is a schematic of an arrangement for generating a vortex beam;
FIG. 3: (a) the method comprises the following steps of (a) obtaining a phase diagram of a Dammann vortex grating, (b) obtaining a vortex light field array diagram, (c) obtaining an OAM mode distribution diagram, and (d) obtaining an OAM mode detection result diagram of a 1-order vortex light beam;
FIG. 4: (a) a near-field light field diagram of a 6-order synthesized vortex light beam, (b) a far-field light field diagram of the 6-order synthesized vortex light beam, (c) a Dammann vortex grating light field distribution diagram, and (d) an OAM mode spectrum of the Dammann vortex light field;
FIG. 5: (a) a synthetic vortex light beam with noise, (b) a Dammann vortex light field distribution diagram with noise, (c) an OAM mode spectrum affected by the noise, and (d) a light beam quality evaluation function convergence curve.
Detailed Description
The following describes embodiments of the present invention in detail, which are developed based on the technical solutions of the present invention, and give detailed implementation manners and specific operation procedures to further explain the technical solutions of the present invention.
The invention provides an active phase locking method for fiber laser coherent synthesis based on Dammann vortex grating, which comprises the following steps:
step 1, splitting the currently output vortex light beam, wherein the low-power part is used as the vortex light beam to be detected.
Specifically, a coherent fiber laser array module outputs vortex beams, referring to fig. 1, firstly, seed lasers are output from a seed source, the seed lasers are amplified by a preamplifier and split into multiple paths by a fiber beam splitter, each path of the sub beam lasers sequentially passes through a phase modulator and a cascade fiber amplifier, the phase modulator realizes real-time control of the phase of each path of the sub beam, the fiber amplifiers are used for improving the power of the sub beam, the sub beam array after power amplification is annularly distributed by a fiber collimator array and then is output to a free space, and a coherent fiber laser array is obtained, namely, a coherent synthesized vortex beam currently output by the coherent fiber laser array module.
The specific arrangement of the coherent fiber laser array is shown in FIG. 2, which includes N circ Each circular ring subarray is provided with unit beams uniformly distributed along the angular direction, and the beam waist radius of each unit beam is w 0 Wavelength λ and amplitude A 0 And the distance between the center of the unit beam on each circular ring subarray and the center of the whole coherent fiber laser array is R.
Defining the emitting end of the fiber collimator array as the initial emitting surface of the fiber laser array (z is 0m), wherein the optical field distribution of the emitting surface coherent fiber laser array is as follows:
Figure BDA0003305025470000041
wherein, (x, y) is the coordinates of the emitting surface, N j Is the jth ringThe number of unit beams included in the shape sub-array, (x) j,h ,y j,h )， j,h The center coordinate and the piston phase of the h unit beam on the j circular sub-array are shown. The central coordinate parameters of the unit beams satisfy:
Figure BDA0003305025470000042
wherein R is j The distance between the beam center of the jth circular sub-array unit and the center of the emitting area array is obtained. In order to generate vortex light beams with topological charge number l, the piston phase parameters of the unit light beams meet the following conditions:
Figure BDA0003305025470000043
the array light beam output by the optical fiber collimator is subjected to high reflection by a high reflection mirror, a reflection part with higher power is used for practical application of a system, a transmission light part with low power is divided into two parts by a beam splitter, one part of the light beam is focused and converged on a CCD camera positioned on a focal plane through a lens for observing a synthetic light spot, and the other part of the light beam is used as a vortex light beam to be detected and is incident to a spatial light modulator loaded with a Darman vortex grating kinoform so as to realize real-time detection of an OAM mode of the vortex light beam.
And 2, generating a vortex light beam array by using the Dammann vortex grating, wherein each vortex light beam in the vortex light beam array corresponds to a known OAM mode, and all vortex light beams correspond to different OAM modes.
The Dammann vortex grating is a special two-dimensional grating integrated with vortex phases, can be used for generating vortex beam arrays as a two-dimensional diffraction element, and vortex beams contained in the arrays have the characteristic of equal power. The two-dimensional dammann vortex grating designed in the embodiment of the present invention (as shown in fig. 3 (a)) can generate a 5 × 5 vortex beam array (as shown in fig. 3 (b)), and the corresponding OAM mode distributions are respectively shown in fig. 3 (c).
And 3, performing coaxial interference on the vortex light beam to be detected and each vortex light beam in the vortex light beam array, detecting an OAM mode component in the vortex optical beam to be detected according to the fact whether the vortex light beam in the interference field has a solid light spot or not as a criterion, and detecting and calculating the light intensity of a target OAM mode specified in the interference field corresponding to the solid light spot.
According to the characteristic that the vortex light beams with topological charge-difference signs interfere with each other and the hollow annular light field structure is degraded into solid light spots, the vortex light beams to be detected and the known vortex light beams of each OAM mode generated by the Dammann vortex grating are subjected to coaxial interference, and the existence of the solid light spots in a plurality of fields proves that the OAM mode opposite to the known topological charge-difference vortex light beams exists in the vortex light beams to be detected. Moreover, because all the vortex light beams of the known OAM mode are distributed in an array, under the condition that the OAM mode distribution is known, the parallel detection of all the OAM mode components in the vortex optical beam to be detected can be realized, and the quantitative analysis of the relative weight of each OAM mode component in the vortex optical beam to be detected can also be realized based on the characteristic of the equal power of the vortex light beam array.
In this embodiment, a detection result of the 1 st order vortex beam OAM mode based on the dammann vortex grating is shown in fig. 3(d), a solid light spot is detected at a position where the OAM mode of the vortex beam array is-1, and a real-time detection capability of the dammann vortex grating to the OAM mode in the vortex optical beam to be detected is proved.
When the target OAM mode component in the vortex optical rotation beam to be detected is obtained through detection, a light beam detection module is further adopted to detect and calculate the light field intensity (light intensity for short) of the solid light spot corresponding to the target OAM mode in the interference field. The specific detection calculation can adopt a CCD camera or a Photoelectric Detector (PD), and then the acquired signals are converted into electric signals through an AD conversion card and transmitted to a phase control module.
The CCD camera is used for collecting far-field light spot form distribution, image information of an interference field is collected, and after image processing and information extraction, light intensity of any one or more target OAM modes in the interference field corresponding to the solid light spots can be obtained, so that multi-mode multiplexing output is realized.
The PD is used for collecting light intensity signals of solid light spots corresponding to a single target OAM mode in an interference field, and has the advantages of high collection speed, high control bandwidth and good real-time performance of the active phase-locking system based on the PD.
Therefore, the CCD camera or the PD acquisition mode is selected and can be determined according to specific application scenes.
Step 4, selecting the light intensity of a designated target OAM mode in an interference field corresponding to a solid light spot as an evaluation function of an SPGD algorithm, calculating a phase control signal of each sub-beam of the next optical fiber laser array by using the SPGD algorithm, applying the phase control signal to a phase modulator module, and performing multiple iterations until the evaluation function value is not changed after the algorithm converges, wherein the target OAM mode intensity in the vortex light beam to be detected is stably converged to the maximum value at the moment, and the output of the vortex light beam with the adjustable OAM mode is realized, wherein the SPGD algorithm is a blind optimization algorithm, and the application in active phase-locked control belongs to the mature prior art, and the basic steps are as follows: the method comprises the steps of parallelly applying small forward and reverse random disturbances to a phase modulation module (the phase modulation module in the embodiment adopts a conventional lithium niobate phase modulator), obtaining an evaluation function, further calculating the change gradient of the evaluation function, applying feedback control to the phase modulator according to a gradient descent principle, and converging the evaluation function to the maximum value or the minimum value after multiple iterations, so that the phase-locked closed-loop control of the whole system is realized.
The method is based on the reason that the vortex light beams are hollow annular light fields, a plurality of vortex light beam arrays in known OAM modes are generated based on the Dammann vortex grating, the vortex light beams to be detected and the vortex light beams in the known OAM modes are coaxially interfered, the characteristic that the mutual interference between the vortex light beams in topological charge-opposite signs is degenerated into solid light spots is achieved, the light field intensity of the solid light spots corresponding to a target OAM mode in an interference field is innovatively selected as an evaluation function, finally, the SPGD algorithm is used for calculating the phase control signals of the sub light beams in an iterative mode, further, the iterative phase locking control is carried out on the phases of the sub light beams, and the target vortex light beams are output.
To demonstrate the beneficial effects of the present invention, a calculation example is given below to further describe the present invention:
lavery et al, 2013, in Science, propose a method for measuring a rotating target rotating speed by using superimposed vortex beams, and provide a feasible scheme for realizing remote sensing measurement of a remote target rotating speed. For long-distance measurement, it is necessary to generate a superimposed vortex beam with high power which can be transmitted over a long distance. The invention can prepare the high-power superposed vortex light beam for measuring the remote target rotating speed, and the specific scheme is as follows:
coherent synthesis vortex light beams generated based on the fiber laser coherent synthesis technology are special superimposed vortex light beams, and the OAM mode distribution of the coherent synthesis vortex light beams is related to the number M of sub light beams and loaded target topological charge l, specifically l-pM (p is an integer). In this example, an optical fiber laser array with M-12 circular ring arrangement is constructed, and a target vortex phase with l-6 loading order is used for generating a superimposed vortex beam with a topological charge number of plus or minus 6, where: parameters of the vortex coherent beam combination system are as follows: subarray number 12, laser beam waist radius w 0 The distance R between the center of each sub-beam and the origin is 1.2mm, the laser working wavelength is 1064nm, the target topological charge number is 6, and the piston phase difference between adjacent sub-beams is pi. First, a near-field optical field pattern, a far-field optical field pattern, a dammann vortex grating optical field distribution, and an OAM mode spectrum of a 6 th-order synthesized vortex beam were numerically calculated in the case of no phase noise in the coherent synthesis system, and the results are shown in fig. 4(a) to (d), respectively.
The result of fig. 4(c) shows that the dammann vortex grating designed in this experimental example can completely implement OAM mode detection on the synthetic vortex light beam, and a CCD camera can be selected for observing the dammann vortex light field distribution in the experiment.
Introducing phase noise on the basis, wherein fig. 5(a) - (c) are respectively a 6 th-order synthetic vortex light beam, a noise Dammann vortex optical rotation field diagram and an OAM mode spectrum influenced by the noise; in order to realize self-adaptive control of phase noise, solid light spot light field intensity in the positive and negative 6-order OAM mode detected by the Dammann vortex grating is selected as an evaluation function (as shown in circles in fig. 4(c) and 5 (b)), and the higher the light field intensity of the solid light spot is, the smaller the influence of noise on the positive and negative 6-order vortex light beams is, and the smaller the expansion of the target OAM mode to the adjacent mode is. In the experimental scheme, the light beam detection module can adopt a photoelectric detector and a pinhole to realize the extraction of an evaluation function, and then the evaluation function is output to the phase locking module through the A/D conversion card to carry out phase locking closed-loop control. The light beam evaluation function convergence curve shown in fig. 5(d) shows that the phase-locked output of the whole system can be realized only by iterating for about 70 steps, and the result proves that the active phase-locking scheme based on the dammann vortex grating can basically correct the positive and negative 6 superposed state synthetic vortex light beams influenced by phase noise to the theoretical synthetic vortex light beams without noise influence, so that the phase-locked output of the positive and negative 6 superposed state synthetic vortex light beams is realized, and the high-power superposed state vortex light beams capable of being used for remote target rotating speed measurement are prepared.
The above embodiments are preferred embodiments of the present application, and those skilled in the art can make various changes or modifications without departing from the general concept of the present application, and such changes or modifications should fall within the scope of the claims of the present application.

Claims (9)

1. The active phase locking method based on the fiber laser coherent synthesis of the Dammann vortex grating is characterized by comprising the following steps:
splitting the currently output vortex light beam, wherein the low-power part is used as the vortex light beam to be detected;
generating a vortex light beam array by using a Dammann vortex grating, wherein each vortex light beam in the vortex light beam array corresponds to a known OAM mode, and all vortex light beams correspond to different OAM modes;
performing coaxial interference on the vortex light beam to be detected and each vortex light beam in the vortex light beam array, detecting an OAM mode component in the vortex light beam to be detected according to the fact whether the vortex light beam in the interference field has a solid light spot or not, and detecting and calculating the light intensity of a target OAM mode in the interference field corresponding to the solid light spot;
selecting the light intensity of a solid light spot corresponding to a specified target OAM mode in an interference field as an evaluation function of an SPGD algorithm, calculating a phase control signal of each sub-beam of the next optical fiber laser array by using the SPGD algorithm, applying the phase control signal to a phase modulator module, and performing iteration for multiple times until the evaluation function value is not changed after the algorithm converges, wherein the target OAM mode intensity in the vortex light beam to be detected is stably converged to the maximum value, and the output of the vortex light beam with the adjustable OAM mode is realized.
2. The method according to claim 1, wherein the method for detecting OAM mode components in the vortex-spinning beam to be detected according to whether the vortex beam has a solid spot in the interference field as a criterion is as follows: and if the light spot is a solid light spot, an OAM mode opposite to the vortex light beam corresponding to the solid light spot exists in the vortex light beam to be detected.
3. The method according to claim 1, wherein the method for detecting and calculating the light intensity of the solid light spot corresponding to the target OAM mode comprises the following steps: and acquiring images of the interference field by using a CCD camera, processing the acquired images and extracting information to obtain the light intensity of any one or more target OAM modes corresponding to the solid light spots in the images.
4. The method according to claim 1, wherein the method for detecting and calculating the light intensity of the solid light spot corresponding to the target OAM mode comprises the following steps: and acquiring the light intensity of the target OAM mode corresponding to the solid light spot in the light field by using a photoelectric detector.
5. The method of claim 1, wherein the vortex beam array is arranged at 5x5, and the OAM mode range covered by the vortex beam array is-12 to 12.
6. The method of claim 1, wherein a lithium niobate phase modulator is employed to phase lock control the respective sub-beams according to the phase control signal.
7. Fiber laser coherent synthesis system based on Dammann vortex grating, its characterized in that includes: the device comprises a coherent fiber laser array module, a light beam processing module, a light beam detection module and a phase control module;
the coherent fiber laser array module is used for: amplifying, splitting, phase modulating and cascade amplifying the seed laser in sequence to obtain vortex light beam output;
the light beam processing module comprises a high reflector, a beam splitter, a Dammann vortex grating and a spatial light modulator;
the high reflector reflects the high-power part in the vortex optical rotation beam output by the coherent fiber laser array module, and the reflected part is used for practical application and transmits the low-power part;
the beam splitter splits the transmitted portion of the high-reflectivity mirror, the beam splitter being 50: 50 beam splitters, wherein a part of light beams are focused and converged on a CCD camera positioned on a focal plane through a lens, and the other part of light beams are used as vortex light beams to be detected and are incident to a spatial light modulator;
the Dammann vortex grating is used for generating a vortex light beam array, wherein each vortex light beam in the vortex light beam array corresponds to a known OAM mode, and all vortex light beams correspond to different OAM modes;
the spatial light modulator is configured to: performing coaxial interference on the vortex light beam to be detected and each vortex light beam in the vortex light beam array;
the beam detection module is used for: detecting and calculating the light intensity of a solid light spot corresponding to a target OAM mode in the vortex optical beam to be detected;
the phase control module is configured to: selecting solid light spot light intensity corresponding to a specified target OAM mode in an interference field as an evaluation function of an SPGD algorithm, calculating a phase control signal of each sub-beam of the next optical fiber laser array by using the SPGD algorithm, applying the phase control signal to a phase modulator module, performing iteration for multiple times until the algorithm is converged and the evaluation function value is not changed any more, and then stably converging the target OAM mode intensity in the vortex light beam to be detected to the maximum value to realize the output of the vortex light beam with the adjustable OAM mode.
8. The system according to claim 7, wherein the light beam detection module acquires an image of the interference field by using a CCD camera, and performs processing and information extraction on the acquired image by using a processor to obtain the light intensity of the solid light spot corresponding to any one or more target OAM modes in the image.
9. The system of claim 7, wherein the beam detection module employs a photodetector to directly collect the light intensity of the solid light spot corresponding to the target OAM mode in the interference light field.
CN202111201308.9A 2021-10-15 2021-10-15 Active phase locking method for fiber laser coherent synthesis based on Dammann vortex grating and fiber laser coherent synthesis system Active CN113937609B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111201308.9A CN113937609B (en) 2021-10-15 2021-10-15 Active phase locking method for fiber laser coherent synthesis based on Dammann vortex grating and fiber laser coherent synthesis system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111201308.9A CN113937609B (en) 2021-10-15 2021-10-15 Active phase locking method for fiber laser coherent synthesis based on Dammann vortex grating and fiber laser coherent synthesis system

Publications (2)

Publication Number Publication Date
CN113937609A CN113937609A (en) 2022-01-14
CN113937609B true CN113937609B (en) 2022-09-23

Family

ID=79279587

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111201308.9A Active CN113937609B (en) 2021-10-15 2021-10-15 Active phase locking method for fiber laser coherent synthesis based on Dammann vortex grating and fiber laser coherent synthesis system

Country Status (1)

Country Link
CN (1) CN113937609B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115102626B (en) * 2022-07-15 2024-01-16 长沙军民先进技术研究有限公司 Device and method for realizing space multi-polarization coding

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112162445A (en) * 2020-10-12 2021-01-01 中国人民解放军国防科技大学 Vortex light array generation method based on optical fiber laser coherent synthesis
CN112198668A (en) * 2020-10-19 2021-01-08 中国人民解放军国防科技大学 Optical field reconstruction system and method for generating vortex light beam by coherent synthesis of fiber laser

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112162445A (en) * 2020-10-12 2021-01-01 中国人民解放军国防科技大学 Vortex light array generation method based on optical fiber laser coherent synthesis
CN112198668A (en) * 2020-10-19 2021-01-08 中国人民解放军国防科技大学 Optical field reconstruction system and method for generating vortex light beam by coherent synthesis of fiber laser

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
"Orbital angular momentum mode detection of the combined vortex beam generated by coherent combining technology";Tao Yu et al.;《Optics Express》;20201123;第28卷(第24期);35795-35806页 *
"相干合成涡旋光束的螺旋谱分析及应用研究";彭一鸣 等;《物理学报》;20191231;第68卷(第21期);214206-1-10页 *

Also Published As

Publication number Publication date
CN113937609A (en) 2022-01-14

Similar Documents

Publication Publication Date Title
CN112198668B (en) Optical field reconstruction system and method for generating vortex light beam by coherent synthesis of fiber laser
CN108196244B (en) Optical fiber array phased array deflection transmitting system based on SPGD algorithm
CN112130337B (en) Synchronous control system and method for phase and inclined phase of fiber laser array piston
CN112255782B (en) Method for generating vortex light beam by inclined controllable coherent fiber laser array
CN101701847B (en) Imaging system for wide dynamic range based on optical grating and CCD imaging detector
CN101393376B (en) Coherent synthesis phase observe and control apparatus based on stripe characteristic extraction
CN207587399U (en) A kind of device that optical eddy is generated using coherent laser array
CN111725696B (en) Piston phase regulation and control system and method of laser coherent array
CN113394653B (en) Laser coherent array and control method
CN110632045A (en) Method and device for generating parallel super-resolution focal spots
CN112816181B (en) High-speed real-time optical fiber laser mode detection method and detection device thereof
CN102901957A (en) Receiving device for three-dimensional (3D) multispectral detection of stripe tube laser radar
CN113937609B (en) Active phase locking method for fiber laser coherent synthesis based on Dammann vortex grating and fiber laser coherent synthesis system
CN112162445B (en) Vortex light array generation method based on optical fiber laser coherent synthesis
CN111193167A (en) Fractal-based coherent fiber laser array and generation system thereof
CN107870441B (en) Optical fiber laser coherent synthesis method based on digital holography
CN104848945A (en) Coherent scanning wavefront detection method and system
CN110729628A (en) Piston phase control system and method
US7710639B2 (en) System and method for uniform illumination of a target area
CN112164973B (en) Phase control system and method for realizing orbital angular momentum light beam mode switching
CN109494563B (en) Doe coherent synthetic laser source based on ring cavity initiative light feedback
CN116125487A (en) Vortex beam comprehensive Doppler frequency shift measurement system and method
CN112803228B (en) Vortex light beam generation method based on spiral line arrangement phase-locked fiber laser array
CN112180613B (en) System and method for generating orbital angular momentum beams with switchable radial and angular orders
US9052497B2 (en) Computing imaging data using intensity correlation interferometry

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
TR01 Transfer of patent right
TR01 Transfer of patent right

Effective date of registration: 20230505

Address after: 430074 No. 2502, 25th Floor, Building A, Wuhan Optics Valley International Business Center, East of Guanshan Avenue and North of Chuangye Street, Wuhan East Lake New Technology Development Zone, Wuhan City, Hubei Province (Wuhan Area of Free Trade Zone)

Patentee after: Wuhan Moguang Technology Co.,Ltd.

Address before: Yuelu District City, Hunan province 410083 Changsha Lushan Road No. 932

Patentee before: CENTRAL SOUTH University