A composite vortex beam separating device and method

Abstract

The application discloses a composite vortex light beam separation device and method, relates to the technical field of mode demultiplexing, and comprises an optical compensation module, a first CCD detector, an optical separation module, a second CCD detector and a data processing module; the first CCD detector, the optical compensation module, the optical separation detector module and the second CCD detector are connected with the data processing module; the first CCD detector and the optical separation module are arranged on an emergent light path of the optical compensation module; and the second CCD detector is arranged on an emergent light path of the optical separation module. The application can realize efficient parallel separation of vortex light of different mode families in a composite vortex light beam.

Description

Technical Field

[0001] This application relates to the field of mode demultiplexing technology, and in particular to a composite vortex beam separation device and method. Background Technology

[0002] Vortex beams, with their helical phase structure and intrinsic orbital angular momentum (OAM) characteristics, hold significant application value in space optical communication. Different vortex beams possess differentiated phase distributions, transmission characteristics, and mode orthogonality, allowing them to serve as independent information carriers for loading information. Composite vortex beam fields formed by coaxial beam combining can overcome the channel dimension limitations of single-mode multiplexing, further enhancing the information capacity and spectral efficiency of space optical communication.

[0003] Existing technologies for vortex beam pattern recognition and separation mostly focus on separating orthogonal vortex modes of the same type of vortex beam with different topological charges or radial orders. Mainstream solutions include mode projection, Fourier domain filtering, and coordinate transformation. These solutions have achieved mature low-crosstalk separation in fixed multiplexing scenarios with the same type of vortex beam mode. However, for separating mixed fields of different types of vortex beams, existing technologies still have significant shortcomings: First, the few solutions that can adapt to the separation of different types of vortex beam modes often require cascading multiple sets of optical elements and multi-channel detection systems. These devices are complex in structure, have low integration, and are extremely poor at withstanding wavefront distortion introduced by free-space transmission. Distortion further damages the characteristic phase structure of different vortex beam modes, leading to a sharp deterioration in separation performance. Second, existing solutions are mostly fixed-structure open-loop designs, only adaptable to preset mode combinations. When faced with composite vortex beam inputs, they struggle to simultaneously handle parallel separation of different modes and adaptive feedback optimization for distortion and dynamic mode changes, severely limiting the application of cross-mode vortex beam multiplexing technology in practical space optical communication systems. Summary of the Invention

[0004] The purpose of this application is to provide a composite vortex beam separation device and method that can achieve efficient parallel separation of vortex beams of different mode families in a composite vortex beam.

[0005] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a composite vortex beam splitting device, comprising: an optical compensation module, a first CCD detector, an optical splitting module, a second CCD detector, and a data processing module; the first CCD detector, the optical compensation module, the optical splitting detection module, and the second CCD detector are connected to the data processing module; the first CCD detector and the optical splitting module are disposed in the output light path of the optical compensation module; the second CCD detector is disposed in the output light path of the optical splitting module. The optical compensation module processes the composite vortex beam to be separated based on the pre-compensation phase to obtain a pre-compensated beam; the first CCD detector acquires the pre-compensated beam and transmits it to the data processing module; the data processing module determines whether the pre-compensated beam meets the compensation requirements; if it does not meet the compensation requirements, the data processing module updates the pre-compensation phase, and the optical compensation module processes the composite vortex beam to be separated based on the updated pre-compensation phase until the compensation requirements are met; if the compensation requirements are met, a compensated composite vortex beam is obtained based on the pre-compensated beam. The optical separation module processes and compensates the composite vortex beam to obtain a separated beam; the second CCD detector acquires the separated beam and transmits it to the data processing module; the data processing module determines whether the separated beam meets the separation requirements; if it does not meet the separation requirements, the data processing module updates the parameters of the optical compensation module and the optical separation module, and uses the updated optical compensation module and the optical separation module to process the composite vortex beam to be separated until the separation requirements are met; if the separation requirements are met, the separated composite beam is obtained based on the separated beam and output to the external receiving surface.

[0006] Secondly, this application provides a method for separating a composite vortex beam, applied to the aforementioned composite vortex beam separating device; the method includes: Using an optical compensation module, a pre-compensated beam is obtained by pre-compensating the phase of the composite vortex beam to be separated. Determine whether the pre-compensated beam meets the compensation requirements; if it does not meet the compensation requirements, update the pre-compensation phase, and process the composite vortex beam to be separated based on the updated pre-compensation phase until the compensation requirements are met; if the compensation requirements are met, obtain the compensated composite vortex beam based on the pre-compensated beam. The compensated composite vortex beam is processed using an optical separation module to obtain a separated beam. Determine whether the separated beam meets the separation requirements; if it does not meet the separation requirements, update the parameters of the optical compensation module and the optical separation module, and use the updated optical compensation module and the optical separation module to process the composite vortex beam to be separated until the separation requirements are met; if the separation requirements are met, obtain the separated composite beam based on the separated beam.

[0007] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a composite vortex beam separation device and method. By using an optical compensation module to pre-compensate the composite vortex beam to be separated based on the pre-compensated phase, combined with a first CCD detector and compensation requirements, the optical compensation module finally outputs a compensated beam that meets the compensation requirements, thereby obtaining a compensated composite vortex beam. This corrects problems such as phase distortion of the composite vortex beam caused by channel interference, and provides a foundation for subsequent efficient separation. By employing an optical separation module to process and compensate the composite vortex beam, combined with a second CCD detector and separation requirements, the optical separation module outputs a separated beam that meets the separation requirements, thus obtaining a separated composite beam. Furthermore, when the separated beam does not meet the separation requirements, the parameters of the optical compensation module and the optical separation module are updated through a data processing module. The updated optical compensation module and optical separation module are then used to process the composite vortex beam to be separated, forming a closed-loop feedback optimization structure. This solves the problems in existing schemes, such as the extremely poor wavefront distortion tolerance introduced by free space transmission, the distortion further destroying the characteristic phase structure of different vortex light modes, leading to a sharp deterioration in separation performance, and the fact that the fixed structure open-loop design can only adapt to preset mode combinations, making it difficult to simultaneously take into account the parallel separation of different modes when composite vortex mode input and the adaptive feedback optimization for distortion and dynamic mode changes. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of the structure of a composite vortex beam separation device according to an embodiment of this application; Figure 2 A schematic flowchart illustrating a composite vortex beam separation method provided in an embodiment of this application; Figure 3 A schematic diagram of the light intensity distribution at the output end of a composite vortex beam to be separated when only the phase surface is loaded and no adaptive compensation is performed, as provided in an embodiment of this application; Figure 4 This is a schematic diagram showing the light intensity distribution at the output end of a composite vortex beam separation method provided in an embodiment of this application after separation.

[0010] Reference numerals: 1-Adaptive optics compensation unit, 11-Collimating and beam expanding optical assembly, 12-Polarizer, 13-First spatial light modulator, 14-First beam splitter, 15-First CCD detector, 2-Optical separation and detection unit, 21-Second spatial light modulator, 22-Third spatial light modulator, 23-Second beam splitter, 24-Second CCD detector, 3-Data processing module. Detailed Implementation

[0011] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0012] When composite vortex beams propagate in space, they face challenges from environmental disturbances. Atmospheric scattering, temperature, and suspended particles all interfere with their transmission, causing beam phase distortion. In space optical communication, this severely impacts communication efficiency and increases the bit error rate. Since vortex beams carry unique orbital angular momentum (OAM), they theoretically possess an infinite number of eigenstates, providing a new dimension for multiplexing in optical communication. Multiplexing dissimilar vortex beams in optical communication can further increase communication capacity and add more functionality. However, demultiplexing composite vortex beams at the receiving end is a crucial issue. Currently, most technologies focus on separating different topological charges of family-specific vortex beams, or suffer from cumbersome devices and low automation. Therefore, this application provides a composite vortex beam separation device and method, which can optimize and compensate the phase in real time with the final separation effect as the feedback target in the presence of system phase disturbance and transmission disturbance. When the overall mode space is linearly independent, it can achieve effective separation of non-family vortex beams, thereby improving the demultiplexing capability and actual communication effect of vortex beams for communication.

[0013] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0014] Scalar vortex beam systems with different optical field distribution functions, radial phases, and amplitude characteristics are defined as different mode families, including but not limited to Laguerre-Gaussian (LG) vortex beams and Bessel-Gaussian (BG) vortex beams. Vortex beams of different mode families possess differentiated phase distributions, transmission characteristics, and mode orthogonality, and can be used as independent information carriers to load information separately. In this application, the composite vortex beam refers to a cross-mode family composite optical field formed by coaxial beam combining. This cross-mode family composite optical field can overcome the channel dimension limitations of single-mode family multiplexing, further improving the information capacity and spectral efficiency of space optical communication. The main objective of this application is to enable efficient parallel separation of vortex beams from different mode families in a mixed optical field at the receiver. This application achieves automatic detection, automatic compensation, and automatic separation of two non-homologous vortex modes through adaptive feedback and dual-phase-plane spiral mapping, and maintains the information loaded on different modes as intact as possible in space optical communication scenarios.

[0015] In one exemplary embodiment, such as Figure 1 As shown, a composite vortex beam separation device is provided, including: an optical compensation module ( Figure 1 (not shown in the image), first CCD detector 15, optical separation module ( Figure 1 (Not shown in the image) The first CCD detector 15, the optical compensation module, the optical separation detection module, and the second CCD detector 24 are connected to the data processing module 3. The first CCD detector 15 and the optical separation module are arranged in the output light path of the optical compensation module. The second CCD detector 24 is arranged in the output light path of the optical separation module.

[0016] The optical compensation module processes the composite vortex beam to be separated based on the pre-compensated phase to obtain a pre-compensated beam. The first CCD detector 15 acquires the pre-compensated beam and transmits it to the data processing module 3. The data processing module 3 determines whether the pre-compensated beam meets the compensation requirements. If it does not meet the compensation requirements, the data processing module 3 updates the pre-compensated phase, and the optical compensation module processes the composite vortex beam to be separated based on the updated pre-compensated phase until the compensation requirements are met. If the compensation requirements are met, a compensated composite vortex beam is obtained based on the pre-compensated beam.

[0017] The optical separation module processes and compensates the composite vortex beam to obtain a separated beam. The second CCD detector 24 acquires the separated beam and transmits it to the data processing module 3. The data processing module 3 determines whether the separated beam meets the separation requirements. If it does not meet the separation requirements, the data processing module 3 updates the parameters of the optical compensation module and the optical separation module, and uses the updated optical compensation module and optical separation module to process the composite vortex beam to be separated until the separation requirements are met. If the separation requirements are met, the separated composite beam is obtained based on the separated beam and output to the external receiving surface.

[0018] In this embodiment, the optical compensation module and the first CCD detector 15 can be integrated into an adaptive optical compensation unit 1. The optical separation module and the second CCD detector 24 can be integrated into an optical separation detection unit.

[0019] In one embodiment, the optical compensation module includes: a collimating and beam-expanding optical component 11, a polarizer 12, a first spatial light modulator 13, and a first beam splitter 14.

[0020] Collimating and expanding optical components 11, polarizer 12, and first spatial light modulator 13 are sequentially arranged in the incident light path of the composite vortex beam to be separated. A first beam splitter 14 is arranged in the exit light path of the first spatial light modulator 13. A first CCD detector 15 is arranged in the exit light path of the first beam splitter 14. An optical separation module is arranged in the other exit light path of the first beam splitter 14. The first spatial light modulator 13 is connected to the data processing module 3.

[0021] The collimating and expanding optical component 11 is used to shape the composite vortex beam to be separated into a collimated and expanded beam. The polarizer 12 is used to perform polarization matching on the collimated and expanded beam to obtain a polarized beam. The first spatial light modulator 13 is used to process the polarized beam based on the compensated phase to obtain a pre-compensated beam. The first beam splitter 14 is used to reflect and transmit the pre-compensated beam into a first monitoring optical path and a first main optical path, respectively.

[0022] The first CCD detector 15 acquires the pre-compensated beam on the first monitoring optical path and transmits it to the data processing module 3. The data processing module 3 determines whether the pre-compensated beam on the first monitoring optical path meets the compensation requirements. If the compensation requirements are not met, the data processing module 3 updates the compensation phase, and the first spatial light modulator 13 processes the polarized beam based on the updated pre-compensated phase until the compensation requirements are met. If the compensation requirements are met, the pre-compensated beam on the first main optical path is output as a compensated composite vortex beam.

[0023] The first spatial light modulator 13 can be a reflective phase-type spatial light modulator.

[0024] Specifically, the collimating and expanding optical component 11 shapes the composite vortex beam to be separated into a collimated and expanded beam suitable for the effective aperture of the first spatial light modulator 13; the polarizer 12 adjusts the collimated and expanded beam to the effective working polarization state of the first spatial light modulator 13 to meet the phase modulation requirements of the first spatial light modulator 13. The first spatial light modulator 13 loads the pre-compensated phase transmitted by the data processing module 3 to compensate for system adaptation phase, low-order aberrations, and transmission disturbances in the polarized beam, thereby improving the separability of the subsequent two-mode separation. That is, the first spatial light modulator 13 performs pre-stage compensation for the phase distortion introduced by the polarized beam during spatial transmission, restoring the input composite vortex beam to be separated to a near-standard composite optical field state, thereby improving the separability of the subsequent optical separation module for different mode families.

[0025] After compensation by the first spatial light modulator 13, a pre-compensated beam is generated and reaches the first beam splitter 14. The first beam splitter 14 splits the pre-compensated beam into a first main optical path and a first monitoring optical path. The first CCD detector 15 collects distortion characterization information such as intensity distribution, ring structure, center drift, and energy diffusion of the pre-compensated beam on the first monitoring optical path, improving the stability and real-time performance of the device's feedback control. The data processing module 3 determines whether the pre-compensated beam meets the set compensation requirements. If the compensation requirements are not met, the pre-compensated phase is corrected and updated to form an updated pre-compensated phase, which is transmitted to the first spatial light modulator 13. In the next iteration, the polarized beam is compensated, thereby accelerating the adaptive compensation update process. Finally, the first spatial light modulator 13 outputs the pre-compensated beam that meets the compensation requirements. The pre-compensated beam is then passed through the first beam splitter 14 to form the pre-compensated beam on the first main optical path, denoted as the compensated composite vortex beam, and output to the optical separation module.

[0026] In one embodiment, the optical separation module includes: a second spatial light modulator 21, a third spatial light modulator 22, and a second beam splitter 23.

[0027] The second spatial light modulator 21 is disposed on the output optical path of the optical compensation module. The third spatial light modulator 22 is disposed on the output optical path of the second spatial light modulator 21. The second beam splitter 23 is disposed on the output optical path of the third spatial light modulator 22. The second CCD detector 24 is disposed on the output optical path of the second beam splitter 23, and the external receiving surface is disposed on another output optical path of the second beam splitter 23. Both the second spatial light modulator 21 and the third spatial light modulator 22 are connected to the data processing module 3.

[0028] The second spatial light modulator 21 is used to process the compensated composite vortex beam to obtain an intermediate reference beam. The third spatial light modulator 22 is used to process the intermediate reference beam to obtain a split beam. The second beam splitter 23 is used to reflect and transmit the split beams to form the second monitoring optical path and the second main optical path, respectively.

[0029] The second CCD detector 24 acquires the separated beam on the second monitoring optical path and transmits it to the data processing module 3. The data processing module 3 determines whether the separated beam on the second monitoring optical path meets the separation requirements. If the separation requirements are not met, the data processing module 3 updates the parameters of the optical compensation module, the second spatial light modulator 21, and the third spatial light modulator 22, and uses the updated optical compensation module, the second spatial light modulator 21, and the third spatial light modulator 22 to process the composite vortex beam to be separated sequentially until the separation requirements are met. If the separation requirements are met, the separated beam on the second main optical path is output as the separated composite beam.

[0030] Both the second spatial light modulator 21 and the third spatial light modulator 22 can be reflective phase-type spatial light modulators.

[0031] Specifically, the pre-compensated beam (i.e., the compensated composite vortex beam) transmitted from the first beam splitter 14 onto the first main optical path is incident on the optical separation module. The compensated composite vortex beam is first incident on the second spatial light modulator 21. A first phase surface phase map is loaded onto the second spatial light modulator 21. This phase map performs phase mapping on the compensated composite vortex beam, causing different mode families to evolve into different intermediate reference states respectively. For non-homogeneous vortex modes, a pre-discriminatory phase mapping is performed, causing the different mode families that were originally composited to evolve into different intermediate reference states respectively. The first phase surface phase map is a pre-discriminatory phase mapping map obtained through backpropagation and composite holographic design based on the preset intermediate reference states corresponding to two non-homogeneous modes.

[0032] Subsequently, the intermediate reference beam generated after modulation by the second spatial light modulator 21 is transmitted to the third spatial light modulator 22. A second phase plane phase map is loaded onto the third spatial light modulator 22, which guides the two intermediate reference states in the intermediate reference beam to their respective output ports. The second phase plane phase map is a port convergence phase map obtained by backpropagation and composite holography design based on a preset output port reference field.

[0033] The optical fields of the second spatial optical modulator 21 and the third spatial optical modulator 22 can both be physically regarded as a propagating beam. The former corresponds to a composite optical field containing two intermediate reference state components (i.e., an intermediate reference beam); the latter outputs a split beam, forming two spatial separation ports on the output surface to achieve the final separation of the two mode families.

[0034] The split beam, modulated by the third spatial light modulator 22, reaches the second beam splitter 23. The second beam splitter 23 divides the split beam into a second main optical path and a second monitoring optical path. The second main optical path can be directly output to an external receiving surface or observation surface to display the two separated vortex beams or two mode family outputs. The second monitoring optical path is guided to the second CCD detector 24. The second CCD detector 24 detects the split beam, acquiring the energy distribution, bright spot position, ring structure, or composite separation result at different output ports of the split beam, and sends the detection result to the data processing module 3. The data processing module 3 determines whether the split beam meets the set separation requirements. When the separation requirements are not met, the parameters of the first spatial light modulator 13, the second spatial light modulator 21, and the third spatial light modulator 22 are updated, and the updated parameters are transmitted to each spatial light modulator. In the next iteration of separation, the updated first spatial light modulator 13, second spatial light modulator 21, and third spatial light modulator 22 are used to process the composite vortex beam to be separated (i.e., the polarized beam adjusted by polarizer 12) in sequence, thereby achieving adaptive feedback update with the goal of achieving the best final separation effect. Among them, the compensation phase loaded in the first spatial light modulator 13 is the pre-compensation phase obtained in the last iteration when the pre-compensation phase is corrected and updated, and this compensation phase remains unchanged when updating the parameters of the first spatial light modulator 13.

[0035] In one embodiment, the process of using the composite vortex beam splitting device is as follows: First, the composite vortex beam to be separated is incident on the adaptive optical compensation unit 1, and after passing through the collimating and beam-expanding optical component 11 and the polarizer 12, it is incident on the first spatial light modulator 13; second, a pre-compensation phase is loaded on the first spatial light modulator 13 to pre-compensate the incident beam; the pre-compensated beam is obtained through the first beam splitter 14 and the first CCD detector 15, and the data processing module 3 adaptively updates the pre-compensation phase according to the pre-compensation beam, and outputs the compensated composite vortex beam through the first beam splitter 14; then, the compensated composite vortex beam is pre-discriminated and port converged sequentially through the second spatial light modulator 21 and the third spatial light modulator 22; finally, the separated beam is obtained through the second beam splitter 23 and the second CCD detector 24, and the data processing module 3 updates the parameters of the first spatial light modulator 13, the second spatial light modulator 21 and the third spatial light modulator 22 according to the separated beam, and transmits the updated parameters to each spatial light modulator respectively, thereby forming a closed-loop feedback control process.

[0036] The above-described device structure enables the following functions: First, it performs adaptive pre-compensation on the incident composite vortex beam to improve the separability of different mode families; second, it achieves automatic separation of different mode families through dual-phase surface mapping; third, it achieves automatic discrimination of the separation results through detection at the final output port; fourth, it achieves intermediate light field auxiliary monitoring and final separation feedback control through joint detection by the first CCD detector 15 and the second CCD detector 24; and fifth, it improves the automation level, stability, and separation accuracy of the device through closed-loop control of the data processing module 3.

[0037] Furthermore, when this device is applied to vortex-based spatial optical communication, if different mode families carry different communication information, this embodiment can first achieve automatic separation between different mode families at the receiving end, thereby ensuring that the information loaded on different mode families corresponds to different output ports. If it is necessary to further recover the independent information on different topological charge number modes within the same mode family, a same-family mode order demultiplexing module can be connected in series after the main output optical path of the second beam splitter 23.

[0038] In one embodiment, the first CCD detector 15 can be omitted, with only the second CCD detector 24 retained as the final feedback detection device. In this case, the device employs a single-detector closed-loop control method based on the final separation effect. This scheme has a simpler structure and is suitable for proof-of-concept or simplified receiving systems. However, in optical scenarios where enhanced compensation stability and faster feedback convergence are required, it is preferable to retain the first CCD detector 15 as an intermediate monitoring branch to improve the stability and real-time performance of the device's feedback control.

[0039] Based on the above embodiments, the beneficial effects of the composite vortex beam separation device proposed in this application are as follows: 1. By organically combining the adaptive optical compensation unit with the dual spatial optical modulation separation unit (i.e., the optical separation detection unit), automatic detection, real-time compensation and stable separation of non-homogeneous composite vortex beams are realized.

[0040] 2. The adaptive optics compensation unit can provide feedback correction for system mismatch and low-order phase distortion in the incident composite light field based on the final separation result, thereby improving the separability and stability of the subsequent separation process.

[0041] 3. The optical separation detection unit guides composite vortex beams of different mode families to different output ports through a two-stage process of pre-judgment phase mapping and port convergence phase mapping, enabling effective differentiation even when the topological charge numbers are the same or different.

[0042] 4. During the separation process, the linear mapping relationship between different mode coefficients and corresponding output ports is maintained, so that the communication information loaded on different vortex modes is not easily damaged under low crosstalk conditions. Therefore, it is suitable for mode demultiplexing and information recovery in vortex optical space optical communication.

[0043] 5. It has the advantages of high automation, strong feedback control capability, clear structure and easy expansion. It can be used as a front-end separation device in the hierarchical demultiplexing system of first dividing into families and then dividing into levels, providing a basis for further separation of different topological load modes in the same family.

[0044] Based on the same inventive concept, this application also provides a method for separating a composite vortex beam applied to the aforementioned composite vortex beam separating device. The solution provided by this method is similar to the solution described in the aforementioned device; therefore, the specific limitations in one or more embodiments of the composite vortex beam separating method provided below can be found in the limitations of the composite vortex beam separating device described above, and will not be repeated here.

[0045] In one exemplary embodiment, such as Figure 2 As shown, a method for separating composite vortex beams is provided, comprising: Step S1: Using the optical compensation module, the composite vortex beam to be separated is processed based on the pre-compensated phase to obtain the pre-compensated beam.

[0046] Step S2: Determine whether the pre-compensated beam meets the compensation requirements. If it does not meet the compensation requirements, update the pre-compensation phase and process the composite vortex beams to be separated based on the updated pre-compensation phase until the compensation requirements are met. If the compensation requirements are met, obtain the compensated composite vortex beam based on the pre-compensated beam.

[0047] Step S3: Use the optical separation module to process the compensated composite vortex beam to obtain the separated beam.

[0048] Step S4: Determine whether the separated beam meets the separation requirements. If the separation requirements are not met, update the parameters of the optical compensation module and the optical separation module, and use the updated optical compensation module and optical separation module to process the composite vortex beam to be separated until the separation requirements are met. If the separation requirements are met, obtain the separated composite beam based on the separated beam.

[0049] Before processing, let the horizontal coordinate of the external receiving surface be... The corresponding polar coordinates are: ,Right now .

[0050] Let a target mode in the first mode family be . One target mode in the second mode family is Then the composite input optical field (i.e., the composite vortex beam to be separated) is expressed as: .in, and This represents the complex coefficients loaded onto two different family patterns. and This represents the information carried by two different family patterns. In all embodiments provided in this application, Indicates the time.

[0051] In the embodiments provided in this application, the first mode family is the Bessel-Gaussian (BG) mode, and the second mode family is the Laguerre-Gaussian (LG) mode, then: .

[0052] in, Indicates the complex amplitude of the BG mode. Represents the normalization coefficient of the BG mode. express Bessel function of order 1, Indicates the radial wavenumber of the BG mode. This represents the width of the Gaussian envelope in the BG mode. This indicates the topology load in BG mode. Indicates the complex amplitude of the LG mode. Represents the normalization coefficient of the LG model. This represents the width of the Gaussian envelope in the LG mode. Indicates the topology load number in LG mode. Indicates the radial order of the LG mode. This represents a generalized Laguerre polynomial. The imaginary unit represents the phase factor of the light field.

[0053] The composite input optical field can then be expressed as: . and These represent the complex coefficients loaded in BG mode and LG mode, respectively.

[0054] In one embodiment, step S1 includes: shaping the composite vortex beam to be separated to obtain a collimated expanded beam; performing polarization matching on the collimated expanded beam to obtain a polarized beam; and processing the polarized beam based on pre-compensated phase to obtain a pre-compensated beam.

[0055] The pre-compensation beam includes the pre-compensation beam on the first monitoring optical path and the pre-compensation beam on the first main optical path. Based on this, step S2, determining whether the pre-compensation beam meets the compensation requirements, includes: using a preceding evaluation function to determine the value of the preceding evaluation function based on the pre-compensation beam on the first monitoring optical path; and determining whether the preceding evaluation function value meets the compensation requirements.

[0056] For example, since a composite vortex beam will generate phase perturbation during spatial propagation, the polarized beam transmitted after shaping and polarization processing can be represented as: For ease of description, time points are omitted in the following embodiments. .

[0057] in, This represents the complex amplitude optical field actually received by the receiver (i.e., the polarized beam transmitted to the first spatial light modulator). This represents the ideal input composite optical field (i.e., the composite vortex beam to be separated). This represents the phase perturbation introduced during spatial propagation. This indicates the phase modulation produced by the phase disturbance on the input beam.

[0058] A polarized beam is incident on the first spatial light modulator, and a pre-compensated phase is applied to its working surface. The compensated optical field (i.e., the pre-compensated beam) is represented as: .

[0059] in, Indicates the pre-compensated beam. This represents the pre-compensated phase loaded on the first spatial optical modulator. In this application, the iteration during the pre-compensated phase update is a local iteration, while the subsequent iterations during the parameter updates of the first, second, and third spatial optical modulators are global iterations.

[0060] To pre-compensate the incident polarized beam, the pre-compensation parameter vector of the first spatial light modulator is defined as: , Indicates the first In the nth iteration, the pre-compensation parameter vector is... There are several pre-compensation parameters. The update of the pre-compensation parameter vector can then be expressed as: .in, Indicates the first The pre-compensation parameter vector at the next iteration Indicates the first Update step size in the next iteration Indicates the first The effective correction amount obtained in the next iteration is based on the feedback result (the feedback result refers to the pre-compensated beam obtained through the first CCD detector).

[0061] In order to characterize the The detection state of the compensated beam at the first CCD detector obtained after each iteration is used to construct the pre-evaluation function, which is expressed as follows: .in, Indicates the first The previous evaluation function value after the next iteration. Indicates the first The normalized correlation coefficient between the optical field of the pre-compensated beam and the target reference optical field after the next iteration of pre-compensation; Indicates the first The normalized residual error of the current detection light intensity distribution collected by the first CCD detector after the next iteration of pre-compensation, relative to the preset reference light intensity distribution, is used to characterize the degree of deviation between the current pre-compensation result (i.e., the pre-compensation beam) and the target reference state. and These are the weighting coefficients.

[0062] The adjacent iteration changes of the previous evaluation function value and the adjacent iteration changes of the pre-compensation parameter vector of the first spatial light modulator are used together as the cutoff criteria (i.e., compensation requirements), expressed as follows: .in, The threshold for the change in the value of the preceding evaluation function. The update threshold for the pre-compensation parameter vector, This indicates taking the 2-norm.

[0063] The criteria for determining whether the preceding adaptive pre-compensation process has reached a stable state are as follows: the change in the preceding evaluation function value reflects the performance improvement between two consecutive local iterations of the pre-compensation phase, and the change in the pre-compensation parameter vector reflects whether the control parameters of the first spatial light modulator tend to stabilize. When both are simultaneously less than their respective preset thresholds and this condition is met for a preset number of consecutive times, the preceding adaptive pre-compensation process is considered to have reached convergence.

[0064] In this embodiment, the update of the pre-compensated phase loaded on the first spatial light modulator can be expressed as: .

[0065] in, Indicates the first The pre-compensated phase is applied to the first spatial optical modulator in the next iteration. ; The coefficient correction amount (i.e., the pre-compensation parameter correction amount) is obtained based on the intermediate optical field distortion characterization information acquired by the first CCD detector. This represents the dimension of the pre-compensation parameter vector; Indicates the first A Zernike pattern.

[0066] This implementation method is a local iteration of independent pre-compensation. Based on this, the final pre-compensation phase is kept constant, and the final pre-compensation parameter vector is used as the initial parameters of the first spatial optical modulator for global iteration in subsequent iterations. Pre-compensation abstracts system errors, assembly errors, or low-order transmission disturbances into pre-compensable phase disturbances, providing a mathematical basis for subsequent adaptive feedback compensation.

[0067] In one embodiment, step S3 includes: processing the compensated composite vortex beam using a second spatial light modulator in the optical separation module to obtain an intermediate reference beam; and processing the intermediate reference beam using a third spatial light modulator in the optical separation module to obtain a separated beam.

[0068] The separated beams include the separated beams on the second monitoring optical path and the separated beams on the second main optical path. Based on this, step S4 determines whether the separated beams meet the separation requirements, including: determining an index value based on the separated beams on the second monitoring optical path using an index function; determining an evaluation value based on the index value using an evaluation function; and determining whether the evaluation value meets the separation requirements.

[0069] In this embodiment, the parameters of the optical compensation module include an adaptive compensation parameter vector. The parameters of the optical separation module include a first parameter vector and a second parameter vector. Based on this, step S4 updates the parameters of the optical compensation module and the optical separation module, including: (1) Keeping the first parameter vector and the second parameter vector unchanged, apply a perturbation to the adaptive compensation parameter vector according to the first perturbation amplitude. Use the first evaluation function to determine the value of the first evaluation function based on the adaptive compensation parameter vector after the perturbation is applied, the first parameter vector, and the second parameter vector. Obtain the updated adaptive compensation parameter vector based on the value of the first evaluation function and the adaptive compensation parameter vector.

[0070] (2) Keeping the updated adaptive compensation parameter vector and the second parameter vector unchanged, apply a perturbation to the first parameter vector according to the second perturbation amplitude. Use the second evaluation function to determine the value of the second evaluation function based on the perturbated first parameter vector, the updated adaptive compensation parameter vector, and the second parameter vector. Obtain the updated first parameter vector based on the value of the second evaluation function and the first parameter vector.

[0071] (3) Keeping the updated adaptive compensation parameter vector and the updated first parameter vector unchanged, apply a perturbation to the second parameter vector according to the third perturbation amplitude. Use the third evaluation function to determine the value of the third evaluation function based on the perturbated second parameter vector, the updated adaptive compensation parameter vector, and the updated first parameter vector. Obtain the updated second parameter vector based on the value of the third evaluation function and the second parameter vector.

[0072] The index values ​​include the energy at the first output port, the energy at the second output port, and the background stray energy. The index function can be expressed as: .

[0073] In the formula, Indicates the first Energy at the first output port in the next iteration. Indicates the first Energy at the second output port during the next iteration. Indicates the first Background stray energy at the next iteration Indicates the first The light field of the separated beam at the output surface coordinate point during the next iteration. Indicates the first The light intensity of the separated beam on the second monitoring optical path during the next iteration. These represent the first output port area, the second output port area, and the non-target area, respectively.

[0074] To further suppress port crosstalk, port crosstalk from the first mode family to the second mode family and port crosstalk from the second mode family to the first mode family are defined as follows: .

[0075] in, This indicates the first mode family input when inputting alone. The output field after the next iteration (i.e., the separated beam). Indicates the second mode family when inputting alone. The output field after the next iteration and They represent the first After each iteration, the port crosstalk from the first mode family to the second mode family and from the second mode family to the first mode family is calculated. The total crosstalk can then be expressed as: . This indicates that, in practical applications, the total crosstalk can be obtained through actual measurement, without the need for calculation using the above formula.

[0076] To ensure that adaptive feedback compensation simultaneously enhances target port energy, suppresses background interference, and minimizes crosstalk, an evaluation function is constructed, expressed as: .

[0077] in, Indicates the first Evaluation value after the next iteration and The weighting coefficients represent the energy of the first output port and the energy of the second output port. It is a constant, specifically a constant to prevent the denominator from being too small; This represents the background leakage penalty coefficient. This represents the crosstalk penalty coefficient.

[0078] Let the adaptive compensation parameter vector of the first spatial light modulator be: .in, Indicates the first In the next iteration, the adaptive compensation parameter vector of the first spatial light modulator is M, where M is the number of adaptive compensation parameters (i.e., the dimension of the adaptive compensation parameter vector, which is consistent with the dimension of the pre-compensation parameter vector). Before the first iteration begins, the initial value of the adaptive compensation parameter vector of the first spatial light modulator is the pre-compensation parameter vector obtained in the last local iteration of the aforementioned pre-compensation.

[0079] Since the first spatial optical modulator is responsible for the pre-stage compensation, when updating the adaptive compensation parameter vector of the first spatial optical modulator, the phases (i.e., the parameters) of the second and third spatial optical modulators remain unchanged in the current iteration. By applying positive and negative perturbations, construct: .in, Indicates the first The perturbation amplitude corresponding to the first spatial light modulator in the next iteration (i.e., the first perturbation amplitude). This represents the disturbance direction vector corresponding to the disturbance amplitude.

[0080] Specifically, for the adaptive compensation parameter vector of the first spatial light modulator, its local evaluation function (i.e., the first evaluation function) is defined as follows: . Indicates the first The parameters of the second and third spatial light modulators are then used in the next iteration. Based on this, the corresponding evaluation function values ​​are calculated: .in, This represents the first evaluation function value after the positive perturbation. This represents the first evaluation function value after a negative perturbation. Indicates the first In each iteration, the current phase control parameter vector A set of small positive and negative perturbations is applied in order to determine the direction of positive optimization.

[0081] The update formula for the adaptive compensation parameter vector of the first spatial optical modulator can be expressed as: .

[0082] This formula represents the formal generation of the parameter vector for the next iteration based on the difference between the objective function values ​​before and after positive and negative perturbations. In the formula, Indicates the first The update step size of the adaptive compensation parameter vector of the first spatial light modulator during the next iteration.

[0083] A first phase surface phase map is loaded into the second spatial light modulator to process the compensated composite vortex beam output by the first spatial light modulator, thereby realizing mode family pre-discrimination mapping.

[0084] The input optical field of the compensated composite vortex beam transmitted to the second spatial light modulator is represented as: .in, This indicates a compensated composite vortex beam. This indicates the number of local iterations in the preceding pre-compensation. This represents the complex amplitude light field (i.e., the compensated composite vortex beam) incident on the second spatial light modulator. Indicates the propagation distance as Free propagation operator, This represents the distance between the first spatial light modulator and the second spatial light modulator.

[0085] Specifically, under paraxial conditions: In the formula, Represents a two-dimensional Fourier transform. This represents the two-dimensional inverse Fourier transform. Indicates wave number, Indicates the operating wavelength. Represents spatial frequency coordinates. This represents the imaginary unit. In this embodiment, for .

[0086] Define intermediate reference states for two different families of modes: .in, This represents the intermediate reference state corresponding to the first mode family. This represents the intermediate reference state corresponding to the second mode family. , These represent the intermediate reference amplitude envelopes corresponding to the first and second mode families, respectively. , These represent the intermediate reference spiral orders corresponding to the first and second mode families, respectively.

[0087] The spiral diagrams of the phase diagram of the first phase plane are as follows: .in, A spiral diagram representing the two intermediate reference states. Indicates to Modulus taking, to limit the phase to Interval.

[0088] Let the distance between the second spatial light modulator and the third spatial light modulator be... By backpropagating the intermediate reference state to the plane of the second spatial light modulator, we obtain: .

[0089] These represent the reference optical fields that are transmitted back from the intermediate reference state to the second spatial optical modulator plane, corresponding to the first mode family and the second mode family, respectively. Indicates the reverse transmission distance. Indicates the propagation distance as The free propagation operator.

[0090] Based on the compensated composite vortex beam, let the light fields of the two mode families incident separately on the second spatial light modulator be respectively... and Then the composite holographic function of the phase map of the first phase plane It can be represented as: .

[0091] in, This represents the weighting coefficients of the two items. Indicates complex conjugation. , The light field distribution of the two mode families incident separately on the second spatial light modulator.

[0092] Therefore, the phase diagram of the first phase plane loaded on the second spatial light modulator can be expressed as: .

[0093] in, This represents the phase diagram of the first phase plane. This indicates phase wrapping, which is used to map the calculated continuous phase to a preset principal value range to meet the periodic phase loading requirements of the spatial light modulator.

[0094] To further reduce the coupling between the two intermediate reference states, the normalized correlation of the intermediate reference states is defined as: .

[0095] in, This represents the normalized correlation between two intermediate reference states. The smaller the value, the closer the two intermediate states are to orthogonality, and the easier it is to reduce crosstalk.

[0096] Therefore, the structural expression for the first phase plane can be further written as: . and This represents the output field of the two mode families after passing through the phase diagram of the first phase plane (i.e., the optical field of the first mode family and the optical field of the second mode family in the intermediate reference beam). Denotes the norm of the squared error. This represents the intermediate state coupling weight, and its value is positive.

[0097] To ensure that the first phase plane phase map not only completes the initial mode family pre-mapping but also suppresses intermediate state coupling based on the actual separation results, let the second phase plane phase map... The first phase plane phase map loaded by the second spatial light modulator in the next iteration is: , .in, The first phase plane phase diagram A correction function, For the first The first iteration One correction factor.

[0098] Let the parameter vector (i.e., the first parameter vector) of the phase map of the first phase plane of the second spatial light modulator be: .

[0099] In order to update the phase map of the first phase plane based on the final output port separation result, while maintaining the current adaptive compensation parameter vector of the first spatial light modulator... And the current parameter vector of the third spatial optical modulator (i.e., the second parameter vector). Under the condition that remains unchanged, for the first parameter vector By applying positive and negative perturbations, construct: .in, The phase diagram of the first phase plane at the 1st The perturbation amplitude at the next iteration (i.e., the second perturbation amplitude). This is the disturbance direction vector corresponding to the disturbance amplitude.

[0100] For the first parameter vector of the second spatial light modulator, its local evaluation function (i.e., the second evaluation function) is defined as follows: That is, while maintaining the updated adaptive compensation parameter vector of the first spatial light modulator. and the second parameter vector of the third spatial light modulator Under the condition that remains unchanged, we only examine the impact of changes in the first parameter vector on the evaluation function. Therefore, we calculate the corresponding evaluation function values: .in, This represents the value of the second evaluation function after the positive perturbation. This represents the value of the second evaluation function after the negative perturbation. Indicates the first In each iteration, the current phase control parameter vector A set of small positive and negative perturbations is applied in order to determine the direction of positive optimization.

[0101] The update formula for the first parameter vector of the second spatial light modulator can then be expressed as: .

[0102] in, This indicates the update step size corresponding to the second spatial light modulator.

[0103] The phase map of the first phase surface on the second spatial light modulator gradually evolves from the initial pre-mapped phase surface to an adaptive first phase surface phase map that matches the actual input state of the current compensated composite vortex beam, thereby gradually reducing the overlap and coupling of the two mode families at the intermediate reference state level.

[0104] A second phase plane phase map is loaded onto the third spatial optical modulator to process the intermediate reference beam output by the second spatial optical modulator, thereby achieving port convergence and separation while maintaining information output.

[0105] Let the center of the two output ports be and Define the local polar angle: .in, Indicates the local polar angle of the first output port. This indicates the local polar angle of the second output port.

[0106] Define the reference fields for the two output ports as follows: .in, , This serves as the reference field for both output ports. , This represents the amplitude envelope of the two output ports. , This indicates the spiral order of the two output ports. , Point The distances to the center of the first port and the center of the second port, respectively.

[0107] The corresponding spiral diagrams of the second phase plane phase diagram are as follows: .in, This represents a spiral diagram corresponding to two reference fields.

[0108] Let the transmission distance from the third spatial optical modulator to the output surface be... Then, the two output reference fields are transmitted in reverse to the third spatial light modulator plane, resulting in: .

[0109] in, , This represents the result of the two output reference fields being transmitted back in reverse to the third spatial optical modulator plane. Indicates the reverse transmission distance. Indicates the propagation distance as The free propagation operator.

[0110] Then the composite holographic function of the phase map of the second phase plane It can be represented as: .

[0111] in, This represents the weighting coefficients of the two items. This indicates the obtained intermediate reference state (corresponding to the reference fields of the two output ports). Indicates complex conjugation.

[0112] Therefore, the second phase plane phase map loaded on the third spatial light modulator It can be represented as: .

[0113] The optical field after passing through the phase map of the second phase surface can be expressed as: .

[0114] In the formula, This represents the intermediate reference state corresponding to the first mode family. This represents the intermediate reference state corresponding to the second mode family. This represents the phase diagram of the second phase plane loaded on the third spatial optical modulator. This represents the phase modulation factor applied by the second phase plane phase map to the intermediate reference beam (including intermediate reference states of both mode families). This represents the optical field after the composite vortex beam is modulated by a third spatial optical modulator. This optical field then travels a further distance... Then, the final output light field is formed on the output surface. .

[0115] Therefore, the final output light field is: In the formula, This represents the optical field after the composite vortex beam is modulated by a third spatial light modulator. This represents the light field distribution on the final output surface.

[0116] To reduce crosstalk at the final output port, the energy of the correct port is defined as: .

[0117] In the formula, This indicates that the first and second mode families are in the corresponding correct output regions, respectively. Effective output energy within the body, Denotes the light field distribution formed on the final output surface when the first mode family is incident alone. This represents the light field distribution formed on the final output surface when the second mode family is incident alone.

[0118] Define the energy leaked by the faulty port as: .

[0119] In the formula, This represents the crosstalk energy leaked from the first mode family to the second output region and from the second mode family to the first output region.

[0120] The low crosstalk optimization objective of the second phase plane phase diagram can then be written as: .

[0121] This formula represents the phase diagram of the second phase plane. To optimize the system, the sum of energies at the correct ports should be maximized, while a penalty term should be used to suppress the sum of energy leaked at the incorrect ports. Specifically, the second phase surface loaded by the third-space optical modulator should, as far as possible, send both modes to their respective correct ports while minimizing the energy crosstalked to the other port. This represents the port crosstalk penalty weight, and its value is positive.

[0122] In order to further suppress erroneous port leakage based on the actual output port energy distribution, let the second phase plane phase diagram be... The phase diagram of the second phase plane loaded by the third spatial light modulator in the next iteration is represented as follows: .

[0123] in, The second phase plane phase diagram A correction function, For the first The first iteration One correction factor.

[0124] Let the parameter vector (i.e., the second parameter vector) of the second phase plane phase map of the third spatial optical modulator 22 be: .

[0125] While maintaining the current adaptive compensation parameter vector of the first spatial light modulator The first parameter vector of the second spatial light modulator Under the condition that remains unchanged, for the second parameter vector By applying positive and negative perturbations, construct: .in, Indicates the first The perturbation amplitude of the second phase plane phase map during the next iteration (i.e., the third perturbation amplitude). This represents the disturbance direction vector corresponding to the disturbance amplitude.

[0126] Furthermore, after updating the first parameter vector of the second spatial light modulator, the local evaluation function (i.e., the third evaluation function) for the second parameter vector of the third spatial light modulator is defined as follows: That is, while maintaining the updated adaptive compensation parameter vector of the first spatial light modulator. and the updated second parameter vector of the second spatial light modulator Under the condition that remains unchanged, we only examine the impact of changes in the second parameter vector on the evaluation function. Therefore, we calculate the corresponding evaluation function values: .in, This represents the value of the third evaluation function after the positive perturbation. This represents the value of the third evaluation function after the negative perturbation. Indicates the first In the next iteration, the current phase control parameter vector A set of small positive and negative perturbations is applied in order to determine the direction of positive optimization.

[0127] The update formula for the second parameter vector of the third spatial light modulator can then be expressed as: .

[0128] in, The update step size corresponding to the third spatial optical modulator.

[0129] The entire composite vortex beam splitter was in the first In each iteration, the adaptive compensation parameter vector update of the first spatial light modulator, the first parameter vector update of the second spatial light modulator, and the second parameter vector update of the third spatial light modulator are completed sequentially, thus forming a block-based alternating joint optimization process with the final output port separation effect as the goal.

[0130] Since the first spatial light modulator differs from the second and third spatial light modulators in terms of their adjustment targets, a global iteration termination flag is defined to determine whether the composite vortex beam separation device has reached a stable separation state. for: The separation condition that is simultaneously satisfied can be expressed as: .

[0131] In the formula, To evaluate the convergence threshold of the function, , and These are the convergence thresholds for updating the adaptive compensation parameter vector, the first parameter vector, and the second parameter vector, respectively. The maximum allowable crosstalk threshold, The minimum separation threshold, The number of times the evaluation value is satisfied consecutively. Indicates the first Crosstalk metrics at the next iteration This indicates taking the L2 norm. Indicates the first The separation degree of the composite vortex beam in the next iteration can be expressed as: .

[0132] The convergence threshold is preferably determined based on a combination of the noise level of the composite vortex beam splitter, the minimum effective adjustment of the device, and the mission performance requirements. Among these, the convergence threshold of the evaluation function... The threshold value can be determined based on the statistical fluctuation of the comprehensive evaluation function under fixed modulation conditions, preferably 2 to 5 times its standard deviation. The update convergence threshold values ​​for the adaptive compensation parameter vector, the first parameter vector, and the second parameter vector are also considered. , and This can be determined experimentally based on the minimum phase modulation resolution or perturbation sensitivity of the corresponding spatial light modulator. Maximum crosstalk threshold Determined based on the allowable port isolation or communication error rate requirements of the composite vortex beam separator. Minimum separation threshold. Determined based on the minimum percentage requirement of effective energy entering the target port from the target mode family. The number of times the evaluation value is consecutively satisfied. The preferred value is 3 to 10, and the more preferred value is 3 to 5.

[0133] when When = 1, the global iteration of the composite vortex beam separation device is considered complete. At this time, the first, second, and third spatial light modulators maintain their current phase loading states and output the final separation result (i.e., the separated composite beam). When =0, the adaptive compensation parameter vector, the first parameter vector, and the second parameter vector are updated sequentially, and the next global iteration continues until the separation condition is met.

[0134] Since the entire device consists of phase modulation and spatial transmission, its effect on the input field constitutes a linear operator. Then we have: , indicating in After the next iteration, the input optical field (i.e., the composite vortex beam to be separated) is used. After passing through the entire separation system, the output optical field (i.e., the separated composite beam) is obtained. ,in Indicates the first The equivalent linear operator for the entire device at the next iteration.

[0135] Substitute into the composite input light field expression have: . This represents the output response of the first mode family after it has passed through the device alone. This represents the output response of the second mode family after passing through the device alone, where , The fact that the information loaded onto the mode families was preserved during the optical path modulation transformation in the device indicates that it was not disrupted, but rather still transmitted to the output end along with the output response corresponding to each mode family. This formula shows that while separating two non-homogeneous composite vortex beams using the method provided in this application, the mapping relationship between the information coefficients loaded onto different modes and different output ports is maintained, thus the information is not destroyed during separation.

[0136] In one embodiment, for the composite vortex beams to be separated (BG beam topological charge lB=2; LG beam topological charge lL=2), the intensity distribution at the output end when only the phase plane is loaded and no adaptive compensation is performed is as follows: Figure 3 As shown. At this point, although the two target regions have shown initial separation, the degree of energy accumulation within the target regions is limited, and there is still some energy leakage and crosstalk.

[0137] For the composite vortex beams to be separated (BG beam topological charge lB=2; LG beam topological charge lL=2), the intensity distribution at the output end after separation using the composite vortex beam separation method described in the above embodiments is as follows: Figure 4 As shown. Compared to Figure 3 The light intensity is more concentrated and the separation energy is higher in the target area, while the leakage energy and crosstalk energy in the non-target area are significantly reduced, indicating that the composite vortex beam separation method can effectively improve the separation effect of composite vortex beams of different mode families.

[0138] Based on the above embodiments, the beneficial effects of the composite vortex beam separation method proposed in this application are mainly reflected in the following aspects: By combining adaptive optical feedback compensation aimed at the final separation effect with a dual-phase-plane spiral mapping separation process, automatic detection, real-time compensation, and stable separation of non-homogeneous composite vortex beams at the receiving end are achieved; wherein, the adaptive optical compensation is not simply aimed at controlling the wavefront flatness, but directly optimizes the separation and crosstalk degree of the two target output ports in a closed loop, thereby effectively suppressing the influence of low-order phase disturbances and crosstalk on the separation effect and improving the separation accuracy and robustness between different mode families; the first phase-plane phase map enhances the distinguishability between different mode families by mapping the two different mode families to different intermediate reference states, and the second phase-plane phase map further converges the intermediate reference states to the two spatially separated output ports, thereby achieving effective separation of non-homogeneous mode vortex beams; at the same time, the method maintains the linear mapping relationship between the input mode coefficients and the output port response, making the communication information loaded on different vortex modes less susceptible to damage under low crosstalk conditions, and thus applicable to mode demultiplexing and information recovery in vortex beam spatial optical communication. Furthermore, this method can also serve as a preliminary separation method that first divides the population into families and then into orders, providing a foundation for further refined separation of different topological load patterns within the same population.

[0139] In one exemplary embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0140] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0141] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0142] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0143] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.

[0144] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A composite vortex beam separation device, characterized in that, include: Optical compensation module, first CCD detector, optical separation module, second CCD detector, and data processing module; The first CCD detector, the optical compensation module, the optical separation detection module, and the second CCD detector are connected to the data processing module; the first CCD detector and the optical separation module are arranged in the output light path of the optical compensation module; the second CCD detector is arranged in the output light path of the optical separation module. The optical compensation module obtains a pre-compensated beam by pre-compensating phase processing of the composite vortex beam to be separated; the first CCD detector acquires the pre-compensated beam and transmits it to the data processing module. The data processing module determines whether the pre-compensated beam meets the compensation requirements. If the compensation requirements are not met, the data processing module updates the pre-compensation phase. The optical compensation module processes the composite vortex beam to be separated based on the updated pre-compensation phase until the compensation requirements are met. If the compensation requirements are met, the compensated composite vortex beam is obtained based on the pre-compensated beam. The optical separation module processes and compensates the composite vortex beam to obtain a separated beam; the second CCD detector acquires the separated beam and transmits it to the data processing module; the data processing module determines whether the separated beam meets the separation requirements; if it does not meet the separation requirements, the data processing module updates the parameters of the optical compensation module and the optical separation module, and uses the updated optical compensation module and the optical separation module to process the composite vortex beam to be separated until the separation requirements are met; if the separation requirements are met, the separated composite beam is obtained based on the separated beam and output to the external receiving surface.

2. The composite vortex beam separation device according to claim 1, characterized in that, The optical compensation module includes: a collimating and beam-expanding optical component, a polarizer, a first spatial light modulator, and a first beam splitter; The collimating and beam-expanding optical components, the polarizer, and the first spatial light modulator are sequentially arranged in the incident light path of the composite vortex beam to be separated; the first beam splitter is arranged in the exit light path of the first spatial light modulator; the first CCD detector is arranged in the exit light path of the first beam splitter; the optical separation module is arranged in the other exit light path of the first beam splitter; the first spatial light modulator is connected to the data processing module. The collimating and expanding optical component is used to shape the composite vortex beam to be separated into a collimated and expanded beam; the polarizer is used to perform polarization matching on the collimated and expanded beam to obtain a polarized beam; the first spatial light modulator is used to process the polarized beam based on the compensated phase to obtain the pre-compensated beam; the first beam splitter is used to reflect and transmit the pre-compensated beam into a first monitoring optical path and a first main optical path, respectively. The first CCD detector acquires the pre-compensated beam on the first monitoring optical path and transmits it to the data processing module; the data processing module determines whether the pre-compensated beam on the first monitoring optical path meets the compensation requirements; if the compensation requirements are not met, the data processing module updates the compensation phase, and the first spatial light modulator processes the polarized beam based on the updated pre-compensated phase until the compensation requirements are met; if the compensation requirements are met, the pre-compensated beam on the first main optical path is output as a compensated composite vortex beam.

3. The composite vortex beam separation device according to claim 1, characterized in that, The optical separation module includes: a second spatial light modulator, a third spatial light modulator, and a second beam splitter; The second spatial light modulator is disposed on the output optical path of the optical compensation module; the third spatial light modulator is disposed on the output optical path of the second spatial light modulator; the second beam splitter is disposed on the output optical path of the third spatial light modulator; the second CCD detector is disposed on the output optical path of the second beam splitter; and the external receiving surface is disposed on the other output optical path of the second beam splitter; both the second spatial light modulator and the third spatial light modulator are connected to the data processing module. The second spatial light modulator is used to process the compensated composite vortex beam to obtain an intermediate reference beam; the third spatial light modulator is used to process the intermediate reference beam to obtain a split beam; the second beam splitter is used to reflect and transmit the split beam into a second monitoring optical path and a second main optical path, respectively. The second CCD detector acquires the separated beam on the second monitoring optical path and transmits it to the data processing module. The data processing module determines whether the separated beam on the second monitoring optical path meets the separation requirements. If the separation requirements are not met, the data processing module updates the parameters of the optical compensation module, the second spatial light modulator, and the third spatial light modulator, and uses the updated optical compensation module, the second spatial light modulator, and the third spatial light modulator to process the composite vortex beam to be separated in sequence until the separation requirements are met. If the separation requirements are met, the separated beam on the second main optical path is output as the separated composite beam.

4. A method for separating composite vortex beams, characterized in that, The method is applied to the composite vortex beam separation device according to any one of claims 1-3; the method includes: Using an optical compensation module, a pre-compensated beam is obtained by pre-compensating the phase of the composite vortex beam to be separated. Determine whether the pre-compensated beam meets the compensation requirements; if it does not meet the compensation requirements, update the pre-compensation phase, and process the composite vortex beam to be separated based on the updated pre-compensation phase until the compensation requirements are met; if the compensation requirements are met, obtain the compensated composite vortex beam based on the pre-compensated beam. The compensated composite vortex beam is processed using an optical separation module to obtain a separated beam. Determine whether the separated beam meets the separation requirements; if it does not meet the separation requirements, update the parameters of the optical compensation module and the optical separation module, and use the updated optical compensation module and the optical separation module to process the composite vortex beam to be separated until the separation requirements are met; if the separation requirements are met, obtain the separated composite beam based on the separated beam.

5. The composite vortex beam separation method according to claim 4, characterized in that, Based on the pre-compensated phase processing of the composite vortex beam to be separated, a pre-compensated beam is obtained, including: The composite vortex beams to be separated are shaped to obtain collimated and expanded beams; Polarization matching is performed on the collimated and expanded beam to obtain a polarized beam; The polarized beam is obtained by processing the pre-compensated phase.

6. The composite vortex beam separation method according to claim 4, characterized in that, The pre-compensation beam includes the pre-compensation beam on the first monitoring optical path and the pre-compensation beam on the first main optical path. Determining whether the pre-compensated beam meets the compensation requirements includes: The value of the pre-compensation beam on the first monitoring optical path is determined by using the pre-evaluation function. Determine whether the value of the preceding evaluation function meets the compensation requirements.

7. The composite vortex beam separation method according to claim 4, characterized in that, The compensated composite vortex beam is processed using an optical separation module to obtain a separated beam, including: The compensated composite vortex beam is processed using the second spatial light modulator in the optical separation module to obtain an intermediate reference beam. The intermediate reference beam is processed using the third spatial light modulator in the optical separation module to obtain the separated beam.

8. The composite vortex beam separation method according to claim 4, characterized in that, The separated beam includes the separated beam in the second monitoring optical path and the separated beam in the second main optical path; Determining whether the separated beams meet the separation requirements includes: The index value is determined based on the separated beams in the second monitoring optical path using an index function; The evaluation value is determined based on the index value using an evaluation function; Determine whether the evaluation value meets the separation requirements.

9. The composite vortex beam separation method according to claim 8, characterized in that, The index values ​​include the energy at the first output port, the energy at the second output port, and the background stray energy; the index function is expressed as: ； In the formula, Indicates the first Energy at the first output port in the next iteration. Indicates the first Energy at the second output port during the next iteration. Indicates the first Background stray energy at the next iteration Indicates the first The light field of the separated beam at the output surface coordinate point during the next iteration. Indicates the first The light intensity of the separated beam on the second monitoring optical path during the next iteration. These represent the first output port area, the second output port area, and the non-target area, respectively.

10. The composite vortex beam separation method according to claim 4, characterized in that, The parameters of the optical compensation module include an adaptive compensation parameter vector; The parameters of the optical separation module include a first parameter vector and a second parameter vector; Update the parameters of the optical compensation module and the optical separation module, including: Keeping the first parameter vector and the second parameter vector unchanged, a perturbation is applied to the adaptive compensation parameter vector according to the first perturbation amplitude; a first evaluation function is used to determine the value of the first evaluation function based on the adaptive compensation parameter vector after the perturbation is applied, the first parameter vector, and the second parameter vector; The updated adaptive compensation parameter vector is obtained based on the first evaluation function value and the adaptive compensation parameter vector; Keeping the updated adaptive compensation parameter vector and the second parameter vector unchanged, a perturbation is applied to the first parameter vector according to the second perturbation amplitude; a second evaluation function is used to determine the value of the second evaluation function based on the perturbated first parameter vector, the updated adaptive compensation parameter vector, and the second parameter vector; The updated first parameter vector is obtained based on the second evaluation function value and the first parameter vector; Keeping the updated adaptive compensation parameter vector and the updated first parameter vector unchanged, a perturbation is applied to the second parameter vector according to the third perturbation amplitude; a third evaluation function is used to determine the value of the third evaluation function based on the perturbated second parameter vector, the updated adaptive compensation parameter vector, and the updated first parameter vector; The updated second parameter vector is obtained based on the third evaluation function value and the second parameter vector.

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