A vector beam inseparability measuring device

Abstract

The application discloses a kind of vector light beam inseparability measuring device, comprising: laser, first beam splitter, vector light beam generation module, quarter-wave plate, first collimator, polarizer, second beam splitter, polarization beam splitter, light field camera module and calculation module;The present application uses light field camera to build measuring device, which can reconstruct the light field complex amplitude of two polarization channels of vector light beam by measuring the off-axis interference hologram under two orthogonal polarization channels of vector light beam, and then completes the inseparability test of vector light beam.The present application does not depend on phase hologram loading device in the process of decoding and calculating the inseparability of vector light beam, so that the inseparability measurement rate of vector light beam and the complexity of optical path are no longer limited by demodulation device, the fast, efficient and low-cost measurement of the inseparability of vector light beam can be realized, and the problem that the inseparability of multi-order vector light beam superposition state cannot be simultaneously measured in the prior art is solved.

Description

Technical Field

[0001] This invention belongs to the field of optical field manipulation and information optics, specifically relating to a vector beam indivisibility measurement device and an anti-turbulence communication system based on vector beam indivisibility coding. Background Technology

[0002] In recent years, free-space optical communication technology, which transmits information in atmospheric channels, has developed rapidly and has been widely used in scientific research, commercial, civilian, and military fields. Compared with traditional free-space radio frequency communication schemes, free-space optical communication has advantages such as smaller antenna systems, higher speeds, stronger anti-eavesdropping capabilities, and unlicensed spectrum. However, despite these advantages, free-space optical communication has a significant drawback: the prevalent atmospheric turbulence in atmospheric channels can damage the intensity and phase of the light beam, causing beam degradation such as beam drift, light intensity flicker, and alignment errors at the receiver. Since most current optical communication systems modulate the signal onto the intensity (direct modulation and detection), phase (phase shift keying), or intensity-phase (quadrature amplitude modulation) of the optical field, these beam intensity and phase damages caused by atmospheric turbulence can lead to a large number of bit errors at the receiver, and even cause the free-space optical communication system to fail.

[0003] In 2022, scientists at the University of the Witwatersrand in South Africa discovered that the indivisibility of a vector beam remains constant when it propagates in a single-sided unitary channel. Their published paper provided a theoretical explanation and experimental verification of this phenomenon. It's important to note that atmospheric turbulence is a typical example of a single-sided unitary channel. Therefore, applying the dimension of vector beam indivisibility to the electrical signal becomes a novel and effective solution to combat atmospheric turbulence effects in free-space optical communication. To achieve such communication based on vector beam indivisibility, measuring the indivisibility of a specific vector beam is crucial, similar to the decoding and information extraction process in a traditional optical communication receiver. Currently, commonly used vector beam indivisibility measurement devices follow this approach: first, the vector beam is polarized and split into two orthogonal circularly polarized vortex beams. Then, these two circularly polarized vortex beams are passed through multiple (typically six) different phase holograms (loaded onto a spatial light modulator or digital micromirror device). This allows demodulation of the two circularly polarized vortex beams under multiple mode bases, obtaining the power weights of various modes. The expected value of the Pauli operator for the vector beam can be calculated based on the power weights of different modes, and thus its indivisibility can be determined.

[0004] However, this method has the following drawbacks: First, the performance of the measurement system, such as the rate and insertion loss, is limited by the performance of the reconfigurable phase hologram loading device. Second, the measurement rate and the simplicity of the device cannot be achieved simultaneously, because it is necessary to measure the intensity of six different phase holograms. Therefore, it is necessary to switch the loading phase hologram six times on a single phase hologram loading device or build a complex six-way system to achieve a single measurement without switching. Third, when the input vector beam is not a single-order but a multi-order superposition state, the rate or simplicity of this scheme will be further degraded. Fourth, the cost of reconfigurable phase hologram loading devices, such as spatial light modulators and digital micromirror arrays, is very high, which will result in a high cost of the measurement system.

[0005] Therefore, developing a device that can effectively circumvent these defects in measuring the indivisibility of vector beams has become an important challenge and is of great significance for free-space turbulence-resistant communication. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a vector beam indivisibility measurement device and an anti-turbulence communication system based on vector beam indivisibility coding. The technical problem to be solved by this invention is achieved through the following technical solution:

[0007] In a first aspect, embodiments of the present invention provide a vector beam indivisibility measurement device, the device comprising:

[0008] The system includes a laser, a first beam splitter, a vector beam generation module, a quarter-wave plate, a first collimator, a polarizer, a second beam splitter, a polarization beam splitter, an optical field camera module, and a computing module; among which,

[0009] The laser is used to generate an input beam; the first beam splitter is used to split the input beam into a reference path and a signal path, which are respectively input to the first collimator and the vector beam generation module.

[0010] The first collimator is used to adjust the input reference beam into a collimated Gaussian beam in free space; the polarizer is used to convert the collimated Gaussian beam into a 45° linearly polarized reference beam.

[0011] The vector beam generation module includes at least one set of collimators and vector beam generators. Each set of collimators and vector beam generators is used to generate a vector beam of a corresponding order according to the input signal beam, and input the vector beam of the corresponding order as a set of vector beams to be measured into the quarter-wave plate. The quarter-wave plate is used to convert the obtained vector beams to be measured into signal light in a superposition state.

[0012] The second beam splitter is used to combine the reference light and the signal light and then perform off-axis interference, and input the resulting interference field beam into the polarization beam splitter; the polarization beam splitter is used to polarize and split the interference field beam and then input it into the light field camera module; the light field camera module is used to obtain off-axis interference holograms under different polarization channels using the light field camera therein; the calculation module is used to calculate the corresponding complex amplitude distribution information of the obtained off-axis interference hologram, and calculate the indivisibility value of the vector beam to be measured based on the obtained complex amplitude distribution information.

[0013] In one embodiment of the present invention, when the vector beam generating module includes at least two sets of collimators and vector beam generators, the vector beam generating module further includes a third beam splitter; wherein, the at least two sets of collimators and vector beam generators are used to generate vector beams of different orders; the third beam splitter is used to combine the vector beams of different orders and input them into the quarter-wave plate.

[0014] In one embodiment of the present invention, the vector beam generator in the vector beam generation module is obtained by combining polarization optics with a Q-plate / vortex waveplate.

[0015] In one embodiment of the present invention, the vector beam generator in the vector beam generation module is a vector beam generation system composed of a preset beam splitter, a preset polarization beam splitter, a preset phase hologram loading device, a preset half-wave plate and a preset quarter-wave plate, which modulates two polarizations into vortex beams of opposite orders and then combines them.

[0016] In one embodiment of the present invention, the vector beam generator in the vector beam generation module is a Sagnac loop based on a polarization-sensitive phase hologram loading device or a polarization-insensitive vortex phase structure.

[0017] In one embodiment of the present invention, the light field camera module includes a first light field camera and a second light field camera; wherein the first light field camera and the second light field camera are respectively used to obtain off-axis interference holograms of the left-hand circularly polarized channel and the right-hand circularly polarized channel in the vector beam to be measured, and input them into the calculation module.

[0018] In one embodiment of the present invention, the light field camera module includes a third light field camera; wherein the third light field camera is used to obtain off-axis interference holograms of the left-hand circularly polarized channel and the right-hand circularly polarized channel in the vector beam to be measured, and input them into the calculation module.

[0019] In one embodiment of the invention, the polarization beam splitter is a Wollaston prism or a displacement polarization beam splitter, used to separate the two orthogonally linearly polarized components of the interference field beam on the same side.

[0020] In one embodiment of the present invention, the process by which the calculation module calculates the corresponding complex amplitude distribution information of the obtained off-axis interferometric hologram and calculates the indivisibility value of the vector beam under test based on the obtained complex amplitude distribution information includes:

[0021] The computation module is used to calculate the complex amplitude distribution information corresponding to the off-axis interference hologram obtained from the vector beam under test; wherein, the complex amplitude distribution information includes intensity and phase.

[0022] The power weights of a set of different modes corresponding to the complex amplitude distribution information are obtained by calculating the overlap integral of the complex amplitude distribution information with the basis of different modes.

[0023] A power weight matrix is ​​formed based on the power weights of all the different modes obtained;

[0024] The indivisibility value of the vector beam under test is calculated using the power weight matrix.

[0025] Secondly, embodiments of the present invention provide an anti-turbulence communication system based on vector beam indivisibility coding, implemented based on the vector beam indivisibility measurement device described in the first aspect. The anti-turbulence communication system based on vector beam indivisibility coding, in addition to the structure of the vector beam indivisibility measurement device, further includes:

[0026] An indivisibility encoder is used to control the vector beam generation module to output a vector beam with a preset indivisibility value based on the level value of an electrical signal; wherein the preset indivisibility value corresponds to the level value;

[0027] In the anti-turbulence communication system based on vector beam indivisibility coding, the vector beam generation module and the quarter-wave plate form a turbulence channel; the calculation module is also used to determine the level value of the corresponding electrical signal based on the preset indivisibility value of the calculated vector beam.

[0028] The beneficial effects of this invention are:

[0029] 1. This invention utilizes the light field camera module to obtain off-axis interference holograms under different polarization channels and uses the calculation module to perform digital domain processing based on the off-axis interference holograms under different polarization channels to realize the numerical calculation of the indivisibility of the vector beam under test. This process does not require the use of a phase hologram loading device to demodulate higher-order modes. Therefore, the measurement performance, such as rate and insertion loss, is not limited by the performance of the phase hologram loading device, and the measurement effect can be guaranteed.

[0030] 2. In the process of calculating the indivisibility value of the present invention, since key steps such as mode demodulation are processed quickly in the digital domain, the present invention can achieve rapid measurement of the indivisibility of vector beams through a single exposure of a light field camera when the optical path is simple.

[0031] 3. The vector beam generation module of the present invention includes at least one set of collimators and vector beam generators. When using one set of collimators and vector beam generators, it is possible to measure the indivisibility of a single-order vector beam. However, without increasing the optical path complexity, it is possible to measure the indivisibility of a superposition state of multiple-order vector beams through at least two sets of collimators and vector beam generators, thus making it more applicable.

[0032] 4. This invention can measure the indivisibility of vector beams without using expensive phase hologram loading devices, and the light field camera required by this invention is low-cost. Therefore, this invention has the advantage of low cost.

[0033] Furthermore, this invention helps to realize free-space turbulence-resistant communication based on the indivisibility of vector structured light. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a vector beam indivisibility measuring device provided in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of a vector beam indivisibility measurement device provided in Embodiment 2;

[0036] Figure 3 Therefore Figure 2 The measurement results of the second-order complete vector beam indivisibility were obtained by simulating the optical path of the mid-vector beam indivisibility measurement device as an example: Figure 3 Figure (a) shows the light field intensity distribution and polarization distribution of the second-order complete vector beam; Figure 3 Figures (b) to (e) show the measurement results under a left-handed circular polarization channel; Figure 3 (f) to (i) are the measurement results under the right-hand circular polarization channel;

[0037] Figure 4(a) is based on Figure 2 The measurement results of the indivisibility of a second-order vector beam under different θ values ​​were obtained by simulating the optical path of the medium vector beam indivisibility measurement device as an example.

[0038] Figure 4(b) is based on Figure 2 The measurement results of the second-order vector beam indivisibility under the condition of changing the phase difference of 2α between the two vortex beams were obtained by simulating the optical path of the medium vector beam indivisibility measurement device as an example.

[0039] Figure 5 This is a schematic diagram of a vector beam indivisibility measurement device provided in Embodiment 3;

[0040] Figure 6 This is a schematic diagram of a vector beam indivisibility measurement device provided in Embodiment 4;

[0041] Figure 7 This is a schematic diagram of a vector beam indivisibility measurement device provided in Embodiment 5;

[0042] Figure 8 This is an example structure of a vector beam generator in an embodiment of the present invention;

[0043] Figure 9(a) is a schematic diagram of a vector beam generator based on a Sagnac loop structure that generates a vector beam using a polarization-sensitive phase hologram loading device.

[0044] Figure 9(b) is a schematic diagram of a vector beam generator based on a polarization-insensitive vortex phase structure to generate a vector beam.

[0045] Figure 10 A schematic diagram of an anti-turbulence communication system based on vector beam indivisibility coding is provided in an embodiment of the present invention.

[0046] Figure 11(a) is a schematic diagram of an anti-turbulence communication system based on vector beam indivisibility coding provided by an embodiment of the present invention based on single-order vector beam indivisibility measurement;

[0047] Figure 11(b) is a schematic diagram of another anti-turbulence communication system based on vector beam indivisibility coding provided by the embodiment of the present invention based on the measurement of single-order vector beam indivisibility. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] In a first aspect, the present invention provides a vector beam indivisibility measurement device, which is described below with reference to different embodiments.

[0050] Example 1

[0051] like Figure 1 As shown, the vector beam indivisibility measuring device may include the following components:

[0052] The system includes a laser, a first beam splitter, a vector beam generation module, a quarter-wave plate, a first collimator, a polarizer, a second beam splitter, a polarization beam splitter, an optical field camera module, and a computing module; among which,

[0053] The laser is used to generate an input beam; the first beam splitter is used to split the input beam into a signal path and a reference path, which are respectively input to the first collimator and the vector beam generation module.

[0054] The first collimator is used to adjust the input reference beam into a collimated Gaussian beam in free space; the polarizer is used to convert the collimated Gaussian beam into a 45° linearly polarized reference beam.

[0055] The vector beam generation module includes at least one set of collimators and vector beam generators. Each set of collimators and vector beam generators is used to generate a vector beam of a corresponding order according to the input signal beam, and input the vector beam of the corresponding order as a set of vector beams to be measured into the quarter-wave plate. The quarter-wave plate is used to convert the obtained vector beams to be measured into signal light in a superposition state.

[0056] The second beam splitter is used to combine the reference light and the signal light and then perform off-axis interference, and input the resulting interference field beam into the polarization beam splitter; the polarization beam splitter is used to polarize and split the interference field beam and then input it into the light field camera module; the light field camera module is used to obtain off-axis interference holograms under different polarization channels using the light field camera therein; the calculation module is used to calculate the corresponding complex amplitude distribution information of the obtained off-axis interference hologram, and calculate the indivisibility value of the vector beam to be measured based on the obtained complex amplitude distribution information.

[0057] in, Figure 1 The dotted lines in the subsequent figures represent the optical axis direction of the beam transmission.

[0058] In this embodiment of the invention, when the vector beam generation module uses only one set of collimators and vector beam generators, the indivisibility measurement of a single-order vector beam can be achieved. When the vector beam generation module uses two or more sets of collimators and vector beam generators, the indivisibility measurement of a superposition state of multiple-order vector beams can be achieved.

[0059] Compared to existing technologies that rely on phase hologram loading devices to calculate the indivisibility of the target vector beam after its generation, the embodiments of the present invention have the following advantages:

[0060] 1. This invention utilizes the light field camera module to obtain off-axis interference holograms under different polarization channels and uses the calculation module to perform digital domain processing based on the off-axis interference holograms under different polarization channels to realize the numerical calculation of the indivisibility of the vector beam under test. This process does not require the use of a phase hologram loading device to demodulate higher-order modes. Therefore, the measurement performance, such as rate and insertion loss, is not limited by the performance of the phase hologram loading device, and the measurement effect can be guaranteed.

[0061] 2. In the process of calculating the indivisibility value of the present invention, since key steps such as mode demodulation are processed quickly in the digital domain, the present invention can achieve rapid measurement of the indivisibility of vector beams through a single exposure of a light field camera when the optical path is simple.

[0062] 3. The vector beam generation module of the present invention includes at least one set of collimators and vector beam generators. When using one set of collimators and vector beam generators, it is possible to measure the indivisibility of a single-order vector beam. However, without increasing the optical path complexity, it is possible to measure the indivisibility of a superposition state of multiple-order vector beams through at least two sets of collimators and vector beam generators, thus making it more applicable.

[0063] 4. This invention can measure the indivisibility of vector beams without using expensive phase hologram loading devices, and the light field camera required by this invention is low-cost. Therefore, this invention has the advantage of low cost.

[0064] To facilitate understanding of the embodiments of the present invention, the second embodiment will be described first, taking the measurement of the indivisibility of a single-order vector beam as an example.

[0065] Example 2

[0066] In this case, the vector beam generation module uses only one set of collimators and a vector beam generator; at this time, Figure 1 Please refer to an exemplary structure of the vector beam indivisibility measurement device shown. Figure 2 As shown. Includes:

[0067] Laser 1; First beam splitter 2; Collimator 3; Vector beam generator 4; Quarter-wave plate 5; First collimator 6; Polarizer 7; Second beam splitter 8; Polarization beam splitter 9; Light field camera module including first light field camera 10 and second light field camera 11; Calculation module 12.

[0068] Among them, the first beam splitter 2 is in Figure 2 The example uses a two-fiber beam splitter, but is not limited to this. Collimator 3 and vector beam generator 4 constitute a vector beam generation module.

[0069] Specifically, the input beam generated by laser 1 is split into a signal path and a reference path by the first beam splitter 2; the reference path beam is input into the first collimator 6, and the signal path beam is input into the collimator 3.

[0070] After the reference beam is input into the first collimator 6, it is adjusted by the first collimator 6 into a collimated Gaussian beam in free space, and then enters the polarizer 7. The polarizer 7 converts the input collimated Gaussian beam into a 45° linearly polarized Gaussian beam, that is, obtains a 45° linearly polarized reference beam, and then enters the second beam splitter 8.

[0071] After the signal beam is input to collimator 3, it is adjusted by collimator 3 into a collimated Gaussian beam in free space, and then enters vector beam generator 4. Vector beam generator 4 converts the input collimated Gaussian beam into a vector beam, which is output as the vector beam to be measured to quarter-wave plate 5. Quarter-wave plate 5 converts the input vector beam to be measured into a superposition state of two linearly polarized vortex beams. Specifically, since the vector beam can be regarded as the superposition of two vortex beams of opposite orders with different circular polarizations, after passing through quarter-wave plate 5, the vector beam to be measured is converted into two linearly polarized vortex beams of opposite orders with x-polarization and y-polarization as the signal light in the superposition state. Then, quarter-wave plate 5 inputs the signal light in the superposition state into the second beam splitter 8.

[0072] The second beam splitter 8 combines the reference light and the signal light, performs off-axis interference to obtain an interference field beam, and inputs the obtained interference field beam into the polarization beam splitter 9.

[0073] The polarization beam splitter 9 polarizes and splits the input interference field beam before inputting it into the first light field camera 10 and the second light field camera 11.

[0074] Off-axis interference holograms of the vector beam under test in two polarization channels can be measured at the first light field camera 10 and the second light field camera 11, respectively. Specifically, the first light field camera 10 and the second light field camera 11 obtain the off-axis interference holograms of the left-hand circular polarization channel and the right-hand circular polarization channel in the vector beam under test, respectively, and input them into the calculation module 12.

[0075] After the off-axis interference holograms output by the first light field camera 10 and the second light field camera 11 are input into the calculation module 12, the calculation module 12 calculates the corresponding complex amplitude distribution information of the obtained off-axis interference holograms respectively, that is, calculates the complex amplitude distribution information of the vector beam under two polarizations, and calculates the indivisibility value of the vector beam under test by performing digital processing in the digital domain based on the obtained complex amplitude distribution information.

[0076] for Figure 2The vector beam generated by vector beam generator 4 in the device has an optical field that can be described as the superposition of two orthogonal circularly polarized vortex beams of opposite orders:

[0077]

[0078] in, Represented by horizontal plane polar coordinates and the vector beam described by the power-related term θ, and These are the expressions for -l-order and l-order vortex beams, respectively. i is the imaginary unit used to represent the spatial phase of the light field. For -l-order and l-order vortex beams, their phases are opposite. l is a natural number greater than 0, such as 1, 2, 3, etc., which correspond to different orders of vortex beams. and These represent left-handed circular polarization and right-handed circular polarization, respectively, while cosθ and sinθ represent the power coefficients of a left-handed circularly polarized first-order vortex beam and a right-handed circularly polarized first-order vortex beam, respectively.

[0079] The indivisibility of this vector beam can be denoted as |sin(2θ)|, that is, the indivisibility value can be calculated using |sin(2θ)|; when θ in |sin(2θ)| takes the value of 0, When π, ..., and other values ​​are available such that |sin(2θ)|=0, the light field described by equation (1) is a circularly polarized vortex beam, and its indivisibility value is 0; when θ in the equation takes the value of ... When the value of |sin(2θ)|=1 is obtained, the light field described by equation (1) is a complete vector light field, and its indivisibility value is 1. When θ in the equation takes other values ​​that make 0<|sin(2θ)|<1, the light field described by equation (1) is a partial vector light field, and its indivisibility value is between 0 and 1 (excluding 0 and 1).

[0080] To measure the indivisibility of the optical field described by equation (1), the traditional method is to pass the optical field through six different demodulated phase holograms (i.e., the phases of the l-th and -l-th order vortex beams, and the ±l-th order vortex beams with 0, ...) in two circularly polarized channels. The phase difference superposition phase is used to obtain the power weights of the six modes under the two polarization channels of the vector light field, and then the Pauli operator expectation value is calculated to finally obtain the indivisibility of the beam.

[0081] In this embodiment of the invention, for a vector beam that has already been generated, the indivisibility measurement process does not use a phase hologram loading device, and there is no need to switch the loading phase hologram multiple times. Instead, the indivisibility value is calculated based on an off-axis interference hologram using a digital domain calculation method.

[0082] In one optional implementation, the process by which the calculation module calculates the corresponding complex amplitude distribution information of the obtained off-axis interferometric hologram and calculates the indivisibility value of the vector beam under test based on the obtained complex amplitude distribution information includes:

[0083] Step a1: Calculate the complex amplitude distribution information corresponding to the off-axis interference hologram obtained from the vector beam under test using the calculation module; wherein, the complex amplitude distribution information includes intensity and phase;

[0084] against Figure 2 The apparatus shown has a vector beam generation module that generates only one set of vector beams to be measured, which enters the quarter-wave plate 5. Therefore, this set of vector beams to be measured is the final vector beam to be measured in this embodiment of the invention. The calculation module 12 calculates the complex amplitude distribution information of the vector beams to be measured under the two polarizations based on the off-axis interference holograms recorded by the first light field camera 10 and the second light field camera 11.

[0085] Specifically, a Fast Fourier Transform (FFT) is performed on the off-axis interference hologram of any polarization channel to obtain the spatial frequency domain. This spatial frequency domain includes a DC term (DC), an AC term (CC), and the conjugate of the AC term (CC). The AC term (CC) contains the intensity and phase information of the optical field to be measured in the polarization channel. Therefore, filtering it out and performing an inverse Fourier Transform yields the intensity and phase distribution of the optical field to be measured in that polarization channel, i.e., the complex amplitude distribution information in that polarization channel.

[0086] Step a2: Calculate the overlap integral of the obtained complex amplitude distribution information with different mode bases to obtain a set of power weights for different modes corresponding to the complex amplitude distribution information;

[0087] Specifically, the power weights of the corresponding modes are obtained by calculating the overlap integral between the complex amplitude distribution information and different mode bases through digital processing in the digital domain.

[0088] The calculation of the overlap integral between the complex amplitude distribution information and any mode basis yields the power weight corresponding to that mode. The calculation formula used is as follows:

[0089]

[0090] Among them, P i This represents the power weight of the i-th mode. The light field distribution of the i-th mode is represented by a known quantity; It represents the conjugate of the light field distribution of the i-th mode. It represents the information on the complex amplitude distribution, that is, the measured complex amplitude of the light field.

[0091] In this embodiment of the invention, since the complex amplitude distribution information of the vector beam under two polarizations is calculated, the overlap integral of the complex amplitude distribution information of the polarization path with any mode basis is calculated using formula (2) under the two polarizations, and the power weights corresponding to different modes under the polarization path are obtained.

[0092] For example, in the case of a single order such as the first order, the overlap integral is performed using the measured complex amplitude of the optical field and the first-order mode basis.

[0093] Step a3: Construct a power weight matrix based on the power weights of all the different modes obtained;

[0094] Specifically, in this embodiment of the invention, the power weights of each mode obtained under each polarization path are combined into a column vector, and then the column vectors obtained from the two polarization paths are combined into a power weight matrix.

[0095] Step a4: Calculate the indivisibility value of the vector beam under test using the power weight matrix.

[0096] Specifically, those skilled in the art will understand that, in relation to the embodiments of the present invention, processing the power weight matrix can yield an indivisibility value corresponding to the vector beam under test. The specific processing method is prior art and will be briefly described in the following examples.

[0097] like Figure 3 As shown, Figure 3 Therefore Figure 2 The result of the second-order complete vector beam indivisibility measurement obtained by simulating the optical path of the device in the embodiment shows that its original indivisibility value was 1.

[0098] Figure 3 In the diagram, (a) shows the light field intensity distribution and polarization distribution of the vector beam; (b) shows the off-axis hologram measured by the left-hand circular polarization channel; (c) shows the spatial frequency domain diagram obtained by performing a Fourier transform on (b); (d) shows the reconstructed light field intensity distribution under the left-hand circular polarization channel; (e) shows the reconstructed light field phase distribution under the left-hand circular polarization channel; (f) shows the off-axis hologram measured by the right-hand circular polarization channel; (g) shows the spatial frequency domain diagram obtained by performing a Fourier transform on (f); (h) shows the reconstructed light field intensity distribution under the right-hand circular polarization channel; and (i) shows the reconstructed light field phase distribution under the right-hand circular polarization channel.

[0099] Specifically, Figure 3 Figure (a) shows the light field intensity and polarization distribution of this second-order complete vector beam. Figure 2 The device in the experiment measures its indivisibility value by first splitting the vector beam into two polarization channels for measurement. For example, Figure 3 Images (b) to (e) show the measurement results under a left-handed circular polarization channel. Figure 3 Image (b) shows an off-axis interferometric hologram measured in a left-hand circular polarization channel. A fast Fourier transform of this off-axis interferometric hologram yields... Figure 3 (c) shows the spatial frequency domain. This spatial frequency domain includes the DC term DC, the AC term CC, and its conjugate. The AC term CC contains the intensity and phase information of the optical field under test. Therefore, filtering it out and performing an inverse Fourier transform yields the intensity and phase distributions of the optical field under the left-hand circular polarization channel, as shown below. Figure 3 As shown in (d) and (e). Similarly, off-axis holograms in a right-handed circularly polarized channel can be obtained as follows. Figure 3 As shown in (f), its spatial frequency domain, reconstruction intensity distribution, and phase distribution are respectively as follows: Figure 3 As shown in (g) to (i), by performing an overlap integral on the optical field distributions of the two reconstructed polarization channels with different mode bases, a 2×6-dimensional power weight matrix recording the power weights of each mode can be obtained. Based on this power weight matrix, the indivisibility value of the vector beam is calculated to be 0.997.

[0100] The specific calculation process is as follows: Let P be the element of this 2×6 dimension matrix. ij Where i takes values ​​of 1 and 2, and j takes values ​​from 1 to 6, the formula for calculating the indivisibility value is:

[0101]

[0102] Furthermore, the number of decimal places in the final calculation result can be appropriately selected. Please refer to the relevant technical explanation for the specific calculation process.

[0103] As can be seen, the present invention obtains the power weights of the vector light fields under the two polarization channels and the six modes by directly calculating the overlap integral in the digital domain, and then calculates the Pauli operator expectation value and obtains the indivisibility value of the vector light field.

[0104] As shown in Figures 4(a) and 4(b), it is based on Figure 2 The results of measuring the indivisibility of different second-order vector beams were obtained by simulating the optical path of the device in the embodiment. Figure 4(a) shows the theoretical values ​​and simulation results of measuring vector beams with different indivisibility, which are obtained by changing the power weight tanθ between the two orthogonal circularly polarized vortex beams constituting them; Figure 4(b) shows the theoretical values ​​and simulation results of measuring various vector beams with an indivisibility of 1, which are obtained by changing the phase difference 2α between the two orthogonal circularly polarized vortex beams constituting them.

[0105] By changing the value of θ in equation (1), a series of vector beams with different indivisibility values ​​can be obtained. Figure 4(a) shows the theoretical values ​​and simulation results of the indivisibility values ​​of the vector beams under different θ values. In the simulation, let θ be... The intervals are uniform from 0 to Take 9 values, in these 9 cases Figure 2 The measurement results of the indivisibility value obtained by the device have very small errors compared with the theoretical value. For the vector light obtained by combining two vortex beams:

[0106]

[0107] Changing the phase difference 2α between the two vortex beams will also produce different vector beams, but the indivisibility value of these vector beams is the same. Here, θ is taken as... The indivisibility values ​​of these different vector beams were measured by varying the size of 2α, and the results are shown in Figure 4(b). Both theoretical and simulation results show that changing the size of the phase difference 2α does not affect the indivisibility value of the vector beam.

[0108] As can be seen, compared with Embodiment 1, the vector beam indivisibility measurement device provided in Embodiment 2 is specifically implemented using a light field camera module containing two light field cameras. The two light field cameras can record off-axis interference holograms of the corresponding polarization channels for the vector beam to be measured, so that the calculation module can decode the indivisibility value.

[0109] Example 3

[0110] Compared to Embodiment 2, in Embodiment 3, the light field camera module includes a third light field camera; for the vector beam indivisibility measurement device provided in this embodiment, please refer to [link to related documentation]. Figure 5 As shown. Figure 5 In the diagram, 13 represents the third light field camera; for the other reference numerals, please refer to the corresponding reference numerals in Embodiment 2. Figure 2 understand.

[0111] The third light field camera 13 is used to obtain off-axis interference holograms of the left-hand circularly polarized channel and the right-hand circularly polarized channel in the vector beam to be measured, and input them into the calculation module 12.

[0112] For Embodiment 3, optionally, the polarization beam splitter 9 is a Wollaston prism or a displacement polarization beam splitter, used to separate the two orthogonally linearly polarized components of the interference field beam on the same side.

[0113] Specifically, these two types of polarization beam splitters can separate orthogonal linearly polarized beams on the same side. Therefore, when using these two types of polarization beam splitters, only one light field camera 13 is needed to record off-axis interference holograms in two polarization channels. After combining the recorded off-axis interference holograms of the left-hand circular polarization channel and the right-hand circular polarization channel, the calculation module 12 can be used to complete the measurement of the indivisibility of the vector beam in two polarization channels.

[0114] The difference from using a single light field camera is that the off-axis interference hologram provided to the calculation module 12 in this embodiment is a combination of the off-axis interference hologram of the left-hand circular polarization channel and the off-axis interference hologram of the right-hand circular polarization channel. The calculation module 12 obtains the off-axis interference hologram of the left-hand circular polarization channel and the off-axis interference hologram of the right-hand circular polarization channel from them, and then calculates the corresponding complex amplitude distribution information, etc., according to the method of Embodiment 2.

[0115] Of course, any optical device capable of separating the two orthogonally linearly polarized components of the interference field beam on the same side can be used as the polarization beam splitter 9 in this embodiment of the invention, and there is no limitation herein.

[0116] Therefore, compared to Embodiment 2, the vector beam indivisibility measurement device provided in Embodiment 3 has a simpler structure.

[0117] Example 4

[0118] Example 4 is illustrated using the measurement of the indivisibility of multi-order vector beams as an example. In this case, the vector beam generation module includes at least two sets of collimators and vector beam generators. Each set of collimators and vector beam generators is used to generate a single-order vector beam as a set of vector beams to be measured, and each set of vector beams to be measured corresponds to multiple different orders.

[0119] Wherein, when the vector beam generating module includes at least two sets of collimators and vector beam generators, the vector beam generating module further includes a third beam splitter; wherein, the at least two sets of collimators and vector beam generators are used to generate vector beams of different orders; the third beam splitter is used to combine the vector beams of different orders and input them into the quarter-wave plate.

[0120] Specifically, an exemplary structure of the vector beam indivisibility measurement device provided in Embodiment 4 can be found in [link to embodiment]. Figure 6 As shown, this is a device for measuring the indivisibility of superposition states of multi-order vector beams, comprising:

[0121] Laser 1; First beam splitter 2; Collimator 3; Vector beam generator 4; Quarter-wave plate 5; First collimator 6; Polarizer 7; Second beam splitter 8; Polarization beam splitter 9; The light field camera module includes a first light field camera 10 and a second light field camera 11; Calculation module 12; Compared to Embodiment 2, Embodiment 4 also includes a collimator 14; Vector beam generator 15; Third beam splitter 16.

[0122] Collimator 3 and vector beam generator 4, as well as collimator 14 and vector beam generator 15, constitute a set of collimators and vector beam generators to generate vector beams of corresponding orders. Then, a third beam splitter 16 combines the two different orders of vector beams and inputs them into a quarter-wave plate 5 to obtain a superposition state of the two different orders of vector beams at the generation end, i.e., obtaining the superposition state signal light, which serves as the final vector beam to be measured. The superposition state signal light is then input into a second beam splitter 8.

[0123] The reference beam passes through the first collimator 6 and the polarizer 7 to obtain a 45° linearly polarized reference beam, which then enters the second beam splitter 8.

[0124] The second beam splitter 8 combines the input reference light and signal light and performs off-axis interference to obtain an interference field beam, which is then input into the polarization beam splitter 9.

[0125] The polarization beam splitter 9 polarizes and splits the input interference field beam before inputting it into the first light field camera 10 and the second light field camera 11.

[0126] For the input vector beam to be measured, the off-axis interference holograms of the vector beam to be measured under two polarization channels can be measured at the first light field camera 10 and the second light field camera 11 respectively, and then input into the calculation module 12.

[0127] The multi-order and single-order cases are similar, the difference being that in the multi-order case, the vector beam to be measured input to the light field camera is a multi-order mixed state, and the off-axis interference hologram measured in each polarization channel is also a multi-order mixed result.

[0128] The calculation module 12 calculates the corresponding complex amplitude distribution information of the obtained off-axis interference hologram, and calculates the indivisibility value of the vector beam to be measured based on the obtained complex amplitude distribution information.

[0129] For single-order cases, such as the first order, the power weights corresponding to the modes are obtained by overlapping the measured complex amplitude and the first-order mode basis, and then the power weight matrix is ​​obtained, such as the exemplary 2×6 power weight matrix in Example 2.

[0130] For multi-order cases, such as the superposition of first and second order polarizations, the off-axis interference holograms of the left-hand circularly polarized channel and the right-hand circularly polarized channel obtained by calculation module 12 are both multi-order mixtures. The corresponding complex amplitude distribution information calculated is also a multi-order mixed complex amplitude, i.e., the mixed first- and second-order optical field complex amplitude obtained from a single measurement. In other words, only one off-axis interference hologram from either the left-hand or right-hand circularly polarized channel is needed to measure the complex amplitude of the optical field of all orders.

[0131] During the calculation, the measured complex amplitude of the optical field is overlapped with the first-order mode basis and the second-order mode basis to achieve separate measurements of different orders. Therefore, compared with the single-order example in Example 2, the multi-order case requires the calculation of two 2*6 power weight matrices, corresponding to the first and second orders respectively, and then the indivisibility value of the vector beam corresponding to that order is calculated using the power weight matrices of each order.

[0132] As can be seen, the vector beam indivisibility measurement device provided in Embodiment 4 can measure the indivisibility of two vector beams of different orders by using off-axis interferometric holograms measured by two light field cameras.

[0133] Of course, based on Embodiment 4, multiple sets of vector beam generation systems consisting of collimators, vector beam generators, etc., can be added to the vector beam generation end. In this way, the vector beam to be measured becomes a superposition of multiple orders of vector beams. For such a superposition of multiple orders of vector beams, the indivisibility of different orders of vector beams can also be calculated based on its off-axis interference hologram. Specific details will not be illustrated or explained here.

[0134] Example 5

[0135] Compared to Embodiment 4, which uses two light field cameras, the measurement of the indivisibility of multi-order vector beams can also be achieved using a single light field camera. An exemplary structure of the vector beam indivisibility measurement device provided in Embodiment 5 can be found in [link to Embodiment 5]. Figure 7 As shown.

[0136] Corresponding to Example 4 Figure 6 In comparison, the difference in Embodiment 5 is that only one light field camera 13 is used. The specific measurement process can be understood by referring to Embodiments 3 and 4, and will not be elaborated here.

[0137] As can be seen, the vector beam indivisibility measurement device provided in Embodiment 4 can measure the indivisibility of two vector beams of different orders by measuring the off-axis interferometric hologram using a light field camera.

[0138] Of course, based on Embodiment 5, this invention can add multiple sets of vector beam generation systems, consisting of collimators, vector beam generators, etc., at the vector beam generation end to calculate the indivisibility of more vector beams of different orders. Specific details will not be illustrated or explained here.

[0139] Regarding the above embodiments, the following provides optional implementations of the vector beam generator in the vector beam generation module.

[0140] (1) In one optional embodiment, the vector beam generator in the vector beam generation module is obtained by combining polarization optical devices with Q plate / vortex wave plate.

[0141] Specifically, the vector beam generator in the vector beam generation module can be composed of polarizing optical devices and a Q plate, or polarizing optical devices and a vortex waveplate.

[0142] Q-plates or vortex plates can convert Gaussian beams with different circular polarizations into vortex beams of opposite order. Superimposing orthogonally polarized, opposite-order circularly polarized vortex beams yields a vector beam output. Since a linearly polarized beam can be considered as the superposition of two orthogonally circularly polarized beams, passing a linearly polarized Gaussian beam through a Q-plate or vortex plate will produce a vector beam output.

[0143] This implementation method can generate vector beams of a fixed order relatively easily.

[0144] (2) In one optional embodiment, the vector beam generator in the vector beam generation module is a vector beam generation system consisting of a preset beam splitter, a preset polarization beam splitter, a preset phase hologram loading device, a preset half-wave plate and a preset quarter-wave plate, which modulates two polarizations into vortex beams of opposite orders and then combines them.

[0145] Among them, the preset beam splitter, preset polarization beam splitter, preset phase hologram loading device, preset half-wave plate and preset quarter-wave plate can be implemented using existing devices.

[0146] Please see Figure 8 The illustrated example structure of the vector beam generator represents a vector beam generator provided by an embodiment of the present invention, which splits and modulates the beams separately and then combines them to generate a vector beam. Specifically, it may include:

[0147] Beam splitter A1, polarization beam splitter A2, first phase hologram loading device A3, half-wave plate A4, second phase hologram loading device A5, and quarter-wave plate A6.

[0148] The direct path of the input Gaussian light is split into x-polarized and y-polarized beams at polarization beam splitter A2. The x-polarized beam is modulated into a vortex beam by the first phase hologram loading device A3; the y-polarized light is adjusted to x-polarization by half-wave plate A4 to ensure the modulation efficiency of the second holographic phase map loading device A5. After being modulated by the second phase hologram loading device A5, it is adjusted to y-polarization again by half-wave plate A4. Polarization beam splitter A2 combines these two vortex beams with different polarizations, and finally, quarter-wave plate A6 converts these two beams into orthogonal circularly polarized vortex beams. Their superposition forms a vector beam.

[0149] This implementation can generate vector beams with adjustable order.

[0150] It should be noted that the first phase hologram loading device A3 and the second phase hologram loading device A5 are used in this embodiment of the invention to generate a vector beam at the vector beam generation end. Compared with the prior art, this embodiment of the invention does not use a phase hologram loading device in the process of calculating the indivisibility value after the vector beam is generated.

[0151] (3) In one optional embodiment, the vector beam generator in the vector beam generation module is a Sagnac loop based on a polarization-sensitive phase hologram loading device or a polarization-insensitive vortex phase structure.

[0152] In one scenario, the vector beam generator can be a Sagnac loop consisting of a beam splitter, a polarization beam splitter, a mirror, a polarization-sensitive phase hologram loading device, a half-wave plate, and a quarter-wave plate.

[0153] For example, Figure 9(a) shows a Sagnac loop structure for generating vector beams based on a polarization-sensitive phase hologram loading device. The phase hologram loading device can be a spatial light modulator, etc. This vector beam generator includes a beam splitter B1, a polarization beam splitter B2, a mirror B3, a phase hologram loading device B4 (effective only for x-polarized light, a polarization-sensitive phase hologram loading device), a half-wave plate B5, a mirror B6, and a quarter-wave plate B7. The dashed line in Figure 9(a) indicates the optical axis direction of the beam transmission.

[0154] In Figure 9(a), after the input Gaussian beam passes through beam splitter B1, its direct path continues to propagate and is split into two Gaussian beams, one x-polarized and one y-polarized, by polarization beam splitter B2. The x-polarized beam passes directly through polarization beam splitter B2, is reflected by mirror B3, and then incident on phase hologram loading device B4, where it is modulated into a vortex beam. This vortex beam is adjusted to y-polarization by half-wave plate B5, reflected by mirror B6, and then reflected at polarization beam splitter B2. The y-polarized beam is reflected at polarization beam splitter B2, reflected by mirror B6, and then adjusted to x-polarization by half-wave plate B5. It is then incident on phase hologram loading device B4 and modulated into a vortex beam. This beam is reflected by mirror B3 and then passes directly through polarization beam splitter B2. Polarization beam splitter B2 combines the two output beams of the loop. The combined beam is reflected at beam splitter B1 and converted into two circularly polarized vortex beams by quarter-wave plate B7. Their superposition forms the vector beam.

[0155] This implementation can generate vector beams with adjustable order and high stability.

[0156] In another case, the vector beam generator can be a Sagnac loop consisting of a polarization beam splitter, a mirror, a polarization-independent phase hologram loading device, and a quarter-wave plate.

[0157] For example, Figure 9(b) shows a Sagnac loop structure for generating vector beams based on a polarization-insensitive vortex phase structure (such as a spiral phase plate). This vector beam generator includes a polarization beam splitter C1, a mirror C2, a polarization-insensitive vortex phase structure (i.e., a polarization-independent phase hologram loading device) C3, a mirror C4, a mirror C5, and a quarter-wave plate C6. The dashed line in Figure 9(b) indicates the optical axis direction of the beam transmission.

[0158] In Figure 9(b), the input Gaussian beam is split into a direct x-polarized beam and a reflected y-polarized beam by polarization beam splitter C1. The direct x-polarized beam is reflected by mirror C2, converted into a vortex beam by polarization-insensitive vortex phase structure C3, and then output directly at polarization beam splitter C1 after reflection by mirrors C4 and C5. The reflected y-polarized beam is reflected by mirrors C5 and C4, converted into a vortex beam by direct polarization-insensitive vortex phase structure C3, and then output after reflection by mirror C2 at polarization beam splitter C1. Since the beam transmitted from both sides through polarization-insensitive vortex phase structure C3 will result in vortex beams of opposite orders, the beam obtained after quarter-wave plate C6 is a vector beam resulting from the superposition of two circularly polarized vortex beams of opposite orders and orthogonal polarization.

[0159] This implementation can generate vector beams with adjustable order and high stability.

[0160] In summary, this invention utilizes a light field camera to construct a device for measuring the indivisibility of a vector beam. This device reconstructs the complex amplitude of the optical field in the two polarization channels of the vector beam by measuring off-axis interference holograms under two orthogonal polarization channels, thereby completing the indivisibility test of the vector beam. This invention, for the generated vector beam, does not rely on a phase hologram loading device during the decoding and calculation of indivisibility. This frees the measurement rate and optical path complexity of the vector beam indivisibility from the limitations of demodulation devices, enabling fast, efficient, and low-cost measurement of vector beam indivisibility. Furthermore, it solves the problem of simultaneously measuring the indivisibility of multiple-order vector beam superposition states, which is difficult in existing technologies.

[0161] Secondly, embodiments of the present invention also provide an anti-turbulence communication system based on vector beam indivisibility coding, implemented based on the vector beam indivisibility measurement device described in the first aspect. The anti-turbulence communication system based on vector beam indivisibility coding, in addition to the structure of the vector beam indivisibility measurement device, further includes:

[0162] An indivisibility encoder is used to control the vector beam generation module to output a vector beam with a preset indivisibility value based on the level value of an electrical signal; wherein the preset indivisibility value corresponds to the level value;

[0163] In the anti-turbulence communication system based on vector beam indivisibility coding, the vector beam generation module and the quarter-wave plate form a turbulence channel; the calculation module is also used to determine the level value of the corresponding electrical signal based on the preset indivisibility value of the calculated vector beam.

[0164] Please refer to the structure of the anti-turbulence communication system based on vector beam indivisibility coding. Figure 10 As shown.

[0165] Figure 10 The indivisibility encoder can be implemented using existing technology. At the transmitting end, the indivisibility encoder can control the vector beam generation module to output a vector beam with a preset indivisibility value based on the level value of the electrical signal, so that the preset indivisibility value matches the level value.

[0166] Specifically, the electrical signal is composed of different symbols of 1 and 0, with 1 corresponding to a high level and 0 corresponding to a low level. Electrical signals (i.e., digital signals) of different levels are encoded into indivisibility values ​​of a certain magnitude. By adjusting the indivisibility value of the vector beam, the electrical signal is loaded onto the transmitted vector beam. After the vector beam passes through a turbulent channel, its indivisibility value can be measured at the receiving end using the working principle of the vector beam indivisibility measurement device provided by this invention. The system's calculation module, acting as a decoder, not only calculates the indivisibility magnitude of the vector beam corresponding to each symbol based on the off-axis interferometric hologram output by the light field camera, but also determines the level value of the electrical signal based on this indivisibility value to complete the decoding, that is, decoding the indivisibility value into digital signals of different levels.

[0167] For details on the specific processing procedures of each module in this system other than the indivisible encoder, please refer to the relevant content in the first section, which will not be elaborated here.

[0168] Furthermore, this system can be implemented using any of the embodiments of the vector beam indivisibility measurement device described in the first aspect above. Specifically, it can perform single-order vector beam indivisibility measurement or multi-order vector beam indivisibility measurement, it can be implemented using one or two light field cameras, and it can adopt any structure of vector beam generator, etc., which will not be elaborated here.

[0169] For ease of visual demonstration, two system structures based on the measurement of the indivisibility of a single-order vector beam are presented below. Please refer to Figures 11(a) and 11(b) for understanding. The two figures respectively utilize two light field cameras and one light field camera. The indivisibility encoder is represented by 100. For details, please refer to... Figure 2 and Figure 5 For simplicity, the system structure based on the measurement of the indivisibility of multi-order vector beams will not be illustrated here; please refer to the relevant content above for understanding.

[0170] The anti-turbulence communication system based on vector beam indivisibility coding provided in this invention is implemented based on the provided vector beam indivisibility measurement device and has the following beneficial effects:

[0171] 1. This invention utilizes the light field camera module to obtain off-axis interference holograms under different polarization channels and uses the calculation module to perform digital domain processing based on the off-axis interference holograms under different polarization channels to realize the numerical calculation of the indivisibility of the vector beam under test. This process does not require the use of a phase hologram loading device to demodulate higher-order modes. Therefore, the measurement performance, such as rate and insertion loss, is not limited by the performance of the phase hologram loading device, and the measurement effect can be guaranteed.

[0172] 2. In the process of calculating the indivisibility value of the present invention, since key steps such as mode demodulation are processed quickly in the digital domain, the present invention can achieve rapid measurement of the indivisibility of vector beams through a single exposure of a light field camera when the optical path is simple.

[0173] 3. The vector beam generation module of the present invention includes at least one set of collimators and vector beam generators. When using one set of collimators and vector beam generators, it is possible to measure the indivisibility of a single-order vector beam. However, without increasing the optical path complexity, it is possible to measure the indivisibility of a superposition state of multiple-order vector beams through at least two sets of collimators and vector beam generators, thus making it more applicable.

[0174] 4. This invention can measure the indivisibility of vector beams without using expensive phase hologram loading devices, and the light field camera required by this invention is low-cost. Therefore, this invention has the advantage of low cost.

[0175] 5. This invention helps to realize free-space anti-turbulence communication based on the indivisibility of vector structured light.

[0176] In this embodiment of the invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0177] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A device for measuring inseparability of a vector light beam, characterized in that, include: The system includes a laser, a first beam splitter, a vector beam generation module, a quarter-wave plate, a first collimator, a polarizer, a second beam splitter, a polarization beam splitter, an optical field camera module, and a computing module; among which, The laser is used to generate an input beam; the first beam splitter is used to split the input beam into a reference path and a signal path, which are respectively input to the first collimator and the vector beam generation module. The first collimator is used to adjust the input reference beam into a collimated Gaussian beam in free space; the polarizer is used to convert the collimated Gaussian beam into a 45° linearly polarized reference beam. The vector beam generation module includes at least one set of collimators and vector beam generators. Each set of collimators and vector beam generators is used to generate a vector beam of a corresponding order according to the input signal beam, and input the vector beam of the corresponding order as a set of vector beams to be measured into the quarter-wave plate. The quarter-wave plate is used to convert the obtained vector beams to be measured into signal light in a superposition state. The second beam splitter is used to combine the reference light and the signal light and then perform off-axis interference, and input the resulting interference field beam into the polarization beam splitter; the polarization beam splitter is used to polarize and split the interference field beam and then input it into the light field camera module; the light field camera module is used to obtain off-axis interference holograms under different polarization channels using the light field camera therein; the calculation module is used to calculate the corresponding complex amplitude distribution information of the obtained off-axis interference hologram, and calculate the indivisibility value of the vector beam to be measured based on the obtained complex amplitude distribution information.

2. The vector beam indivisibility measuring device according to claim 1, characterized in that, When the vector beam generation module includes at least two sets of collimators and vector beam generators, the vector beam generation module further includes a third beam splitter; wherein, the at least two sets of collimators and vector beam generators are used to generate vector beams of different orders; the third beam splitter is used to combine the vector beams of different orders and input them into the quarter-wave plate.

3. The vector beam indivisibility measuring device according to claim 1, characterized in that, The vector beam generator in the vector beam generation module is based on a combination of polarization optics and a Q-plate / vortex waveplate.

4. The vector beam indivisibility measuring device according to claim 1, characterized in that, The vector beam generator in the vector beam generation module is a vector beam generation system consisting of a preset beam splitter, a preset polarization beam splitter, a preset phase hologram loading device, a preset half-wave plate, and a preset quarter-wave plate, which modulates two polarizations into vortex beams of opposite orders and then combines them.

5. The vector beam indivisibility measuring device according to claim 1, characterized in that, The vector beam generator in the vector beam generation module is a Sagnac loop based on a polarization-sensitive phase hologram loading device or a polarization-insensitive vortex phase structure.

6. The vector beam indivisibility measuring device according to claim 1, characterized in that, The light field camera module includes a first light field camera and a second light field camera; wherein, the first light field camera and the second light field camera are used to obtain off-axis interference holograms of the left-hand circularly polarized channel and the right-hand circularly polarized channel in the vector beam to be measured, respectively, and input them into the calculation module.

7. The vector beam indivisibility measuring device according to claim 1, characterized in that, The light field camera module includes a third light field camera; wherein the third light field camera is used to obtain off-axis interference holograms of the left-hand circularly polarized channel and the right-hand circularly polarized channel in the vector beam to be measured, and input them into the calculation module.

8. The vector beam indivisibility measuring device according to claim 7, characterized in that, The polarization beam splitter is a Wollaston prism or a displacement polarization beam splitter, used to separate the two orthogonally linearly polarized components of the interference field beam on the same side.

9. The vector beam indivisibility measuring device according to claim 1, characterized in that, The calculation module calculates the corresponding complex amplitude distribution information of the obtained off-axis interferometric hologram, and calculates the indivisibility value of the vector beam under test based on the obtained complex amplitude distribution information, including: The computational module is used to calculate the complex amplitude distribution information corresponding to the off-axis interferometric hologram obtained from the vector beam under test; wherein, the complex amplitude distribution information includes intensity and phase; The power weights of a set of different modes corresponding to the complex amplitude distribution information are obtained by calculating the overlap integral of the complex amplitude distribution information with the basis of different modes. A power weight matrix is ​​formed based on the power weights of all the different modes obtained; The indivisibility value of the vector beam under test is calculated using the power weight matrix.

10. A turbulence-resistant communication system based on vector beam indivisibility coding, characterized in that, Based on the vector beam indivisibility measurement device according to any one of claims 1 to 9, the anti-turbulence communication system based on vector beam indivisibility coding further includes, on the basis of the structure of the vector beam indivisibility measurement device: An indivisibility encoder is used to control the vector beam generation module to output a vector beam with a preset indivisibility value based on the level value of an electrical signal; wherein the preset indivisibility value corresponds to the level value; In the anti-turbulence communication system based on vector beam indivisibility coding, the vector beam generation module and the quarter-wave plate form a turbulence channel; the calculation module is also used to determine the level value of the corresponding electrical signal based on the preset indivisibility value of the calculated vector beam.

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