CN117589290A - Vector beam inseparability measuring device - Google Patents

Abstract

The invention discloses a vector beam inseparability measuring device, which comprises: the device comprises a laser, a first beam splitter, a vector beam generating module, a quarter wave plate, a first collimator, a polarizer, a second beam splitter, a polarizing beam splitter, a light field camera module and a calculating module; according to the invention, the measuring device is built by using the optical field camera, and the device can reconstruct the complex amplitude of the optical field under the two polarization channels of the vector beam by measuring the off-axis interference holograms under the two orthogonal polarization channels of the vector beam, so that the individuation test of the vector beam is completed. The method does not depend on a phase hologram loading device in the process of decoding and calculating the vector beam inseparability, so that the vector beam inseparability measurement rate and the light path complexity are not limited by a demodulation device, the vector beam inseparability can be measured rapidly, efficiently and at low cost, and the problem that the multi-order vector beam superposition state inseparability simultaneous measurement is difficult to realize in the prior art is solved.

Description

Vector beam inseparability measuring device

Technical Field

The invention belongs to the field of light field regulation and information optics, and particularly relates to a vector beam inseparability measuring device and an anti-turbulence communication system based on vector beam inseparability codes.

Background

In recent years, free-space optical communication technology for transmitting information in an atmospheric channel has been rapidly developed, and is widely used in the fields of scientific research, commercial use, civil use, military use and the like. Compared with the traditional free space radio frequency communication scheme, the free space optical communication has the advantages of smaller antenna system, faster speed, stronger anti-eavesdropping capability, no frequency spectrum authorization and the like. However, while free space optical communication has so many advantages, it has a significant drawback: the ubiquitous atmospheric turbulence in the atmospheric channel can damage the intensity and phase of the beam in the channel, causing beam degradation such as receiver beam drift, light intensity flicker, alignment errors, etc. Since most of the signals of the optical communication system are loaded on the intensity (direct alignment detection), the phase (phase shift keying) or the intensity-phase (quadrature amplitude modulation) of the optical field at present through modulation, the intensity and the phase damage of the light beams caused by the atmospheric turbulence can cause a large number of bit errors at the receiving end, and even cause the failure of the free space optical communication system.

Scientists at university of south africa, gold mountain, have discovered that when a vector beam is transmitted in a single-sided unitary channel, its inseparability can always remain at the original value, and they have also performed theoretical explanation and experimental verification of this phenomenon in published papers. It should be noted that atmospheric turbulence is a typical single-sided unitary channel. Thus, loading the electrical signal in the inseparable dimension of the vector beam becomes a novel and effective solution to the effects of atmospheric turbulence in free-space optical communications. To achieve such communication based on vector beam inseparability, measurement of inseparability of a particular vector beam is of great importance, similar to the process of decoding and information extraction of received signals in conventional optical communication system receivers. The vector beam inseparability measuring device commonly used at present follows: the vector light beam is polarized and split into two orthogonal circular polarized vortex light beams, and then the two circular polarized vortex light beams respectively pass through various (typically, six) phase holograms (loaded on a spatial light modulator or a digital micromirror device), so that the two circular polarized vortex light beams can be demodulated under various mode bases to obtain power weights of various modes. The expected value of the bubble figure of the vector beam can be calculated according to the power weights of different modes, and the indivisible property of the vector beam can be calculated.

However, such a method has the following drawbacks: first, the performance of the measurement system, such as rate, insertion loss, etc., is limited by the performance of the reconfigurable phase hologram loading device; secondly, the measuring speed and the simplicity of the device cannot be achieved, and because the intensity of the holograms passing through six different phases needs to be measured, the phase holograms can be switched on a single phase hologram loading device for six times or a complex six-way system is built to realize single measurement without switching; thirdly, in the case that the input vector beam is not in a single-order but in a multi-order superposition state, the speed or simplicity of the scheme is further deteriorated; fourth, reconfigurable phase hologram loading devices such as spatial light modulators, digital micromirror arrays are costly, which can result in high cost measurement systems.

Therefore, developing a device that effectively avoids these shortcomings that measures vector beam inseparability is an important challenge and has great significance for free-space anti-turbulence communication.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a vector beam inseparability measuring device and an anti-turbulence communication system based on vector beam inseparability coding. The technical problems to be solved by the invention are realized by the following technical scheme:

In a first aspect, an embodiment of the present invention provides a vector beam inseparability measurement device, including:

the device comprises a laser, a first beam splitter, a vector beam generating module, a quarter wave plate, a first collimator, a polarizer, a second beam splitter, a polarizing beam splitter, a light field camera module and a calculating module; wherein,

the laser is used for generating an input light beam; the first beam splitter is used for splitting the input light beam into a reference path and a signal path, and inputting the reference path and the signal path into the first collimator and the vector light beam generating module respectively;

the first collimator is used for adjusting an input reference path light beam into a collimated Gaussian light beam in free space; the polarizer is used for converting the collimated Gaussian beam into reference light with 45-degree linear polarization;

the vector beam generating module comprises at least one group of collimators and vector beam generators, wherein each group of collimators and vector beam generator is used for generating vector beams of corresponding orders according to input signal paths and inputting the vector beams of the corresponding orders into the quarter wave plate as a group of vector beams to be detected; the quarter wave plate is used for converting the obtained vector light beam to be detected into signal light in a superposition state;

The second beam splitter is used for carrying out off-axis interference after combining the reference light and the signal light, and inputting the obtained interference field light beam into the polarization beam splitter; the polarization beam splitter is used for carrying out polarization beam splitting on the interference field light beam and inputting the interference field light beam into the light field camera module; the light field camera module is used for obtaining off-axis interference holograms under different polarization channels by utilizing a light field camera in the light field camera module; the calculation module is used for calculating corresponding complex amplitude distribution information of the obtained off-axis interference hologram, and calculating the non-partitionability value of the vector light beam to be measured according to the obtained complex amplitude distribution information.

In one embodiment of the invention, when the vector beam generating module comprises at least two sets of collimators and a vector beam generator, the vector beam generating module further comprises a third beam splitter; wherein the at least two groups of collimators and the vector beam generator are used for generating vector beams with different orders; the third beam splitter is used for combining the vector light beams with different orders and inputting the vector light beams into the quarter wave plate.

In one embodiment of the invention, the vector beam generator in the vector beam generating module is based on polarizing optics in combination with a Q-plate/vortex plate.

In one embodiment of the present invention, the vector beam generator in the vector beam generating module is a vector beam generating system formed by 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, wherein two paths of polarization are respectively modulated into vortex beams with opposite orders and then combined.

In one embodiment of the 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.

In one embodiment of the invention, the light field camera module comprises a first light field camera and a second light field camera; the first light field camera and the second light field camera are respectively used for obtaining an off-axis interference hologram of a left-handed circular polarization channel and an off-axis interference hologram of a right-handed circular polarization channel in the vector light beam to be detected, and inputting the off-axis interference hologram and the off-axis interference hologram of the right-handed circular polarization channel into the computing module.

In one embodiment of the invention, the light field camera module comprises a third light field camera; the third light field camera is used for obtaining an off-axis interference hologram of the left-handed circular polarization channel and an off-axis interference hologram of the right-handed circular polarization channel in the vector light beam to be detected, and inputting the off-axis interference hologram and the off-axis interference hologram of the right-handed circular polarization channel into the calculation module.

In an embodiment of the invention, the polarizing beam splitter is a wollaston prism or a displacement polarizing beam splitter for separating two orthogonal linear polarization components of the interference field beam on the same side.

In one embodiment of the present invention, the calculating module calculates the corresponding complex amplitude distribution information for the obtained off-axis interference hologram, and calculates the value of the inseparability of the vector beam to be measured according to the obtained complex amplitude distribution information, including:

calculating corresponding complex amplitude distribution information of the off-axis interference hologram obtained by the vector light beam to be detected by using a calculation module; wherein the complex amplitude distribution information includes intensity and phase.

The overlapping integral size of the obtained complex amplitude distribution information and different mode bases is calculated to obtain a group of power weights of different modes corresponding to the complex amplitude distribution information;

forming a power weight matrix according to the obtained power weights of all different modes;

and calculating the non-partitionability value of the vector light beam to be measured by using the power weight matrix.

In a second aspect, an embodiment of the present invention provides an anti-turbulence communication system based on a vector beam inseparability code, which is implemented based on the vector beam inseparability measurement device of the first aspect, and further includes, based on a structure of the vector beam inseparability measurement device:

The non-partitionability encoder is used for controlling the vector beam generating module to output a vector beam with a preset non-partability value according to the level value of the electric signal; wherein the preset indivisible value coincides with the level value;

in the anti-turbulence communication system based on vector beam inseparability coding, a turbulence channel is arranged between the vector beam generating module and the quarter wave plate; the calculation module is also used for judging the level value of the corresponding electric signal according to the calculated preset inseparable value of the vector light beam.

The invention has the beneficial effects that:

1. according to the invention, the optical field camera module is utilized to obtain the off-axis interference holograms under different polarization channels, and the calculation module is utilized to realize the numerical calculation of the insertibility of the vector beam to be measured based on the digital domain processing of the off-axis interference holograms under different polarization channels.

2. In the process of calculating the individuation numerical value, key steps such as mode demodulation and the like are rapidly processed in a digital domain, so that the method can realize rapid measurement of the individuation of the vector beam through single exposure of the light field camera under the condition of simple light path.

3. The vector beam generating module comprises at least one group of collimators and vector beam generators, and can realize the measurement of the individuation of the single-order vector beam when the group of collimators and vector beam generators are adopted, but can realize the measurement of the individuation of the multi-order vector beam superposition state under the condition of not improving the complexity of an optical path, so that the application is stronger.

4. The invention can realize the measurement of the vector beam inseparability without using an expensive phase hologram loading device, and the cost of the light field camera required by the invention is lower, so the invention has the advantage of low cost.

Further, the invention facilitates free-space turbulence-resistant communication based on vector structured light insertibility.

Drawings

FIG. 1 is a schematic diagram of a device for measuring the individuality of a vector beam according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a device for measuring the individuality of vector beam according to the second embodiment;

FIG. 3 is a 2-order full vector beam individuality measurement result obtained by simulation using the vector beam individuality measurement apparatus of FIG. 2 as an embodiment optical path: FIG. 3 (a) is a graph of the light field intensity distribution and polarization distribution of the 2 nd order full vector beam; graphs (b) - (e) in fig. 3 are measurement results under the left-hand circularly polarized channel; fig. 3 (f) to (i) show measurement results in the right-hand circularly polarized beam path;

FIG. 4 (a) is a 2-order vector beam individuation measurement result under different θ values obtained by simulation using the vector beam individuation measurement device of FIG. 2 as an example optical path;

FIG. 4 (b) is a 2-order vector beam individuation measurement result in the case of changing the phase difference 2α of two eddy currents by simulation using the vector beam individuation measurement device of FIG. 2 as an embodiment optical path;

FIG. 5 is a schematic view showing a structure of a vector beam inseparability measuring device according to a third embodiment;

FIG. 6 is a schematic diagram of a structure of a vector beam inseparability measuring device according to a fourth embodiment;

FIG. 7 is a schematic view of a structure of a vector beam inseparability measuring device according to a fifth embodiment;

FIG. 8 is an exemplary configuration of a vector beam generator in an embodiment of the invention;

FIG. 9 (a) is a schematic diagram of a vector beam generator for generating a Sagnac loop structure of vector beams based on a polarization sensitive phase hologram loading device;

FIG. 9 (b) is a schematic diagram of a vector beam generator of the Sagnac loop structure that generates vector beams based on polarization insensitive vortex phase structure;

FIG. 10 is a schematic diagram of a structure of an anti-turbulence communication system based on vector beam inseparability coding according to an embodiment of the present invention;

FIG. 11 (a) is a schematic diagram of a structure of an anti-turbulence communication system based on vector beam inseparability coding according to an embodiment of the present invention based on single-order vector beam inseparability measurement;

fig. 11 (b) is a schematic structural diagram of another anti-turbulence communication system based on vector beam inseparability coding provided by the embodiment of the present invention based on single-order vector beam inseparability measurement.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In a first aspect, the present invention provides a vector beam inseparability measuring device, which is described in different embodiments below.

Example 1

As shown in fig. 1, the vector beam inseparability measuring device may include the following components:

the device comprises a laser, a first beam splitter, a vector beam generating module, a quarter wave plate, a first collimator, a polarizer, a second beam splitter, a polarizing beam splitter, a light field camera module and a calculating module; wherein,

The laser is used for generating an input light beam; the first beam splitter is used for splitting the input light beam into a signal path and a reference path, and inputting the signal path and the reference path into the first collimator and the vector light beam generating module respectively;

the first collimator is used for adjusting an input reference path light beam into a collimated Gaussian light beam in free space; the polarizer is used for converting the collimated Gaussian beam into reference light with 45-degree linear polarization;

the vector beam generating module comprises at least one group of collimators and vector beam generators, wherein each group of collimators and vector beam generator is used for generating vector beams of corresponding orders according to input signal paths and inputting the vector beams of the corresponding orders into the quarter wave plate as a group of vector beams to be detected; the quarter wave plate is used for converting the obtained vector light beam to be detected into signal light in a superposition state;

the second beam splitter is used for carrying out off-axis interference after combining the reference light and the signal light, and inputting the obtained interference field light beam into the polarization beam splitter; the polarization beam splitter is used for carrying out polarization beam splitting on the interference field light beam and inputting the interference field light beam into the light field camera module; the light field camera module is used for obtaining off-axis interference holograms under different polarization channels by utilizing a light field camera in the light field camera module; the calculation module is used for calculating corresponding complex amplitude distribution information of the obtained off-axis interference hologram, and calculating the non-partitionability value of the vector light beam to be measured according to the obtained complex amplitude distribution information.

Wherein the dashed lines in fig. 1 and the subsequent figures represent the optical axis direction of the beam transmission.

According to the embodiment of the invention, when the vector beam generating module only adopts one group of collimators and vector beam generators, the measurement of the individuation of the single-order vector beam can be realized, and when the vector beam generating module adopts more than two groups of collimators and vector beam generators, the measurement of the individuation of the multi-order vector beam superposition state can be realized.

Compared with the prior art that the device is dependent on the phase hologram loading device in the process of calculating the non-partitionability value of the vector beam to be measured after the vector beam to be measured is generated, the embodiment of the invention has the following beneficial effects:

1. according to the invention, the optical field camera module is utilized to obtain the off-axis interference holograms under different polarization channels, and the calculation module is utilized to realize the numerical calculation of the insertibility of the vector beam to be measured based on the digital domain processing of the off-axis interference holograms under different polarization channels.

2. In the process of calculating the individuation numerical value, key steps such as mode demodulation and the like are rapidly processed in a digital domain, so that the method can realize rapid measurement of the individuation of the vector beam through single exposure of the light field camera under the condition of simple light path.

3. The vector beam generating module comprises at least one group of collimators and vector beam generators, and can realize the measurement of the individuation of the single-order vector beam when the group of collimators and vector beam generators are adopted, but can realize the measurement of the individuation of the multi-order vector beam superposition state under the condition of not improving the complexity of an optical path, so that the application is stronger.

4. The invention can realize the measurement of the vector beam inseparability without using an expensive phase hologram loading device, and the cost of the light field camera required by the invention is lower, so the invention has the advantage of low cost.

In order to facilitate understanding of the embodiment of the present invention, first, description of the second embodiment will be made by taking the measurement of the individuality of the single-order vector beam as an example.

Example two

In this case, the vector beam generation module employs only one set of collimators and vector beam generators; at this time, an exemplary structure of the vector beam individuality measuring apparatus shown in fig. 1 is shown in fig. 2. Comprising the following steps:

A laser 1; a first beam splitter 2; a collimator 3; a vector beam generator 4; a quarter wave plate 5; a first collimator 6; a polarizer 7; a second beam splitter 8; a polarizing beam splitter 9; the light field camera module comprises a first light field camera 10 and a second light field camera 11; a calculation module 12.

The first beam splitter 2 is illustrated in fig. 2 as a two-way optical fiber beam splitter, but is not limited thereto. The collimator 3 and the vector beam generator 4 constitute a vector beam generating module.

Specifically, an input beam generated by the laser 1 is divided into a signal path and a reference path by the first beam splitter 2; the reference path light beam is input into the first collimator 6, and the signal path light beam is input into the collimator 3;

after the reference path light beam is input into the first collimator 6, the reference path light beam is adjusted into a collimated Gaussian light beam in free space by the first collimator 6, and then enters the polarizer 7; the polarizer 7 converts the input collimated gaussian beam into a 45 ° linearly polarized gaussian beam, i.e. a 45 ° linearly polarized reference beam, and then enters the second beam splitter 8.

After the signal path light beam is input into the collimator 3, the signal path light beam is adjusted into a collimated Gaussian light beam in free space by the collimator 3, and then enters the vector light beam generator 4; the vector beam generator 4 converts the input collimated Gaussian beam into a vector beam, and outputs the vector beam to the quarter wave plate 5 as a vector beam to be measured; the input vector beam to be measured is converted into two superimposed states of linear polarized vortex beams by the quarter wave plate 5, specifically, the vector beam can be regarded as superimposed of two vortex beams with different circular polarizations and opposite orders, so that after the vector beam to be measured passes through the quarter wave plate 5, the vector beam to be measured is converted into two linear polarized vortex beams with opposite orders of x polarization and y polarization to serve as signal light in the superimposed state. The quarter wave plate 5 then inputs the signal light in the superimposed state to the second beam splitter 8.

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

The polarization beam splitter 9 performs polarization beam splitting on the input interference field beam, and then inputs the interference field beam into the first light field camera 10 and the second light field camera 11.

Off-axis interference holograms of vector light beams to be measured under two polarized 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 respectively obtain an off-axis interference hologram of the left-hand circular polarization channel and an off-axis interference hologram of the right-hand circular polarization channel in the vector light beam to be measured, and input the off-axis interference holograms into the calculation module 12.

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 corresponding complex amplitude distribution information for the obtained off-axis interference holograms, namely, calculates complex amplitude distribution information of the vector light beam to be measured under two paths of polarization, and calculates the indivisible numerical value of the vector light beam to be measured by carrying out digital processing in a digital domain according to the obtained complex amplitude distribution information.

For the vector beam generated by the vector beam generator 4 in the apparatus of fig. 2, the optical field can be written as a superposition of two orthogonal circularly polarized vortex beams of opposite order:

wherein,representing the polar coordinates from the transverse plane +.>The vector beam described by the power related term theta,and->The vortex beam expressions of-l order and l order respectively, i is an imaginary unit for representing the spatial phase of the light field, and for the vortex beams of-l order and l order, their phases are opposite; l is a natural number greater than 0, such as 1, 2, 3, etc., corresponding to different orders of vortex light beams respectively; />And->Respectively representing the left-hand circular polarization and the right-hand circular polarization, and cos theta and sin theta respectively represent the power coefficients of the left-hand circular polarization-l-order vortex light beam and the right-hand circular polarization l-order vortex light beam.

The inseparability of the vector beam can be denoted as |sin (2θ) |, i.e., the inseparability value is calculated by |sin (2θ) |; when the value of theta in the |sin (2 theta) | is 0,When pi … … and the like can make the value of |sin (2θ) |=0, the light field described by formula (1) is a circularly polarized vortex light beam, and the indivisible value thereof is 0; the value of theta in the formula isWhen the values of |sin (2θ) |=1 are equal, the light field described by the formula (1) is a full vector light field, and the indivisible value is 1; theta in the equivalent formula Others make 0<|sin(2θ)|<When the value of 1 is the value, the light field described by the formula (1) is a partial vector light field, and the value of the indivisible numerical value is between 0 and 1 (the value does not contain 0 and 1).

For the optical field described by formula (1), the individuality is measured by passing the optical field through six different demodulation phase holograms (i-order, -l-order vortex beam phases, respectively, and + -l-order vortex beam with 0:, under two circularly polarized channels,The phase difference superimposed phase), the power weights of six modes under the two polarized channels of the vector light field are obtained, further the expected value of the Brix operator is calculated, and finally the insertibility of the light beam is obtained.

The embodiment of the invention aims at the generated vector beam, does not adopt a phase hologram loading device in the process of measuring the inseparability of the vector beam, does not need to switch and load the phase hologram for a plurality of times, and calculates the inseparability value by utilizing a digital domain calculation mode based on the off-axis interference hologram.

In an optional implementation manner, the calculating module calculates corresponding complex amplitude distribution information for the obtained off-axis interference hologram, and calculates the value of the inseparability of the vector beam to be measured according to the obtained complex amplitude distribution information, which includes:

Step a1, calculating corresponding complex amplitude distribution information of an off-axis interference hologram obtained by the vector light beam to be detected by using a calculation module; wherein the complex amplitude distribution information includes intensity and phase;

for the arrangement shown in fig. 2, the vector beam generating module generates only one set of vector beams to be measured into the quarter waveplate 5. Therefore, the set of vector beams to be measured is the vector beam to be measured finally in the embodiment of the invention. The calculating module 12 calculates complex amplitude distribution information of the vector light beam to be measured under two paths of polarization according to the off-axis interference holograms recorded by the first light field camera 10 and the second light field camera 11.

Specifically, the off-axis interference hologram of any polarization channel is subjected to fast Fourier transform to obtain a spatial frequency domain. The spatial frequency domain comprises direct current term DC, alternating current term CC and conjugate of alternating current term CC, and alternating current term CC contains the intensity and phase information of the light field to be detected of the polarized channel, so that the intensity and phase distribution of the light field to be detected under the polarized channel can be obtained by filtering and performing inverse Fourier transform, and complex amplitude distribution information under the polarized channel is obtained.

Step a2, calculating the overlapping integral size of the obtained complex amplitude distribution information and different mode bases to obtain a group of power weights of different modes corresponding to the complex amplitude distribution information;

Specifically, the overlapping integral size of complex amplitude distribution information and different mode bases is calculated by digital processing in a digital domain, and the power weight of a corresponding mode is obtained;

the overlapping integral size of the complex amplitude distribution information and any mode base is calculated to obtain the power weight corresponding to the mode, and the adopted calculation formula is as follows:

wherein P is _i Representing the power weight of the i-th mode,representing the ith mode light field distribution as a known quantity;representing the conjugate of the i-th mode light field distribution. />Representing complex amplitude distribution information, i.e. measured light field complex amplitudes.

For the embodiment of the invention, because the complex amplitude distribution information of the vector light beam to be measured under two paths of polarization is calculated, the overlapping integral size of the complex amplitude distribution information of the path of polarization and any mode base is calculated by using a formula (2) under the two paths of polarization, and the power weights corresponding to different modes under the path of polarization are obtained.

For example, the single-order case, such as the 1 st order case, is to use the measured complex amplitude of the light field and the 1 st order mode basis for overlap integration.

Step a3, forming a power weight matrix according to the obtained power weights of all different modes;

specifically, for the embodiment of the invention, the power weight of each mode obtained under each path of polarization is formed into a column vector, and then the column vectors obtained by two paths of polarization are formed into a power weight matrix.

And a step a4 of calculating the non-partitionability value of the vector light beam to be measured by using the power weight matrix.

Specifically, for the embodiment of the present invention, it can be understood by those skilled in the art that, by processing the power weight matrix, an indivisible value corresponding to the vector beam to be measured may be obtained, and a specific processing method belongs to the prior art, and is briefly described in the following examples.

As shown in fig. 3, fig. 3 is a result of measurement of the 2 nd-order full vector beam individuality obtained by simulation using the device of fig. 2 as an embodiment optical path, and its original individuality value is 1.

In fig. 3, (a) is a light field intensity distribution and polarization distribution of the vector beam; (b) The figure is an off-axis hologram measured for a left-hand circularly polarized channel; (c) The diagram is a schematic diagram of the spatial frequency domain of the diagram obtained by carrying out Fourier transform on the diagram (b); (d) The figure is the light field intensity distribution under the reconstructed left-hand circularly polarized channel; (e) The figure is the light field phase distribution under the reconstructed left-hand circularly polarized channel; (f) The figure is an off-axis hologram measured for a right-handed circularly polarized channel; (g) The diagram is a schematic diagram of the spatial frequency domain of the diagram obtained by carrying out Fourier transform on the diagram (f); (h) The figure is the light field intensity distribution under the reconstructed right-hand circularly polarized channel; (i) The figure is the light field phase distribution under the reconstructed right-hand circularly polarized channel.

Specifically, the (a) graph in fig. 3 is the light field intensity distribution and polarization distribution diagram of the 2 nd order perfect vector beam. The measurement of the value of its inseparability using the apparatus of fig. 2 is performed by first splitting the vector beam into two polarized channels. For example, fig. 3 (b) to (e) show measurement results under the left-hand circular polarization channel, fig. 3 (b) is an off-axis interference hologram measured under the left-hand circular polarization channel, and the spatial frequency domain shown in fig. 3 (c) can be obtained by performing fast fourier transform on the off-axis interference hologram. The spatial frequency domain comprises a direct current term DC, an alternating current term CC and conjugate thereof, wherein the alternating current term CC contains the intensity and phase information of the light field to be detected, so that the intensity and phase distribution of the light field to be detected under the left-hand circular polarization channel can be obtained by filtering and performing inverse Fourier transform, and the intensity and phase distribution of the light field to be detected under the left-hand circular polarization channel are shown in fig. 3 (d) and (e), respectively. Similarly, an off-axis hologram under a right-hand circularly polarized channel can be obtained as shown in fig. 3 (f), and the spatial frequency domain, the reconstructed intensity distribution, and the phase distribution are shown in fig. 3 (g) to (i), respectively. By performing overlapping integration on the light field distribution under the reconstructed two polarization channels and different mode bases, a 2×6-dimension power weight matrix recording the power weights of each mode can be obtained, and the individuation numerical value of the vector beam is calculated to be 0.997 according to the power weight matrix.

The specific calculation process is as follows: the matrix element of the 2X 6 dimension is denoted as P _ij Wherein i takes the values 1, 2, j takes the values 1 to 6, and the calculation formula of the inseparable numerical value is as follows:

and, the decimal place of the final calculation result can be appropriately selected. For a specific calculation process, refer to the related art for understanding.

Therefore, the invention directly calculates the power weights of the vector light field under two polarization channels and the overlapped integration of the six modes in the digital domain, thereby calculating the expected value of the Brix operator and obtaining the indivisible value of the vector light field.

As shown in fig. 4 (a) and 4 (b), the results of different 2-order vector beam inseparability measurements obtained by simulation using the device of fig. 2 as the light path of the embodiment are shown. FIG. 4 (a) is a theoretical value and simulation result of measurement of vector beams having different insertibilities, which are obtained by changing the power weight tan θ between two orthogonal circularly polarized vortex beams constituting the same; fig. 4 (b) is a theoretical value and simulation result of measurement of various vector beams each having an individuality of 1, which are obtained by changing the phase difference 2α between two orthogonal circularly polarized vortex beams constituting the vector beams.

By changing the magnitude of θ in the variation (1), a series of vector light beams having different values of inseparability can be obtained. As shown in fig. 4 (a), the theoretical value of the non-partitionability value of the vector beam and the result of the simulation calculation are obtained under the condition of different values of θ. Simulation time θIs uniformly from 0 to +.>Taking 9 values, the device in fig. 2 has very little error from the theoretical value in the measurement of the indivisible values in these 9 cases. Vector light is obtained by combining two vortex beams:

changing the phase difference 2α of the two eddy currents can also result in different vector beams, but the values of the insertibilities of these vector beams are the same. Here, the value of θ isChanging the size of 2α measures the individuality values of these different vector beams, as shown in fig. 4 (b). Both the theoretical results and the simulation results show that changing the magnitude of the phase difference 2α does not affect the indivisible value of the vector light.

It can be seen that, compared with the first embodiment, the vector beam inseparability measuring device provided in the second embodiment is specifically implemented by using a light field camera module including two light field cameras, where the two light field cameras can record off-axis interference holograms of corresponding polarization channels for the vector beam to be measured respectively, so as to allow the computing module to decode the inseparability value.

Example III

In contrast to the second embodiment, in the third embodiment, the light field camera module includes a third light field camera; the vector beam inseparability measuring device provided in this embodiment is shown in fig. 5. In fig. 5, 13 denotes a third light field camera, and the rest of reference numerals refer to fig. 2 corresponding to embodiment two.

The third light field camera 13 is configured to obtain an off-axis interference hologram of the left-hand circular polarization channel and an off-axis interference hologram of the right-hand circular polarization channel in the vector light beam to be measured, and input the off-axis interference holograms to the calculation module 12.

For embodiment three, the polarizing beam splitter 9 is optionally a wollaston prism or a displacement polarizing beam splitter for separating the two orthogonal linear polarization components of the interference field beam on the same side.

Specifically, the two types of polarizing beam splitters can separate orthogonal linear polarized light beams on the same side, so when the two types of polarizing beam splitters are used, only one light field camera 13 is used to record off-axis interference holograms under two polarizing channels, and the recorded off-axis interference holograms of a left-handed circular polarizing channel and the recorded off-axis interference holograms of a right-handed circular polarizing channel are combined and input into the calculation module 12 to finish measurement of the individuation of vector light beams under the two polarizing channels.

The difference from using a light field camera is that the off-axis interference hologram provided to the calculation module 12 in the embodiment of the present invention 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, from which 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 are obtained by the calculation module 12, respectively, and then the corresponding complex amplitude distribution information and the like are calculated, respectively, in the manner of the second embodiment.

Of course, any optical device capable of separating the two orthogonal linear polarization components of the interference field beam on the same side may be used as the polarizing beam splitter 9 of the embodiment of the present invention, without limitation.

Therefore, the vector beam inseparability measuring device structure provided in the third embodiment is simplified as compared with the second embodiment.

Example IV

The description of the fourth embodiment is made taking the measurement of the inseparability of the multi-order vector beam as an example. In this case, the vector beam generating module includes at least two sets of collimators and vector beam generators, each set of collimators and vector beam generator being configured to generate a single order vector beam as a set of vector beams to be measured, each set of vector beams to be measured corresponding to a plurality of different orders.

Wherein, when the vector beam generating module comprises at least two groups of collimators and a vector beam generator, the vector beam generating module further comprises a third beam splitter; wherein the at least two groups of collimators and the vector beam generator are used for generating vector beams with different orders; the third beam splitter is used for combining the vector light beams with different orders and inputting the vector light beams into the quarter wave plate.

Specifically, an exemplary structure of the vector beam inseparable measuring device provided in the fourth embodiment is shown in fig. 6, and is a device for measuring inseparability of a multi-order vector beam superposition state, including:

a laser 1; a first beam splitter 2; a collimator 3; a vector beam generator 4; a quarter wave plate 5; a first collimator 6; a polarizer 7; a second beam splitter 8; a polarizing beam splitter 9; the light field camera module comprises a first light field camera 10 and a second light field camera 11; a calculation module 12; compared with the second embodiment, the fourth embodiment further includes a collimator 14; a vector beam generator 15; a third beam splitter 16.

The collimator 3 and the vector beam generator 4, and the collimator 14 and the vector beam generator 15 respectively form a group of collimator and vector beam generator to respectively generate vector beams with corresponding orders, and then the vector beams with two different orders are combined by the third beam splitter 16 and input into the quarter wave plate 5, so that a superposition state of the vector beams with two different orders is obtained at the generating end, namely, signal light with the superposition state is obtained and is used as a vector beam to be finally measured. The signal light in the superimposed state is then input to the second beam splitter 8.

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

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

The polarization beam splitter 9 performs polarization beam splitting on the input interference field beam, and then inputs the interference field beam into the first light field camera 10 and the second light field camera 11.

For the input vector light beam to be measured, off-axis interference holograms of the vector light 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 input into the calculation module 12.

The multi-order and single-order cases are similar, except that the vector beam to be measured input into the light field camera for the multi-order case is a multi-order hybrid, and the off-axis interference hologram under each polarization channel measured is also a multi-order hybrid result.

The calculating module 12 calculates the corresponding complex amplitude distribution information for the obtained off-axis interference hologram, and calculates the value of the insertibility of the vector beam to be measured according to the obtained complex amplitude distribution information.

For the single-order case, for example, 1 st order, the measured complex amplitude and the 1 st order mode base are used for performing overlapped integration to obtain the power weight corresponding to the mode, so as to obtain the power weight matrix, for example, the power weight matrix of 2×6 in the second embodiment is obtained.

For the multi-order case, such as the case of 1-order and 2-order superposition, the off-axis interference holograms of the left-hand circular polarization channel and the off-axis interference holograms of the right-hand circular polarization channel obtained by the calculation module 12 are both the multi-order mixed results. The corresponding complex amplitude distribution information is calculated respectively, and the complex amplitude is also the complex amplitude of the multi-order mixture, namely the 1-order and 2-order mixed optical field complex amplitude obtained by single measurement. That is, only one off-axis interference hologram of either the left-hand circularly polarized channel or the right-hand circularly polarized channel is required to measure the complex amplitude of the light field of all orders.

During calculation, the measured light field complex amplitude is overlapped and integrated with the 1-order mode base and the 2-order mode base respectively, so that different-order separation measurement is realized. Therefore, compared with the single-order case example in the second embodiment, the multi-order case calculates two 2*6 power weight matrices corresponding to the 1 st order and the 2 nd order respectively, and then calculates the individuation value corresponding to the vector beam of each order by using the power weight matrix of each order.

It can be seen that the vector beam inseparability measuring device provided in the fourth embodiment can measure the inseparability of two vector beams with different orders through the off-axis interference holograms measured by the two light field cameras.

Of course, on the basis of the fourth embodiment, the embodiment of the present invention may further add a plurality of groups of vector beam generating systems formed by collimators, vector beam generators, and the like at the vector beam generating end, so that the vector beam to be measured is in a superposition state of more vector beams. For such a multi-order vector beam superposition state, the insertibility of the different order vector beams can also be calculated from their off-axis interference holograms. And in particular will not be illustrated or described herein.

Example five

Compared with the fourth embodiment, which adopts two light field cameras, the implementation of the measurement of the inseparability of the multi-order vector beam can also be realized by adopting one light field camera, and an exemplary structure of the vector beam inseparability measuring device provided in the fifth embodiment is shown in fig. 7.

The fifth embodiment differs from the fourth embodiment in fig. 6 in that it is implemented with only one light field camera 13. The specific measurement process is understood in conjunction with the third embodiment and the fourth embodiment, and will not be described herein.

It can be seen that the vector beam inseparability measuring device provided in the fourth embodiment can measure the inseparability of two vector beams with different orders through the off-axis interference hologram measured by one light field camera.

Of course, on the basis of the fifth embodiment, the embodiments of the present invention may further add a plurality of groups of vector beam generating systems formed by collimators, vector beam generators, and the like at the vector beam generating end, so as to calculate the individuation of more vector beams with different orders. And in particular will not be illustrated or described herein.

For each of the above embodiments, alternative implementations of the vector beam generator in the vector beam generating module are given below.

(1) In an alternative embodiment, the vector beam generator in the vector beam generating module is based on polarizing optics in combination with a Q-plate/vortex plate.

Specifically, the vector beam generator in the vector beam generating module may be composed of a polarizing optical device and a Q-plate, or a polarizing optical device and a vortex wave plate.

The Q plate or the vortex wave plate can convert Gaussian beams with different circular polarizations into vortex beams with opposite orders, and vector beam output can be obtained by superposition of circular polarization vortex beams with orthogonal polarizations and opposite orders. Since the linearly polarized light beam can be regarded as the superposition of two orthogonal circularly polarized light beams, the vector beam output can be obtained by passing the linearly polarized Gaussian beam through the Q plate or the vortex wave plate.

This embodiment can produce a vector beam of a fixed order relatively simply.

(2) In an optional implementation manner, the vector beam generator in the vector beam generating module is a vector beam generating system which is formed by 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, and two paths of polarization are respectively modulated into vortex beams with opposite orders and then combined.

The preset beam splitter, the preset polarization beam splitter, the preset phase hologram loading device, the preset half wave plate and the preset quarter wave plate can be realized by adopting the existing devices.

Referring to fig. 8, an exemplary structure of a vector beam generator is shown, which is a vector beam generator for generating vector beams by separately modulating and combining split beams according to an embodiment of the present invention. Specifically, the method comprises the following steps:

a beam splitter A1, a polarizing beam splitter A2, a first phase hologram loading device A3, a half-wave plate A4, a second phase hologram loading device A5 and a quarter-wave plate A6.

The straight path of the input gaussian light is split into x-polarization and y-polarization at the polarizing beam splitter A2. The x polarization is modulated into a vortex beam by the first phase hologram loading device A3; the y polarized light is adjusted to x polarization by the half-wave plate A4 to ensure the modulation efficiency of the second hologram loading device A5, and is adjusted to y polarization again through the half-wave plate A4 after being modulated by the second hologram loading device A5. The polarized beam splitter A2 combines the two vortex beams with different polarization, and the quarter wave plate A6 finally converts the two vortex beams into orthogonal circularly polarized vortex beams, and the orthogonal circularly polarized vortex beams are overlapped to form a vector beam.

This embodiment may produce a vector beam with adjustable orders.

It should be noted that, in the embodiment of the present invention, the first phase hologram loading device A3 and the second phase hologram loading device A5 are used to generate the vector beam at the vector beam generating end.

(3) In an alternative embodiment, the vector beam generator in the vector beam generating module is a sagnac loop based on a polarization-sensitive phase hologram loading device or a polarization-insensitive vortex phase structure.

In one case, the vector beam generator may be a sagnac loop formed by a beam splitter, a polarizing beam splitter, a mirror, a polarization sensitive phase hologram loading device, a half wave plate, a quarter wave plate, and the like.

For example, fig. 9 (a) is a vector beam generator of a sagnac loop structure based on polarization sensitive phase completion with a hologram loading device generating a vector beam. Wherein the phase hologram loading device may be a spatial light modulator or the like. The vector beam generator includes a beam splitter B1, a polarizing 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 broken line in fig. 9 (a) is the optical axis direction of the light beam transmission.

In fig. 9 (a), after the input gaussian beam passes through the beam splitter B1, its straight path continues to transmit and is split into two gaussian beams of x-polarization and y-polarization by the polarization beam splitter B2. The x-polarization path passes through the polarization beam splitter B2, is reflected by the reflecting mirror B3 and then enters the phase hologram loading device B4 to be modulated into vortex light beams, the vortex light beams are adjusted to y polarization by the half-wave plate B5, and are reflected at the polarization beam splitter B2 after being reflected by the reflecting mirror B6; the y polarization path is reflected at the polarization beam splitter B2, and is adjusted to be x polarization beam through the half-wave plate B5 after being reflected by the reflecting mirror B6, and the x polarization beam is incident on the phase hologram loading device B4 and modulated to be vortex beam, and the beam is directly connected at the polarization beam splitter B2 after being reflected by the reflecting mirror B3. The polarization beam splitter B2 completes the beam combination of the two paths of light output by the loop, the combined light is reflected at the beam splitter B1 and converted into two circularly polarized vortex beams by the quarter wave plate B7, and the superposition of the two circularly polarized vortex beams is a vector beam.

This embodiment can produce a vector beam with an adjustable order and high stability.

In another case, the vector beam generator may be a sagnac loop formed by a polarizing beam splitter, a mirror, a polarization independent phase hologram loading device, a quarter wave plate, etc.

For example, fig. 9 (b) is a vector beam generator of a sagnac loop structure that generates vector beams based on a polarization insensitive vortex phase structure (e.g., a spiral phase plate, etc.). The vector beam generator comprises a polarizing 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 broken line in fig. 9 (b) is the optical axis direction of the light beam transmission.

In fig. 9 (b), the input gaussian beam is split by the polarizing beam splitter C1 into a straight x-polarized beam and a reflected y-polarized beam. The straight-through x polarized light beam is reflected by a reflector C2, is converted into a vortex light beam by a polarization insensitive vortex phase structure C3, and is directly output at a polarization beam splitter C1 after being reflected by a reflector C4 and a reflector C5; after the reflection path y polarized light beam is reflected by the reflector C5 and the reflector C4, the straight-through polarization insensitive vortex phase structure C3 is converted into a vortex light beam, and after the vortex light beam is reflected by the reflector C2, the vortex light beam is reflected and output at the polarization beam splitter C1. Since the light beam is transmitted from the front side and the back side through the polarization insensitive vortex phase structure C3, the vortex light beam with opposite orders is obtained, and therefore, the obtained quarter wave plate C6 is a vector light beam obtained by overlapping two paths of circularly polarized vortex light beams with opposite orders and orthogonal polarization.

This embodiment can produce a vector beam with an adjustable order and high stability.

In summary, the device for measuring the individuation of the vector beam is built by using the optical field camera, and the device can reconstruct the complex amplitude of the optical field under the two polarization channels of the vector beam by measuring the off-axis interference holograms under the two orthogonal polarization channels of the vector beam, so as to finish the individuation test of the vector beam. The method aims at the generated vector beam, and does not depend on a phase hologram loading device in the process of decoding and calculating the inseparability, so that the measurement rate and the light path complexity of the vector beam inseparability are not limited by a demodulation device, the rapid, efficient and low-cost measurement of the vector beam inseparability can be realized, and the problem that the prior art is difficult to realize the simultaneous measurement of the inseparability of the multi-order vector beam superposition state is solved.

In a second aspect, an embodiment of the present invention further provides an anti-turbulence communication system based on a vector beam inseparable code, which is implemented based on the vector beam inseparable measurement device of the first aspect, and further includes:

The non-partitionability encoder is used for controlling the vector beam generating module to output a vector beam with a preset non-partability value according to the level value of the electric signal; wherein the preset indivisible value coincides with the level value;

in the anti-turbulence communication system based on vector beam inseparability coding, a turbulence channel is arranged between the vector beam generating module and the quarter wave plate; the calculation module is also used for judging the level value of the corresponding electric signal according to the calculated preset inseparable value of the vector light beam.

The structure of the anti-turbulence communication system based on vector beam inseparability coding is shown in fig. 10.

The indivisible encoder in fig. 10 may be implemented using the prior art. At the transmitting end, the non-partitionable encoder can control the vector beam generating module to output a vector beam with a preset non-partitionable value according to the level value of the electric signal, so that the preset non-partitionable value accords with the level value.

Specifically, the electrical signal is composed of different symbols of 1 and 0, 1 corresponds to a high level, and 0 corresponds to a low level. The electrical signals (i.e., digital signals) of different level values are encoded into a magnitude of the non-partitionability value, and by modulating the non-partitionability value of the vector beam, the electrical signals are loaded on the transmitted vector beam. After the vector beam is transmitted through a turbulent flow channel, the measurement of the individuation value of the vector beam can be completed by using the working principle of the measuring device for the individuation of the vector beam, and a calculating module of the system is used as a decoder to calculate the individuation value of the vector beam corresponding to each code element according to the off-axis interference hologram output by the light field camera, and judge the level value of the electric signal according to the individuation value to complete decoding, namely, the individuation value is decoded into digital signals with different level values.

For specific processing procedures of each module in the system except for the indivisible encoder, please refer to the related content of the first aspect, which is not described herein.

Moreover, the system may be implemented using any of the embodiments of the vector beam individuality measuring means of the first aspect. Specifically, the single-order vector beam inseparability measurement may be performed, the multi-order vector beam inseparability measurement may be performed, the single-order vector beam inseparability measurement may be performed by using one or two light field cameras, and any structure of the vector beam generator may be adopted, which is not described herein.

For visual presentation, two system structures based on single-order vector beam inseparability measurement are given below, please see fig. 11 (a) and fig. 11 (b), respectively, for understanding that the two figures are implemented by two light field cameras and one light field camera, respectively. Wherein the non-partitional encoder is denoted 100. Please understand in detail with reference to fig. 2 and 5. For simplicity, the system architecture based on multi-order vector beam inseparability measurement is not illustrated here, please understand in conjunction with the foregoing.

The turbulence-resistant communication system based on vector beam inseparability coding provided by the embodiment of the invention is realized based on the provided vector beam inseparability measuring device, and has the following beneficial effects:

1. According to the invention, the optical field camera module is utilized to obtain the off-axis interference holograms under different polarization channels, and the calculation module is utilized to realize the numerical calculation of the insertibility of the vector beam to be measured based on the digital domain processing of the off-axis interference holograms under different polarization channels.

2. In the process of calculating the individuation numerical value, key steps such as mode demodulation and the like are rapidly processed in a digital domain, so that the method can realize rapid measurement of the individuation of the vector beam through single exposure of the light field camera under the condition of simple light path.

3. The vector beam generating module comprises at least one group of collimators and vector beam generators, and can realize the measurement of the individuation of the single-order vector beam when the group of collimators and vector beam generators are adopted, but can realize the measurement of the individuation of the multi-order vector beam superposition state under the condition of not improving the complexity of an optical path, so that the application is stronger.

4. The invention can realize the measurement of the vector beam inseparability without using an expensive phase hologram loading device, and the cost of the light field camera required by the invention is lower, so the invention has the advantage of low cost.

5. The invention is helpful for realizing free space turbulence-resistant communication based on vector structure light insertibility.

In embodiments of the present invention, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A vector beam inseparability measuring device, comprising:

The device comprises a laser, a first beam splitter, a vector beam generating module, a quarter wave plate, a first collimator, a polarizer, a second beam splitter, a polarizing beam splitter, a light field camera module and a calculating module; wherein,

the laser is used for generating an input light beam; the first beam splitter is used for splitting the input light beam into a reference path and a signal path, and inputting the reference path and the signal path into the first collimator and the vector light beam generating module respectively;

the first collimator is used for adjusting an input reference path light beam into a collimated Gaussian light beam in free space; the polarizer is used for converting the collimated Gaussian beam into reference light with 45-degree linear polarization;

the vector beam generating module comprises at least one group of collimators and vector beam generators, wherein each group of collimators and vector beam generator is used for generating vector beams of corresponding orders according to input signal paths and inputting the vector beams of the corresponding orders into the quarter wave plate as a group of vector beams to be detected; the quarter wave plate is used for converting the obtained vector light beam to be detected into signal light in a superposition state;

the second beam splitter is used for carrying out off-axis interference after combining the reference light and the signal light, and inputting the obtained interference field light beam into the polarization beam splitter; the polarization beam splitter is used for carrying out polarization beam splitting on the interference field light beam and inputting the interference field light beam into the light field camera module; the light field camera module is used for obtaining off-axis interference holograms under different polarization channels by utilizing a light field camera in the light field camera module; the calculation module is used for calculating corresponding complex amplitude distribution information of the obtained off-axis interference hologram, and calculating the non-partitionability value of the vector light beam to be measured according to the obtained complex amplitude distribution information.

2. The vector beam individuality measuring apparatus of claim 1, wherein when the vector beam generating module includes at least two sets of collimators and a vector beam generator, the vector beam generating module further includes a third beam splitter; wherein the at least two groups of collimators and the vector beam generator are used for generating vector beams with different orders; the third beam splitter is used for combining the vector light beams with different orders and inputting the vector light beams into the quarter wave plate.

3. The device for measuring the individuality of the vector beam according to claim 1, wherein the vector beam generator in the vector beam generating module is obtained based on a combination of a polarizing optical device and a Q plate/vortex wave plate.

4. The device for measuring the indivisible vector beam according to claim 1, wherein the vector beam generator in the vector beam generating module is a vector beam generating system which is formed by 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, and two paths of polarization are respectively modulated into vortex beams with opposite orders and then combined.

5. The vector beam individuality measuring apparatus of claim 1, wherein the vector beam generator in the vector beam generating 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 inseparability measurement device of claim 1, wherein the light field camera module comprises a first light field camera and a second light field camera; the first light field camera and the second light field camera are respectively used for obtaining an off-axis interference hologram of a left-handed circular polarization channel and an off-axis interference hologram of a right-handed circular polarization channel in the vector light beam to be detected, and inputting the off-axis interference hologram and the off-axis interference hologram of the right-handed circular polarization channel into the computing module.

7. The vector beam inseparability measurement device of claim 1, wherein the light field camera module comprises a third light field camera; the third light field camera is used for obtaining an off-axis interference hologram of the left-handed circular polarization channel and an off-axis interference hologram of the right-handed circular polarization channel in the vector light beam to be detected, and inputting the off-axis interference hologram and the off-axis interference hologram of the right-handed circular polarization channel into the calculation module.

8. The vector beam individuality measuring apparatus of claim 7, wherein the polarizing beam splitter is a wollaston prism or a displacement type polarizing beam splitter for separating two orthogonal linear polarization components of the interference field beam on the same side.

9. The apparatus according to claim 1, wherein the calculating module calculates the corresponding complex amplitude distribution information for the obtained off-axis interference hologram, and calculates the value of the inseparability of the vector beam to be measured based on the obtained complex amplitude distribution information, comprising:

calculating corresponding complex amplitude distribution information of the off-axis interference hologram obtained by the vector light beam to be detected by using a calculation module; wherein the complex amplitude distribution information includes intensity and phase.

The overlapping integral size of the obtained complex amplitude distribution information and different mode bases is calculated to obtain a group of power weights of different modes corresponding to the complex amplitude distribution information;

forming a power weight matrix according to the obtained power weights of all different modes;

and calculating the non-partitionability value of the vector light beam to be measured by using the power weight matrix.

10. A vector beam inseparable coding based turbulence resistant communication system, characterized in that it is realized based on a vector beam inseparable measuring device according to any of claims 1 to 9, said vector beam inseparable coding based turbulence resistant communication system further comprising, on the basis of the structure of said vector beam inseparable measuring device:

The non-partitionability encoder is used for controlling the vector beam generating module to output a vector beam with a preset non-partability value according to the level value of the electric signal; wherein the preset indivisible value coincides with the level value;

in the anti-turbulence communication system based on vector beam inseparability coding, a turbulence channel is arranged between the vector beam generating module and the quarter wave plate; the calculation module is also used for judging the level value of the corresponding electric signal according to the calculated preset inseparable value of the vector light beam.