Space division multiplexing method and system based on multi-petal-shaped perfect vortex array

Abstract

The invention discloses a space division multiplexing method and system based on a multi-petal-shaped perfect vortex array, and relates to the technical field of optical communication, and the method comprises the steps: carrying out the coaxial superposition of a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field, and obtaining a petal-shaped perfect vortex; the multiple petal-shaped perfect vortex light beams are coaxially multiplexed, and multiple petal-shaped perfect vortexes are obtained; the orbital angular momentum is identified according to the number of petal-shaped hot spots in the multiple petal-shaped perfect vortexes; performing orbital angular momentum incoherent detection according to the identified orbital angular momentum; the multi-petal-shaped perfect vortexes are arranged at different spatial positions to form a multi-petal-shaped perfect vortex array of an M-row * M-column structure, and space division multiplexing is carried out; and replacing a light field in a random spatial position in the multi-petal-shaped perfect vortex array with a Gaussian beam, and reading a light spot distribution condition by taking the spatial position of the Gaussian beam as a starting point mark. According to the invention, space division multiplexing can be realized, the information coding and decoding efficiency is improved, and the information transmission secrecy security is enhanced.

Description

Technical Field

[0001] The present application relates to the field of optical communication technology, and in particular to a space division multiplexing method and system based on a multi-petal perfect vortex array. Background Art

[0002] Continuously improving information transmission capabilities has always been a goal pursued in the field of communications, but limited bandwidth resources cannot meet the needs of the explosive growth of information. Although the widespread application of multiplexing technologies such as wavelength division multiplexing, time division multiplexing, polarization multiplexing, and modulation technologies such as orthogonal frequency division multiplexing, orthogonal amplitude modulation, and code division multiple access has alleviated the pressure of the explosive growth of information to a certain extent, due to the exhaustion of resources in amplitude, phase, frequency / wavelength, polarization state, and time dimensions, the capacity of existing communication systems cannot meet the growing demand for communication capacity. Since the orbital angular momentum carried by the vortex beam has an infinite number of eigenstates, and different modes are orthogonal to each other, the introduction of the vortex beam provides spatial dimension resources, which is expected to fundamentally solve the communication capacity crisis.

[0003] At present, improving communication capacity through orbital angular momentum reuse has received widespread attention. Most of the methods used are to directly superimpose vortex beams of multiple modal orbital angular momentums with the same beam waist radius parameters, and then complete information encoding and decoding by coherent detection and identification of orbital angular momentum at the receiving end of the communication system (Alan E. Willner, Huibin Zhou, Xinzhou Su, Hao Song, Kai Pang, and Haoqian Song, "Utilizing Structured Modal Beams in Free-Space Optical Communications for Performance Enhancement", IEEE Journal of Selected Topics in Quantum Electronics, 29, 3700213, 2023). This method has two main problems. On the one hand, the spot size of the vortex beam will show a positive correlation with the value of the orbital angular momentum, which causes overlapping interference of the superimposed light field spot; on the other hand, identifying the orbital angular momentum through coherent detection is sensitive to the environment, and the recognition accuracy is easily affected by environmental factors, which reduces the recognition accuracy and increases the communication bit error rate.

[0004] Therefore, based on the two problems of the current vortex beam that directly superimposes multiple modal orbital angular momentum, there is an urgent need to provide a space-division multiplexing method and system based on a multi-petal perfect vortex array to achieve space-division multiplexing, improve information coding efficiency and enhance the confidentiality and security of information transmission. Summary of the invention

[0005] The purpose of this application is to provide a space division multiplexing method and system based on a multi-petal perfect vortex array, which can realize space division multiplexing, improve information encoding and decoding efficiency and enhance the confidentiality and security of information transmission.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, the present application provides a space division multiplexing method based on a multi-petal perfect vortex array, and the space division multiplexing method based on a multi-petal perfect vortex array comprises:

[0008] Obtaining a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field;

[0009] Coaxially superimposing the perfect vortex beam light field and the conjugate mode of the perfect vortex beam light field to obtain a petal-shaped perfect vortex; the petal-shaped perfect vortex is the light field after conjugate superposition;

[0010] Coaxially multiplexing multiple petal-shaped perfect vortex beams to obtain multiple petal-shaped perfect vortices; identifying orbital angular momentum according to the number of petal-shaped bright spots in the multiple petal-shaped perfect vortices; and performing incoherent detection of orbital angular momentum according to the identified orbital angular momentum;

[0011] Multiple petal perfect vortices are placed at different spatial positions to form a multiple petal perfect vortex array with M rows × M columns for space division multiplexing;

[0012] The light field in random spatial positions in the multi-petal perfect vortex array is replaced by a Gaussian beam, and the light spot distribution is read with the spatial position of the Gaussian beam as the starting point.

[0013] Optionally, the step of acquiring a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field specifically includes:

[0014] Using the formula Determine the light field E(r,φ) of the perfect vortex beam in the cylindrical coordinate system;

[0015] Among them, (r, φ) is the polar coordinate, r and φ are the polar diameter and polar angle respectively, φ=arctan(y / x), i is the imaginary unit, ω0 is the beam waist radius, ω is the width of the bright ring of the light spot, R is the radius of the perfect vortex beam, l is the topological charge of the beam, which represents the mode number of orbital angular momentum, exp() is the exponential function, x and y are the horizontal and vertical coordinates in the rectangular coordinate system, respectively.

[0016] Optionally, the coaxial superposition of the perfect vortex beam light field and the conjugate mode of the perfect vortex beam light field to obtain a petal-shaped perfect vortex specifically includes:

[0017] Using the formula E′(r,φ)=E(r,φ)+E * (r, φ) determines the petal-shaped perfect vortex E′(r, φ);

[0018] Among them, E * (r,φ) is the conjugate mode of the light field of the vortex beam, and * is the conjugate.

[0019] Optionally, multiple petal-shaped perfect vortex beams are coaxially multiplexed to obtain multiple petal-shaped perfect vortices; and the orbital angular momentum is identified according to the number of petal-shaped bright spots in the multiple petal-shaped perfect vortices; and the orbital angular momentum is incoherently detected according to the identified orbital angular momentum, specifically including:

[0020] Using the formula Determine the light field U(r,φ) of a multi-petal perfect vortex;

[0021] Among them, E j ′(r,φ) is the light field of the jth petal-shaped perfect vortex from the inside to the outside, and the parameters l j is the topological charge of the jth perfect vortex from the inside out, R j is the radius of the jth petal perfect vortex, and N is the number of multiplexed petal perfect vortex beams.

[0022] Optionally, placing multiple petal-shaped perfect vortices at different spatial positions to form a multiple petal-shaped perfect vortex array with an M-row×M-column structure for space division multiplexing specifically includes:

[0023] Using the formula Determine the multi-petal perfect vortex array U′(r′,φ′);

[0024] Among them, r′ and φ′ are the polar diameter and polar angle of moving to the new spatial position, respectively. Polar angle φ s =arctan(y s / x s ), (x s ,y s ) is the center coordinate of the spot at the sth spatial position in the M×M array, from top to bottom and from left to right, x s =x±d,y s =y±d, d is the translation amount.

[0025] Optionally, multiple petal-shaped perfect vortices are placed at different spatial positions to form a multiple petal-shaped perfect vortex array with an M-row×M-column structure for space division multiplexing, and then further comprising:

[0026] Using the formula Determine the light intensity I(r′,φ′) of the multi-petal perfect vortex array;

[0027] Here, |·| represents the modulus value.

[0028] Optionally, replacing the light field in a random spatial position in the multi-petal perfect vortex array with a Gaussian beam, and reading the light spot distribution with the spatial position of the Gaussian beam as the starting point mark, specifically includes:

[0029] Using the formula Determine the light intensity U of the multi-petal perfect vortex array after replacing it with a Gaussian beam Array (r′,φ′);

[0030] Among them, E Gauss is a Gaussian beam, A0 is a constant, w is the spot size of the Gaussian beam, δ(·) is the Dirac function, k is a constant, and the value range of k is 1 to M 2 .

[0031] Optionally, replacing the light field in a random spatial position in the multi-petal perfect vortex array with a Gaussian beam, and reading the light spot distribution with the spatial position of the Gaussian beam as the starting point mark, specifically includes:

[0032] Using the Gaussian beam spot as the starting point mark, the topological charge in the multi-petal perfect vortex array of M×M structure is read in the order of increasing spatial position columns and rows.

[0033] When reading the light spot at the last row and the last column in the multi-petal perfect vortex array, determining whether all the spatial positions in the multi-petal perfect vortex array are read;

[0034] If all are read, stop;

[0035] If not all of them are read, the light spots at the unread spatial positions are read in ascending order of spatial position columns and rows until the starting point mark is read again, and the reading is terminated.

[0036] Optionally, the method of taking the Gaussian beam spot as a starting point mark and sequentially reading the topological charge in the multi-petal perfect vortex array of M×M structure in ascending order of spatial position columns and rows specifically includes:

[0037] Each multi-petal perfect vortex in the multi-petal perfect vortex array is read sequentially from the inside to the outside.

[0038] In a second aspect, the present application provides a space division multiplexing system based on a multi-petal perfect vortex array, the space division multiplexing system based on a multi-petal perfect vortex array comprising:

[0039] A light field acquisition module, used for acquiring a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field;

[0040] A petal-shaped perfect vortex determination module is used to coaxially superimpose a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field to obtain a petal-shaped perfect vortex; the petal-shaped perfect vortex is a light field after conjugate superposition;

[0041] An orbital angular momentum incoherent detection module is used to coaxially multiplex multiple petal-shaped perfect vortex beams to obtain multiple petal-shaped perfect vortices; and identify the orbital angular momentum according to the number of petal-shaped bright spots in the multiple petal-shaped perfect vortices; and perform orbital angular momentum incoherent detection based on the identified orbital angular momentum;

[0042] A space division multiplexing module is used to place multiple petal-shaped perfect vortices at different spatial positions to form a multiple petal-shaped perfect vortex array with an M-row×M-column structure for space division multiplexing;

[0043] The light spot distribution reading module is used to replace the light field in the random spatial position in the multi-petal perfect vortex array with a Gaussian beam, and read the light spot distribution with the spatial position of the Gaussian beam as the starting point mark.

[0044] According to the specific embodiments provided in this application, this application has the following technical effects:

[0045] The present application provides a space division multiplexing method and system based on a multiple-petal perfect vortex array, wherein a petal perfect vortex is obtained by coaxially superimposing a perfect vortex beam light field and a conjugate mode of a perfect vortex beam light field, and perfect vortices with different spot sizes are coaxially superimposed and multiplexed to avoid mutual interference between the spots; multiple petal perfect vortex beams are coaxially multiplexed to obtain multiple petal perfect vortices; based on the fact that there is a two-fold numerical relationship between the number of bright spots of the multiple petal perfect vortex and the modal value of the orbital angular momentum, the orbital angular momentum is directly identified by observing the spot morphology, and the orbital angular momentum is incoherently detected based on the identified orbital angular momentum; multiple petal perfect vortices are placed in different spatial positions to combine into a multiple petal perfect vortex array, so as to realize space division multiplexing and improve the efficiency of information encoding and decoding; and a Gaussian beam is used to randomly replace the light field at a certain position in the multiple petal perfect vortex array to enhance the confidentiality and security of information transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 This is a schematic flow chart of a space division multiplexing method based on a multi-petal perfect vortex array in one embodiment of the present application;

[0048] Figure 2 It is a schematic diagram of the determination process of a multi-petal perfect vortex array;

[0049] Figure 3 Schematic diagram of the two-dimensional light intensity distribution of a petal-shaped perfect vortex;

[0050] Figure 4 It is a schematic diagram of the decoding sequence of a multi-petal perfect vortex array;

[0051] Figure 5 Two-dimensional light intensity distribution diagram of a multi-petal perfect vortex array when the topological charge is set to l=s and k=10. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0053] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0054] In an exemplary embodiment, Figure 1 As shown, a space division multiplexing method based on a multi-petal perfect vortex array is provided, and the method includes the following S101 to S105. Wherein:

[0055] S101, acquiring a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field;

[0056] Using the formula Determine the light field E(r,φ) of the perfect vortex beam in the cylindrical coordinate system;

[0057] Among them, (r, φ) is the polar coordinate, r and φ are the polar diameter and polar angle respectively, φ=arctan(y / x), i is the imaginary unit, ω0 is the beam waist radius, ω is the width of the bright ring of the spot, R is the radius of the perfect vortex beam, l is the topological charge of the beam, which represents the number of orbital angular momentum modes, and its value can be any integer, exp() is the exponential function, and x and y are the horizontal and vertical coordinates in the rectangular coordinate system. For the perfect vortex beam field, the conjugate mode is taken, denoted by E * (r,φ), * indicates conjugation;

[0058] S102, coaxially superimposing the perfect vortex beam light field and the conjugate mode of the perfect vortex beam light field to obtain a petal-shaped perfect vortex; the petal-shaped perfect vortex is the light field after conjugate superposition;

[0059] S102 specifically includes:

[0060] Using the formula E′(r,φ)=E(r,φ)+E * (r, φ) determines the petal-shaped perfect vortex E′(r, φ);

[0061] The light field after conjugate superposition is from the hollow bright ring ( Figure 2 (a)) changes into multiple petal-shaped bright spots ( Figure 2 (b) of the Regulations).

[0062] S103, coaxially multiplexing a plurality of petal-shaped perfect vortex beams to obtain a multi-petal-shaped perfect vortex; and identifying the orbital angular momentum according to the number of petal-shaped bright spots in the multi-petal-shaped perfect vortex; and performing incoherent detection of the orbital angular momentum according to the identified orbital angular momentum;

[0063] Multiple petal-shaped perfect vortex beams are coaxially multiplexed. Assuming that the beam parameters except l and R remain the same, the expression of the multiplexed multiple petal-shaped perfect vortex light field is:

[0064]

[0065] Among them, E j ′(r,φ) is the light field of the jth petal-shaped perfect vortex from the inside to the outside, and the parameters l j is the topological charge of the jth perfect vortex from the inside out, R j is the radius of the jth petal perfect vortex, and N is the number of multiplexed petal perfect vortex beams.

[0066] S104, the multi-petal perfect vortex ( Figure 2 (c) of the vortex array) are placed at different spatial positions to form a multi-petal perfect vortex array with M rows × M columns ( Figure 2 (d) of the original image), space division multiplexing is performed; assuming that the center of the initial U(r,φ) spot is located at the origin of the spatial plane rectangular coordinate system Oxy, then U(r,φ) moves to different spatial positions and combines to obtain a multi-petal perfect vortex array U′(r′,φ′):

[0067]

[0068] Among them, r′ and φ′ are the polar diameter and polar angle of moving to the new spatial position, respectively. Polar angle φ s =arctan(y s / xs ), (x s ,y s ) is the center coordinate of the spot at the sth spatial position in the M×M array, from top to bottom and from left to right, x s =x±d,y s =y±d, d is the translation amount.

[0069] Using the formula Determine the light intensity I(r′,φ′) of the multi-petal perfect vortex array;

[0070] Here, |·| represents the modulus value.

[0071] like Figure 3 As shown, the light spot presents multiple petal-shaped bright spots, and the number of bright spots has a fixed numerical relationship with the topological charge value of the conjugate superposition light beam, and the number of bright spots is equal to 2l. Therefore, observing the petal-shaped perfect vortex light spot morphology can directly obtain the modal value of orbital angular momentum and realize orbital angular momentum identification. The petal-shaped perfect vortex corresponding to different topological charge values ​​is mapped one by one with the digital sequence, so that different petal-shaped perfect vortices represent different digital information, and the number of captured light spots is observed at the receiving end of the communication system to read the corresponding topological charge, restore the transmitted information, and realize the incoherent detection encoding and decoding of the information.

[0072] S105, replacing the light field in the random spatial position of the multi-petal perfect vortex array with a Gaussian beam, and reading the light spot distribution with the spatial position of the Gaussian beam as the starting point mark, that is, performing multi-petal perfect vortex array decoding.

[0073] S105 specifically includes:

[0074] Using the formula Determine the light intensity U of the multi-petal perfect vortex array after replacing it with a Gaussian beam Array (r′,φ′);

[0075] Among them, E Gauss is a Gaussian beam, A0 is a constant, A0=1, w is the spot size of the Gaussian beam, δ(·) is the Dirac function, k is a constant, and the value range of k is 1~M 2 .

[0076] S105 specifically includes:

[0077] S51, using the Gaussian beam spot as the starting point mark (such as Figure 4 The topological charge in the multiple-petal perfect vortex array of M×M structure is read in ascending order of spatial position columns and rows (the position circled by the dotted line in the middle); each multiple-petal perfect vortex in the multiple-petal perfect vortex array is read in order from the inside to the outside.

[0078] S52, when reading the light spot at the last row and the last column in the multi-petal perfect vortex array, determining whether all the spatial positions in the multi-petal perfect vortex array are read;

[0079] S53, if all are read, stop;

[0080] S54, if not all are read, then read the light spots at the unread spatial positions in ascending order of spatial position columns and rows until the starting point mark is read again, and then terminate the reading.

[0081] like Figure 4 As shown in the figure, the arrow indicates the reading rule. First, find the part with the bright spot in the center. This part corresponds to the randomly set Gaussian beam, which is used as the starting point for reading the multi-petal perfect vortex. The M×M array is read in the order of increasing columns and rows. The position where the Gaussian beam is set may appear at any position in the array. Therefore, the starting point for reading may not be at the first spatial position of the first row and the first column of the array, resulting in the need to read the remaining positions after reading the end of the array.

[0082] This application provides a hexadecimal encoding and decoding scheme, such as Figure 3 The two-dimensional light intensity distribution diagram of the petal-shaped perfect vortex with topological charge l=1~16 is given. If l=1~16 is matched one by one with the hexadecimal numbers 0~F, the perfect vortex of different forms will correspond to different digital symbols.

[0083] For a 4-row, 4-column multi-petal perfect vortex array, the multi-petal perfect vortex is further randomly replaced with a Gaussian beam at a certain spatial position. The light field expression after replacement is:

[0084]

[0085] k is a random value between 1 and 16. Then, a 4×4 distributed multi-petal perfect vortex array is obtained, which is randomly displaced by a Gaussian beam at a certain position in space.

[0086] Taking the same value for the topological charge of each multi-petal perfect vortex, and setting the topological charge value l = s, and setting k = 10, we get Figure 5The two-dimensional light intensity distribution diagram of the multiple-petal perfect vortex array shown in the figure. First, the obtained light spot is evenly divided into 16 parts, and then starting from the Gaussian beam spot position, the light spots at the spatial positions of s=11 to 16 are read in the order of increasing columns and rows. It can be observed that for each multiple-petal vortex, the number of petal structures is 22, 26, 28, 30, and 32, respectively. At this time, there are still light spots at spatial positions that have not been read, so return to the first row and the first column of the array to continue reading in the order of increasing columns and rows, that is, read from the s=1 position until the Gaussian beam is read again, and finally complete the reading of the remaining space s=1 to 9, and the number of petal structures read is 2, 4, 6, 8, 10, 12, 14, 16, and 18, respectively.

[0087] If the multi-petal vortex topological charge at the s-th spatial position is denoted from the inside to the outside as {m1,…,m8} s , then for Figure 5 In the given example, the topological charge of the 4×4 multi-petal perfect vortex array finally read is {m1=11,…,m8=11} s＝11 、{m1=12,…,m8=12} s＝12 、{m1=13,…,m8=13} s＝13 、{m1=14,…,m8=14} s＝14 、{m1=15,…,m8=15} s＝15 、{m1=16,…,m8=16} s＝16 、{m1=1,…,m8=1} s＝1 、{m1=2,…,m8=2} s＝2 、{m1=3,…,m8=3} s＝3 、{m1=4,…,m8=4} s＝4 、{m1=5,…,m8=5} s＝5 、{m1=6,…,m8=6} s＝6 、{m1=7,…,m8=7} s＝7 、{m1=8,…,m8=8} s＝8 、{m1=9,…,m8=9} s＝9 ; All topological charges and Figure 3By comparing with the formulated hexadecimal encoding and code control chart, the corresponding digital sequences are {A,A,A,A,A,A,A,A}, {B,B,B,B,B,B,B,B,B}, {C,C,C,C,C,C,C,C,C}, {D,D,D,D,D,D,D,D}, {E,E,E,E,E,E,E,E}, {F,F,F,F,F,F,F,F}, {0,0,0,0,0,0,0,0}, {1,1,1,1,1,1,1,1}, {2,2,2,2,2,2,2,2}, {3,3,3,3,3,3,3,3,3}, {4,4,4,4,4,4,4,4}, {5,5,5,5,5,5,5,5}, {6,6,6,6,6,6,6,6}, {7,7,7,7,7,7,7,7}, {8,8,8,8,8,8,8,8}; combine the obtained digital sequence from front to back to obtain a digital sequence of 120 hexadecimal numbers, thereby realizing information reading and restoration.

[0088] The present application is different from the current method of coaxially superimposing vortex beams of the same size. The present application uses coaxially superimposed perfect vortex beams of different sizes, which not only fully utilizes the advantage that the spot size of the perfect vortex beam is not affected by the value of the topological charge, but also keeps the coaxially superimposed beams independent of each other in space, so that the superimposed vortexes can overcome the problem of overlapping interference of spots caused by direct superposition of vortex beams while maintaining the spatial reuse of orbital angular momentum; the perfect vortex beams that are conjugated to each other are coaxially superimposed to obtain a petal-shaped perfect vortex, and the numerical relationship between the number of bright spots of the petal-shaped perfect vortex spot and the topological charge of the beam is doubled, and it is proposed to directly observe the spot distribution, identify the orbital angular momentum, and perform incoherent detection encoding and decoding according to the orbital angular momentum; the present application can directly obtain the modal information of the orbital angular momentum carried by the beam, without the need to identify the orbital angular momentum through the interference method currently used;

[0089] Based on the multiple-petal perfect vortex, this application further designs an array-distributed space-division multiplexing structure to expand the utilization rate of orbital angular momentum space resources and improve the efficiency of information encoding and decoding; and uses a Gaussian beam to randomly permute the light field at a certain position in the array, and uses this as the starting point to read the light spot distribution, thereby increasing the difficulty of decryption and effectively enhancing the confidentiality and security performance of information transmission.

[0090] Based on the same inventive concept, the embodiment of the present application also provides a space division multiplexing system based on a multiple petal perfect vortex array for implementing the space division multiplexing method based on a multiple petal perfect vortex array involved above. The implementation scheme for solving the problem provided by the system is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more embodiments of the space division multiplexing system based on a multiple petal perfect vortex array provided below can be referred to the limitations of the space division multiplexing method based on a multiple petal perfect vortex array above, and will not be repeated here.

[0091] In an exemplary embodiment, a space division multiplexing system based on a multi-petal perfect vortex array is provided, comprising:

[0092] A light field acquisition module, used for acquiring a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field;

[0093] A petal-shaped perfect vortex determination module is used to coaxially superimpose a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field to obtain a petal-shaped perfect vortex; the petal-shaped perfect vortex is a light field after conjugate superposition;

[0094] An orbital angular momentum incoherent detection module is used to coaxially multiplex multiple petal-shaped perfect vortex beams to obtain multiple petal-shaped perfect vortices; and identify the orbital angular momentum according to the number of petal-shaped bright spots in the multiple petal-shaped perfect vortices; and perform orbital angular momentum incoherent detection based on the identified orbital angular momentum;

[0095] A space division multiplexing module is used to place multiple petal-shaped perfect vortices at different spatial positions to form a multiple petal-shaped perfect vortex array with an M-row×M-column structure for space division multiplexing;

[0096] The light spot distribution reading module is used to replace the light field in the random spatial position in the multi-petal perfect vortex array with a Gaussian beam, and read the light spot distribution with the spatial position of the Gaussian beam as the starting point mark.

[0097] In an exemplary embodiment, a computer device is provided, which may be a server or a terminal. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Wherein, the processor, the memory and the input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. Wherein, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a space division multiplexing method based on a multi-petal perfect vortex array is implemented.

[0098] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0099] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0100] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0101] In this application, all actions to obtain signals, information or data are carried out in compliance with the relevant data protection laws and policies of the country where they are located and with the authorization given by the owner of the corresponding device.

[0102] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A space division multiplexing method based on a multi-petal perfect vortex array, characterized in that: The space division multiplexing method based on the multi-petal perfect vortex array comprises: Obtaining a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field; Coaxially superimposing the perfect vortex beam light field and the conjugate mode of the perfect vortex beam light field to obtain a petal-shaped perfect vortex; the petal-shaped perfect vortex is the light field after conjugate superposition; Coaxially multiplexing multiple petal-shaped perfect vortex beams to obtain multiple petal-shaped perfect vortices; identifying orbital angular momentum according to the number of petal-shaped bright spots in the multiple petal-shaped perfect vortices; and performing incoherent detection of orbital angular momentum according to the identified orbital angular momentum; Multiple petal perfect vortices are placed at different spatial positions to form a multiple petal perfect vortex array with M rows × M columns for space division multiplexing; The light field in random spatial positions in the multi-petal perfect vortex array is replaced by a Gaussian beam, and the light spot distribution is read with the spatial position of the Gaussian beam as the starting point.

2. The space division multiplexing method based on the multi-petal perfect vortex array according to claim 1, characterized in that: The obtaining of the perfect vortex beam light field and the conjugate mode of the perfect vortex beam light field specifically includes: Using the formula Determine the light field E(r,φ) of the perfect vortex beam in the cylindrical coordinate system; Among them, (r, φ) is the polar coordinate, r and φ are the polar diameter and polar angle respectively, φ=arctan(y / x), i is the imaginary unit, ω0 is the beam waist radius, ω is the width of the bright ring of the light spot, R is the radius of the perfect vortex beam, l is the topological charge of the beam, which represents the mode number of orbital angular momentum, exp() is the exponential function, x and y are the horizontal and vertical coordinates in the rectangular coordinate system, respectively.

3. The space division multiplexing method based on the multi-petal perfect vortex array according to claim 2, characterized in that: The coaxial superposition of the perfect vortex beam light field and the conjugate mode of the perfect vortex beam light field to obtain a petal-shaped perfect vortex specifically includes: Using the formula E′(r,φ)=E(r,φ)+E * (r, φ) determines the petal-shaped perfect vortex E′(r, φ); Among them, E * (r,φ) is the conjugate mode of the perfect vortex beam light field, and * is the conjugate mode.

4. The space division multiplexing method based on the multi-petal perfect vortex array according to claim 3 is characterized in that: Multiple petal-shaped perfect vortex beams are coaxially multiplexed to obtain a multi-petal-shaped perfect vortex; and the orbital angular momentum is identified according to the number of petal-shaped bright spots in the multi-petal-shaped perfect vortex; And performing orbital angular momentum incoherent detection based on the identified orbital angular momentum, specifically including: Using the formula Determine the light field U(r,φ) of a multi-petal perfect vortex; Among them, E j ′(r,φ) is the light field of the jth petal-shaped perfect vortex from the inside to the outside, and the parameters l j is the topological charge of the jth perfect vortex from the inside out, R j is the radius of the jth petal perfect vortex, and N is the number of multiplexed petal perfect vortex beams.

5. The space division multiplexing method based on the multi-petal perfect vortex array according to claim 4, characterized in that: Placing multiple petal-shaped perfect vortices at different spatial positions to form a multiple petal-shaped perfect vortex array with an M-row×M-column structure for space division multiplexing specifically includes: Using the formula Determine the multi-petal perfect vortex array U′(r′,φ′); Among them, r′ and φ′ are the polar diameter and polar angle of moving to the new spatial position, respectively. Polar angle φ s =arctan(y s / x s ), (x s ,y s ) is the center coordinate of the spot at the sth spatial position in the M×M array, from top to bottom and from left to right, x s =x±d,y s =y±d, d is the translation amount.

6. The space division multiplexing method based on the multi-petal perfect vortex array according to claim 5, characterized in that: Placing multiple petal-shaped perfect vortices at different spatial positions to form a multiple petal-shaped perfect vortex array with M rows × M columns for space division multiplexing, and then including: Using the formula Determine the light intensity I(r′,φ′) of the multi-petal perfect vortex array; Here, |·| represents the modulus value.

7. The space division multiplexing method based on the multi-petal perfect vortex array according to claim 6, characterized in that: The method of replacing the light field in a random spatial position in the multi-petal perfect vortex array with a Gaussian beam and reading the light spot distribution with the spatial position of the Gaussian beam as the starting point mark specifically includes: Using the formula Determine the light intensity U of the multi-petal perfect vortex array after replacing it with a Gaussian beam Array (r′,φ′); Among them, E Gauss is a Gaussian beam, A0 is a constant, w is the spot size of the Gaussian beam, δ(·) is the Dirac function, k is a constant, and the value range of k is 1 to M 2 .

8. The space division multiplexing method based on multi-petal perfect vortex array according to claim 1, characterized in that: The method of replacing the light field in a random spatial position in the multi-petal perfect vortex array with a Gaussian beam and reading the light spot distribution with the spatial position of the Gaussian beam as the starting point mark specifically includes: Using the Gaussian beam spot as the starting point mark, the topological charge in the multi-petal perfect vortex array of M×M structure is read in the order of increasing spatial position columns and rows. When reading the light spot at the last row and the last column in the multi-petal perfect vortex array, determining whether all the spatial positions in the multi-petal perfect vortex array are read; If all are read, stop; If not all of them are read, the light spots at the unread spatial positions are read in ascending order of spatial position columns and rows until the starting point mark is read again, and the reading is terminated.

9. The space division multiplexing method based on the multi-petal perfect vortex array according to claim 8, characterized in that: The method uses the Gaussian beam spot as a starting point mark and sequentially reads the topological charge in the multi-petal perfect vortex array of the M×M structure in the order of increasing spatial position columns and rows, specifically including: Each multi-petal perfect vortex in the multi-petal perfect vortex array is read sequentially from the inside to the outside.

10. A space division multiplexing system based on a multi-petal perfect vortex array, characterized in that: The space division multiplexing system based on the multi-petal perfect vortex array includes: A light field acquisition module, used for acquiring a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field; A petal-shaped perfect vortex determination module is used to coaxially superimpose a perfect vortex beam light field and a conjugate mode of the perfect vortex beam light field to obtain a petal-shaped perfect vortex; the petal-shaped perfect vortex is a light field after conjugate superposition; An orbital angular momentum incoherent detection module is used to coaxially multiplex multiple petal-shaped perfect vortex beams to obtain multiple petal-shaped perfect vortices; and identify the orbital angular momentum according to the number of petal-shaped bright spots in the multiple petal-shaped perfect vortices; and perform orbital angular momentum incoherent detection based on the identified orbital angular momentum; A space division multiplexing module is used to place multiple petal-shaped perfect vortices at different spatial positions to form a multiple petal-shaped perfect vortex array with an M-row×M-column structure for space division multiplexing; The light spot distribution reading module is used to replace the light field in the random spatial position in the multi-petal perfect vortex array with a Gaussian beam, and read the light spot distribution with the spatial position of the Gaussian beam as the starting point mark.

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