A space division multiplexing method and system based on multi-petal perfect vortex array

Abstract

The present application discloses a space division multiplexing method and system based on a multi-petal perfect vortex array, relating to the field of optical communication technology. The method comprises coaxially superimposing a perfect vortex beam light field and a conjugate mode of a perfect vortex beam light field to obtain a petal perfect vortex; coaxially multiplexing multiple petal perfect vortex beams to obtain a multi-petal perfect vortex; identifying orbital angular momentum based on the number of petal bright spots in the multi-petal perfect vortex; and performing incoherent detection of orbital angular momentum based on the identified orbital angular momentum; placing the multi-petal perfect vortex at different spatial positions to form a multi-petal perfect vortex array with an M-row × M-column structure, and performing space division multiplexing; replacing the light field at random spatial positions in the multi-petal perfect vortex array with a Gaussian beam, and reading the light spot distribution using the spatial position of the Gaussian beam as the starting point. The present application can achieve space division multiplexing, improve information encoding and decoding efficiency, and enhance the confidentiality and security of information transmission.

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 communications field. However, limited bandwidth resources cannot meet the needs of the explosive growth in information volume. Although the widespread application of multiplexing technologies such as wavelength division multiplexing, time division multiplexing, and polarization multiplexing, as well as modulation technologies such as orthogonal frequency division multiplexing, orthogonal amplitude modulation, and code division multiple access has alleviated the pressure of the explosive growth in information volume to a certain extent, the capacity of existing communication systems cannot meet the growing demand for communication capacity due to the exhaustion of resources in the amplitude, phase, frequency / wavelength, polarization state, and time dimensions. Because the orbital angular momentum carried by vortex beams has an infinite number of eigenstates, and the different modes are orthogonal to each other, the introduction of vortex beams provides spatial dimensional resources and is expected to fundamentally solve the communication capacity crisis.

[0003] Currently, increasing communication capacity through orbital angular momentum reuse has received widespread attention. Most methods used to achieve this goal are to directly superimpose vortex beams with multiple modes of orbital angular momentum with the same beam waist radius parameter. The orbital angular momentum is then identified through coherent detection at the receiving end of the communication system to complete information encoding and decoding (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 major problems. On the one hand, the spot size of the vortex beam varies positively with the value of the orbital angular momentum, which causes overlapping interference in the superimposed light field spots. On the other hand, identifying 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 encoding and decoding 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 the efficiency of information encoding and decoding, 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, the space division multiplexing method based on the multi-petal perfect vortex array comprising:

[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 a multi-petal-shaped perfect vortex; identifying orbital angular momentum based on the number of petal-shaped bright spots in the multi-petal-shaped perfect vortex; and performing incoherent detection of orbital angular momentum based on the identified orbital angular momentum;

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

[0012] The light field at a random spatial position 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 obtaining of the perfect vortex beam light field and the 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 cylindrical coordinates;

[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 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, exp() is the exponential function, and 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 American 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 orbital angular momentum is identified based on the number of petal-shaped bright spots in the multiple petal-shaped perfect vortices; and orbital angular momentum is incoherently detected based on the identified orbital angular momentum, specifically including:

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

[0021] Among them, E j ′(r,φ) is the light field of the jth petal-shaped perfect vortex from the inside out, and the parameters l j is the topological charge of the jth petal-shaped perfect vortex from the inside out, R j is the radius of the jth petal-shaped perfect vortex, and N is the number of multiplexed petal-shaped 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-lobed 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 sth spatial position spot 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, and space division multiplexing is performed, which then includes:

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

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

[0028] Optionally, replacing the light field at 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 a starting point mark, specifically includes:

[0029] Using the formula Determine the light intensity U of the multi-lobed 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~M 2 .

[0031] Optionally, replacing the light field at 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 a starting point mark, specifically includes:

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

[0033] When reading the light spot at the last row and last column of the multi-petal perfect vortex array, determining whether all spatial positions in the multi-petal perfect vortex array have been 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 using 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-lobed perfect vortex in the multi-lobed 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 the multi-petal perfect vortex array comprising:

[0039] A light field acquisition module, used to acquire 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 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;

[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; identify the orbital angular momentum based on 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 a 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.

[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, which obtains a petal perfect vortex by coaxially superimposing a perfect vortex beam light field and a conjugate mode of a perfect vortex beam light field, and coaxially superimposing and multiplexing perfect vortices with different spot sizes to avoid mutual interference between the spots; coaxially multiplexing multiple petal perfect vortex beams to obtain multiple petal perfect vortices; based on the fact that the number of bright spots of the multiple petal perfect vortex is twice the modal value of the orbital angular momentum, the orbital angular momentum is directly identified by observing the spot morphology and incoherent detection of the orbital angular momentum is performed based on the identified orbital angular momentum; the multiple petal perfect vortices are placed in different spatial positions and combined into a multiple petal perfect vortex array to realize space division multiplexing and improve the efficiency of information encoding and decoding; and the light field at a certain position in the multiple petal perfect vortex array is randomly replaced by a Gaussian beam 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 following briefly introduces the drawings required for use in the embodiments. 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 creative work.

[0047] Figure 1 This is a 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 Schematic diagram of the process for determining 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 Schematic diagram of the decoding sequence of a multi-petal perfect vortex array;

[0051] Figure 5 Two-dimensional light intensity distribution of a multi-lobed 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 this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0053] In order to make the above-mentioned purposes, 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, which includes the following S101 to S105.

[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 cylindrical coordinates;

[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 and recorded as 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) part) changes into multiple petal-shaped bright spots ( Figure 2 (b) of the .

[0062] S103, coaxially multiplexing the plurality of petal-shaped perfect vortex beams to obtain a multi-petal-shaped perfect vortex; identifying 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 based on the identified orbital angular momentum;

[0063] Multiple petal-shaped perfect vortex beams are coaxially multiplexed. Assuming that the beam parameters except l and R are 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 out, and the parameters l j is the topological charge of the jth petal-shaped perfect vortex from the inside out, R j is the radius of the jth petal-shaped perfect vortex, and N is the number of multiplexed petal-shaped perfect vortex beams.

[0066] S104, the multi-petal perfect vortex ( Figure 2 (c) of the vortex array) are placed in different spatial positions to form a multi-petal perfect vortex array with M rows × M columns ( Figure 2 (d) of the vortex matrix, 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, the multiple petal perfect vortex array U′(r′,φ′) is obtained by moving U(r,φ) to different spatial positions and combining them:

[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 sth spatial position spot 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-lobed perfect vortex array;

[0070] Here, |·| represents the modulo 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 beam, and the number of bright spots is equal to 2l. Therefore, observing the morphology of the petal-shaped perfect vortex light spot can directly obtain the modal value of the orbital angular momentum and realize orbital angular momentum identification. The petal-shaped perfect vortex corresponding to different topological charge values ​​is mapped one-to-one with the digital sequence, so that different petal-shaped perfect vortices can represent different digital information. At the receiving end of the communication system, the number of captured light spots is observed to read the corresponding topological charge, restore the transmitted information, and realize the incoherent detection and decoding of the information.

[0072] S105, replacing the light field at 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, 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-lobed 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 with an 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 an order from the inside to the outside.

[0078] S52, when reading the light spot at the last row and last column of the multi-petal perfect vortex array, determining whether all spatial positions in the multi-petal perfect vortex array have been 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 arrows indicate the reading rules. First, find the part with the bright spot in the center. This part corresponds to the randomly set Gaussian beam and is used as the starting point for reading the multi-petal perfect vortex. The M×M array is read in increasing order of columns and rows. The position of the Gaussian beam may appear at any position in the array. Therefore, the starting point of the reading may not be the first spatial position of the first row and the first column of the array. As a result, after reading the end of the array, it is necessary to read the remaining positions.

[0082] This application provides a hexadecimal encoding and decoding solution, 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, then perfect vortices of different forms 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, in which a certain position in space is randomly displaced by a Gaussian beam.

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

[0087] If the multi-lobed 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-lobed 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 ; Combine all topological charges with 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}, {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}; combine the obtained digital sequences from front to back to obtain a digital sequence consisting of 120 hexadecimal numbers, thereby realizing information reading and restoration.

[0088] The present application is different from the current method of coaxial superposition of vortex beams of the same size. The present application uses coaxial superposition of 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 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 coaxial superposition of mutually conjugated perfect vortex beams is used to obtain petal-shaped perfect vortices, and the numerical relationship between the number of bright spots of the petal-shaped perfect vortex spot and the doubled topological charge of the beam is used to propose direct observation of the spot distribution, identification of the orbital angular momentum, and incoherent detection encoding and decoding based on 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 currently used interference method;

[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 embodiments of the present application also provide 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. The implementation solution provided by this system is similar to the implementation solution described in the above method. Therefore, the specific limitations of one or more space division multiplexing system embodiments based on a multiple petal perfect vortex array provided below can be found in the above limitations on the space division multiplexing method based on a multiple petal perfect vortex array, 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 to acquire 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 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;

[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; identify the orbital angular momentum based on 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 a 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.

[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 (I / O for short) and a communication interface. 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. 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 via a network connection. When the computer program is executed by the processor, a space division multiplexing method based on a multi-lobed 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 skilled in the art will understand that all or part of the processes in the above-mentioned embodiment methods can be implemented 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 memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may 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 may 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 databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may include, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic units, data processing logic units based on quantum computing, and the like.

[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 can 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 document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may 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 includes: 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 a multi-petal-shaped perfect vortex; identifying orbital angular momentum based on the number of petal-shaped bright spots in the multi-petal-shaped perfect vortex; and performing incoherent detection of orbital angular momentum based on the identified orbital angular momentum; Multiple petal-shaped perfect vortices are placed at different spatial positions to form a multiple petal-shaped perfect vortex array with M rows × M columns for space division multiplexing. The light field at a random spatial position 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 cylindrical coordinates; 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, exp() is the exponential function, and 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 field, and * represents the conjugate mode.

4. The space division multiplexing method based on the multi-petal perfect vortex array according to claim 3, 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 based on 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-lobed perfect vortex; Among them, E j ′(r,φ) is the light field of the jth petal-shaped perfect vortex from the inside out, and the parameters l j is the topological charge of the jth petal-shaped perfect vortex from the inside out, R j is the radius of the jth petal-shaped perfect vortex, and N is the number of multiplexed petal-shaped 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-lobed 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 sth spatial position spot 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: 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, which then includes: Using the formula Determine the light intensity I(r′,φ′) of the multi-lobed perfect vortex array; Here, |·| represents the modulo 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 at 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 specifically includes: Using the formula Determine the light intensity U of the multi-lobed 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~M 2 .

8. The space division multiplexing method based on the multi-petal perfect vortex array according to claim 1, characterized in that: The method of replacing the light field at 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 specifically includes: Using the Gaussian beam spot as the starting point, the topological charge in the M×M multi-petal perfect vortex array is read in ascending order of spatial position columns and rows. When reading the light spot at the last row and last column of the multi-petal perfect vortex array, determining whether all spatial positions in the multi-petal perfect vortex array have been 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 M×M structure in ascending order of spatial position columns and rows, specifically including: Each multi-lobed perfect vortex in the multi-lobed 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 to acquire 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 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; 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; identify the orbital angular momentum based on 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 a 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.

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