Mode division multiplexing systems, methods, devices, and storage media

Abstract

This invention provides a mode-division multiplexing (MDF) system, method, device, and storage medium, relating to the field of optical communication technology. The MDF system includes at least: multiple cascaded optical fiber transmission units across multiple spans and a central controller. Each optical fiber transmission unit includes multimode or few-mode fiber and a mode adjustment unit. The mode adjustment unit calculates the transmission parameters of the optical fiber transmission unit and sends these parameters to the central controller. The central controller acquires the transmission parameters of the optical fiber transmission units in each span, generates a target mode round-robin strategy for the corresponding span, and sends it to the mode adjustment unit to update the optical signal module. The central controller adaptively selects the target mode round-robin strategy based on the real-time transmission environment, adaptively adjusting each span to reduce differential mode group delay (DMD) and mode-dependent loss (MDL), adapting to different span lengths and different transmission environments, and improving the transmission performance of multimode or few-mode fiber.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and more particularly to modulus-division multiplexing systems, methods, devices, and storage media. Background Technology

[0002] Multimode fiber can overcome the capacity limitations of single-mode fiber and improve the transmission rate of communication systems by using multiple modes to transmit information. Multimode fiber includes few-mode fiber, in which light propagates along multiple paths. However, as the number of transmission modes increases, mode-dependent loss (MDL) and differential mode group delay (DMD) inevitably occur during transmission. MDL and DMD significantly increase the computational complexity of the transmission signal at the receiving end of the communication system, thus limiting the transmission distance of few-mode fiber.

[0003] In related technologies, to minimize the accumulation of Differential Mode Group Delay (DMD) and reduce the impact of Mode Dependent Loss (MDL) in the link, mode switching is performed in multimode fiber. Different modes are transmitted in rotation across different channels in different segments of the transmission link using mode polling devices. However, most mode polling strategies in these technologies are based on ideal transmission link conditions. This results in less than ideal effects on reducing DMD and mitigating MDL when segment lengths are inconsistent or transmission conditions are poor. Summary of the Invention

[0004] The main objective of this application is to propose a modular multiplexing system, method, device, and storage medium to reduce the cumulative delay of differential mode group in the transmission link and reduce mode-dependent loss.

[0005] To achieve the above objectives, a first aspect of this application proposes a modular multiplexing system, comprising:

[0006] A transmitter is used to modulate communication signals to obtain an optical signal module, the optical signal module comprising a first preset number of optical signals with different transmission modes;

[0007] A receiver is used to receive the optical signal module and demodulate the optical signal module to obtain the communication signal.

[0008] Multiple cascaded fiber optic transmission units are provided, with the first cascaded fiber optic transmission unit connected to the transmitter and the last cascaded fiber optic transmission unit connected to the receiver, for transmitting the optical signal module emitted by the transmitter to the receiver.

[0009] The central controller is used to acquire the transmission parameters of the optical fiber transmission unit in each segment, and generate the target mode round-robin strategy for the optical fiber transmission unit in the corresponding segment based on the transmission parameters.

[0010] The optical fiber transmission unit includes a multimode fiber and a mode adjustment unit. The mode adjustment unit is used to receive the optical signal module transmitted from the multimode fiber, calculate the transmission parameters of the optical fiber transmission unit based on the optical signal module, send the transmission parameters to the central controller, and adjust the transmission mode of the optical signal in the optical signal module according to the target mode round-robin strategy from the central controller to update the transmission mode of the optical signal in the optical signal module, and send the adjusted optical signal module to the multimode fiber of the next span.

[0011] In some embodiments, the mode adjustment unit includes: a link characterization unit, a link controller, and a mode polling device;

[0012] One end of the link characterization unit is connected to the multimode optical fiber, and is used to calculate the transmission parameters based on each optical signal in the optical signal module transmitted in the current segment of the multimode optical fiber, and send the transmission parameters to the central controller.

[0013] The link controller is used to receive the target mode polling strategy of the optical fiber transmission unit generated by the central controller according to the transmission parameters, and send the target mode polling strategy to the mode polling device;

[0014] One end of the mode-rotating device is connected to the multimode fiber of the current span, and the other end is connected to the multimode fiber of the next span, and is also connected to the link controller. It is used to adjust the transmission mode of the optical signal in the optical signal module according to the target mode-rotating strategy in order to update and transmit the optical signal module.

[0015] In some embodiments, the central controller executes the following when generating the target mode round-robin strategy for the corresponding span of the optical fiber transmission unit based on the transmission parameters:

[0016] Calculate the candidate score for each candidate round-robin strategy in the preset round-robin strategy group based on the transmission parameters;

[0017] The candidate round-robin strategy with the largest candidate score is selected as the target pattern round-robin strategy for the corresponding segment.

[0018] In some embodiments, the transmission parameters include: mode group delay parameters and mode-related loss parameters, and the step of calculating the candidate score of each candidate round-robin strategy in the preset round-robin strategy group based on the transmission parameters includes:

[0019] The group delay score of each candidate round-robin strategy is calculated based on the group delay parameters of the pattern.

[0020] The loss score for each candidate round-robin strategy is calculated based on the pattern-related loss parameters.

[0021] The candidate score of the candidate round-robin strategy is calculated based on the loss score, loss weight, group delay score, and group delay weight.

[0022] In some embodiments, the mode group delay parameter includes the mode delay value of each optical signal in the optical signal module in the current transmission mode, and the mode-related loss parameter includes the loss value of each optical signal in the optical signal module in the current transmission mode;

[0023] The transmission mode of the optical signal is updated using the candidate polling strategy to obtain transmission mode adjustment pairs, each of which contains one or two transmission modes.

[0024] Calculate the mean value of the mode delay value of the transmission mode in each transmission mode adjustment pair to obtain the first delay mean value of the transmission mode adjustment pair, and use the average value of the first delay mean value as the group delay score;

[0025] Calculate the mean of the loss values ​​of the transmission modes in each transmission mode adjustment pair to obtain the second mean loss value of the transmission mode adjustment pair, and use the average value of the second mean loss value as the loss score.

[0026] In some embodiments, the candidate round-robin strategy includes: a sequential round-robin strategy, a pairwise round-robin strategy, a round-robin recommendation strategy based on a genetic algorithm, or a round-robin strategy that iterates through the maximum and minimum values; updating the transmission mode of the optical signal using the candidate round-robin strategy to obtain transmission mode adjustment pairs includes:

[0027] When the candidate polling strategy is a sequential polling strategy, the transmission mode at the current position and the transmission mode at the next position are cyclically exchanged according to the numbering order of the transmission modes;

[0028] When the candidate round-robin strategy is a pairwise round-robin strategy, the transmission modes are grouped according to the number of groups to obtain multiple mode groups. Each mode group is numbered according to the numbering order of the transmission modes. The mode group at the current position is cyclically swapped with the mode group at the next position according to the numbering order of the mode groups.

[0029] When the candidate round-robin strategy is a round-robin recommendation strategy based on a genetic algorithm, the population information of the transmission mode is generated, the population information is input into the genetic recommendation algorithm for population iteration, and after the iteration condition is reached, the recommendation sequence corresponding to the population information is obtained, and the transmission mode is exchanged according to the recommendation sequence.

[0030] When the candidate round-robin strategy is a round-robin strategy that iterates through the maximum and minimum values, the mode group delay parameters and / or the mode-related loss parameters of the transmission mode are sorted, and the transmission modes are exchanged according to the sorting results.

[0031] The transmission mode adjustment pair includes two transmission modes that have been switched and / or one transmission mode that has not been switched.

[0032] In some embodiments, the mode polling device includes: an optical switch module and a polling unit;

[0033] One end of the optical switch module is connected to the multimode fiber of the current span, the other end of the optical switch module is connected to one end of the polling unit, and the other end of the polling unit is connected to the multimode fiber of the next span.

[0034] The link controller generates switching control commands for the polling unit according to the target mode polling strategy;

[0035] The optical switch module is connected to the link controller and is used to receive the switch command and connect the multimode fiber and the target polling unit according to the switch command, so that the polling unit generates a second transmission mode according to the target mode polling strategy and the first transmission mode. The first transmission mode is the transmission mode in the optical signal module received in the current segment, and the second transmission mode is the transmission mode in the optical signal module output in the current segment.

[0036] In some embodiments, the mode cycling device further includes: a few-mode combiner; the cycling unit includes a second preset number of mode circulators, the second preset number being obtained based on the first preset number;

[0037] One end of the mode circulator is connected to the optical switch module, the other end of the mode circulator is connected to one end of the few-mode combiner, and the other end of the few-mode combiner is connected to the multimode fiber in the next span.

[0038] In some embodiments, the optical switch module includes a second preset number of few-mode optical switches, and the mode cycling device further includes: a few-mode beam splitter, one end of which is connected to the multimode fiber of the current span, and the other end of which is sequentially connected to one end of the few-mode optical switch, and the other end of which is sequentially connected to the mode circulator; the mode circulator rotates in a fixed rotation mode.

[0039] In some embodiments, the mode cycling device further includes: a few-mode combiner; the optical switch module includes: a MEMS optical switch; the cycling unit includes a second preset number of mode circulators;

[0040] When the optical switch module is a MEMS optical switch, one end of the MEMS optical switch is connected to the multimode optical fiber of the current span, and the other end of the MEMS optical switch is connected to one end of the mode circulator, for selecting at least one of the mode circulators according to the switching command.

[0041] The other end of the mode circulator is connected to one end of the few-mode combiner, and the other end of the few-mode combiner is connected to the multimode fiber in the next span.

[0042] In some embodiments, the mode circulator includes: a demultiplexer, a multiplexer, and a first preset number of mode switches; the demultiplexer includes a first input terminal and a first preset number of first output terminals, and the multiplexer includes a first preset number of second input terminals and a first second output terminal; the second preset number is obtained based on the first preset number;

[0043] The first input terminal is connected to the MEMS optical switch, the first output terminal is sequentially connected to one end of the mode switch, the other end of the mode switch is sequentially connected to the second input terminal, and the second output terminal is connected to the few-mode combiner.

[0044] In some embodiments, the mode cycling device includes: an optical switch module and a photonic lantern module; the photonic lantern module includes: a demultiplexed photonic lantern and a multiplexed photonic lantern, the demultiplexed photonic lantern includes a third input terminal and a second preset number of third output terminals, the optical switch module includes a second preset number of fourth input terminals and a second preset number of fourth output terminals; the multiplexed photonic lantern includes a second preset number of fifth input terminals and a third fifth output terminal;

[0045] The multimode fiber in the current span is connected to the third input end, the third output end is connected to the fourth input end in sequence, the fourth output end is connected to the fifth input end in sequence, and the fifth output end is connected to the multimode fiber in the next span.

[0046] In some embodiments, the mode cycling device includes: a spatial light modulator and a reflector arranged in parallel, wherein a phase plate is disposed on the light incident surface of the spatial light modulator;

[0047] The mode-rotating device performs the following steps when adjusting the transmission mode of the optical signal in the optical signal module according to the target mode-rotating strategy to update the optical signal module:

[0048] When the optical signal in the optical signal module is incident on the spatial light modulator at a preset angle and reaches the phase plate, and is reflected multiple times between the spatial light modulator and the reflector, during each reflection process, the phase plate modulates the transmission mode of the optical signal in the optical signal module according to the target mode cyclic strategy.

[0049] In some embodiments, the optical fiber transmission unit further includes an amplifier, one end of which is connected to the mode adjustment unit and the other end of which is connected to the next span of the multimode optical fiber.

[0050] To achieve the above objectives, a second aspect of the present application proposes a mode division multiplexing method, which is applied to the central processing unit of a mode division multiplexing system as described in any of the first aspects, to obtain the transmission parameters of the optical fiber transmission unit in each segment, and to generate a target mode round-robin strategy for the optical fiber transmission unit in the corresponding segment based on the transmission parameters.

[0051] In one embodiment, the central controller executes the following when generating the target mode round-robin strategy for the corresponding span of the optical fiber transmission unit based on the transmission parameters:

[0052] Calculate the candidate score for each candidate round-robin strategy in the preset round-robin strategy group based on the transmission parameters;

[0053] The candidate round-robin strategy with the largest candidate score is selected as the target pattern round-robin strategy for the corresponding segment.

[0054] In one embodiment, the transmission parameters include: mode group delay parameters and mode-related loss parameters. The step of calculating the candidate score for each candidate round-robin strategy in the preset round-robin strategy group based on the transmission parameters includes:

[0055] The group delay score of each candidate round-robin strategy is calculated based on the group delay parameters of the pattern.

[0056] The loss score for each candidate round-robin strategy is calculated based on the pattern-related loss parameters.

[0057] The candidate score of the candidate round-robin strategy is calculated based on the loss score, loss weight, group delay score, and group delay weight.

[0058] In one embodiment, the mode group delay parameter includes the mode delay value of each optical signal in the optical signal module under the current transmission mode, and the mode-related loss parameter includes the loss value of each optical signal in the optical signal module under the current transmission mode;

[0059] The transmission mode of the optical signal is updated using the candidate polling strategy to obtain transmission mode adjustment pairs, each of which contains one or two transmission modes.

[0060] Calculate the mean value of the mode delay value of the transmission mode in each transmission mode adjustment pair to obtain the first delay mean value of the transmission mode adjustment pair, and use the average value of the first delay mean value as the group delay score;

[0061] Calculate the mean of the loss values ​​of the transmission modes in each transmission mode adjustment pair to obtain the second mean loss value of the transmission mode adjustment pair, and use the average value of the second mean loss value as the loss score.

[0062] In one embodiment, the candidate round-robin strategy includes: a sequential round-robin strategy, a pairwise round-robin strategy, a round-robin recommendation strategy based on a genetic algorithm, or a round-robin strategy that iterates through the maximum and minimum values; updating the transmission mode of the optical signal using the candidate round-robin strategy to obtain transmission mode adjustment pairs includes:

[0063] When the candidate polling strategy is a sequential polling strategy, the transmission mode at the current position and the transmission mode at the next position are cyclically exchanged according to the numbering order of the transmission modes;

[0064] When the candidate round-robin strategy is a pairwise round-robin strategy, the transmission modes are grouped according to the number of groups to obtain multiple mode groups. Each mode group is numbered according to the numbering order of the transmission modes. The mode group at the current position is cyclically swapped with the mode group at the next position according to the numbering order of the mode groups.

[0065] When the candidate round-robin strategy is a round-robin recommendation strategy based on a genetic algorithm, the population information of the transmission mode is generated, the population information is input into the genetic recommendation algorithm for population iteration, and after the iteration condition is reached, the recommendation sequence corresponding to the population information is obtained, and the transmission mode is exchanged according to the recommendation sequence.

[0066] When the candidate round-robin strategy is a round-robin strategy that iterates through the maximum and minimum values, the mode group delay parameters and / or the mode-related loss parameters of the transmission mode are sorted, and the transmission modes are exchanged according to the sorting results.

[0067] The transmission mode adjustment pair includes two transmission modes that have been switched and / or one transmission mode that has not been switched.

[0068] To achieve the above objectives, a third aspect of this application provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the modular multiplexing method described in the second aspect above.

[0069] To achieve the above objectives, a fourth aspect of the present application provides a storage medium, which is a computer-readable storage medium storing a computer program that, when executed by a processor, implements the modular multiplexing method described in the second aspect above.

[0070] The mode division multiplexing system, method, device, and storage medium proposed in this application include at least: multiple cascaded optical fiber transmission units across multiple spans and a central controller. Each optical fiber transmission unit includes a multimode fiber and a mode adjustment unit. The mode adjustment unit receives optical signal modules transmitted from the multimode fiber, calculates the transmission parameters of the optical fiber transmission unit based on the optical signal modules, and sends the transmission parameters to the central controller. The central controller obtains the transmission parameters of the optical fiber transmission units in each span and generates a target mode round-robin strategy for the corresponding span of optical fiber transmission units based on the transmission parameters. Then, the mode adjustment unit adjusts the transmission mode of the optical signal in the optical signal module according to the received target mode round-robin strategy to update the optical signal module, and sends the adjusted optical signal module to the multimode fiber of the next span. In this embodiment, the mode adjustment unit in each span of the optical fiber transmission unit sends the calculated transmission parameters to the central controller. The central controller adaptively selects the target mode round-robin strategy according to the real-time transmission environment and performs adaptive adjustment on each span to obtain the minimum differential mode group delay (DMD) and mode-dependent loss (MDL). It can adapt to different span lengths and different transmission environments, thereby improving the transmission performance of multimode optical fiber. Attached Figure Description

[0071] Figure 1 This is a schematic diagram of the module division multiplexing system provided in an embodiment of the present invention.

[0072] Figure 2 This is a schematic diagram of the mode adjustment unit of a modular multiplexing system provided in another embodiment of the present invention.

[0073] Figure 3 This is a flowchart illustrating the process by which the central controller of a mode division multiplexing system generates a target mode round-robin strategy for the corresponding fiber optic transmission unit based on transmission parameters, according to another embodiment of the present invention.

[0074] Figure 4 yes Figure 3 Flowchart of step S110.

[0075] Figure 5 This is a schematic diagram of the optical signal of a mode division multiplexing system provided in another embodiment of the present invention.

[0076] Figure 6 This is a flowchart illustrating the calculation of group delay and loss values ​​by the central controller of a modular multiplexing system according to another embodiment of the present invention.

[0077] Figure 7 yes Figure 6 Flowchart of step S610.

[0078] Figure 8a This is a schematic diagram of the sequential round-robin strategy of a modular multiplexing system provided in another embodiment of the present invention.

[0079] Figure 8b This is a schematic diagram of the pairwise round-robin strategy of a modular multiplexing system provided in another embodiment of the present invention.

[0080] Figure 8c This is a schematic diagram of a round-robin recommendation strategy based on a genetic algorithm for a modular multiplexing system provided in another embodiment of the present invention.

[0081] Figure 9 This is a schematic diagram of the mode rotation device structure of a mode division multiplexing system provided in another embodiment of the present invention.

[0082] Figure 10 This is a schematic diagram of the fixed rotation mode of the modal multiplexing system provided in another embodiment of the present invention.

[0083] Figure 11 This is a schematic diagram of the mode looper structure of a modular multiplexing system provided in another embodiment of the present invention.

[0084] Figure 12 This is a schematic diagram of the structure of a second preset number of few-mode optical switches in the mode-rotating device of a mode-division multiplexing system provided in another embodiment of the present invention.

[0085] Figure 13 This is a schematic diagram of the structure of a MEMS optical switch module in the mode rotation device of a mode division multiplexing system provided in another embodiment of the present invention.

[0086] Figure 14 This is a schematic diagram of the mode looper structure of a modular multiplexing system provided in another embodiment of the present invention.

[0087] Figure 15This is a schematic diagram of the optical switch module and photonic lantern module in the mode rotation device of a mode division multiplexing system provided in another embodiment of the present invention.

[0088] Figure 16 This is a schematic diagram of the spatial light modulator and reflector in the mode rotation device of a mode division multiplexing system provided in another embodiment of the present invention.

[0089] Figures 17a-17c This is a schematic diagram comparing the effects of a variable round-robin strategy provided in another embodiment of the present invention.

[0090] Figure 18 This is a schematic diagram comparing the effects of a variable round-robin strategy provided in another embodiment of the present invention.

[0091] Figure 19 This is a schematic diagram of the hardware structure of the electronic device provided in an embodiment of the present invention. Detailed Implementation

[0092] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0093] It should be noted that although functional modules are divided in the device schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart.

[0094] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the invention.

[0095] Optical fiber communication: using optical fibers as independent channels to transmit information. Currently, space-division multiplexing optical fiber communication takes three forms: the first is based on multi-core fiber multiplexing, using each core of a single fiber as an independent channel; the second is based on multimode fiber (FMF) or multimode fiber multiplexing, using each orthogonal mode within the fiber as an independent channel; the third combines the first two methods, utilizing both the individual cores and the modes within them for communication.

[0096] Mode: Used to describe how optical signals propagate within the glass core of an optical fiber. A mode is the propagation path of light; different modes have different but mutually orthogonal field distributions, so they can be considered as separate propagation paths. In single-mode fiber, light propagates along one path; while in multimode fiber, light propagates along multiple paths.

[0097] With the continuous growth in bandwidth demand, fiber optic transmission systems will inevitably face the problem of limited single-mode fiber capacity, thus leading to the development of mode-division multiplexing (MDM) technology. Multimode fiber can overcome the capacity limitations of single-mode fiber and improve the transmission rate of communication systems. It uses multiple modes to transmit information, with light propagating along multiple paths. However, as the number of transmission modes increases, mode-dependent loss (MDL) and differential mode group delay (DMD) inevitably occur during transmission. MDL and DMD significantly increase the computational complexity of the receiving end of the communication system for the transmitted signal, thereby limiting the transmission distance of multimode fiber.

[0098] In related technologies, to minimize the accumulation of Differential Mode Group Delay (DMD) and reduce the impact of Mode Dependent Loss (MDL) in the link, mode switching is performed in multimode fiber. Different modes are transmitted in rotation across different channels in different segments of the transmission link using mode polling devices. However, most mode polling strategies in these technologies are based on ideal transmission link conditions. This results in less than ideal effects on reducing DMD and mitigating MDL when segment lengths are inconsistent or transmission conditions are poor.

[0099] Based on this, embodiments of the present invention provide a mode division multiplexing system, method, device, and storage medium. The mode division multiplexing system uses the mode adjustment unit in each span of the optical fiber transmission unit to send the calculated transmission parameters to the central controller. The central controller adaptively selects the target mode round-robin strategy according to the real-time transmission environment and performs adaptive adjustment on each span to obtain the reduction effect of the lowest differential mode group delay (DMD) and mode-dependent loss (MDL). It can adapt to different span lengths and different transmission environments, thereby improving the transmission performance of multimode optical fiber.

[0100] The present invention provides a modular multiplexing system, method, device and storage medium, which are specifically described through the following embodiments. First, the modular multiplexing system in the embodiments of the present invention is described.

[0101] It should be noted that the embodiments of the present invention can be applied to multimode optical fibers. Here, multimode optical fibers can be traditional multimode optical fibers or few-mode optical fibers. The following embodiments use few-mode optical fibers for illustration. The embodiments of the present invention do not impose specific limitations on this.

[0102] Figure 1This is a schematic diagram of the module division multiplexing system in an embodiment of the present invention.

[0103] Reference Figure 1 The modular multiplexing system 10 includes:

[0104] Transmitter 100 is used to modulate the communication signal to be transmitted, thereby obtaining an optical signal module. It is understood that the optical signal module obtained from the communication signal can include a small number of optical signals; that is, the obtained optical signals can be transmitted in orthogonal modes in a multimode fiber. To distinguish them, each optical signal has a different transmission mode. The number of optical signals is a first preset number, which can be set according to actual needs.

[0105] In the communication system, receiver 200 is used to receive the optical signal module transmitted by transmitter 100 via the transmission system. After receiving the optical signal module, receiver 200 demodulates the optical signal module to obtain the communication signal that needs to be transmitted.

[0106] The transmission channel consists of multiple cascaded fiber optic transmission units 300, with N units used as an example in the diagram. The number of segments N and the length of each segment can be determined based on the actual transmission distance. The cascaded fiber optic transmission units 300 connect the starting position (transmitter 100) to the destination position (receiver 200). The first segment of the fiber optic transmission unit 300 is connected to the transmitter 100, and after passing through N-2 cascaded fiber optic transmission units 300, the last segment of the fiber optic transmission unit 300 is connected to the receiver 200, thus enabling the transmission of optical signals through the transmission channel.

[0107] The central controller 400 is connected to each fiber optic transmission unit 300 in each span. It is used to acquire the transmission parameters sent by each fiber optic transmission unit 300 in each span and generate the target mode polling strategy for the corresponding fiber optic transmission unit 300 in real time based on the received transmission parameters. This strategy guides the fiber optic transmission unit 300 in the corresponding span to poll the transmission mode of the optical signal. The purpose is to enable each fiber optic transmission unit 300 in each span to obtain the lowest differential mode group delay (DMD) and mode-dependent loss (MDL).

[0108] The optical fiber transmission unit 300 includes a multimode optical fiber 310 and a mode adjustment unit 320. The mode adjustment unit 320 receives an optical signal module transmitted from the multimode optical fiber 310, calculates the transmission parameters of the optical fiber transmission unit in real time based on the received optical signal module, and then sends the transmission parameters to the central controller 400. Then, it receives a target mode round-robin strategy sent from the central controller 400 to adjust the transmission mode of the optical signal in the optical signal module, thereby updating the optical signal module, and sending the adjusted optical signal module to the multimode optical fiber 310 of the next span of the optical fiber transmission unit 300.

[0109] In one embodiment, the optical fiber transmission unit 300 further includes an amplifier 330. One end of the amplifier 330 is connected to the mode adjustment unit 320, and the other end is connected to the multimode optical fiber 310 of the next span. Its purpose is to amplify the adjusted optical signal module output by the mode adjustment unit 320 to compensate for some transmission loss before sending it to the next span for transmission, thereby improving the transmission performance of the communication channel to a certain extent. It is understood that the amplification factor of the amplifier 330 can be set according to actual needs. In one embodiment, the amplifier 330 can be a multimode optical fiber amplifier.

[0110] Therefore, the continuous laser in transmitter 100 is modulated to obtain an optical signal module, which then enters the multimode fiber 310 of the first span-span transmission unit 300. At the end of this span, it enters the mode adjustment unit 320 for channel replacement, and then passes through amplifier 330 before entering the multimode fiber 310 of the next span-span transmission unit 300, where channel switching occurs again, until the receiver 200 receives the signal. The mode division multiplexing system of this embodiment utilizes the mode adjustment unit in each span-span transmission unit to send the calculated transmission parameters to the central controller. The central controller adaptively selects a target mode round-robin strategy based on the real-time transmission environment, adaptively adjusting each span to adapt to different span lengths and different transmission environments, thereby improving the transmission performance of the multimode fiber.

[0111] Figure 2 This is a schematic diagram of the mode adjustment unit in an embodiment of the present invention.

[0112] Reference Figure 2 The modular division multiplexing system of this invention utilizes the concept of software-defined networking to separate the polling management and control of the mode adjustment unit. The mode adjustment unit 320 includes: a link characterization unit 321, a link controller 322, and a mode polling device 323.

[0113] One end of the link characterization unit 321 is connected to the multimode fiber 310 of the current span, and can calculate the transmission parameters characterizing the transmission performance of the current span based on the signal information of each optical signal in the optical signal module transmitted in the multimode fiber 310 of the current span. The other end is connected to the central controller 400 and sends the transmission parameters to the central controller 400.

[0114] One end of the link controller 322 is connected to the central controller 400 and receives the target mode rounding strategy of the cross-segment optical fiber transmission unit 300 generated by the central controller 400 according to the transmission parameters. The other end of the link controller 322 is connected to the mode rounding device 323 and sends the received target mode rounding strategy to the mode rounding device 323.

[0115] One end of the mode polling device 323 is connected to the multimode fiber 310 of the current span to receive optical signal modules. The other end of the mode polling device 323 is connected to the multimode fiber 310 of the next span and to the link controller 322 to receive the target mode polling strategy and adjust the transmission mode of each optical signal in the received optical signal module according to the target polling strategy to update the optical signal module.

[0116] In the above embodiments, since the communication environments of different segments are different, this application embodiment inserts a mode polling device 323 and a link characterization unit 321 at all segment connections. When the communication link environment changes, that is, before the optical signal module enters the next segment or the receiving end of the receiver 200, the link characterization unit 321 measures the transmission parameters of the link, such as the values ​​of differential mode group delay (DMD) and mode correlation loss (MDL), so that the central controller 400 can evaluate the channel performance of each transmission mode in the segment and guide the formulation of the target mode polling strategy based on the real-time link situation.

[0117] The selection of a suitable target mode round-robin strategy aims to adjust the transmission performance of the communication channel, with the goal of achieving the lowest differential mode group delay (DMD) and mode-dependent loss (MDL) performance. For example, the central controller 400, based on information uploaded by the link characterization unit 321, determines that the energy difference or group delay difference between the optical signal of one transmission mode and that of another transmission mode in a certain segment's end optical signal module is the largest. If so, the energy of these two channels is swapped, and other mode channels are adjusted similarly. The purpose of the target mode round-robin strategy is to identify the transmission modes that need to be swapped. By selecting the most effective target mode round-robin strategy and performing intelligent adjustment, the overall differential mode group delay (DMD) and mode-dependent loss (MDL) performance can be balanced, achieving the lowest computational complexity at the receiver and optimal transmission performance of the link.

[0118] In one embodiment, the link characterization unit 321 measures the delay and transmission matrix of each transmission mode before each segment enters the mode polling device as transmission parameters before polling transmission. These transmission parameters are then returned to the central controller to calculate parameters such as Differential Mode Group Delay (DMD) and Mode Dependent Loss (MDL). The central controller selects a target mode polling strategy based on the parameters of each segment in the link and returns the target mode polling strategy to the link controller 322. The new polling strategy is then executed through the programmable mode polling device 323. Simultaneously, the central controller can record the transmission parameters of each link and monitor and predict potential link impairments using machine learning methods, thereby dynamically adjusting the target mode polling strategy and further improving the transmission performance of the communication system.

[0119] Reference Figure 2 The modular multiplexing system enables separation of control and mode control. The mode-rotating devices reside on the link devices, while their control plane is on the central controller. The central controller issues the target mode-rotating strategy to the link controller, which is responsible for executing the strategy on each device. This separation allows for centralized control; the central controller only needs to manage and configure the link controller to issue the target mode-rotating strategy, eliminating the need for individual device-by-device operation. Furthermore, the system leverages open interfaces for strategy extension. The central controller can define a new rotation strategy programmatically using the open interfaces provided by the link controller, which can then run on the mode-rotating devices.

[0120] As can be seen from the above, referring to Figure 2 In the modular division multiplexing system, the link controller receives the target mode polling strategy from the central controller and then distributes it to each mode polling device. The mode polling device then performs the corresponding mode conversion, thereby optimizing the overall link as a whole. This optimizes and improves both differential mode group delay (DMD) and mode-dependent loss (MDL), significantly increasing transmission capacity.

[0121] In one embodiment, reference is made to Figure 3 In this embodiment of the application, when the central controller generates the target mode round-robin strategy for the corresponding span of optical fiber transmission unit based on the transmission parameters, it executes the following steps:

[0122] Step S110: Calculate the candidate score of each candidate round-robin strategy in the preset round-robin strategy group based on the transmission parameters.

[0123] In one embodiment, the central controller pre-stores multiple candidate round-robin strategies to form a preset round-robin strategy group. The preset round-robin strategy group includes multiple candidate round-robin strategies, including: sequential round-robin strategy, pairwise round-robin strategy, round-robin recommendation strategy based on genetic algorithm, or traversal of maximum and minimum value round-robin strategy. These candidate round-robin strategies will be described in detail below.

[0124] In one embodiment, the transmission parameters include: differential mode group delay parameters and mode-dependent loss parameters. When signals propagate in multiple modes in a multimode fiber, some light travels along the fiber center, while others travel along paths closer to the core cladding. Different optical signals have different propagation paths in the multimode fiber; the propagation modes at the outer edge are called higher-order modes, and those closer to the core center are called lower-order modes. Furthermore, the propagation speeds of higher-order and lower-order modes are different. Therefore, the arrival time of each propagation mode's optical signal at the fiber exit end is different. The differential mode group delay parameters of this embodiment can be obtained based on the difference in arrival times. Simultaneously, the mode-dependent loss parameters of this embodiment can be calculated based on the difference in energy loss of the same optical signal before and after propagation.

[0125] In one embodiment, reference is made to Figure 4 The steps for calculating the candidate score of each candidate round-robin strategy in the preset round-robin strategy group based on the transmission parameters include:

[0126] Step S1110: Calculate the group delay score for each candidate round-robin strategy based on the differential mode group delay parameters.

[0127] Step S1120: Calculate the loss score of each candidate round-robin strategy based on the loss parameters related to the differential mode.

[0128] In one embodiment, the differential mode group delay parameter includes the difference in mode delay values ​​of each optical signal in the optical signal module under the current transmission mode, and the mode-dependent loss parameter includes the difference in loss values ​​of each optical signal in the optical signal module under the current transmission mode.

[0129] Reference Figure 5 If there are 5 optical signals, LP1, LP2, LP3, LP4, and LP5, with input energies of 2E, E, 3E, 2E, and 4E at the multimode fiber inlet and output energies of E, E, E, E, and E at the multimode fiber outlet, respectively, and arrival times of each signal at the outlet being different (t, 4t, 3t, 5t, and 2t), then, based on LP4 which arrives earliest at the outlet, the mode delay values ​​of each signal in the current transmission mode are obtained as follows: {(5t-t=4t), (t), (2t), (0), (3t)}. The mode loss value of each signal in the current transmission mode is calculated using the difference between the output and input energies: {(2E-E=E), (0), (2E), (E), (3E)}.

[0130] Therefore, in the above embodiments, it is necessary to calculate the group delay score and loss score for each candidate polling strategy. (Refer to...) Figure 6The process of calculating the group delay score and loss score includes the following steps:

[0131] Step S610: Update the transmission mode of the optical signal using a candidate round-robin strategy to obtain a transmission mode adjustment pair.

[0132] In one embodiment, a transmission mode adjustment pair is obtained by exchanging one or two transmission modes. The transmission mode adjustment pair includes the two exchanged transmission modes and / or the one transmission mode that has not been exchanged. Here, "one" can be understood as, for example, if the number of transmission modes is odd, after exchanging them in pairs, there may be some transmission modes that do not need to be exchanged. In this case, the transmission mode adjustment pair contains the same communication channel before and after the exchange, and therefore only contains one transmission mode.

[0133] In one embodiment, since the candidate round-robin strategies include: sequential round-robin strategy, pairwise round-robin strategy, round-robin recommendation strategy based on genetic algorithm, or traversal of maximum and minimum value round-robin strategy, the round-robin strategy in this embodiment is a variable round-robin strategy. A suitable strategy is selected from the candidate round-robin strategies. The round-robin method of each candidate round-robin strategy is described below. (Refer to...) Figure 7 Step S610 includes the following steps:

[0134] Step S611: When the candidate round-robin strategy is the sequential round-robin strategy, the transmission mode of the current position and the transmission mode of the next position are cyclically exchanged according to the number order of the transmission modes.

[0135] In one embodiment, reference is made to Figure 8a This is a schematic diagram of the sequential round-robin strategy. Before round-robin, the optical signal module contains 6 optical signals, with transmission modes of mode 1: LP01, mode 2: LP11a, mode 3: LP11b, mode 4: LP21a, mode 5: LP21b, and mode 6: LP02. Then, based on the sequential round-robin strategy, the transmission mode at the current position is cyclically exchanged with the transmission mode at the next position according to the numbering order of the transmission modes, that is: mode 1 is exchanged with mode 2, mode 2 with mode 3, mode 3 with mode 4, mode 4 with mode 5, mode 5 with mode 6, and mode 6 with mode 1. At this time, 6 transmission mode adjustment pairs are obtained, namely

[12] ,

[23] ,

[34] ,

[45] ,

[56] , and

[61] . It can be understood that multiple round-robin processes may be executed in the same segment, and after the current round is completed, the next round continues to perform sequential round-robin.

[0136] Step S612: When the candidate round-robin strategy is a pairwise round-robin strategy, the transmission modes are grouped according to the number of groups to obtain multiple mode groups. Each mode group is numbered according to the numbering order of the transmission modes. The mode group at the current position is cyclically swapped with the mode group at the next position according to the numbering order of the mode groups.

[0137] In one embodiment, reference is made to Figure 8b The diagram illustrates the pairwise polling strategy. Before polling, the optical signal module contains six optical signals with transmission modes: Mode 1: LP01, Mode 2: LP11a, Mode 3: LP11b, Mode 4: LP21a, Mode 5: LP21b, and Mode 6: LP02. The optical signals are divided into two groups, each with three transmission modes. Each mode group is numbered according to the numbering order of the transmission modes. According to the numbering order of the mode groups, we get Mode Group 1: {Mode 1, Mode 2, Mode 3} and Mode Group 2: {Mode 4, Mode 5, Mode 6}. Then, the mode group at the current position is cyclically swapped with the mode group at the next position. That is, the transmission modes of Mode Group 1 and Mode Group 2 are swapped, i.e., Mode 1 is swapped with Mode 4, Mode 2 with Mode 5, Mode 3 with Mode 6, Mode 4 with Mode 2, Mode 5 with Mode 3, and Mode 6 with Mode 1. At this time, four transmission mode adjustment pairs are obtained, namely

[13] ,

[24] ,

[31] , and

[42] . Understandably, the grouping and switching methods can be set according to actual needs. Furthermore, if multiple rounds of iteration are executed within the same segment, the next round will continue with paired iterations after the current round is completed.

[0138] Step S613: When the candidate round-robin strategy is a round-robin recommendation strategy based on genetic algorithm, generate the population information of the transmission mode, input the population information into the genetic recommendation algorithm for population iteration, and after reaching the iteration condition, obtain the recommendation sequence corresponding to the population information, and exchange the transmission modes according to the recommendation sequence.

[0139] In one embodiment, a genetic recommendation algorithm for population iteration is first constructed, and then population information is constructed according to the transmission pattern and in numerical order. For example... Figure 8c In the schematic diagram of the round-robin recommendation strategy based on genetic algorithm, the optical signal module contains four optical signals before round-robin, with transmission modes of mode 1: LP01, mode 2: LP11a, mode 3: LP11b, and mode 4: LP11c. An initial population is generated based on the transmission modes of the optical signals, represented as {1,2,3,4}. The initial population is input into the genetic recommendation algorithm to perform genetic and / or mutation operations to iterate the population. When a preset number of iterations is reached or the fitness value of the population reaches a preset threshold, the iteration stops. The population obtained from the last iteration is used as the recommendation sequence, and the transmission modes are then exchanged according to the recommendation sequence. For example... Figure 8cThe initial population is {1,2,3,4}, and the final population is {3,4,2,1}. This means that: mode 1 is swapped with the transmission mode at position 3 (mode 3), mode 2 is swapped with the transmission mode at position 4 (mode 4), mode 3 is swapped with the transmission mode at position 2 (mode 2), and mode 4 is swapped with the transmission mode at position 1 (mode 1), thus obtaining 4 transmission mode adjustment pairs, namely

[13] ,

[24] ,

[32] and

[41] . It is understandable that multiple round-robin processes may be executed in the same segment, and after the current round is completed, the next round will continue to be performed based on the genetic algorithm.

[0140] Step S614: When the candidate round-robin strategy is the maximum-minimum round-robin strategy, sort the mode group delay parameters and / or mode-related loss parameters of the transmission modes, and exchange the transmission modes according to the sorting results.

[0141] In one embodiment, a round-robin strategy for traversing extreme values ​​sorts the mode group delay parameters and / or mode-dependent loss parameters of the transmission modes in descending or ascending order. The extreme values ​​can be the maximum values; in this case, the maximum values ​​of the transmission parameters are iterated over each time, and the maximum value is swapped with the minimum value. After the swap, the parameters can be reordered, or the second largest value can be swapped with the second smallest value based on the previous sorting result, until the swapping process is complete.

[0142] Reference Figure 5 If the mode loss values ​​are sorted, the sorting result from smallest to largest is: LP5, LP3, LP1, LP4 and LP2. Then, LP5 is switched to LP2 first, and then LP3 is switched to LP4. LP1 remains unchanged and is still transmitted in its own transmission channel. It can be seen that there are 3 transmission mode adjustment pairs, namely

[52] ,

[25] ,

[34] ,

[43] and [1]. It is understandable that multiple round-robin processes may be executed in the same segment. After the current round is completed, the next round will continue to be performed based on the genetic algorithm.

[0143] Step S620: Calculate the mean value of the mode delay of each transmission mode in the transmission mode adjustment pair to obtain the first delay mean value of the transmission mode adjustment pair, and use the average value of the first delay mean value as the group delay score.

[0144] Step S630: Calculate the mean value of the loss of the transmission mode in each transmission mode adjustment pair to obtain the second mean value of the loss of the transmission mode adjustment pair, and use the average value of the second mean value of the loss as the loss score.

[0145] In one embodiment, after obtaining the transmission mode adjustment pair, the average mode delay value of the transmission mode for each transmission mode adjustment pair is calculated to obtain the first average delay value of the transmission mode adjustment pair. For example, the above embodiment... Figure 8c The four transmission mode adjustment pairs are

[13] ,

[24] ,

[32] , and

[41] . The mean values ​​of mode delay for modes 1 and 3, modes 2 and 4, modes 3 and 2, and modes 4 and 1 are calculated respectively. The average of these four values ​​is then used to obtain the first mean delay. Similarly, the second mean loss is calculated.

[0146] Step S1130: Calculate the candidate scores of the candidate round-robin strategies based on the mode-related loss score, mode-related loss weight, differential group delay score, and differential group delay weight.

[0147] In one embodiment, different weights can be assigned to loss and group delay based on their respective impacts on communication performance. These weights can be set according to actual needs. Then, based on the loss score S, loss weight a, group delay score Q, and group delay weight b, the candidate score H of the candidate round-robin strategy is calculated, expressed as:

[0148]

[0149] Step S120: Select the candidate round-robin strategy with the largest candidate score as the target pattern round-robin strategy for the corresponding segment.

[0150] In one embodiment, the candidate score for each candidate round-robin strategy is calculated, and the candidate round-robin strategy with the largest candidate score is selected as the target mode round-robin strategy for the corresponding segment.

[0151] It is understood that the embodiments of this application perform real-time independent calculations for each span, which can maximize the beneficial effects of mode round-robin in a modal division multiplexing system. In actual transmission systems, the span length difference may be as high as 40km. The variable round-robin strategy of this embodiment can improve transmission performance in multimode fiber links. Different transmission modes are exchanged through mode round-robin devices, and the exchange rules are formulated by the round-robin strategy generated in real time by the central controller. The central controller obtains the transmission performance of the previous span through feedback from the link characterization unit, and performs real-time mode switching in that span accordingly. Then it moves to the next span and repeats the above mode round-robin operation at the next node until it reaches the receiver. At this time, the global differential mode group delay (DMD) or mode-dependent loss (MDL) of the entire transmission process is theoretically minimized.

[0152] The structure of the mode cycling device in the embodiments of this application is described below.

[0153] Reference Figure 9The mode rotation device 323 includes an optical switch module 3231 and a rotation unit 3232, wherein one end of the optical switch module 3231 is connected to the multimode fiber 310 of the current span, the other end of the optical switch module 3231 is connected to one end of the rotation unit 3232, and the other end of the rotation unit 3232 is connected to the multimode fiber 310 of the next span.

[0154] During operation, the link controller 322 generates a switching control command for the polling unit 3232 according to the target mode polling strategy. Then, the optical switch module 3231 connects to the link controller 322 to receive the switching command and connects the multimode fiber 310 and the target polling unit 3232 according to the switching command. The switching command received by the polling unit 3232 selects to switch the first transmission mode to the second transmission mode. That is, it generates the second transmission mode according to the target mode polling strategy and the first transmission mode. The first transmission mode is the transmission mode in the optical signal module received in the current segment, and the second transmission mode is the transmission mode in the optical signal module output in the current segment.

[0155] Reference Figure 10 The following explanation uses three transmission modes as examples. Mode 1 is represented as LP. 01 Mode 2 is represented as LP 11a Mode 3 is represented as LP 11b There are three transmission modes, assuming they are Mode 1, Mode 2, and Mode 3. Theoretically, there are 3! ways to switch between these three transmission modes. (Refer to...) Figure 10 Switching method 1 is as follows: the three modes continue their respective transmission modes without change, and the corresponding connection methods are represented as: mode 1 -> mode 1, mode 2 -> mode 2, and mode 3 -> mode 3. Mode 11 is used to represent the switch from mode 1 to mode 1, and so on. Mode 2 -> mode 2 is represented as mode 22, and mode 3 -> mode 3 is represented as mode 33. Switching mode 2 is: Mode 1 and Mode 2 are swapped, while Mode 3 remains unchanged. The corresponding connectivity is represented as Mode 12, Mode 21, and Mode 33. Switching mode 3 is: Mode 1 switches to Mode 2, Mode 2 switches to Mode 3, and Mode 3 switches to Mode 1. The corresponding connectivity is represented as Mode 12, Mode 23, and Mode 31. Switching mode 4 is: Mode 2 and Mode 3 are swapped, while Mode 1 remains unchanged. The corresponding connectivity is represented as Mode 23, Mode 32, and Mode 11. Switching mode 5 is: Mode 1 and Mode 3 are swapped, while Mode 2 remains unchanged. The corresponding connectivity is represented as Mode 13, Mode 31, and Mode 22. Switching mode 6 is: Mode 1 switches to Mode 3, Mode 2 switches to Mode 1, and Mode 3 switches to Mode 2. The corresponding connectivity is represented as Mode 13, Mode 21, and Mode 32.

[0156] In one embodiment, when mode 1->mode 1, mode 11 is used to indicate a switch from mode 1 to mode 1, and so on. Figure 10 Any of these switching methods can be implemented using a mode looper 3233. (See reference...) Figure 11 Assuming that the rotation mode of the mode circulator 3233 is a fixed rotation mode, the on / off state of the switch represents different connection modes. Figure 13 The mode circulator 3233 implements switching mode 3, specifically implementing modes 12, 23, and 31. It can be seen that the mode circulator 3233 in this embodiment can switch between any of the above transmission modes by means of a switch selection.

[0157] In one embodiment, reference is made to Figure 12 The mode cycling device 323 further includes a few-mode combiner 324, and the cycling unit 3232 includes a second preset number of mode circulators 3233, the second preset number being obtained based on the first preset number. One end of the mode circulator 3233 is connected to the optical switch module 3231, and the other end of the mode circulator 3233 is connected to one end of the few-mode combiner 324. The other end of the few-mode combiner 324 is connected to the multimode fiber 310 of the next span. Optical signals of different transmission modes are combined and output through the few-mode combiner 324. Where the first preset number is n, then the second preset number is... .

[0158] Reference Figure 12 The optical switch module 3231 includes a second preset number of few-mode optical switches. The mode cyclic device 323 further includes a few-mode beam splitter 325. One end of the few-mode beam splitter 325 is connected to the multimode fiber 310 of the current span, and the other end of the few-mode beam splitter 325 is connected to one end of the few-mode optical switch. The other end of the few-mode optical switch is sequentially connected to the mode cyclic device 3233. The output of the few-mode beam splitter 325 is the optical signal of the first preset number of transmission modes.

[0159] In this embodiment, six pattern loopers 3233 are configured, and the rotation mode of the pattern loopers 3233 is a fixed rotation mode, that is, the above-mentioned functions are implemented by the six pattern loopers 3233 respectively. Figure 10 The system offers six polling modes. If a specific mode needs to be switched, a multi-mode optical switch can be used to select the corresponding mode circulator 3233 connected to the system, thereby improving the switching efficiency of mode polling. Combined with... Figure 10 and Figure 12Six mode loopers (3233) are configured to implement the six switching modes mentioned above. The first mode looper implements mode 1, the second implements mode 2, the third implements mode 3, the fourth implements mode 4, the fifth implements mode 5, and the sixth implements mode 6. The purpose of this configuration is to eliminate the need for complex switching, making it simple and intuitive. Mode cycling can be achieved by selecting and connecting the corresponding mode looper through a switch. Figure 12 The purpose of the few-mode beam splitter 325 is to split the optical signal in the optical signal module. For example, if the target mode rotation strategy for the current segment is a sequential rotation strategy, then switching mode 3 needs to be implemented: switching mode 1 to mode 2, mode 2 to mode 3, and mode 3 to mode 1. After beam splitting, connecting to the third mode circulator will achieve this. Then, the output signal of the third mode circulator is combined by the few-mode combiner 324 to obtain the output optical signal module for that segment. This method is simple, intuitive, and easy to implement.

[0160] In one embodiment, reference is made to Figure 13 Compared to Figure 12 The structure of the optical switch module 3231 is changed. In this embodiment, the optical switch module 3231 is a MEMS optical switch. The mode cycling device 323 further includes a few-mode combiner 324, and the cycling unit 3232 includes a second preset number of mode circulators 3233. When the optical switch module 3231 is a MEMS optical switch, one end of the MEMS optical switch is connected to the multimode fiber 310 of the current span, and the other end of the MEMS optical switch is connected to one end of the mode circulator 3233, used to select at least one mode circulator 3233 according to the switching command. The other end of the mode circulator 3233 is connected to one end of the few-mode combiner 324, and the other end of the few-mode combiner 324 is connected to the multimode fiber 310 of the next span. This embodiment is compared to... Figure 11 In terms of structure, less light energy is lost.

[0161] Reference Figure 14 The mode circulator 3233 includes a demultiplexer 3234, a multiplexer 3235, and a first preset number of mode switches 3236. The demultiplexer 3234 includes a first input terminal and a first preset number of first output terminals, and the multiplexer 3235 includes a first preset number of second input terminals and a first second output terminal. The first input terminal is connected to a MEMS optical switch, the first output terminal is sequentially connected to one end of a mode switch, the other end of a mode switch is sequentially connected to a second input terminal, and the second output terminal is connected to a few-mode combiner. Figure 14 by Figure 10Taking switching mode 3 as an example, the figure illustrates the switching methods of modes 12, 23, and 31. It can be seen that in this embodiment, the mode circulator 3233 performs mode switching by switching mode switch 3236. When a certain mode circulation strategy is adopted, the various modes transmitted in the multimode fiber are first converted into single-mode transmission signals by a demultiplexer. Then, the connection order of the demultiplexer and the single-mode end of the multiplexer is changed by an optical switch, so that the multiplexing is converted to the specified mode, thereby realizing mode conversion.

[0162] In another implementation, refer to Figure 15 The mode cycling device 3233 includes: an optical switch module 3231 and a photonic lantern module 3237, wherein the photonic lantern module 3237 includes: a demultiplexed photonic lantern PL1 and a multiplexed photonic lantern PL2. The demultiplexed photonic lantern PL1 includes a third input terminal and a second preset number of third output terminals. The optical switch module 3231 includes a second preset number of fourth input terminals and a second preset number of fourth output terminals. The multiplexed photonic lantern PL2 includes a second preset number of fifth input terminals and a third fifth output terminal.

[0163] The multimode fiber 310 of the current segment is connected to the third input end, the third output end is connected to the fourth input end in sequence, the fourth output end is connected to the fifth input end in sequence, and the fifth output end is connected to the multimode fiber 310 of the next segment. When a certain mode rotation strategy is adopted, the specific mode conversion is completed by switching each optical switch module 3231.

[0164] Understandably, the optical switch module 3231 here can be referenced. Figure 12 and Figure 13 Configure the settings.

[0165] In another embodiment, reference Figure 16 The mode cycling device 2322 includes a parallel-arranged spatial light modulator 3238 and a reflector L1, wherein a phase plate 3239 is provided on the light-incident surface of the spatial light modulator 3238. When the optical signal in the optical signal module is at a preset angle... When the incident spatial light modulator 3238 reaches the phase plate, it undergoes multiple reflections between the spatial light modulator 3238 and the reflector L1. During each reflection, the phase distribution of the optical signal changes due to the different thicknesses of different regions of the phase plate, thus achieving the conversion between the fundamental mode and higher-order modes. Furthermore, the transmission mode of the optical signal in the optical signal module can be modulated according to the target mode cycling strategy, thereby changing the transmission mode.

[0166] In one embodiment, the above Figure 16The spatial light modulator can be a liquid crystal display (LCD) screen, or it can be replaced with a flexible surface or a tunable metasurface device. It directly changes the mode of light in a multimode fiber through reflection or transmission, thereby achieving the purpose of executing a specific mode rotation strategy. This embodiment, through a reasonable design of the phase distribution on the spatial light modulator and the use of a fiber array to support more parallel beam incidence, allows each beam to be incident at a corresponding position, completing different phase or amplitude modulations. This supports more modes of conversion and multiplexing, is simple and convenient, improves system efficiency, and can complete multiple modes of conversion and multiplexing.

[0167] Under the same transmission environment and equipment conditions, Figure 16 mode cycling device and Figure 12 , Figure 13 and Figure 15 Compared with the solution that combines optical switch module and polling unit, the advantages of this embodiment are that the structure is simple and only requires spatial light modulator, which saves the expensive cost of optical switch, and the adjustment speed is fast, reducing the time of mechanical switching.

[0168] The above Figure 12 This illustrates a scenario where the mode circulator includes a second preset number of few-mode optical switches and a second preset number of mode circulators; Figure 13 This illustrates a scenario where the mode circulator includes a MEMS optical switch and a second preset number of mode circulators. Figure 15 This illustrates a mode circulator comprising an optical switch module and a photonic lantern module; Figure 16 The illustration shows a mode-rotating device comprising a spatial light modulator and a mirror arranged in parallel. It is evident that in the above embodiments, the transmission mode can be switched using a mode circulator.

[0169] In one embodiment, the parameters of a step-index multimode fiber are used as design conditions, with transmission modes LP01, LP11a, and LP11b. The typical differential mode group delay is 2.36 ns / km. A differential mode group delay of 0.001 ns / km is temporarily added between the two modes LP11a and LP11b to distinguish them. N spans are designed, where 2 ≤ N ≤ 9. The span length is selected using a Gaussian distribution with a mean of 80 and a variance of 20. The results are evaluated using three methods: no polling, sequential polling, and traversing the maximum and minimum values ​​(specifically, traversing the minimum and maximum values). The average of the maximum and minimum values ​​from 100 different span lengths is then used to compare the group delay results, thereby evaluating the effectiveness of the traversing the maximum and minimum value polling and sequential polling strategies. The traversal results can be implemented using the mode polling device of the mode division multiplexing system described in the above embodiment.

[0170] This embodiment describes a comparison of the effects of sequential round-robin as the number of segments increases with the variable round-robin strategy of this embodiment. The variable round-robin strategy of this embodiment flexibly adjusts the strategy based on the feedback from the characterization test. During simulation, the round-robin strategy for traversing the maximum and minimum values ​​includes traversing the maximum value and traversing the minimum value.

[0171] For example Figure 17a In the three-mode transmission, as the number of segments increases, the maximum group delay when traversing the maximum value increases linearly, while the maximum group delay when traversing the minimum value decreases continuously from being greater than the group delay value when traversing in sequence. The group delay value when traversing in sequence varies within a certain range and is generally small. Figure 17b The diagram illustrates sequential round-robin and minimum value traversal in detail. It can be seen that the sequential round-robin strategy has a certain improvement effect on the total group delay, but the minimum value traversal strategy is more effective in the later stages of the segment. The effects of the two strategies fluctuate with the increase of the number of segments. Figure 17c In this process, the group delay of the sequential round-robin strategy is compared with that of the minimum and maximum values, respectively. The smaller the ratio, the closer the optimization effects of the two round-robin strategies are. In the early segments, the sequential round-robin strategy and the minimum value approach have similar effects, while in the later segments, the optimization effects of all three approaches are similar. In general, different segments require selecting the optimal round-robin strategy to improve the overall transmission performance. Therefore, this embodiment of the application uses real-time transmission parameter readings to adjust the round-robin strategy in real time to select the best-performing strategy.

[0172] In another embodiment, the parameters of a step-index quad-mode multimode fiber are used as simulation conditions, with transmission modes LP01, LP11, and LP02. Typical differential mode group delay values ​​are: LP02-LP01 3.0 ps / km, LP11-LP01 2.0 ps / km, and LP21-LP01 3.9 ps / km, respectively. N spans are designed, where 1 ≤ N ≤ 13. The span length is selected using a Gaussian distribution with a mean of 80 and a variance of 20. The group delay is obtained through sequential round-robin, paired round-robin, round-robin recommendation strategy based on a genetic algorithm, or round-robin with traversing the maximum value. The average of the differential mode group delay (DMD) results for 100 different span lengths is taken, and the results are referenced... Figure 18 To make it clear, Figure 18 The plot does not include data generated by iterating through the maximum value. (See reference...) Figure 18It is evident that the sequential round-robin strategy and the paired round-robin strategy achieve optimal results when the number of spans and the number of modes are multiples of each other (6 spans, 12 spans). That is, in six-mode transmission, after the signal is transmitted through 6N (N is a positive integer) segments of multimode fiber, it will traverse each mode, and the differential mode group delay can be compensated to the greatest extent. The round-robin recommendation strategy based on the genetic algorithm outperforms the above two round-robin strategies. The cumulative group delay remains around 100ps starting from 3 spans, and the group delay increases slowly with the number of spans, showing a relatively stable effect.

[0173] The two simulation examples above demonstrate that the communication performance varies across different spans, and different polling strategies result in different performance improvements. Therefore, it is necessary to adjust the transmission parameters for each span in real time. The mode division multiplexing system in this application utilizes the mode adjustment unit in the fiber optic transmission unit of each span to send the calculated transmission parameters to the central controller. The central controller adaptively selects the target mode polling strategy based on the real-time transmission environment and adaptively adjusts each span to achieve the lowest differential mode group delay (DMD) and mode-dependent loss (MDL) reduction. This system can adapt to different span lengths and different transmission environments, thereby improving the transmission performance of multimode fiber.

[0174] In one embodiment, the mode division multiplexing system of this application can be accessed as part of a software-defined network in an optical communication network. At the same time, the mode division multiplexing system can open third-party interfaces to intelligently control the mode rotation of the link.

[0175] On the other hand, embodiments of the present invention also provide a mode division multiplexing method, applied to the central processing unit of the mode division multiplexing system as described in any of the above embodiments, which can obtain the transmission parameters of each segment of optical fiber transmission unit and generate a target mode round-robin strategy for the corresponding segment of optical fiber transmission unit based on the transmission parameters.

[0176] In one embodiment, the central controller executes the following when generating the target mode round-robin strategy for the corresponding span of fiber optic transmission units based on the transmission parameters:

[0177] Calculate the candidate score for each candidate round-robin strategy in the preset round-robin strategy group based on the transmission parameters;

[0178] The candidate strategy with the highest candidate score is selected as the target pattern rotation strategy for the corresponding segment.

[0179] In one embodiment, the transmission parameters include: mode group delay parameters and mode-related loss parameters. The candidate score for each candidate round-robin strategy in the preset round-robin strategy group is calculated based on the transmission parameters, including:

[0180] The group delay score for each candidate polling strategy is calculated based on the pattern group delay parameters.

[0181] The loss score for each candidate round-robin strategy is calculated based on the pattern-related loss parameters.

[0182] The candidate scores for candidate round-robin strategies are calculated based on the loss score, loss weight, group delay score, and group delay weight.

[0183] In one embodiment, the mode group delay parameter includes the mode delay value of each optical signal in the optical signal module in the current transmission mode, and the mode-related loss parameter includes the loss value of each optical signal in the optical signal module in the current transmission mode.

[0184] The transmission mode of the optical signal is updated using a candidate polling strategy to obtain transmission mode adjustment pairs, each of which contains one or two transmission modes.

[0185] Calculate the mean of the mode delay values ​​of the transmission modes in each transmission mode adjustment pair to obtain the first delay mean of the transmission mode adjustment pair, and use the average of the first delay mean as the group delay score;

[0186] Calculate the mean value of the transmission mode in each transmission mode adjustment pair to obtain the second mean value of the transmission mode adjustment pair, and use the average value of the second mean value of the loss as the loss score.

[0187] In one embodiment, the candidate round-robin strategy includes: a sequential round-robin strategy, a pairwise round-robin strategy, a round-robin recommendation strategy based on a genetic algorithm, or a round-robin strategy that iterates through the maximum and minimum values; the transmission mode of the optical signal is updated using the candidate round-robin strategy to obtain transmission mode adjustment pairs, including:

[0188] When the candidate round-robin strategy is a sequential round-robin strategy, the transmission mode of the current position and the transmission mode of the next position are cyclically swapped according to the number order of the transmission modes;

[0189] When the candidate round-robin strategy is a pairwise round-robin strategy, the transmission modes are grouped according to the number of groups to obtain multiple mode groups. Each mode group is numbered according to the numbering order of the transmission modes. The mode group at the current position is cyclically swapped with the mode group at the next position according to the numbering order of the mode groups.

[0190] When the candidate round-robin strategy is a round-robin recommendation strategy based on genetic algorithm, the population information of the transmission mode is generated, the population information is input into the genetic recommendation algorithm for population iteration, and after the iteration condition is reached, the recommendation sequence corresponding to the population information is obtained. The transmission mode is exchanged according to the recommendation sequence.

[0191] When the candidate round-robin strategy is the maximum-minimum round-robin strategy, the mode group delay parameters and / or mode-related loss parameters of the transmission modes are sorted, and the transmission modes are swapped according to the sorting results.

[0192] The transmission mode adjustment pair includes two transmission modes that have been switched and / or one transmission mode that has not been switched.

[0193] It is understandable that the specific implementation process of the modular multiplexing method can be found in the description of the modular multiplexing system above, and will not be repeated here.

[0194] This invention also provides an electronic device, comprising:

[0195] At least one memory;

[0196] At least one processor;

[0197] At least one program;

[0198] The program is stored in a memory, and the processor executes the at least one program to implement the modular multiplexing method described above. This electronic device can be any smart terminal.

[0199] Please see Figure 19 , Figure 19 The hardware structure of an electronic device according to another embodiment is illustrated. The electronic device includes:

[0200] The processor 1901 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present invention.

[0201] The memory 1902 can be implemented in the form of ROM (Read-Only Memory), static storage device, dynamic storage device, or RAM (Random Access Memory). The memory 1902 can store the operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory 1902 and is called and executed by the processor 1901 to execute the modular multiplexing system of the embodiments of this invention.

[0202] The input / output interface 1903 is used to implement information input and output;

[0203] Communication interface 1904 is used to enable communication and interaction between this device and other devices. Communication can be achieved via wired means (e.g., USB, Ethernet cable) or wireless means (e.g., mobile network, Wi-Fi, Bluetooth).

[0204] Bus 1905 transmits information between various components of the device (e.g., processor 1901, memory 1902, input / output interface 1903, and communication interface 1904);

[0205] The processor 1901, memory 1902, input / output interface 1903 and communication interface 1904 are connected to each other within the device via bus 1905.

[0206] This application embodiment also provides a storage medium, which is a computer-readable storage medium, storing a computer program that, when executed by a processor, implements the above-described modular multiplexing method.

[0207] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0208] The mode division multiplexing system, method, device, and storage medium proposed in this invention include at least: multiple cascaded optical fiber transmission units across multiple spans and a central controller. Each optical fiber transmission unit includes a multimode fiber and a mode adjustment unit. The mode adjustment unit receives optical signal modules transmitted from the multimode fiber, calculates the transmission parameters of the optical fiber transmission unit based on the optical signal modules, and sends the transmission parameters to the central controller. The central controller obtains the transmission parameters of the optical fiber transmission units in each span and generates a target mode round-robin strategy for the corresponding span of optical fiber transmission units based on the transmission parameters. Then, the mode adjustment unit adjusts the transmission mode of the optical signal in the optical signal module according to the received target mode round-robin strategy to update the optical signal module, and sends the adjusted optical signal module to the multimode fiber of the next span. In this embodiment, the mode adjustment unit in each span of the optical fiber transmission unit sends the calculated transmission parameters to the central controller. The central controller adaptively selects the target mode round-robin strategy according to the real-time transmission environment and performs adaptive adjustment on each span to obtain the minimum differential mode group delay (DMD) and mode-dependent loss (MDL). It can adapt to different span lengths and different transmission environments, thereby improving the transmission performance of multimode optical fiber.

[0209] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0210] Those skilled in the art will understand that the technical solutions illustrated in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than illustrated, or combine certain steps, or different steps. The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of the solution in this embodiment according to actual needs.

[0211] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0212] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0213] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0214] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0215] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, the functional units in the various embodiments of this application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The integrated units described above can be implemented in hardware or as software functional units.

[0216] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0217] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A modular multiplexing system, characterized in that, include: A transmitter is used to modulate communication signals to obtain an optical signal module, wherein the optical signal module includes a first preset number of optical signals with different transmission modes; A receiver is used to receive the optical signal module and demodulate the optical signal module to obtain the communication signal. Multiple cascaded fiber optic transmission units are provided, with the first cascaded fiber optic transmission unit connected to the transmitter and the last cascaded fiber optic transmission unit connected to the receiver, for transmitting the optical signal module emitted by the transmitter to the receiver. The central controller is used to acquire the transmission parameters of the optical fiber transmission unit in each segment, and generate the target mode round-robin strategy for the optical fiber transmission unit in the corresponding segment based on the transmission parameters. The transmission parameters include: mode group delay parameters and mode-related loss parameters. The optical fiber transmission unit includes: a multimode fiber and a mode adjustment unit. The mode adjustment unit is used to receive the optical signal module transmitted from the multimode fiber, calculate the transmission parameters of the optical fiber transmission unit based on the optical signal module, send the transmission parameters to the central controller, and adjust the transmission mode of the optical signal in the optical signal module according to the target mode round-robin strategy from the central controller to update the transmission mode of the optical signal in the optical signal module, and send the adjusted optical signal module to the multimode fiber of the next span. When the central controller generates the target mode round-robin strategy for the corresponding segment of the optical fiber transmission unit based on the transmission parameters, it performs the following steps: calculating the group delay score of each candidate round-robin strategy based on the mode group delay parameter, and calculating the mode-related loss score of each candidate round-robin strategy based on the mode-related loss parameter; calculating the candidate score of the candidate round-robin strategy based on the mode-related loss score, the mode-related loss weight, the group delay score, and the group delay weight; and selecting the candidate round-robin strategy with the largest candidate score as the target mode round-robin strategy for the corresponding segment.

2. The modular multiplexing system according to claim 1, characterized in that, The mode adjustment unit includes: a link characterization unit, a link controller, and a mode polling device; One end of the link characterization unit is connected to the multimode optical fiber, and is used to calculate the transmission parameters based on each optical signal in the optical signal module transmitted in the current segment of the multimode optical fiber, and send the transmission parameters to the central controller. The link controller is used to receive the target mode polling strategy of the optical fiber transmission unit generated by the central controller according to the transmission parameters, and send the target mode polling strategy to the mode polling device; One end of the mode-rotating device is connected to the multimode fiber of the current span, and the other end is connected to the multimode fiber of the next span, and is also connected to the link controller. It is used to adjust the transmission mode of the optical signal in the optical signal module according to the target mode-rotating strategy in order to update and transmit the optical signal module.

3. The modular multiplexing system according to claim 2, characterized in that, The mode group delay parameter includes the mode delay value of each optical signal in the optical signal module under the current transmission mode, and the mode-related loss parameter includes the loss value of each optical signal in the optical signal module under the current transmission mode. The transmission mode of the optical signal is updated using the candidate polling strategy to obtain transmission mode adjustment pairs, each of which contains one or two transmission modes. Calculate the mean value of the mode delay value of the transmission mode in each transmission mode adjustment pair to obtain the first delay mean value of the transmission mode adjustment pair, and use the average value of the first delay mean value as the group delay score; Calculate the mean of the loss values ​​of the transmission modes in each transmission mode adjustment pair to obtain the second mean loss value of the transmission mode adjustment pair, and use the average value of the second mean loss value as the loss score.

4. The modular multiplexing system according to claim 3, characterized in that, The candidate round-robin strategy includes: sequential round-robin strategy, pairwise round-robin strategy, round-robin recommendation strategy based on genetic algorithm, or round-robin strategy that iterates through the maximum and minimum values; updating the transmission mode of the optical signal using the candidate round-robin strategy to obtain transmission mode adjustment pairs includes: When the candidate polling strategy is a sequential polling strategy, the transmission mode at the current position and the transmission mode at the next position are cyclically exchanged according to the numbering order of the transmission modes; When the candidate round-robin strategy is a pairwise round-robin strategy, the transmission modes are grouped according to the number of groups to obtain multiple mode groups. Each mode group is numbered according to the numbering order of the transmission modes. The mode group at the current position is cyclically swapped with the mode group at the next position according to the numbering order of the mode groups. When the candidate round-robin strategy is a round-robin recommendation strategy based on a genetic algorithm, the population information of the transmission mode is generated, the population information is input into the genetic recommendation algorithm for population iteration, and after the iteration condition is reached, the recommendation sequence corresponding to the population information is obtained, and the transmission mode is exchanged according to the recommendation sequence. When the candidate round-robin strategy is a round-robin strategy that iterates through the maximum and minimum values, the mode group delay parameters and / or the mode-related loss parameters of the transmission mode are sorted, and the transmission modes are exchanged according to the sorting results. The transmission mode adjustment pair includes two transmission modes that have been switched and / or one transmission mode that has not been switched.

5. The modular multiplexing system according to any one of claims 2 to 4, characterized in that, The mode-rotating device includes: an optical switch module and a rotation unit; One end of the optical switch module is connected to the multimode fiber of the current span, the other end of the optical switch module is connected to one end of the polling unit, and the other end of the polling unit is connected to the multimode fiber of the next span. The link controller generates switching control commands for the polling unit according to the target mode polling strategy; The optical switch module is connected to the link controller and is used to receive a switch command and connect the multimode fiber and the target polling unit according to the switch command, so that the polling unit generates a second transmission mode according to the target mode polling strategy and the first transmission mode. The first transmission mode is the transmission mode in the optical signal module received in the current segment, and the second transmission mode is the transmission mode in the optical signal module output in the current segment.

6. The modular multiplexing system according to claim 5, characterized in that, The mode cycling device further includes: a few-mode combiner; the cycling unit includes a second preset number of mode circulators, the second preset number being obtained based on the first preset number; One end of the mode circulator is connected to the optical switch module, the other end of the mode circulator is connected to one end of the few-mode combiner, and the other end of the few-mode combiner is connected to the multimode fiber in the next span.

7. The modular multiplexing system according to claim 6, characterized in that, The optical switch module includes a second preset number of few-mode optical switches, and the mode cycling device further includes a few-mode beam splitter. One end of the few-mode beam splitter is connected to the multimode fiber of the current span, and the other end of the few-mode beam splitter is sequentially connected to one end of the few-mode optical switch. The other end of the few-mode optical switch is sequentially connected to the mode circulator. The mode circulator rotates in a fixed rotation mode.

8. The modular multiplexing system according to claim 5, characterized in that, The mode cycling device further includes: a few-mode combiner; the optical switch module includes: a MEMS optical switch; the cycling unit includes a second preset number of mode circulators; When the optical switch module is a MEMS optical switch, one end of the MEMS optical switch is connected to the multimode optical fiber of the current span, and the other end of the MEMS optical switch is connected to one end of the mode circulator, for selecting at least one of the mode circulators according to the switching command. The other end of the mode circulator is connected to one end of the few-mode combiner, and the other end of the few-mode combiner is connected to the multimode fiber in the next span.

9. The modular multiplexing system according to claim 8, characterized in that, The mode circulator includes: a demultiplexer, a multiplexer, and a first preset number of mode switches; the demultiplexer includes a first input terminal and a first preset number of first output terminals, and the multiplexer includes a first preset number of second input terminals and a first second output terminal; the second preset number is obtained according to the first preset number; The first input terminal is connected to the MEMS optical switch, the first output terminal is sequentially connected to one end of the mode switch, the other end of the mode switch is sequentially connected to the second input terminal, and the second output terminal is connected to the few-mode combiner.

10. The modular multiplexing system according to any one of claims 2 to 4, characterized in that, The mode cycling device includes: an optical switch module and a photonic lantern module; the photonic lantern module includes: a demultiplexed photonic lantern and a multiplexed photonic lantern, the demultiplexed photonic lantern includes a third input terminal and a second preset number of third output terminals, the optical switch module includes a second preset number of fourth input terminals and a second preset number of fourth output terminals; the multiplexed photonic lantern includes a second preset number of fifth input terminals and a third fifth output terminal; The multimode fiber in the current span is connected to the third input end, the third output end is connected to the fourth input end in sequence, the fourth output end is connected to the fifth input end in sequence, and the fifth output end is connected to the multimode fiber in the next span.

11. The modular multiplexing system according to any one of claims 2 to 4, characterized in that, The mode cycling device includes: a spatial light modulator and a reflector arranged in parallel, wherein a phase plate is provided on the light incident surface of the spatial light modulator; The mode-rotating device performs the following steps when adjusting the transmission mode of the optical signal in the optical signal module according to the target mode-rotating strategy to update the optical signal module: When the optical signal in the optical signal module is incident on the spatial light modulator at a preset angle and reaches the phase plate, and is reflected multiple times between the spatial light modulator and the reflector, during each reflection process, the phase plate modulates the transmission mode of the optical signal in the optical signal module according to the target mode cyclic strategy.

12. The modular multiplexing system according to claim 1, characterized in that, The optical fiber transmission unit further includes an amplifier, one end of which is connected to the mode adjustment unit and the other end of which is connected to the multimode optical fiber of the next span.

13. A modular multiplexing method, characterized in that, A central processing unit applied to a mode division multiplexing system as described in any one of claims 1 to 12 acquires the transmission parameters of the optical fiber transmission unit in each segment, and generates a target mode round-robin strategy for the corresponding segment of the optical fiber transmission unit based on the transmission parameters.

14. An electronic device, characterized in that, The electronic device includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the modular multiplexing method of claim 13.

15. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the modular multiplexing method of claim 13.

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