Fiber nonlinear compensation method and system for Raman amplified ultra-long single-span optical communication

Abstract

The present invention provides a method and system for optical fiber nonlinearity compensation in Raman-amplified ultra-long single-span optical communications. The method comprises: step S1: acquiring link information of the Raman-amplified ultra-long single-span optical communications system; step S2: calculating the step size and other parameters of the optical fiber nonlinearity compensation algorithm based on the acquired information; and step S3: executing the optical fiber nonlinearity compensation algorithm using the step size and other parameters. The present invention uses the link information of the Raman-amplified ultra-long single-span optical communications system to estimate the actual signal power envelope, and uses this actual signal power envelope to optimize the step size of the optical fiber nonlinearity compensation algorithm, thereby effectively compensating for optical fiber nonlinear damage and increasing link capacity.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber communication technology, and in particular to an optical fiber nonlinear compensation method and system for Raman amplified ultra-long single-span optical communication. Background Art

[0002] With the advancement of coherent optical transmission technology, fiber channel capacity is rapidly approaching the Shannon limit. To further increase the capacity of current optical network infrastructure, addressing fiber nonlinear impairments has become crucial. This is particularly true in the context of global telecommunications, where the coverage of global internet networks needs to be expanded. To achieve this goal, Raman amplification in ultra-long single-span optical communication systems is often chosen. Raman amplification can lead to more pronounced fiber nonlinear impairments, which in turn limit system capacity. Fiber nonlinearity compensation algorithms have become a key method for increasing capacity.

[0003] In the prior art, the "Multi-parameter Blind Adaptive Fiber Nonlinear Compensation Algorithm" was published on pages 1746 to 1756 of the May 2018 issue of the Journal of Lightwave Technology. This paper uses a multi-parameter adaptive algorithm to blindly and adaptively optimize parameters such as the fiber nonlinear coefficient. However, this method does not consider Raman amplified ultra-long single-span optical communication systems, nor does it consider the adaptive optimization of fiber nonlinear algorithm parameters in multi-carrier systems. Summary of the Invention

[0004] In view of the defects in the prior art, the object of the present invention is to provide a method and system for optical fiber nonlinear compensation for Raman amplified ultra-long single-span optical communication.

[0005] According to the present invention, a method for optical fiber nonlinear compensation for Raman amplified ultra-long single-span optical communication is provided, comprising:

[0006] Step S1: obtaining link information of a Raman amplified ultra-long single-span optical communication system;

[0007] Step S2: Calculating the step size and other parameters of the optical fiber nonlinear compensation algorithm based on the acquired information;

[0008] Step S3: Execute the fiber nonlinear compensation algorithm using the fiber nonlinear compensation algorithm step size and other fiber nonlinear compensation algorithm parameters.

[0009] Preferably, the Raman amplification ultra-long single-span optical communication system link information includes Raman amplification gain, optical fiber span length and optical fiber span attenuation, and is obtained from the Raman amplification ultra-long single-span optical communication system.

[0010] Preferably, step S2 includes the following sub-steps:

[0011] Step S2.1: Optimizing the step size of the fiber nonlinear compensation algorithm using an adaptive algorithm based on the Raman amplified ultra-long single-span optical communication system link information;

[0012] Step S2.2: Calculate other fiber nonlinear compensation algorithm parameters using the optimized fiber nonlinear compensation algorithm step size; the other fiber nonlinear compensation algorithm parameters include the fiber nonlinear coefficient and the CSN filter transfer function.

[0013] Preferably, the step S2.1 includes the following sub-steps:

[0014] Step S2.1.1: Assuming that the pump light power in Raman amplification is not depleted by the signal light, solve the stimulated Raman scattering equation to obtain the analytical solution of the signal power envelope;

[0015] Step S2.1.2: Substituting the link information of the Raman amplified ultra-long single-span optical communication system into the signal power envelope analytical solution to estimate the actual signal power envelope in the Raman amplified ultra-long single-span optical communication system;

[0016] Step S2.1.3: Initialize the step size of the fiber nonlinear compensation algorithm according to the actual signal power envelope, and obtain the signal power value corresponding to the step size;

[0017] Step S2.1.4: Calculate the error between the signal power value and the actual signal power envelope, and adaptively optimize the step size of the fiber nonlinear compensation algorithm.

[0018] Preferably, the step S2.2 includes the following sub-steps:

[0019] Step S2.2.1: Calculate the fiber nonlinear coefficient of each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope;

[0020] Step S2.2.2: Calculate the CSN filter transfer function for each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope;

[0021] Step S2.2.3: Calculate the remaining parameters of the fiber nonlinear compensation algorithm based on the fiber nonlinear coefficient and the CSN filter transfer function.

[0022] According to the present invention, a fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication is provided, comprising:

[0023] Module M1: Acquires link information of Raman amplified ultra-long single-span optical communication system;

[0024] Module M2: Calculates the step size and other parameters of the optical fiber nonlinear compensation algorithm based on the acquired information;

[0025] Module M3: Executes the fiber nonlinear compensation algorithm using the fiber nonlinear compensation algorithm step size and other fiber nonlinear compensation algorithm parameters.

[0026] Preferably, the Raman amplification ultra-long single-span optical communication system link information includes Raman amplification gain, optical fiber span length and optical fiber span attenuation, and is obtained from the Raman amplification ultra-long single-span optical communication system.

[0027] Preferably, the module M2 includes the following submodules:

[0028] Module M2.1: Optimize the step size of the fiber nonlinear compensation algorithm using an adaptive algorithm based on Raman amplification of the link information of the ultra-long single-span optical communication system;

[0029] Module M2.2: Calculate other fiber nonlinear compensation algorithm parameters using the optimized fiber nonlinear compensation algorithm step size; the other fiber nonlinear compensation algorithm parameters include the fiber nonlinear coefficient and the CSN filter transfer function.

[0030] Preferably, the module M2.1 includes the following submodules:

[0031] Module M2.1.1: Assuming that the pump light power in Raman amplification is not depleted by the signal light, solve the stimulated Raman scattering equation to obtain the analytical solution of the signal power envelope;

[0032] Module M2.1.2: Substituting the link information of the Raman amplified ultra-long single-span optical communication system into the signal power envelope analytical solution to estimate the actual signal power envelope in the Raman amplified ultra-long single-span optical communication system;

[0033] Module M2.1.3: Initialize the step size of the fiber nonlinear compensation algorithm based on the actual signal power envelope and obtain the signal power value corresponding to the step size;

[0034] Module M2.1.4: Calculate the error between the signal power value and the actual signal power envelope, and adaptively optimize the step size of the fiber nonlinear compensation algorithm.

[0035] Preferably, the module M2.2 includes the following submodules:

[0036] Module M2.2.1: Calculate the fiber nonlinear coefficient for each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained through adaptive optimization and the actual signal power envelope;

[0037] Module M2.2.2: Calculate the CSN filter transfer function for each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope;

[0038] Module M2.2.3: Calculate the remaining parameters of the fiber nonlinear compensation algorithm based on the fiber nonlinear coefficient and the CSN filter transfer function.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The present invention uses Raman amplification to estimate the actual signal power envelope of an ultra-long single-span optical communication system link information. This is then used to optimize the step size of the fiber nonlinear compensation algorithm, thereby effectively compensating for fiber nonlinear damage and improving link capacity. Compared to systems without this nonlinear compensation algorithm, a signal-to-noise ratio improvement of more than 1 dB can be achieved in single-channel, single-carrier systems operating at 200 GBaud or above.

[0041] 2. By adopting a structure suitable for fiber nonlinear compensation in ultra-high baud rate and multi-carrier systems, the present invention further optimizes other fiber nonlinear compensation algorithm parameters based on the step size optimization results of the fiber nonlinear compensation algorithm, thereby achieving the purpose of effectively compensating for fiber nonlinear damage in ultra-high baud rate and multi-carrier systems. Compared with not using this nonlinear compensation algorithm, a signal-to-noise ratio improvement of more than 2 dB can be achieved in single-channel multi-carrier systems with an operating frequency of 200 GBaud or above.

[0042] Other beneficial effects of the present invention will be explained through the introduction of specific technical features and technical solutions in the specific implementation methods. Those skilled in the art should be able to understand the beneficial technical effects brought about by the introduction of these technical features and technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0044] Figure 1 Flowchart of the present invention.

[0045] Figure 2 This is a block diagram of the parameter adaptation principle of the optical fiber nonlinear compensation algorithm of the present invention.

[0046] Figure 3 This is a principle block diagram of the optical fiber nonlinear compensation algorithm of the present invention.

[0047] Figure 4 This is a block diagram of the transceiver and link of the present invention.

[0048] Figure 5 This is the algorithm performance diagram of the present invention. DETAILED DESCRIPTION

[0049] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0050] Reference Figure 1 As shown, a method for optical fiber nonlinear compensation for Raman amplified ultra-long single-span optical communication includes:

[0051] Step 1: In the Raman amplified ultra-long single-span optical communication system, link information of the Raman amplified ultra-long single-span optical communication system, such as Raman amplification gain, optical fiber span length, and optical fiber span attenuation, is obtained;

[0052] Step 2: Reference Figure 2 As shown, based on the link information of the Raman amplified ultra-long single-span optical communication system, an adaptive algorithm is used to optimize the step size of the fiber nonlinear compensation algorithm;

[0053] Step 2.1: Assuming that the pump light power in Raman amplification is not depleted by the signal light, the stimulated Raman scattering equation is solved to obtain the analytical solution of the signal power envelope;

[0054] The process of solving the stimulated Raman scattering equation is as follows:

[0055] The process of stimulated Raman scattering can be described by the following coupled equations:

[0056]

[0057] Among them, P s (z) is the signal power, is the forward pump power, is the backward pump power, v s / v p is the signal / pump frequency, α s and α p is the signal / pump attenuation coefficient, C R (v s ,v p ) is the Raman gain coefficient, and z is the transmission distance. The stimulated Raman scattering equation can be simplified and decoupled into a first-order linear differential equation, which can be solved using the constant variation method. The undetermined coefficients in the solution of the stimulated Raman scattering equation are determined by the signal input fiber power, and its closed-form solution is:

[0058]

[0059] L is the span length.

[0060] Step 2.2: The Raman amplification gain G of the Raman amplified ultra-long single-span optical communication system obtained in step 1 is converted to dB , fiber span length L and fiber span attenuation are brought into the signal power envelope analytical solution (3), and by adjusting and Make Thus, the actual signal power envelope in Raman amplified ultra-long single-span optical communication systems is estimated;

[0061] Step 2.3: Initialize the step size of the fiber nonlinear compensation algorithm based on the actual signal power envelope, and obtain the signal power value corresponding to the step size;

[0062] Step 2.4: Calculate the error between the signal power value and the actual signal power envelope, and adaptively optimize the step size of the fiber nonlinear compensation algorithm.

[0063] Step 3: Reference Figure 3 As shown, the optimized fiber nonlinear compensation algorithm step size is used to calculate other fiber nonlinear compensation algorithm parameters (fiber nonlinear coefficient, CSN filter transfer function and other parameters);

[0064] Step 3.1: Calculate the nonlinear coefficient of each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization in step 2 and the actual signal power envelope;

[0065] The expression of the nonlinear coefficient is:

[0066]

[0067] Where γ is the nonlinear constant of the optical fiber, which is about 1.3 per watt per kilometer in standard single-mode optical fiber, and L k is the step size of the kth step of the fiber nonlinear compensation algorithm.

[0068] Step 3.2: Calculate the CSN filter transfer function for each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization in step 2 and the actual signal power envelope;

[0069] The expression of the CSN filter transfer function is:

[0070]

[0071] Where Δβ=β2(ω I -ω P ) is the group velocity difference between the interference subcarrier and the observation subcarrier, ω is the frequency (where ω I and ω Pare the frequencies of the interference subcarrier and the observation subcarrier respectively), is the equivalent attenuation, the expression is:

[0072]

[0073] Among them, z k and z k+1 are the starting positions of the kth step and the k+1th step respectively.

[0074] Step 3.3: Based on the fiber nonlinear coefficient and CSN filter transfer function obtained in steps 3.1 and 3.2, further search to obtain several other parameters of the fiber nonlinear compensation algorithm, such as the dispersion compensation ratio in each step of fiber nonlinear compensation and the low-pass filter bandwidth.

[0075] Step 4: Execute the Fiber Nonlinear Compensation algorithm using the algorithm step size and other Fiber Nonlinear Compensation algorithm parameters. The Fiber Nonlinear Compensation algorithm is divided into several identical steps, each of which executes the process from Step 4.1 to Step 4.4 until the last step is completed.

[0076] Step 4.1: Compensate for signal dispersion and attenuation using the dispersion compensation ratio found in step 3.3.

[0077] Step 4.2: Compensate for the nonlinearity within the subcarrier using the nonlinear coefficients obtained in step 3.1.

[0078] Step 4.3: Compensate for inter-subcarrier nonlinearity using the nonlinear coefficients obtained in step 3.1 and the CSN filter transfer function obtained in step 3.2.

[0079] Step 4.4: Compensate for the dispersion and attenuation of the remaining signal according to the dispersion compensation ratio found in step 3.3.

[0080] Reference Figure 4 As shown, the present invention uses Raman amplification to estimate the actual signal power envelope of an ultra-long single-span optical communication system link information, and uses this actual signal power envelope to optimize the step size of the fiber nonlinear compensation algorithm, thereby effectively compensating for fiber nonlinear impairments and increasing link capacity. Compared to not using this nonlinear compensation algorithm, a signal-to-noise ratio improvement of more than 1 dB can be achieved in single-channel, single-carrier systems operating at 200 GBaud or above. By adopting a fiber nonlinear compensation structure suitable for ultra-high baud rate, multi-carrier systems, and based on the step size optimization results of the fiber nonlinear compensation algorithm, other fiber nonlinear compensation algorithm parameters are further optimized, thereby effectively compensating for fiber nonlinear impairments in ultra-high baud rate, multi-carrier systems. Compared to not using this nonlinear compensation algorithm, a signal-to-noise ratio improvement of more than 2 dB can be achieved in single-channel, multi-carrier systems operating at 200 GBaud or above.

[0081] The present invention also provides an optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication. The optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication can be implemented by executing the process steps of the optical fiber nonlinear compensation method for Raman amplified ultra-long single-span optical communication. That is, those skilled in the art can understand the optical fiber nonlinear compensation method for Raman amplified ultra-long single-span optical communication as a preferred implementation of the optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication.

[0082] Specifically, a fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication includes:

[0083] Module M1: Acquires link information of Raman amplified ultra-long single-span optical communication system;

[0084] Module M2: Calculates the step size and other parameters of the optical fiber nonlinear compensation algorithm based on the acquired information;

[0085] Module M3: Executes the fiber nonlinear compensation algorithm using the fiber nonlinear compensation algorithm step size and other fiber nonlinear compensation algorithm parameters.

[0086] The Raman amplification ultra-long single-span optical communication system link information includes Raman amplification gain, optical fiber span length, and optical fiber span attenuation, and is obtained from the Raman amplification ultra-long single-span optical communication system.

[0087] The module M2 includes the following submodules:

[0088] Module M2.1: Optimize the step size of the fiber nonlinear compensation algorithm using an adaptive algorithm based on Raman amplification of the link information of the ultra-long single-span optical communication system;

[0089] Module M2.2: Calculate other fiber nonlinear compensation algorithm parameters using the optimized fiber nonlinear compensation algorithm step size; the other fiber nonlinear compensation algorithm parameters include the fiber nonlinear coefficient and the CSN filter transfer function.

[0090] The module M2.1 includes the following submodules:

[0091] Module M2.1.1: Assuming that the pump light power in Raman amplification is not depleted by the signal light, solve the stimulated Raman scattering equation to obtain the analytical solution of the signal power envelope;

[0092] Module M2.1.2: Substituting the link information of the Raman amplified ultra-long single-span optical communication system into the signal power envelope analytical solution to estimate the actual signal power envelope in the Raman amplified ultra-long single-span optical communication system;

[0093] Module M2.1.3: Initialize the step size of the fiber nonlinear compensation algorithm based on the actual signal power envelope and obtain the signal power value corresponding to the step size;

[0094] Module M2.1.4: Calculate the error between the signal power value and the actual signal power envelope, and adaptively optimize the step size of the fiber nonlinear compensation algorithm.

[0095] The module M2.2 includes the following submodules:

[0096] Module M2.2.1: Calculate the fiber nonlinear coefficient for each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained through adaptive optimization and the actual signal power envelope;

[0097] Module M2.2.2: Calculate the CSN filter transfer function for each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope;

[0098] Module M2.2.3: Calculate the remaining parameters of the fiber nonlinear compensation algorithm based on the fiber nonlinear coefficient and the CSN filter transfer function.

[0099] Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, and units provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same functions of the system and its various devices, modules, and units provided by the present invention in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; the devices, modules, and units for implementing various functions can also be considered as both software modules implementing the method and structures within the hardware component.

[0100] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for optical fiber nonlinearity compensation in Raman amplified ultra-long single-span optical communication, characterized in that: include: Step S1: obtaining link information of a Raman amplified ultra-long single-span optical communication system; Step S2: Calculating the step size and other parameters of the optical fiber nonlinear compensation algorithm based on the acquired information; Step S3: Execute the fiber nonlinear compensation algorithm using the fiber nonlinear compensation algorithm step size and other fiber nonlinear compensation algorithm parameters; The step S2 includes the following sub-steps: Step S2.1: Optimizing the step size of the fiber nonlinear compensation algorithm using an adaptive algorithm based on the Raman amplified ultra-long single-span optical communication system link information; The specific steps include: Step S2.1.1: Assuming that the pump light power in Raman amplification is not depleted by the signal light, solve the stimulated Raman scattering equation to obtain the analytical solution of the signal power envelope; The process of solving the stimulated Raman scattering equation is as follows: The stimulated Raman scattering process is described by the following coupled equations: in, is the signal power, is the forward pump power, is the backward pump power, is the signal / pump frequency, and is the signal / pump attenuation coefficient, is the Raman gain coefficient, is the transmission distance; the stimulated Raman scattering equation is simplified and decoupled into a first-order linear differential equation and solved by the constant variation method; the undetermined coefficients in the solution of the stimulated Raman scattering equation are determined according to the signal input fiber power, and its closed-form solution is: in, is the span length; Step S2.1.2: Obtain the Raman amplified gain of the ultra-long single-span optical communication system , Fiber span length And the fiber span attenuation is brought into the above formula, by adjusting and , making , thereby obtaining the actual signal power envelope in the Raman amplified ultra-long single-span optical communication system; Step S2.1.3: Initialize the step size of the fiber nonlinear compensation algorithm according to the actual signal power envelope, and obtain the signal power value corresponding to the step size; Step S2.1.4: Calculate the error between the signal power value and the actual signal power envelope, and adaptively optimize the step size of the fiber nonlinear compensation algorithm; Step S2.2: Calculate other fiber nonlinear compensation algorithm parameters using the optimized fiber nonlinear compensation algorithm step size; the other fiber nonlinear compensation algorithm parameters include the fiber nonlinear coefficient and the CSN filter transfer function.

2. The optical fiber nonlinear compensation method for Raman amplified ultra-long single-span optical communication according to claim 1, characterized in that: The Raman amplification ultra-long single-span optical communication system link information includes Raman amplification gain, optical fiber span length, and optical fiber span attenuation, and is obtained from the Raman amplification ultra-long single-span optical communication system.

3. The optical fiber nonlinear compensation method for Raman amplified ultra-long single-span optical communication according to claim 1, characterized in that: The step S2.2 includes the following sub-steps: Step S2.2.1: Calculate the fiber nonlinear coefficient of each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope; Step S2.2.2: Calculate the CSN filter transfer function for each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope; Step S2.2.3: Calculate the remaining parameters of the fiber nonlinear compensation algorithm based on the fiber nonlinear coefficient and the CSN filter transfer function.

4. A fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication, characterized in that: include: Module M1: Acquires link information of Raman amplified ultra-long single-span optical communication system; Module M2: Calculates the step size and other parameters of the optical fiber nonlinear compensation algorithm based on the acquired information; Module M3: Executes the fiber nonlinear compensation algorithm using the fiber nonlinear compensation algorithm step size and other fiber nonlinear compensation algorithm parameters; The module M2 includes the following submodules: Module M2.1: Optimize the step size of the fiber nonlinear compensation algorithm using an adaptive algorithm based on Raman amplification of the link information of the ultra-long single-span optical communication system; Specific modules include: Module M2.1.1: Assuming that the pump light power in Raman amplification is not depleted by the signal light, solve the stimulated Raman scattering equation to obtain the analytical solution of the signal power envelope; The process of solving the stimulated Raman scattering equation is as follows: The stimulated Raman scattering process is described by the following coupled equations: in, is the signal power, is the forward pump power, is the backward pump power, is the signal / pump frequency, and is the signal / pump attenuation coefficient, is the Raman gain coefficient, is the transmission distance; the stimulated Raman scattering equation is simplified and decoupled into a first-order linear differential equation and solved by the constant variation method; the undetermined coefficients in the solution of the stimulated Raman scattering equation are determined according to the signal input fiber power, and its closed-form solution is: in, is the span length; Module M2.1.2: Obtained Raman amplified gain of ultra-long single-span optical communication system , Fiber span length And the fiber span attenuation is brought into the above formula, by adjusting and , making , thereby obtaining the actual signal power envelope in the Raman amplified ultra-long single-span optical communication system; Module M2.1.3: Initialize the step size of the fiber nonlinear compensation algorithm based on the actual signal power envelope and obtain the signal power value corresponding to the step size; Module M2.1.4: Calculates the error between the signal power value and the actual signal power envelope, and adaptively optimizes the step size of the fiber nonlinear compensation algorithm; Module M2.2: Calculate other fiber nonlinear compensation algorithm parameters using the optimized fiber nonlinear compensation algorithm step size; the other fiber nonlinear compensation algorithm parameters include the fiber nonlinear coefficient and the CSN filter transfer function.

5. The optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication according to claim 4, characterized in that: The Raman amplification ultra-long single-span optical communication system link information includes Raman amplification gain, optical fiber span length, and optical fiber span attenuation, and is obtained from the Raman amplification ultra-long single-span optical communication system.

6. The optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication according to claim 4, characterized in that: The module M2.2 includes the following submodules: Module M2.2.1: Calculate the fiber nonlinear coefficient for each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained through adaptive optimization and the actual signal power envelope; Module M2.2.2: Calculate the CSN filter transfer function for each step of the fiber nonlinear compensation algorithm based on the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope; Module M2.2.3: Calculate the remaining parameters of the fiber nonlinear compensation algorithm based on the fiber nonlinear coefficient and the CSN filter transfer function.

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