Optical fiber nonlinear compensation method and system for Raman amplification ultra-long single-span optical communication

Abstract

The invention provides an optical fiber nonlinear compensation method and system for Raman amplification ultra-long single-span optical communication. The method comprises the following steps: S1, acquiring link information of a Raman amplification ultra-long single-span optical communication system; s2, calculating according to the obtained information to obtain a step length of an optical fiber nonlinear compensation algorithm and parameters of other optical fiber nonlinear compensation algorithms; and S3, executing an optical fiber nonlinear compensation algorithm by using the optical fiber nonlinear compensation algorithm step length and other optical fiber nonlinear compensation algorithm parameters. According to the method, link information of the ultra-long single-span optical communication system is amplified through Raman, the actual signal power envelope is estimated, the actual signal power envelope is used for step length optimization of an optical fiber nonlinear compensation algorithm, and therefore the purposes of effectively compensating optical fiber nonlinear damage and improving the link capacity are achieved.

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 development of coherent optical transmission technology, the capacity of optical fiber channels is rapidly approaching the Shannon limit. In order to further increase the capacity of the current optical network infrastructure, it is essential to solve the nonlinear damage of optical fiber. Especially in the case of global telecommunications, it is necessary to expand the coverage of the global Internet network. In order to achieve this goal, Raman amplification ultra-long single-span optical communication systems are generally selected. Raman amplification will cause more significant nonlinear damage to the optical fiber, and nonlinear damage to the optical fiber will cause the system capacity to be limited. The optical fiber nonlinear compensation algorithm has become an important method to increase capacity.

[0003] In the prior art, the journal "Journal of Lightwave Technology" in May 2018, pages 1746 to 1756, disclosed a "multi-parameter blind adaptive fiber nonlinear compensation algorithm", in which a multi-parameter adaptive algorithm was used to blindly adaptively optimize parameters such as fiber nonlinear coefficients. However, this method does not consider Raman amplification 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 includes:

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

[0007] Step S2: Calculate the step size and other parameters of the optical fiber nonlinear compensation algorithm according to 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 link information of the Raman amplification ultra-long single-span optical communication system 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: using an adaptive algorithm to optimize the step size of the optical fiber nonlinear compensation algorithm according to the link information of the Raman amplified ultra-long single-span optical communication system;

[0012] Step S2.2: using the optimized fiber nonlinear compensation algorithm step size, calculate other fiber nonlinear compensation algorithm parameters; 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 will not be 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 length of the optical fiber nonlinear compensation algorithm according to the actual signal power envelope, and obtain the signal power value corresponding to the step length;

[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 optical 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 according to 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 of each step of the fiber nonlinear compensation algorithm according to 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, an optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication includes:

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

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

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

[0026] Preferably, the link information of the Raman amplification ultra-long single-span optical communication system 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: Based on the Raman amplification of the link information of the ultra-long single-span optical communication system, an adaptive algorithm is used to optimize the step size of the optical fiber nonlinear compensation algorithm;

[0029] Module M2.2: using the optimized fiber nonlinear compensation algorithm step size, calculating other fiber nonlinear compensation algorithm parameters; the other fiber nonlinear compensation algorithm parameters include fiber nonlinear coefficient and 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 will not be 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 according to 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 of each step of the fiber nonlinear compensation algorithm according to the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope;

[0037] Module M2.2.2: Calculate the CSN filter transfer function 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;

[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 link information of an ultra-long single-span optical communication system, and uses the actual signal power envelope to optimize the step size of the optical fiber nonlinear compensation algorithm, thereby achieving the purpose of effectively compensating for optical fiber nonlinear damage and improving link capacity; compared with not using the nonlinear compensation algorithm, a signal-to-noise ratio improvement of more than 1-dB can be achieved in a single-channel single-carrier system with a speed of more than 200GBaud.

[0041] 2. The present invention adopts a structure suitable for fiber nonlinear compensation of ultra-high baud rate and multi-carrier systems, and based on the step size optimization result of the fiber nonlinear compensation algorithm, further optimizes other fiber nonlinear compensation algorithm parameters, thereby achieving the purpose of effectively compensating for fiber nonlinear damage in ultra-high baud rate and multi-carrier systems; compared with not using the nonlinear compensation algorithm, a signal-to-noise ratio improvement of more than 2-dB can be achieved in a single-channel multi-carrier system with a speed of more than 200GBaud.

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

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

[0044] Figure 1 It is a flow chart of the present invention.

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

[0049] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments 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 of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope 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 comprises:

[0051] Step 1: in a Raman amplified ultra-long single-span optical communication system, obtaining Raman amplification gain, optical fiber span length, optical fiber span attenuation and other Raman amplified ultra-long single-span optical communication system link information;

[0052] Step 2: Reference Figure 2 As shown, according to 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 optical fiber nonlinear compensation algorithm;

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

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

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

[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 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:

[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 dB , the fiber span length L and the 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 the Raman-amplified ultra-long single-span optical communication system is estimated;

[0061] Step 2.3: 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;

[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 according to 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 of each step of the fiber nonlinear compensation algorithm according to 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 and obtain other parameters remaining in the fiber nonlinear compensation algorithm, such as the proportion of dispersion compensation in each step of fiber nonlinear compensation, low-pass filter bandwidth, etc.

[0075] Step 4: Use the fiber nonlinear compensation algorithm step size and other fiber nonlinear compensation algorithm parameters to execute the fiber nonlinear compensation algorithm. 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 the dispersion and attenuation of the signal according to the dispersion compensation ratio searched in step 3.3;

[0077] Step 4.2: Compensate for the nonlinearity within the subcarrier according to the nonlinear coefficient obtained in step 3.1;

[0078] Step 4.3: Compensate for inter-subcarrier nonlinearity according to the nonlinear coefficient 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 searched in step 3.3.

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

[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 realized 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, an optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication includes:

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

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

[0085] Module M3: Execute 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: 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 optical fiber nonlinear compensation algorithm;

[0089] Module M2.2: using the optimized fiber nonlinear compensation algorithm step size, calculating other fiber nonlinear compensation algorithm parameters; the other fiber nonlinear compensation algorithm parameters include fiber nonlinear coefficient and 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 will not be 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 according to 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 of each step of the fiber nonlinear compensation algorithm according to the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope;

[0097] Module M2.2.2: Calculate the CSN filter transfer function 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;

[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 know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions 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 as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0100] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for optical fiber nonlinear 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: Calculate the step size and other parameters of the optical fiber nonlinear compensation algorithm according to 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.

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 comprises the following sub-steps: Step S2.1: using an adaptive algorithm to optimize the step size of the optical fiber nonlinear compensation algorithm according to the link information of the Raman amplified ultra-long single-span optical communication system; Step S2.2: using the optimized fiber nonlinear compensation algorithm step size, calculate other fiber nonlinear compensation algorithm parameters; the other fiber nonlinear compensation algorithm parameters include the fiber nonlinear coefficient and the CSN filter transfer function.

4. The optical fiber nonlinear compensation method for Raman amplified ultra-long single-span optical communication according to claim 3, characterized in that: The step S2.1 comprises the following sub-steps: Step S2.1.1: Assuming that the pump light power in Raman amplification will not be depleted by the signal light, solve the stimulated Raman scattering equation to obtain the analytical solution of the signal power envelope; 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; Step S2.1.3: Initialize the step length of the optical fiber nonlinear compensation algorithm according to the actual signal power envelope, and obtain the signal power value corresponding to the step length; 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 optical fiber nonlinear compensation algorithm.

5. The optical fiber nonlinear compensation method for Raman amplified ultra-long single-span optical communication according to claim 4, 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 according to 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 of each step of the fiber nonlinear compensation algorithm according to 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.

6. An optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication, characterized in that: include: Module M1: Acquisition of Raman amplified ultra-long single-span optical communication system link information; Module M2: Calculate the step size and other parameters of the optical fiber nonlinear compensation algorithm based on the acquired information; Module M3: Execute the fiber nonlinear compensation algorithm using the fiber nonlinear compensation algorithm step size and other fiber nonlinear compensation algorithm parameters.

7. The optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication according to claim 6, 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.

8. The optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication according to claim 6, characterized in that: The module M2 Includes the following submodules: Module M2.1: Based on the Raman amplification of the link information of the ultra-long single-span optical communication system, an adaptive algorithm is used to optimize the step size of the optical fiber nonlinear compensation algorithm; Module M2.2: using the optimized fiber nonlinear compensation algorithm step size, calculating other fiber nonlinear compensation algorithm parameters; the other fiber nonlinear compensation algorithm parameters include fiber nonlinear coefficient and CSN filter transfer function.

9. The optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication according to claim 8, characterized in that: The module M2.1 includes the following submodules: Module M2.1.1: Assuming that the pump light power in Raman amplification will not be depleted by the signal light, solve the stimulated Raman scattering equation to obtain the analytical solution of the signal power envelope; 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; Module M2.1.3: 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; 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.

10. The optical fiber nonlinear compensation system for Raman amplified ultra-long single-span optical communication according to claim 9, characterized in that: The module M2.2 includes the following submodules: Module M2.2.1: Calculate the fiber nonlinear coefficient of each step of the fiber nonlinear compensation algorithm according to the step size of the fiber nonlinear compensation algorithm obtained by adaptive optimization and the actual signal power envelope; Module M2.2.2: Calculate the CSN filter transfer function 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; 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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