Nonlinear effect suppression link and design method thereof

Abstract

The application relates to a nonlinear effect inhibiting link and a design method thereof. By adopting two wavelength converters in an optical fiber link and calculating the placement positions of the two wavelength converters and the parameters of a dispersion compensation unit according to a specific method, full-optical nonlinear compensation can be realized on the basis of original transceivers, and the compensation method mainly considers the wavelength correlation of fiber loss, dispersion and nonlinear coefficient. The placement position calculation method needs to calculate the correction values of fiber loss and nonlinear coefficient according to the signal waveband and the conversion target waveband, and the placement positions of the two wavelength converters in the optical fiber link are determined on the basis of the correction values. On the basis of completing the placement position design, the dispersion values required to be compensated in the wavelength converters are calculated according to the dispersion of the signal waveband and the conversion target waveband, so that the optimal nonlinear compensation effect is realized.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, specifically to a nonlinear effect suppression link and its design method. Background Technology

[0002] When optical signals are transmitted through optical fibers, nonlinear effects such as self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM) occur. These nonlinear effects are related to optical power and fiber length and accumulate with transmission distance. For dense wavelength-division multiplexing (DWDM) transmission, when the optical power entering the transmission fiber is high and the transmission distance is long, the noise introduced by nonlinear effects cannot be ignored. In long-distance optical transmission, due to the influence of nonlinear effects in the fiber, the transmitting optical power cannot be increased indefinitely, thus limiting the transmission distance. Therefore, suppressing the nonlinearity generated in the fiber is key to increasing the power of the optical system and thus increasing the transmission distance. However, since the nonlinear process is related to the signal optical power, which changes with transmission, and the wavelength distribution in DWDM systems is diverse with mutual influence between wavelengths, it is difficult to simulate the nonlinear process with a simple model; that is, nonlinear compensation often has high complexity.

[0003] Existing nonlinear compensation techniques are mainly implemented through digital signal processing (DSP), such as the Digital Back Propagation (DBP) algorithm. This algorithm establishes a channel model by incorporating parameters such as the actual link length, loss, dispersion, and nonlinearity. It then negates the dispersion and nonlinearity parameters, iteratively calculating the received electrical signal to transmit a virtual link with the opposite sign to the actual link, thereby canceling out the nonlinearity accumulated during transmission. This method consumes significant computational resources, has high latency and energy consumption, and the benefits are not substantial, typically around 1 dB. Summary of the Invention

[0004] This application provides a nonlinear effect suppression link, its design method, device, and computer-readable storage medium, which can solve the technical problem of poor nonlinear compensation effect in the prior art.

[0005] In a first aspect, embodiments of this application provide a nonlinear effect suppression link, the nonlinear effect suppression link including a first wavelength converter and a second wavelength converter, wherein: One end of the first wavelength converter is connected to the signal transmitting end via a first optical fiber link, and the other end is connected to one end of the second wavelength converter via a second optical fiber link; the other end of the second wavelength converter is connected to the signal receiving end via a third optical fiber link; the first wavelength converter is used to convert the optical signal from the first band to the second band, and the second wavelength converter is used to convert the optical signal from the second band to the first band; The distance between the first wavelength converter and the signal transmitter is The distance between the first wavelength converter and the second wavelength converter is The distance between the second wavelength converter and the signal receiver is And satisfy:

[0006]

[0007] in, This refers to the link distance between the signal transmitter and the signal receiver. The nonlinear coefficients for the first band are... This refers to the fiber loss in the first band. For the nonlinear coefficients of the second band, For the fiber loss in the second band, It is a natural constant.

[0008] In conjunction with the first aspect, in one implementation method, .

[0009] In conjunction with the first aspect, in one embodiment, the first wavelength converter includes a first dispersion compensation device, and the second wavelength converter includes a second dispersion compensation device.

[0010] In conjunction with the first aspect, in one embodiment, the compensation value of the first dispersion compensation device is... The compensation value of the second dispersion compensation device is ,in:

[0011]

[0012]

[0013]

[0014] The dispersion value at the phase-matched wavelength. For the first band of fiber chromatic dispersion, This refers to the chromatic dispersion of the fiber in the second band.

[0015] In conjunction with the first aspect, in one embodiment, the first dispersion compensation device and the second dispersion compensation device are dispersion compensation optical fibers or chirped fiber gratings.

[0016] Secondly, embodiments of this application provide a method for designing a nonlinear effect suppression link, the method comprising: The distance between the first wavelength converter and the signal transmitter is determined using a location design formula. The distance between the first wavelength converter and the second wavelength converter and the distance between the second wavelength converter and the signal receiver The location design formula includes:

[0017]

[0018] in, This refers to the link distance between the signal transmitter and the signal receiver. The nonlinear coefficients for the first band are... This refers to the fiber loss in the first band. For the nonlinear coefficients of the second band, For the fiber loss in the second band, It is a natural constant.

[0019] In conjunction with the second aspect, in one implementation, the location design formula further includes: .

[0020] In conjunction with the second aspect, in one embodiment, the nonlinear effect suppression link design method further includes: The compensation value of the first dispersion compensation device in the first wavelength converter is determined according to the compensation value design formula. And the compensation value of the second dispersion compensation device in the second wavelength converter. The compensation value design formula includes:

[0021]

[0022]

[0023]

[0024] The dispersion value at the phase-matched wavelength. For the first band of fiber chromatic dispersion, This refers to the chromatic dispersion of the fiber in the second band.

[0025] Thirdly, embodiments of this application provide a nonlinear effect suppression link design device, the nonlinear effect suppression link design device including a processor, a memory, and a nonlinear effect suppression link design program stored in the memory and executable by the processor, wherein when the nonlinear effect suppression link design program is executed by the processor, it implements the steps of the nonlinear effect suppression link design method as described in the second aspect.

[0026] Fourthly, embodiments of this application provide a computer-readable storage medium storing a nonlinear effect suppression link design program, wherein when the nonlinear effect suppression link design program is executed by a processor, it implements the steps of the nonlinear effect suppression link design method as described in the second aspect.

[0027] The beneficial effects of the technical solutions provided in this application include: In this embodiment, one end of the first wavelength converter is connected to the signal transmitting end via a first optical fiber link, and the other end is connected to one end of the second wavelength converter via a second optical fiber link; the other end of the second wavelength converter is connected to the signal receiving end via a third optical fiber link; the first wavelength converter is used to convert the optical signal from a first band to a second band, and the second wavelength converter is used to convert the optical signal from the second band to the first band; the distance between the first wavelength converter and the signal transmitting end is... The distance between the first wavelength converter and the second wavelength converter is The distance between the second wavelength converter and the signal receiver is And satisfy:

[0028]

[0029] in, This refers to the link distance between the signal transmitter and the signal receiver. The nonlinear coefficients for the first band are... This refers to the fiber loss in the first band. For the nonlinear coefficients of the second band, For the fiber loss in the second band, It is a natural constant. Through the embodiments of this application, by employing two wavelength converters in the optical fiber link and determining the placement of the two wavelength converters according to a specific method, the signal degradation caused by the accumulation of nonlinear effects during optical fiber transmission can be effectively compensated. Attached Figure Description

[0030] Figure 1 A schematic diagram illustrating traditional C-band direct transmission and the nonlinear accumulation at the fiber optic end. Figure 2 This is a schematic diagram of nonlinear compensation based on the scheme of this application (taking the conversion to S-band as an example) and the nonlinear accumulation at the end of the optical fiber; Figure 3 This is a schematic diagram of the structure of an embodiment of the nonlinear effect suppression link of this application; Figure 4 This is a schematic diagram comparing the transmission performance of the direct transmission scheme and the scheme of this application when the single-wavelength optical power of the fiber input is 0dBm. Figure 5 This is a schematic diagram comparing the transmission performance of the direct transmission scheme and the scheme in this application when the single-wavelength optical power of the fiber input is 5dBm. Figure 6 Schematic diagram of SRS power transfer with wavelength conversion compensation; Figure 7 A comparative diagram of transmission results considering the correction of nonlinear coefficients and loss coefficients to account for band differences; Figure 8 This diagram illustrates the effect of the ratio of the transmission distances of the first and last fiber optic segments on the nonlinear suppression effect. Figure 9 A schematic diagram of wavelength conversion phase mismatch introduced by dispersion; Figure 10 A schematic diagram showing the dispersion compensation efficiency for different segment lengths; Figure 11 A schematic diagram of a nonlinear compensation system for switching between C-band and L-band; Figure 12 A schematic diagram illustrating the compensation for SRS power transfer during C-band and L-band switching; Figure 13 A schematic diagram of a nonlinear compensation system for C-band to S-band and L-band to U-band conversion; Figure 14 A schematic diagram of a nonlinear compensation system for switching between the S+Cb band and the Cr+L band; Figure 15 This is a schematic diagram of the hardware structure of the nonlinear effect suppression link design device involved in the embodiments of this application. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0032] First, some of the technical terms used in this application will be explained to help those skilled in the art understand this application.

[0033] Analysis of the nonlinear noise accumulation process of the k-th wave of a wavelength-division multiplexing (WDM) signal propagating along an optical fiber reveals that nonlinear phase shifts such as SPM, XPM, and FWM accumulate in the imaginary part. Therefore, phase conjugation can directly negate this nonlinear accumulation. Furthermore, FWM not only generates noise within the channel but also introduces new wavelength sidebands outside the original wavelength range. A wavelength converter can achieve phase conjugation by negating the imaginary part of the complex amplitude of the aforementioned signal. Based on the Kerr effect in custom optical devices, such as the third-order FWM effect, or the second-order harmonic generation (SHG) and difference frequency generation (DFG) effects, broadband wavelength conversion can be achieved. This involves symmetrically flipping the original multi-wavelength signal, resulting in a conjugate signal. Taking C-band to S-band conversion as an example, ideally, the converted conjugate signal can compensate for the generated nonlinear noise after propagating the same distance in the optical fiber. Figure 1 and Figure 2 As shown, Figure 1 A schematic diagram illustrating traditional C-band direct transmission and the nonlinear accumulation at the fiber optic end. Figure 2 This is a schematic diagram of nonlinear compensation based on the scheme of this application (taking the conversion to S-band as an example) and the nonlinear accumulation at the end of the optical fiber.

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0035] In one aspect, embodiments of this application provide a nonlinear effect suppression link.

[0036] In one embodiment, reference is made to Figure 3 , Figure 3 This is a schematic diagram of the structure of an embodiment of the nonlinear effect suppression link of this application. Figure 3 As shown, the nonlinear effect suppression link includes a first wavelength converter WC1 and a second wavelength converter WC2, wherein: One end of the first wavelength converter WC1 is connected to the signal transmitting end Tx via a first optical fiber link, and the other end is connected to one end of the second wavelength converter WC2 via a second optical fiber link; the other end of the second wavelength converter WC2 is connected to the signal receiving end Rx via a third optical fiber link; the first wavelength converter WC1 is used to convert the optical signal from the first band A to the second band B, and the second wavelength converter WC2 is used to convert the optical signal from the second band B to the first band A; The distance between the first wavelength converter WC1 and the signal transmitter Tx is The distance between the first wavelength converter WC1 and the second wavelength converter WC2 is The distance between the second wavelength converter WC2 and the signal receiver Rx is... And satisfy:

[0037]

[0038] in, The link distance from the signal transmitter Tx to the signal receiver Rx. The nonlinear coefficients of the first band A are... For the fiber loss in the first band A, For the nonlinear coefficients of the second band B, For the fiber loss in the second band B, It is a natural constant.

[0039] In this embodiment, in the above formula , , The value is known.

[0040] Based on the above, the judgment is... Is it known? If so, no additional processing is needed; if not, the fiber loss value of the second band B needs to be measured. , or according to For fitting calculations, the preferred method is to use fiber standards or batch loss curves, based on known... Perform translation correction calculations.

[0041] Furthermore, to judge Is it known? If so, no additional processing is needed; if not, the effective mode area of ​​band A needs to be calculated first. Then by formula The effective mode field area of ​​band B is obtained. And then according to get Alternatively, the effective mode field area of ​​band B can be calculated using methods such as finite element modeling. And then according to get .in, The center wavelength of band A, The center wavelength of band B, is the second-order nonlinear refractive index coefficient of the optical fiber.

[0042] Two wavelength converters, WC1 and WC2, are used in the optical fiber transmission link to convert A-band signals to B-band and B-band signals back to A-band, respectively. Wavelength converters WC1 and WC2 are capable of converting full-band or partial A-band signals to B-band and vice versa, respectively. Furthermore, their frequency domain response exhibits symmetrical phase spectrum reversal, enabling phase conjugation of full-band or partial A-band signals.

[0043] Furthermore, in one embodiment, .

[0044] In this embodiment, in order to further optimize the nonlinear effect suppression effect, the limitation is... .

[0045] In this embodiment, one end of the first wavelength converter is connected to the signal transmitting end via a first optical fiber link, and the other end is connected to one end of the second wavelength converter via a second optical fiber link; the other end of the second wavelength converter is connected to the signal receiving end via a third optical fiber link; the first wavelength converter is used to convert the optical signal from a first band to a second band, and the second wavelength converter is used to convert the optical signal from the second band to the first band; the distance between the first wavelength converter and the signal transmitting end is... The distance between the first wavelength converter and the second wavelength converter is The distance between the second wavelength converter and the signal receiver is And satisfy:

[0046]

[0047] in, This refers to the link distance between the signal transmitter and the signal receiver. The nonlinear coefficients for the first band are... This refers to the fiber loss in the first band. For the nonlinear coefficients of the second band, For the fiber loss in the second band, It is a natural constant. Through the embodiments of this application, by employing two wavelength converters in the optical fiber link and determining the placement of the two wavelength converters according to a specific method, the signal degradation caused by the accumulation of nonlinear effects during optical fiber transmission can be effectively compensated.

[0048] Furthermore, in one embodiment, the first wavelength converter includes a first dispersion compensation device, and the second wavelength converter includes a second dispersion compensation device.

[0049] Furthermore, in one embodiment, the compensation value of the first dispersion compensation device is... The compensation value of the second dispersion compensation device is ,in:

[0050]

[0051]

[0052]

[0053] The dispersion value at the phase-matched wavelength. For the first band of fiber chromatic dispersion, This refers to the chromatic dispersion of the fiber in the second band.

[0054] Furthermore, in one embodiment, the first dispersion compensation device and the second dispersion compensation device are dispersion compensation optical fibers or chirped fiber gratings.

[0055] In this embodiment, The value is known.

[0056] Based on the above, the judgment is... Is it known? If so, no additional processing is needed. If not, it needs to be determined based on the fiber dispersion slope. ,pass Calculated .

[0057] By placing two wavelength converters at specific locations along the optical fiber link, the first dispersion compensation device and the second dispersion compensation device compensate the optical signal according to specific compensation values, thereby further optimizing the nonlinear effect suppression effect.

[0058] The signal degradation compensation effect during transmission was simulated using a nonlinear Schrödinger equation model. The simulation conditions were as follows: Band A was a C-band, employing 40 wavelengths within the C120 range with a wavelength spacing of 150 GHz. Band B was an S-band, with a conversion efficiency of 0 dB and an input fiber single-wavelength power of 0 dBm. The simulation results are as follows. Figure 4 As shown, Figure 4This diagram illustrates a comparison of the transmission performance of the direct transmission scheme and the scheme described in this application when the single-wavelength optical power input to the fiber is 0 dBm. The direct transmission scheme involves direct transmission of C-band optical signals between the signal transmitter and receiver. It is evident that by employing the scheme described in this application, the noise sidebands generated by the FWM are significantly suppressed, and an approximately 2 dB SNR improvement is achieved at the end.

[0059] Furthermore, increasing the single-wavelength power of the input fiber to 5 dBm further exacerbates the nonlinear degradation, as the nonlinear effect intensifies with increasing power. Simulation results are as follows: Figure 5 As shown, Figure 5 This diagram illustrates a comparison of the transmission performance between the direct transmission scheme and the scheme described in this application when the single-wavelength optical power input to the fiber is 5 dBm. Figure 5 As shown, even with a larger effective mode area fiber, nonlinear impairment still increases, and the noise sideband power generated by FWM rises significantly, resulting in a 3.5 dB deterioration in the direct transmission SNR compared to the case with 0 dBm input power. By adopting the solution of this application, the noise sideband generated by FWM is significantly suppressed, and an SNR improvement of approximately 5 dB at the end is achieved. Therefore, in scenarios with high input power and strong nonlinearity, the benefits of this invention in nonlinear suppression are more significant.

[0060] In summary, this application can compensate for signal degradation caused by nonlinear effects, allowing for increased transmitter power and extended transmission distance.

[0061] In addition, the principle upon which this application is based is all-optical conversion, which is transparent to modulation format and modulation rate, and can be compatible with any optical module. It compensates for nonlinearity while also compensating for dispersion, reducing the dispersion accumulated at the receiver. If a wavelength conversion device with gain (such as an optical parametric amplifier) ​​is used, amplification can be achieved during band conversion, thus replacing the original optical amplifier at the corresponding location, compensating for nonlinearity without increasing the number of disks or system complexity. Furthermore, this invention can also compensate for power transfer caused by the SRS effect during WDM signal transmission, such as... Figure 6 As shown, Figure 6 This diagram illustrates SRS power transfer compensation for wavelength conversion. Especially in extended band systems, this invention can compensate for power transfer between bands, which is beneficial for wavelength equalization in extended band systems and reduces the difficulty of OSNR leveling at the receiving end.

[0062] The technical solution of this application will be further described below through four embodiments: Example 1: Multi-segment C-band EDFA amplification system, using S-band for wavelength conversion.

[0063] The length interval configuration of the wavelength converter position is based on the nonlinear inductive phase shift Ø NL ≈γP in Leff , where P in For single-wavelength fiber input power, L eff Let be the effective length of the optical fiber. Considering the commutation between nonlinear accumulation and elimination, it is obvious that... : : =1:2:1. A simulation of 1000km transmission (100km single span) using a 25Gbd PM-QPSK signal was conducted. The simulation used G.652.D fiber, and the amplifier noise figure was 6dB. In this configuration, the effects of fiber nonlinearity, dispersion, loss, and other parameters were not considered. The simulated Q2VS single-wavelength input power results are as follows: Figure 7 As shown. Figure 7 A comparative diagram showing transmission results after correcting for nonlinear coefficients and loss coefficients to account for band differences. The difference in the nonlinear coefficient γ before and after the band conversion is considered. Even better, ,Right now .in, If the fiber optic manufacturer does not provide Parameters can be based on existing ones. Parameters, used to deduce the effective mode area of ​​the fiber Calculated using methods such as finite element modeling Thus, the calculation is obtained . The value is usually 1.2 to 2 times that, in this simulation case there are Therefore, the fiber length calculated by correcting this parameter is... , and It will improve the system's transmission performance, such as Figure 7 As shown.

[0064] Furthermore, considering the difference in fiber loss coefficient between the C-band and S-band where the signal is located before and after wavelength conversion, according to the definition of effective fiber length, it is required that... Even better The specific values ​​are calculated using numerical methods. If the manufacturer does not provide... Parameters can be referenced from the fiber loss curve and compared with actual conditions. Perform fitting calculations. Correction. Further improvements will be made to transmission performance, such as... Figure 7 As shown.

[0065] In addition to determining S-band transmission With C-band transmission , Apart from the relationship between them, , The ratio also needs to be optimized (i.e., the "better value" mentioned above), that is, to change... occupy The ratio is used to calculate the maximum allowable increase in single-wavelength fiber input power. Figure 8 visible, Figure 8 This diagram illustrates the impact of the ratio of the transmission distance between the first and last fiber segments on the nonlinearity suppression effect. It can be seen that, under normal circumstances, and When the values ​​are equal, the nonlinear suppression effect is optimal.

[0066] Considering the effects of fiber chromatic dispersion across different wavelength bands: Since the transmitted signal is a broadband WDM signal, the phase matching between each wavelength and the pump varies with wavelength due to dispersion, leading to phase matching failure, reduced wavelength conversion efficiency, and decreased nonlinear suppression. For example... Figure 9 As shown, Figure 9 This diagram illustrates the wavelength conversion phase mismatch introduced by dispersion. Dispersion can be adjusted by adding a dispersion compensation unit within the wavelength converter; the dispersion compensation device and compensation value have been explained above. Taking dispersion-compensating fiber (DCF) as an example, its required length can be determined by the compensation value it provides. However, since dispersion compensation can only achieve relatively complete compensation for a certain wavelength (generally the center wavelength), and because the dispersion slope of the transmission fiber is not constant, there will still be a decrease in compensation efficiency for edge wavelengths, such as... Figure 10 As shown, Figure 10 This diagram illustrates the dispersion compensation efficiency for different segment lengths.

[0067] Example 2: C+L band transmission system, with C and L bands mutually convertible.

[0068] This invention can also be applied to C+L systems, utilizing the interchangeability of the C-band and L-band to achieve simultaneous compensation for the nonlinearities of the C-band and L-band. For example... Figure 11 As shown, Figure 11This diagram illustrates a nonlinear compensation system for C-band and L-band intermodulation. After transmission through L1, the C+L signal is split into C-band and L-band paths via a band coupler and wavelength selective switch. The original C-band signal carrying services is then converted to the L-band via a wavelength converter, achieving phase conjugation; similarly, the original L-band signal carrying services is converted to the C-band via a wavelength converter, also achieving phase conjugation. These converted signals are then combined via a band coupler and wavelength selective switch for continued transmission along the fiber optic link. After transmission through L2, the conjugated signals from the L-band and C-band are converted back to the C-band and L-band respectively in a similar manner, combined, and then transmitted through L3. At the end of the link, nonlinear suppression of both C and L bands is achieved. If an interconversion scheme is adopted, since the optimal L1, L2, and L3 values ​​for the C-band and L-band are not theoretically identical, and staggering the converter positions for the C-band and L-band signals would cause spectral overlap between the C-band signal and the signal converted from the L-band conjugate on the transmission link, wavelength conversion for both bands needs to be performed at the same location. In summary, using L1:L2:L3=1:2:1 in this system will provide a more balanced compensation effect. However, at each wavelength converter, the dispersion accumulation caused by phase mismatch can be compensated using the calculation method in Example 1 to achieve better conversion efficiency and nonlinear suppression.

[0069] This solution fully utilizes various single boards in the existing C+L system. Based on the existing C+L system, it can be achieved simply by connecting a wavelength converter at the site location and changing the fiber optic cable of the band coupler of the C+L multiplexer after conversion (or changing the wavelength assignment port of the wavelength conversion switch).

[0070] This invention can also compensate for power transfer caused by the SRS effect during the transmission of C+L signals, such as... Figure 12 As shown, Figure 12 This diagram illustrates the compensation for SRS power transfer during C-band and L-band switching. In addition to compensating for power transfer between channels, this invention can also compensate for power transfer from C-band to L-band, bringing the receiver slope closer to zero. SRS compensation facilitates wavelength equalization in C+L bands and reduces the difficulty of OSNR leveling at the receiver.

[0071] Example 3: C+L band transmission system, using S and U bands for wavelength conversion.

[0072] Nonlinear suppression of the C+L system can also be achieved by converting the C-band signal to the shorter wavelength S-band and the L-band signal to the longer wavelength U-band, such as... Figure 13 As shown, Figure 13This diagram illustrates a nonlinear compensation system for C-band to S-band conversion and L-band to U-band conversion. This conversion method avoids the problem of not being able to set the optimal wavelength converter positions for C and L bands separately due to spectral overlap (wavelength conflict) in C and L band conversion schemes. Figure 13 In the C-band, CS wavelength conversion and LU wavelength conversion occur at different spatial distances. Specifically, for the C-band, the fiber optic link distances L1, L2, and L3 corresponding to positions WC1 and WC2 are respectively L... I L II +2ΔL、L III For the L-band, the fiber optic link distances L1, L2, and L3 corresponding to the locations WC1 and WC2 are respectively L... I +ΔL、L II L III +ΔL. Based on the foregoing, calculate the L1, L2, and L3 values ​​for the C-band and L-band respectively, and then obtain L based on the above relationship. I L II L III The values ​​of ΔL are used to determine the optimal deployment location for each wavelength converter.

[0073] Example 4: S+C+L band system, with S+C and C+L bands mutually convertible.

[0074] For systems with more bands, such as the S+C+L system, a wavelength converter with a wider conversion bandwidth can also be used. The C-band is divided into a short-wave band (Cb) and a long-wave band (Cr), thus symmetrically dividing the total spectrum of the S+C+L band into two parts: S+Cb and Cr+L. Similar to the steps in Example 2, the signals in the S+Cb band and the Cr+L band are converted to the Cr+L and S+Cb bands respectively using a broadband converter, achieving phase conjugation. After transmission, they are converted back to the S+Cb and Cr+L bands respectively. Figure 14 As shown, Figure 14 This is a schematic diagram of a nonlinear compensation system for the interconversion between the S+Cb and Cr+L bands. Although the spectral division method for band conversion (S+Cb and Cr+L) differs from the spectral division method (S, C, and L) of the amplification station in the link, both before and after the conversion produce complete S+C+L band signals. Therefore, the introduction of wavelength conversion will not affect the optical amplification in the link. Through the scheme of this application, the nonlinear noise and SRS power transfer in the S+C+L band can also be compensated simultaneously.

[0075] Secondly, embodiments of this application also provide a method for designing a nonlinear effect suppression link.

[0076] In one embodiment, the nonlinear effect suppression link design method includes: The distance between the first wavelength converter and the signal transmitter is determined using a location design formula. The distance between the first wavelength converter and the second wavelength converter and the distance between the second wavelength converter and the signal receiver The location design formula includes:

[0077]

[0078] in, This refers to the link distance between the signal transmitter and the signal receiver. The nonlinear coefficients for the first band are... This refers to the fiber loss in the first band. For the nonlinear coefficients of the second band, For the fiber loss in the second band, It is a natural constant.

[0079] Furthermore, in one embodiment, the location design formula further includes: .

[0080] Furthermore, in one embodiment, the nonlinear effect suppression link design method further includes: The compensation value of the first dispersion compensation device in the first wavelength converter is determined according to the compensation value design formula. And the compensation value of the second dispersion compensation device in the second wavelength converter. The compensation value design formula includes:

[0081]

[0082]

[0083]

[0084] The dispersion value at the phase-matched wavelength. For the first band of fiber chromatic dispersion, This refers to the chromatic dispersion of the fiber in the second band.

[0085] Furthermore, in one embodiment, the first dispersion compensation device and the second dispersion compensation device are dispersion compensation optical fibers or chirped fiber gratings.

[0086] The specific implementation of the nonlinear effect suppression link design method can be referred to the various implementations of the nonlinear effect suppression link described above, and will not be repeated here.

[0087] Thirdly, embodiments of this application provide a nonlinear effect suppression link design device, which can be a personal computer (PC), laptop computer, server, or other device with data processing capabilities.

[0088] Reference Figure 15 , Figure 15 This is a schematic diagram of the hardware structure of the nonlinear effect suppression link design device involved in the embodiments of this application. In the embodiments of this application, the nonlinear effect suppression link design device may include a processor, a memory, a communication interface, and a communication bus.

[0089] The communication bus can be of any type and is used to interconnect the processor, memory, and communication interface.

[0090] Communication interfaces include input / output (I / O) interfaces, physical interfaces, and logical interfaces used for interconnecting devices within the nonlinear effect suppression link design device, as well as interfaces used for interconnecting the nonlinear effect suppression link design device with other devices (such as other computing devices or user equipment). Physical interfaces can be Ethernet interfaces, fiber optic interfaces, ATM interfaces, etc.; user equipment can be displays, keyboards, etc.

[0091] Memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0092] The processor can be a general-purpose processor, which can call the nonlinear effect suppression link design program stored in memory and execute the nonlinear effect suppression link design method provided in the embodiments of this application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the nonlinear effect suppression link design program is called can be referred to the various embodiments of the nonlinear effect suppression link design method of this application, and will not be repeated here.

[0093] Those skilled in the art will understand that Figure 15The hardware structure shown does not constitute a limitation of this application and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0094] Fourthly, embodiments of this application also provide a computer-readable storage medium.

[0095] The present application stores a nonlinear effect suppression link design program on a computer-readable storage medium, wherein when the nonlinear effect suppression link design program is executed by a processor, it implements the steps of the nonlinear effect suppression link design method as described above.

[0096] The method implemented when the nonlinear effect suppression link design program is executed can be referred to in various embodiments of the nonlinear effect suppression link design method of this application, and will not be repeated here.

[0097] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0098] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0099] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0100] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0101] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0102] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0103] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A nonlinear effect suppression link, characterized in that, The nonlinear effect suppression link includes a first wavelength converter and a second wavelength converter, wherein: One end of the first wavelength converter is connected to the signal transmitting end via a first optical fiber link, and the other end is connected to one end of the second wavelength converter via a second optical fiber link; the other end of the second wavelength converter is connected to the signal receiving end via a third optical fiber link; the first wavelength converter is used to convert optical signals from the first band to the second band, and the second wavelength converter is used to convert optical signals from the second band to the first band; The distance between the first wavelength converter and the signal transmitter is The distance between the first wavelength converter and the second wavelength converter is The distance between the second wavelength converter and the signal receiver is And satisfy: in, This refers to the link distance between the signal transmitter and the signal receiver. The nonlinear coefficients for the first band are... For the fiber loss in the first band, For the nonlinear coefficients of the second band, For the fiber loss in the second band, It is a natural constant.

2. The nonlinear effect suppression link as described in claim 1, characterized in that, 。 3. The nonlinear effect suppression link as described in claim 1, characterized in that, The first wavelength converter includes a first dispersion compensation device, and the second wavelength converter includes a second dispersion compensation device.

4. The nonlinear effect suppression link as described in claim 3, characterized in that, The compensation value of the first dispersion compensation device is The compensation value of the second dispersion compensation device is ,in: The dispersion value at the phase-matched wavelength. For the first band of fiber chromatic dispersion, This refers to the chromatic dispersion of the fiber in the second band.

5. The nonlinear effect suppression link as described in claim 4, characterized in that, The first dispersion compensation device and the second dispersion compensation device are dispersion compensation optical fibers or chirped fiber gratings.

6. A method for designing a nonlinear effect suppression link, characterized in that, The nonlinear effect suppression link design method includes: The distance between the first wavelength converter and the signal transmitter is determined using a location design formula. The distance between the first wavelength converter and the second wavelength converter and the distance between the second wavelength converter and the signal receiver The location design formula includes: in, This refers to the link distance between the signal transmitter and the signal receiver. The nonlinear coefficients for the first band are... For the fiber loss in the first band, For the nonlinear coefficients of the second band, For the fiber loss in the second band, It is a natural constant; The first wavelength converter is used to convert optical signals from the first band to the second band, and the second wavelength converter is used to convert optical signals from the second band to the first band.

7. The nonlinear effect suppression link design method as described in claim 6, characterized in that, The location design formula also includes: 。 8. The nonlinear effect suppression link design method as described in claim 6, characterized in that, The nonlinear effect suppression link design method further includes: The compensation value of the first dispersion compensation device in the first wavelength converter is determined according to the compensation value design formula. And the compensation value of the second dispersion compensation device in the second wavelength converter. The compensation value design formula includes: The dispersion value at the phase-matched wavelength. For the first band of fiber chromatic dispersion, This refers to the chromatic dispersion of the fiber in the second band.

9. A nonlinear effect suppression link design device, characterized in that, The nonlinear effect suppression link design device includes a processor, a memory, and a nonlinear effect suppression link design program stored in the memory and executable by the processor, wherein when the nonlinear effect suppression link design program is executed by the processor, it implements the steps of the nonlinear effect suppression link design method as described in any one of claims 6 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a nonlinear effect suppression link design program, wherein when the nonlinear effect suppression link design program is executed by a processor, it implements the steps of the nonlinear effect suppression link design method as described in any one of claims 6 to 8.

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