Optical signal-to-noise ratio equalization method for multi-band system, controller, and management and control system

Abstract

The present application discloses an optical signal-to-noise ratio (OSNR) equalization method for a multi-band system, a controller, and a management and control system. A transmission path from an optical input end to an optical output end of the multi-band system is sequentially provided with, for each band, an optical booster amplifier (OBA), an optical pre‑amplifier (OPA), and an optical line amplifier (OLA). The optical signal-to-noise ratio equalization method comprises: acquiring output powers of the OBA, the OLA and the OPA of each band, and adjusting amplification gains of the OLA and the OPA of each band on the basis of the output powers of the OBA, the OLA and the OPA of each band so as to satisfy a first condition (S110); and acquiring an OSNR of the OPA of each band, adjusting an amplification gain of the OBA of each band on the basis of the OSNR of the OPA of each band so as to satisfy a second condition, and adjusting a gain slope of the OBA of each band on the basis of the OSNR of the OPA of each band so as to satisfy a third condition (S120).

Description

Optical signal-to-noise ratio equalization method, controller and control system for multi-band systems

[0001] Cross-reference of related applications

[0002] This application is based on and claims priority to Chinese Patent Application No. 202411434423.4, filed on October 14, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of network communication technology, and in particular to an optical signal-to-noise ratio equalization method, controller and control system for multi-band systems. Background Technology

[0004] To meet the high-capacity transmission requirements of current optical communication systems, Dense Wavelength Division Multiplexing (DWDM) technology extends the transmission bands of optical systems to multiple bands, which is an effective solution for addressing the continuous increase in optical network capacity. However, multi-band optical transmission systems exhibit stimulated Raman scattering (SRS), resulting in a power transfer from shortwave to longwave. This SRS effect accumulates over long distances and across multiple bands, leading to complex power transfer between bands and channels. Consequently, significant differences in the optical signal-to-noise ratio (OSNR) performance exist between different bands and channels after transmission.

[0005] In related technologies, the OSNR equalization strategy for multi-band optical transmission systems is relatively simple. For example, it is based on the difference between the average optical signal-to-noise ratio at the receiver and the optical signal-to-noise ratio of each optical signal, and adjusts the attenuators at the input end to make the OSNR of each optical signal consistent. Since the SRS effect in multi-band optical transmission systems has a very complex impact on optical signals, this OSNR equalization strategy is relatively simple and has limited adjustment capability. Therefore, a more complete OSNR equalization strategy is needed. Summary of the Invention

[0006] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0007] This application provides an optical signal-to-noise ratio equalization method, controller, and management system for a multi-band system.

[0008] In a first aspect, embodiments of this application provide an optical signal-to-noise ratio (OSNR) equalization method for a multi-band system. The transmission path from the optical input to the optical output of the multi-band system is sequentially provided with an optical power amplifier (OBA), a preamplifier (OPA), and an optical line amplifier (OLA) corresponding to each band. The OSNR equalization method includes: acquiring the output power of the OBA, OLA, and OPA for each band; adjusting the amplification gain of the OLA and OPA for each band based on the output power of the OBA, OLA, and OPA for each band to satisfy a first condition; acquiring the optical signal-to-noise ratio (OSNR) of the OPA for each band; and adjusting the amplification gain of the OBA for each band based on the OSNR of the OPA for each band. The gain is amplified to satisfy the second condition, and the gain slope of the OBA in each band is adjusted according to the OSNR of the OPA in each band to satisfy the third condition; wherein, the first condition is that the power difference between the output power of the OLA and the output power of the OBA in each band, and the power difference between the output power of the OPA and the output power of the OBA in each band, are all not greater than a preset power threshold; the second condition is that the difference between the OSNR of the OPA in each band and the average OSNR of the entire band is not greater than a preset OSNR threshold; the third condition is that the adjustment amount of the gain slope of the OBA, the OLA and the OPA in each band is not greater than a preset adjustment amount.

[0009] Secondly, embodiments of this application provide a controller, including at least one processor and a memory for communicatively connecting to the at least one processor; the memory stores instructions executable by the at least one processor, which, when executed by the at least one processor, enable the at least one processor to perform the optical signal-to-noise ratio equalization method as described above.

[0010] Thirdly, embodiments of this application provide a control system, including a controller as described above, the controller being connected to the OBA, the OLA and the OPA.

[0011] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions for causing a computer to perform the optical signal-to-noise ratio equalization method as described above.

[0012] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0013] The accompanying drawings are used to provide a further understanding of the technical solutions of this application and form part of the specification. They are used together with the examples of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0014] Figure 1 is a system framework diagram of an optical multiplexing section of a multi-band system provided in an embodiment of this application;

[0015] Figure 2 is an overall flowchart of an optical signal-to-noise ratio equalization method provided in an embodiment of this application;

[0016] Figure 3 is another overall flowchart of an optical signal-to-noise ratio equalization method provided in one embodiment of this application;

[0017] Figure 4 is a flowchart of cross-segment loss adjustment provided in an embodiment of this application;

[0018] Figure 5 is a flowchart of a method for determining a first condition according to an embodiment of this application;

[0019] Figure 6 is a flowchart of a control system performing cross-segment loss adjustment configuration (OLA) according to an embodiment of this application;

[0020] Figure 7 is a flowchart of a control system performing cross-segment loss adjustment configuration (OPA) according to an embodiment of this application;

[0021] Figure 8 is a flowchart of inter-band adjustment provided in an embodiment of this application;

[0022] Figure 9 is a flowchart of a method for determining a second condition according to an embodiment of this application;

[0023] Figure 10 is a flowchart of a control system performing inter-band adjustment configuration (OBA) according to an embodiment of this application;

[0024] Figure 11 is a flowchart of intra-band adjustment provided in an embodiment of this application;

[0025] Figure 12 is a flowchart of a method for determining a third condition according to an embodiment of this application;

[0026] Figure 13 is a flowchart of a control system performing intra-band adjustment configurations OBA, OLA, and OPA according to an embodiment of this application;

[0027] Figure 14 is a flowchart of channel-level adjustment provided in an embodiment of this application;

[0028] Figure 15 is a flowchart of the optical signal-to-noise ratio equalization method provided in the example of this application;

[0029] Figure 16 is a schematic diagram of the structural connection of a controller provided in one embodiment of this application. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various implementations. Simultaneously, the steps or actions described in the method description can be rearranged or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0031] In the description of this application, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0032] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0033] To enhance the transmission capacity of existing optical networks and meet the network traffic demands of new applications and services characterized by large video, multiple users, and high bursts, it is necessary to consider that the physical locations of operator equipment rooms, line sites, and fiber optic link lengths are difficult to change during the actual deployment of optical networks and the upgrading and replacement of old and new equipment. Therefore, the upgrade of optical network equipment needs to ensure that existing optical fibers and site infrastructure are utilized as much as possible, without changing the fiber type and site distribution, in order to maximize the savings in network construction costs. Thus, ensuring that the transmission distance remains almost unchanged while increasing the single-wavelength rate and fiber capacity is an important logic in the evolution of wavelength division optical transmission systems.

[0034] The main ways to increase single-wavelength rate are to increase the baud rate while maintaining the modulation order, or to increase the modulation order while maintaining the baud rate. Higher-order modulation formats require higher OSNR to ensure transmission performance, which in turn requires higher input power. However, in silica fiber, the input power is limited by nonlinear effects, making it impossible to further increase OSNR. In this case, increasing the baud rate while maintaining the modulation order is a more suitable choice. This means that a single wavelength will occupy a wider channel, requiring continuous expansion of the optical transmission system's bandwidth. Therefore, multi-band optical transmission systems are an effective solution to address the continuous increase in optical network capacity. Currently, the low-loss wavelength range of optical fiber is 1260nm to 1625nm, divided into six bands: O, E, S, C, L, and U.

[0035] The wavelength range of the O-band (Original Band) is from 1260nm to 1360nm;

[0036] The wavelength range of the E-band (Extended Band) is from 1360nm to 1460nm;

[0037] The S-band (Short Band) has a wavelength range from 1460 nm to 1530 nm;

[0038] The C-band (Conventional Band) has a wavelength range from 1530 nm to 1565 nm;

[0039] The L-band (Long Band) has a wavelength range from 1565 nm to 1625 nm;

[0040] The U-band (Ultra Long Band) has a wavelength range from 1625nm to 1675nm.

[0041] To expand network transmission capacity, multi-band systems transmit at least two of the aforementioned wavelengths in optical fibers. However, transmitting multiple wavelengths in optical fibers can lead to nonlinear effects. The most typical inelastic scattering is stimulated Raman scattering (SRS), which exhibits a power transfer from short wavelengths to long wavelengths. The transfer bandwidth caused by SRS can reach up to 40 THz. Furthermore, after long-distance, multi-segment transmission, SRS transfer accumulates, resulting in complex inter-band and inter-channel power transfers in multi-band systems. This leads to significant differences in OSNR performance between different bands and channels after transmission. To ensure the stability of the transmission system, it is necessary to suppress the SRS effect between multiple wavelengths.

[0042] To suppress nonlinear effects such as stimulated Raman oscillation, OSNR equalization is typically used to adjust optical devices in optical transmission networks to ensure consistent OSNR across all services at the receiver, thereby optimizing the performance of each service. Related technologies usually involve collecting the OSNR of each service at the receiver, calculating the average OSNR, and then using the difference between the OSNR of each service and the average OSNR as an adjustment factor to regulate the attenuation parameters at the transmitter, thus ensuring consistent OSNR across all services at the receiver. This OSNR equalization method is relatively simple, relying solely on the difference in OSNR at the receiver to adjust the attenuation parameters at the transmitter. However, in practical applications, OSNR flatness cannot be guaranteed to be optimal because adjusting the attenuation parameters leads to power variations across services and affects intra-band and inter-band power transfer. Clearly, further optimization of OSNR equalization is needed.

[0043] Based on this, this application provides an optical signal-to-noise ratio (OSNR) equalization method, controller, and management system for a multi-band system. OSNR equalization in a multi-band system is achieved through three conditions and corresponding adjustment methods. First, the amplification gain of the OLA and OPA in each band is adjusted by controlling the output power of the OBA, OLA, and OPA to meet the first condition. Under the premise of meeting the first condition, the amplification gain of the OBA in each band is adjusted by controlling the OSNR of the OPA in each band to meet the second condition, and the gain slope of the OBA in each band is adjusted to meet the third condition. The simultaneous fulfillment of all three conditions after adjustment indicates that the current multi-band system has completed the three stages of cross-band loss adjustment, inter-band adjustment, and intra-band adjustment. The OSNR flatness caused by the SRS effect is suppressed. The entire process ultimately ensures that the OSNR flatness between bands meets the requirements after light transmission in the multi-wavelength system, guaranteeing network operation stability and reliability.

[0044] Referring to the multi-band system shown in Figure 1, the optical input and output ends of the multi-band system are equipped with optical transformation units (OTUs) for each band. In Figure 1, the OTU at the optical input end is denoted as OTU Tx, and the OTU at the optical output end is denoted as OTU Rx. A single optical multiplexing section between OTU Tx and OTU Rx is sequentially equipped with a wavelength selective switch (WSS) at the transmitting end, an optical booster amplifier (OBA), an optical pre-amplifier (OPA), an optical line amplifier (OLA), and a WSS at the receiving end for each band. Figure 1 illustrates, for example, a multi-band system that simultaneously transmits six bands: O+E+S+C+L+U. In practical applications, a multi-band system can transmit fewer bands simultaneously, such as transmitting O+E band, E+S band, S+C band, C+L band, L+U band, O+E+S band, S+C+L band, C+L+U band, E+S+C+L band, S+C+L+U band, O+E+S+C+L band, or E+S+C+L+U band, etc. This application does not impose any limitations.

[0045] Referring to the flowchart of the optical signal-to-noise ratio (SNR) equalization method shown in Figure 2, and applied to the aforementioned multi-band system, the optical SNR equalization method includes, but is not limited to, the following steps:

[0046] Step S110: Obtain the output power of OBA, OLA and OPA of each band, and adjust the amplification gain of OLA and OPA of each band according to the output power of OBA, OLA and OPA of each band to meet the first condition.

[0047] Step S120: Obtain the optical signal-to-noise ratio (OSNR) of the OPA in each band, adjust the amplification gain of the OBA in each band according to the OSNR of the OPA in each band to meet the second condition, and adjust the gain slope of the OBA in each band according to the OSNR of the OPA in each band to meet the third condition.

[0048] in,

[0049] The first condition is that the power difference between the output power of OLA and the output power of OBA in each band, and the power difference between the output power of OPA and the output power of OBA in each band, are not greater than the preset power threshold.

[0050] The second condition is that the difference between the OSNR of each band and the mean OSNR of the whole band is not greater than the preset OSNR threshold.

[0051] The third condition is that the adjustment amount of the gain slope of OBA, OLA and OPA in each band is not greater than the preset adjustment amount.

[0052] As mentioned above, multi-band systems suffer from severe SRS shift, and channel additions and subtractions significantly affect the SRS shift effect. Therefore, multi-band systems typically employ dummy light technology to keep the system in a full-wavelength state. When the actual number of channels increases / decreases, the dummy light is rapidly added / subtracted at the corresponding wavelength to ensure stable SRS shift and avoid drastic fluctuations in system power or OSNR due to channel additions or subtractions. On the other hand, to ensure flexible and efficient service scheduling, the dummy light is generally added at the top of the multiplexing section and terminated at the bottom, without being transmitted across multiplexing sections. Therefore, the OSNR equalization strategy can be executed independently and in parallel in each multiplexing section. Thus, the optical SNR equalization method in this application is applicable to a single optical multiplexing section (for example, Figure 1 shows the architecture of a single optical multiplexing section). The OSNR equalization process is implemented through three steps: cross-segment loss adjustment, inter-band adjustment, and intra-band adjustment within the optical multiplexing section.

[0053] Utilizing the monitoring and reporting functions of OBA, OLA, and OPA, the control system monitors information such as attenuation, amplification gain, gain slope, output power, and OSNR of each band of OBA, OLA, and OPA in the optical multiplexing section. The control system centrally processes and executes the row OSNR equalization calculation process from steps S110 to S120 above and outputs the adjustment value, which is then distributed to the corresponding OBA, OLA, and OPA for configuration. Based on this, the control system determines whether the configured OBA, OLA, and OPA meet the first, second, and third conditions mentioned above. If all three conditions are met simultaneously, it indicates that the OSNR unevenness caused by the SRS effect in the optical multiplexing section has been suppressed after the current configuration. Otherwise, the control system continues to adjust the OBA, OLA, and OPA until it obtains an adjustment value that makes the configured OBA, OLA, and OPA simultaneously meet the above three conditions.

[0054] From the above three conditions, it can be seen that the first condition corresponds to adjusting the cross-segment loss within the optical multiplexing section, the second condition corresponds to adjusting the power transfer between bands within the optical multiplexing section, and the third condition corresponds to adjusting the power difference between different channels within the bands of the optical multiplexing section. Cross-segment loss adjustment ends after the first condition is met, ensuring that the power difference between the output power of the OLA and the OBA of each band, and the power difference between the output power of the OPA and the OBA of each band, are all no greater than a preset power threshold. Afterwards, inter-band and intra-band adjustments are performed, requiring the simultaneous satisfaction of the second and third conditions. Specifically, the difference between the OSNR of the OPA of each band and the average OSNR of the entire band must not exceed a preset OSNR threshold, and the adjustment amount of the gain slope of the OBA, OLA, and OPA of each band must not exceed a preset adjustment amount.

[0055] In practical applications, firstly, cross-segment loss adjustment is performed according to step S110 to meet the first condition. Then, inter-band adjustment and intra-band adjustment are performed according to step S120 to meet the second and third conditions. After the adjustment in step S120, the first condition may not be met. Therefore, after inter-band adjustment and intra-band adjustment are performed to meet the second and third conditions, the control system continues to monitor the attenuation, amplification gain, gain slope, output power, and OSNR of each band's OBA, OLA, and OPA, and re-determines whether the current multi-band system still meets the first condition. If it does not meet the first condition, cross-segment loss adjustment is performed again according to step S110 to meet the first condition. Then, inter-band adjustment and intra-band adjustment are performed again according to step S120 to meet the second and third conditions, and so on, until inter-band adjustment and intra-band adjustment meet the second and third conditions. After that, the optical multiplexing segment also meets the first condition.

[0056] By adjusting the loss across bands, inter-band adjustment, and intra-band adjustment as described above, the optical multiplexing sections of the multi-band system are adjusted from three aspects: cross-band loss adjustment, inter-band adjustment, and intra-band adjustment. The output power difference is compensated by adjusting the amplification gain of the OLA and OPA of each band, the power difference between bands is balanced by adjusting the amplification gain of the OBA of each band, and the power difference between different channels within the band is balanced by adjusting the gain slope of the OBA of each band. Therefore, compared with the traditional single-method OSNR equalization scheme, the embodiments of this application can make adjustments from multiple aspects, effectively suppressing the OSNR unevenness caused by the SRS effect within the optical multiplexing section, and optimizing the function of each service.

[0057] Referring to Figure 3, in some embodiments, the optical signal-to-noise ratio equalization method of this application further includes:

[0058] Step S130: If the first condition, the second condition, and the third condition are met simultaneously, adjust the channel attenuation value of the wavelength selection switch WSS at the optical input end according to the OSNR of the OPA in each band.

[0059] After the above-mentioned cross-segment loss adjustment, inter-band adjustment, and intra-band adjustment, the OSNR unevenness caused by the SRS effect in the optical multiplexing segment is effectively suppressed when the first, second, and third conditions are met simultaneously. However, there are still residual wavelength-dependent losses and OA Ripple, collectively referred to as channel loss Ripple. This channel loss Ripple cannot be compensated by adjusting the OA gain and gain slope. Therefore, there are still some differences in the OSNR of each channel after inter-band and intra-band adjustment. In this embodiment, the OSNR can be suppressed by adjusting the WSS attenuation at the transmitting end of the optical multiplexing segment to ensure the flatness of the OSNR at the receiving end of the optical multiplexing segment.

[0060] The adjustment in step S130 above is referred to as channel-level adjustment in this application. In conjunction with the aforementioned cross-band loss adjustment, inter-band adjustment and intra-band adjustment, the power of each channel in the multi-band system can be effectively adjusted through the four adjustment steps, the OSNR performance of the multi-band system can be balanced, and the system performance can be kept stable and reliable after long-distance transmission.

[0061] The implementation of cross-band loss adjustment, inter-band adjustment, intra-band adjustment, and channel-level adjustment will be explained in detail below.

[0062] Referring to Figure 4, in step S110 corresponding to cross-band loss adjustment, the amplification gain of OLA and OPA in each band is adjusted according to the output power of OBA, OLA and OPA in each band to meet the first condition, including:

[0063] Step S210: Determine the difference between the output power of the OLA in each band and the output power of the OBA in each band as the first power difference value, and determine the difference between the output power of the OPA in each band and the output power of the OBA in each band as the second power difference value.

[0064] Step S220: If the first power difference and the second power difference do not meet the first condition, adjust the amplification gain of the OLA of each band according to the first power difference, and / or adjust the amplification gain of the OPA of each band according to the second power difference.

[0065] Step S230: Determine again whether the first power difference and the second power difference obtained after adjusting the amplification gain meet the first condition.

[0066] To compensate for cross-band losses, it is necessary to adjust the amplification gain of the OLA and / or OPA within the optical multiplexing section. The control system acquires the output power of the OBA, the output power of the OLA, and the output power of the OPA for each band, as well as the amplification gain of the OLA and the OPA for each band. Calculations are performed separately for each band. For the same band, the difference between the output power of the OLA and the OBA is calculated to obtain the first power difference, and the difference between the output power of the OPA and the OBA is calculated to obtain the second power difference. Then, it is determined whether the first power difference and the second power difference for each band meet a first condition, i.e., whether both the first power difference and the second power difference for each band are less than a preset power threshold. If the first condition is met, inter-band adjustment and intra-band adjustment are initiated. If the first condition is not met, the amplification gain of the OLA is adjusted according to the first power difference for the same band, and / or the amplification gain of the OPA is adjusted according to the second power difference for the same band. After adjusting the amplification gain of the OLA and / or the amplification gain of the OPA, the control system reacquires the output power of the OBA, OLA and OPA for each band, recalculates the first power difference and the second power difference for each band, and then determines whether the first condition is met.

[0067] Referring to Figure 5, in some embodiments, the determination of the first condition can be performed according to the following steps:

[0068] Step S310: Determine the maximum power difference based on the absolute value of the first power difference of each band and the absolute value of the second power difference of each band;

[0069] In step S320, if the maximum power difference is less than the preset power threshold, it is determined that the first condition is met; if the maximum power difference is greater than the preset power threshold, it is determined that the first condition is not met.

[0070] Since a multi-band system has multiple bands, the calculation results for the first and second power differences also include multiple values. For example, if a multi-band system has three bands, six power differences are calculated: the first power difference for each of the three bands and the second power difference for each of the three bands. The maximum power difference is selected from these values ​​and then compared with a preset power threshold. If the maximum power difference is less than the preset power threshold, it indicates that the output power of the OBA, OLA, and OPA meets the first condition under the current configuration. If the maximum power difference is greater than the preset power threshold, the first condition is not met. The failure to meet the first condition may be due to one or more power differences in the first power difference exceeding the preset power threshold, or one or more power differences in the second power difference exceeding the preset power threshold, or one or more power differences in both the first and second power differences exceeding the preset power threshold. For these three possible cases, different methods can be used to adjust the amplification gain of the OLA and / or the OPA. A detailed explanation follows:

[0071] When the first power difference or the second power difference is greater than the preset power threshold, it is necessary to adjust the amplification gain of the OLA and / or the amplification gain of the OPA, including the following situations:

[0072] ①If only one or more of the first power differences are greater than the preset power threshold, then adjust the amplification gain of the OLA in each band, but do not adjust the amplification gain of the OPA in each band.

[0073] ② If only one or more power differences in the first power difference are greater than the preset power threshold, then only adjust the amplification gain of the OLA in those bands whose power difference is greater than the preset power threshold, and do not adjust the amplification gain of the OLA in other bands and the amplification gain of the OPA in each band.

[0074] ③ If only one or more of the second power differences are greater than the preset power threshold, then adjust the amplification gain of the OPA in each band, but do not adjust the amplification gain of the OLA in each band.

[0075] ④ If only one or more of the second power differences are greater than the preset power threshold, then only adjust the amplification gain of the OPAs in those bands whose power differences are greater than the preset power threshold, and do not adjust the amplification gain of the OPAs in other bands or the amplification gain of the OLAs in each band.

[0076] ⑤ If one or more power differences between the first power difference and the second power difference are greater than the preset power threshold, then adjust the amplification gain of the OLA and the amplification gain of the OPA in each band.

[0077] ⑥ If one or more power differences in both the first power difference and the second power difference are greater than the preset power threshold, then adjust the amplification gain of the OLA bands corresponding to those power differences greater than the preset power threshold, and adjust the amplification gain of the OPA bands corresponding to those power differences greater than the preset power threshold.

[0078] Referring to Figure 6, the step S220 above, which adjusts the amplification gain of the OLA in each band according to the first power difference, includes:

[0079] Step S410: Obtain the current amplification gain value of the OLA in each band, and determine the first target amplification gain value of each band based on the current amplification gain value of the OLA in each band and the first power difference.

[0080] Step S420: Configure the first target amplification gain value of each band to the corresponding band's OLA.

[0081] The first power difference for each band is calculated. Based on the first power difference for each band, the current amplification gain value of the corresponding OLA for that band is adjusted. After adjustment, the first target amplification gain for each band is obtained. The control system then configures the first target amplification gain of each band to the corresponding OLA. For cases ② or ⑥ above, the control system only needs to configure the first target amplification gain of the OLAs for those bands whose power difference is greater than the preset power threshold.

[0082] Referring to Figure 7, the step S220 above, which adjusts the amplification gain of the OPA for each band based on the second power difference, includes:

[0083] Step S510: Obtain the current amplification gain value of the OPA in each band, and determine the second target amplification gain value of each band based on the current amplification gain value of the OPA in each band and the second power difference.

[0084] Step S520: Configure the second target amplification gain value of each band to the corresponding band's OPA.

[0085] The second power difference for each band is calculated. Based on the second power difference for each band, the current amplification gain value of the corresponding OPA for that band is adjusted. After adjustment, the second target amplification gain for each band is obtained. The control system then configures the second target amplification gain for each band to the corresponding OPA. For cases ③ or ⑥ above, the control system only needs to configure the second target amplification gain for the OPAs of those bands whose power difference is greater than the preset power threshold.

[0086] In one embodiment, the multi-band system transmits six bands: O+E+S+C+L+U. Then:

[0087] The OBA output power for each band is expressed as follows:

[0088] The OLA output power for each band is expressed as follows: Where the subscript n represents the nth OLA, and n is a positive integer;

[0089] The OPA output power for each band is expressed as follows:

[0090] The difference between the OLA output power and the OBA output power of each band, and the difference between the OPA output power and the OBA output power of each band, are calculated as follows:

[0091] Then determine whether the maximum value of ΔP satisfies the first condition, that is, determine whether ΔP max =max{ΔP}≤Th1, if ΔP max If the power is less than the preset power threshold Th1, then it directly enters inter-band adjustment and intra-band adjustment. If ΔP max If the power is greater than the preset power threshold Th1, then read the current amplification gain of the OLA in each band. Read the current amplification gain of the OPA in each band. The current amplification gain of OLA / OPA in each band is adjusted using ΔP as the adjustment amount, as shown in the following formula:

[0092] The OLA-adjusted amplification gain for each band in the above formula is: The adjusted amplification gain for each band is as follows:

[0093] Referring to Figure 8, in step S120 corresponding to inter-band adjustment, the amplification gain of the OBA of each band is adjusted according to the OSNR of the OPA of each band to satisfy the second condition, including:

[0094] Step S610: Determine the mean OSNR of the entire band based on the OSNR of the output end of the OPA of each band, and determine the difference between the OSNR of the output end of the OPA of each band and the mean OSNR of the entire band as the first OSNR difference.

[0095] Step S620: If the first OSNR difference does not meet the second condition, adjust the amplification gain of the OBA for each band according to the first OSNR difference.

[0096] Step S630: Determine again whether the first OSNR difference obtained after adjusting the amplification gain satisfies the second condition.

[0097] Under the influence of the SRS effect, shortwave power shifts to longwave power in a multi-band system, specifically from O-band to E-band, E-band to S-band, S-band to C-band, C-band to L-band, and L-band to U-band. This results in the lowest average power in the O-band and the highest average power in the U-band after transmission through optical fiber, with significant power differences between bands. Furthermore, the noise figures of the amplifiers in each band are not identical, ultimately leading to substantial differences in the average OSNR between bands. Accordingly, in this embodiment, the OSNR of each band is detected at the receiver of the optical multiplexing section. Then, the average OSNR of each band (i.e., the OSNR at the output of the OPA of each band) and the average OSNR of the entire band are calculated to obtain the first OSNR difference. Then, it is determined whether the first OSNR difference meets the second condition, that is, whether the first OSNR difference is less than the preset OSNR threshold. If the second condition is not met, the amplification gain of the OBA in each band is adjusted according to the first OSNR difference, and the second condition is checked again after adjustment. If the second condition is met, it is also necessary to check whether the intra-band adjustment meets the third condition. If both the second and third conditions are met, since the inter-band conditions and intra-band adjustments will affect the inter-band SRS transfer, it is necessary to check whether the first condition is met again, until the first, second, and third conditions are met simultaneously, then channel-level adjustment is entered.

[0098] The OSNR mean of each band (i.e., the OSNR at the output of the OPA in each band) refers to the average OSNR of multiple channels within the same band, while the OSNR mean of the entire band is the average of the OSNR mean of each band. Therefore, referring to Figure 9, the second condition can be determined by following these steps:

[0099] Step S710: For each band at the output end of the OPA, the average OSNR of all channels within the same band is determined as the OSNR within the band.

[0100] Step S720: Determine the mean OSNR of the entire band based on the OSNR within each band.

[0101] Step S730: Determine the difference between the OSNR within each band and the mean OSNR of the entire band, and determine the maximum value of the difference as the maximum OSNR difference.

[0102] In step S740, if the maximum OSNR difference is less than the preset OSNR threshold, it is determined that the second condition is met; if the maximum OSNR difference is greater than the preset OSNR threshold, it is determined that the second condition is not met.

[0103] The average OSNR of all channels within the same band is calculated and used as the OSNR for that band. The average OSNR of all bands transmitted in a multi-band system is then calculated and used as the average OSNR for the entire band. Since a multi-band system has multiple bands, there are multiple differences obtained by subtracting the average OSNR of each band from the average OSNR of the entire band. The maximum value among these differences is taken, and then compared with a preset OSNR threshold. If the maximum OSNR difference is less than the preset OSNR threshold, it indicates that the OSNR under the current configuration meets the requirements for inter-band adjustment. If the maximum OSNR difference is greater than the preset OSNR threshold, the amplification gain of the OBA (Optical Base Arm) for each band needs to be adjusted.

[0104] Referring to Figure 10, step S620 above, which adjusts the amplification gain of the OBA for each band based on the first OSNR difference, includes:

[0105] Step S810: Obtain the current amplification gain value of the OBA for each band, and determine the third target amplification gain value for each band based on the current amplification gain value of the OBA for each band and the first OSNR difference.

[0106] Step S820: Configure the third target amplification gain value of each band to the corresponding band's OBA.

[0107] If the second condition is not met, the amplification gain value of the OBA needs to be adjusted. The control system obtains the current amplification gain value of the OBA in each band and calculates the first OSNR difference of each band. Then, based on the first OSNR difference of each band and the current amplification gain value of the OBA in each band, the control system calculates the third target amplification gain value of each band. Finally, the control system assigns the third target amplification gain value of each band to the OBA of the corresponding band.

[0108] In one embodiment, the multi-band system transmits six bands: O+E+S+C+L+U. Then:

[0109] The control system reads the OSNR spectrum (in this application, OSNR spectrum refers to the total OSNR of each channel in the same band) from the output of the OPA at the receiver of the optical multiplexer section. O (λ) / OSNR E (λ) / OSNR S (λ) / OSNR C (λ) / OSNR L (λ) / OSNR U (λ), and then calculate the mean OSNR of each band and the mean OSNR of the entire band, as shown in the following formula:

[0110] The mean OSNR values ​​for each band in the formula are respectively OSNR O,Avg / OSNR E,Avg / OSNR S,Avg / OSNR C,Avg / OSNR L,Avg / OSNR U,Avg The mean OSNR across the entire band is expressed as OSNR. Avg , where N O / N E / N S / N C / N L / N U This represents the number of channels in each band.

[0111] Then, the difference ΔOSNR between the mean OSNR of each band and the mean OSNR of the entire band is calculated, as shown in the following formula. This difference ΔOSNR reflects the level of OSNR difference between bands. According to the basic formula for calculating OSNR, the OSNR difference between bands can be compensated by adjusting the output power (i.e., input power) of the OBA at the transmitting end of each band in the optical multiplexing section. Therefore, ΔOSNR can be used as the gain adjustment amount of the OBA.

[0112] Then determine whether the maximum value of ΔOSNR satisfies the second condition, that is, determine ΔOSNR. max =max{ΔOSNR}≤Th2. If ΔOSNR max If the OSNR is less than the preset threshold Th2, it is necessary to determine whether the third condition for in-band adjustment is met; if ΔOSNR max If the value is greater than the preset OSNR threshold Th2, then read the current amplification gain of the OBA for each band. The ΔOSNR of each band is used as the adjustment value to adjust the current amplification gain of the OBA of each band, as shown in the following formula:

[0113] The OBA-adjusted amplification gain for each band in the above formula is:

[0114] Referring to Figure 11, in step S120 corresponding to intra-band adjustment, the gain slope of the OBA of each band is adjusted according to the OSNR of the OPA of each band to satisfy the third condition, including:

[0115] Step S910: Fit the OSNR of the output end of the OPA of each band to obtain the fitting gain slope of each band.

[0116] Step S920: Determine the adjustment amount of the gain slope of OBA, OLA and OPA for each band based on the fitted gain slope of each band.

[0117] Step S930: If the adjustment amount of the gain slope does not meet the third condition, adjust the gain slope of OBA, OLA and OPA of each band according to the adjustment amount of the gain slope.

[0118] Step S940: Determine again whether the adjustment amount of the gain slope obtained after adjusting the gain slope meets the third condition.

[0119] The SRS effect not only affects power differences between bands but also causes power differences between different channels within a band. Therefore, due to the SRS transfer effect between channels, the OSNR within each band at the transmitter end of the optical multiplexing section is not flat. Thus, it is necessary to adjust the gain slope of each band, i.e., by presetting a certain slope at the receiver end of the optical multiplexing section to achieve a flat OSNR within the band at the transmitter end. Accordingly, in this embodiment, the OSNR of each band is detected at the receiver end of the optical multiplexing section, and then the OSNR of each channel in the same band is linearly fitted to obtain the fitted gain slope. The fitted gain slope is allocated among OBA, OLA, and OPA to obtain the adjustment amount of the gain slope of OBA, OLA, and OPA for each band. Then, it is determined whether the adjustment amount of the gain slope meets the third condition, that is, whether the adjustment amount of the gain slope of OBA, OLA, and OPA in each band is less than the preset adjustment amount. If the third condition is not met, the gain slope of OBA, OLA, and OPA in each band is adjusted according to the adjustment amount of the gain slope of OBA, OLA, and OPA in each band. After adjustment, the judgment is repeated to see if the third condition is met. If the third condition is met, and the second condition is also met at this time, since the inter-band conditions and intra-band adjustments will affect the inter-band SRS transfer, it is necessary to judge whether the first condition is met again, until the first, second, and third conditions are met simultaneously, then channel-level adjustment is entered.

[0120] Therefore, it can be seen that both inter-band adjustment and intra-band adjustment are based on the OSNR of the OPA output. Thus, the control system can first calculate the first OSNR difference required for inter-band adjustment and the adjustment amount of the gain slope required for intra-band adjustment based on the OSNR of the OPA output, and then perform inter-band adjustment and intra-band adjustment respectively. Finally, it can determine whether the second and third conditions are met at the same time.

[0121] Referring to Figure 12, the third condition can be determined by following these steps:

[0122] Step S1010: Based on the fitted gain slope of each band, the preset gain slope allocation ratio, and the number of fiber optic spans in the transmission path, determine the adjustment amount of the gain slope of OBA, OLA, and OPA for each band.

[0123] Step S1020: Determine the maximum value among the adjustment amounts of the gain slope as the maximum gain slope adjustment amount;

[0124] In step S1030, if the maximum gain slope adjustment amount is less than the preset adjustment amount, it is determined that the third condition is met; if the maximum gain slope adjustment amount is greater than the preset adjustment amount, it is determined that the third condition is not met.

[0125] Based on a preset gain slope allocation ratio, fitted gain slopes are assigned to OBA, OLA, and OPA, resulting in the adjustment amounts of the gain slopes for OBA, OLA, and OPA. The sum of the adjustment amounts for the gain slopes of OBA and OPA equals the adjustment amount for the gain slope of OLA. For the gain slope adjustment amount in a specific band, the number of fiber spans within the optical multiplexing section also needs to be considered. Therefore, by combining the fitted gain slopes of each band, the preset gain slope allocation ratio, and the number of fiber spans in the transmission path, the adjustment amounts of the gain slopes for OBA, OLA, and OPA can be calculated. Since a multi-band system has multiple bands, there are also multiple possible adjustment values ​​for the calculated gain slope. The maximum value among these adjustment values ​​is taken, and then the maximum value (i.e., the maximum gain slope adjustment value) is compared with the preset adjustment value. If the maximum gain slope adjustment value is less than the preset adjustment value, it indicates that the gain slope of OBA, OLA, and OPA under the current configuration meets the requirements for intra-band adjustment. If the maximum gain slope adjustment value is greater than the preset adjustment value, then the gain slope of OBA, OLA, and OPA in each band needs to be adjusted.

[0126] Referring to Figure 13, step S930 above, which adjusts the gain slopes of OBA, OLA, and OPA for each band according to the adjustment amount of the gain slope, includes:

[0127] Step S1110: Obtain the current gain slope of OBA, OLA and OPA for each band, and determine the target gain slope of OBA, OLA and OPA for each band based on the current gain slope and the adjustment amount of the gain slope.

[0128] Step S1120: Configure the target gain slope of each band's OBA, OLA, and OPA to the corresponding band's OBA, OLA, and OPA.

[0129] If the third condition is not met, the gain slopes of OBA, OLA, and OPA in each band need to be adjusted. The control system obtains the current gain slopes of OBA, OLA, and OPA in each band and calculates the adjustment amount of the gain slopes of OBA, OLA, and OPA in each band. Then, based on the adjustment amount of the gain slopes of OBA, OLA, and OPA in each band and the current gain slopes of OBA, OLA, and OPA in each band, the target gain slopes of OBA, OLA, and OPA in each band are calculated. Finally, the control system assigns the target gain slopes of OBA, OLA, and OPA in each band to the corresponding OBA, OLA, and OPA in the band.

[0130] In one embodiment, the multi-band system transmits six bands: O+E+S+C+L+U. Then:

[0131] The control system reads the OSNR spectrum (in this application, OSNR spectrum refers to the total OSNR of each channel in the same band) from the output of the OPA of the optical multiplexer. O (λ) / OSNR E (λ) / OSNR S (λ) / OSNR C (λ) / OSNR L (λ) / OSNR U (λ), and then perform linear fitting on these OSNR spectra respectively to obtain the fitting slope T. O,Fit / T E,Fit / T S,Fit / T C,Fit / T L,Fit / T U,Fit Then, the adjustment amount of the gain slope for OBA, OLA, and OPA in each band is calculated according to the following formula:

[0132] In the above formula, N is the number of fiber spans within the optical multiplexing section, α is the slope distribution ratio between OBA and OPA, and the adjustment amount of the gain slope of OBA is expressed as ΔT. O,OBA / ΔT E,1BA / ΔT S,OBA / ΔT C,OBA / ΔT L,OBA / ΔT U,OBA The adjustment amount of the gain slope of OLA is expressed as ΔT. O,OLA,n / ΔT E,OLA,n / ΔT S,OLA,n / ΔT C,OLA,n / ΔT L,OLA,n / ΔT U,OLA,n The adjustment amount of the gain slope of OPA is expressed as ΔT. O,OPA / ΔT E,OPA / ΔTS,OPA / ΔT C,OPA / ΔT L,OPA / ΔT U,OPA .

[0133] Then determine whether the maximum value of ΔT satisfies the third condition, that is, determine whether ΔT max =max{ΔT}≤Th3. If ΔT max If the value is less than the preset adjustment amount Th3, then the first condition ΔP is satisfied simultaneously. max ≤Th1 second condition ΔOSNR max Based on ≤Th2, channel-level adjustment can be implemented if ΔT max If the gain is greater than the preset adjustment value Th3, then the current gain slopes of OBA, OLA, and OPA for each band are read, respectively. The gain slope adjustment ΔT for each band is used to adjust the current gain slope of OBA, OLA, and OPA for each band, as shown in the following formula:

[0134] The gain slope after OBA adjustment for each band in the above formula is: The OLA-adjusted gain slope for each band is The gain slope after OPA adjustment for each band is

[0135] The control system performs channel-level adjustments when the first, second, and third conditions are met simultaneously.

[0136] Referring to Figure 14, in step S130 corresponding to channel-level adjustment, the channel attenuation value of the wavelength selection switch WSS at the optical input is adjusted according to the OSNR of the OPA in each band, including:

[0137] Step S1210: Fit the OSNR of each band by fitting the OSNR of the output end of the OPA.

[0138] Step S1220: Determine the attenuation adjustment amount of WSS at the optical input end based on the OSNR at the output end of OPA for each band and the fitted OSNR for each band.

[0139] Step S1230: Obtain the current channel attenuation value of WSS at the optical input end, and determine the target channel attenuation value based on the current channel attenuation value and the attenuation adjustment amount;

[0140] Step S1240: Configure the target channel attenuation value to the WSS at the optical input end.

[0141] Channel-level adjustment is used to eliminate channel loss ripple. Since channel loss ripple cannot be compensated by adjusting OA gain and gain slope, the attenuation value of the WSS at the transmitting end of the optical multiplexing section can be adjusted. After completing cross-segment loss adjustment, inter-band adjustment, and intra-band adjustment, the configuration parameters of OBA, OLA, and OPA within the optical multiplexing section are usually updated. The control system reacquires the OSNR of the output end of the OPA in each band, and then performs linear fitting based on the OSNR of the OPA output end to obtain the fitted OSNR of each band. Then, it calculates the difference between the OSNR of the OPA output end of each band and the fitted OSNR of the corresponding band, and this difference is used as the attenuation adjustment amount of the WSS. The attenuation adjustment amount of the WSS is used to adjust the channel attenuation value of the WSS at the receiving end (i.e., the aforementioned optical input end) of the optical multiplexing section. After adjusting the attenuation value, the four adjustment steps of this embodiment are completed.

[0142] In one embodiment, the multi-band system transmits six bands: O+E+S+C+L+U. Then:

[0143] The control system reads the OSNR spectrum (in this application, OSNR spectrum refers to the total OSNR of each channel in the same band) from the output of the OPA of the optical multiplexer. O (λ) / OSNR E (λ) / OSNR S (λ) / OSNR C (λ) / OSNR L (λ) / OSNR U (λ), and then perform linear fitting on these OSNR spectra respectively to obtain the fitted OSNR spectra for each band, which are expressed as OSNR. O,Fit (λ) / OSNR E,Fit (λ) / OSNR S,Fit (λ) / OSNR C,Fit (λ) / OSNR L,Fit (λ) / OSNR U,Fit (λ), then calculate the difference between the OSNR at the output end of the OPA in each band and the fitted OSNR in each band, and calculate the attenuation adjustment ΔA of the WSS at the transmitter end of the optical multiplexing section as follows:

[0144] In the above formula, the attenuation adjustment amounts for the six bands O+E+S+C+L+U are respectively ΔA O (λ) / ΔA E (λ) / ΔA S (λ) / ΔA C (λ) / ΔA L (λ) / ΔA U(λ), and then the control system reads the current channel attenuation value A of the WSS at the transmitting end of the optical multiplex section. O,old (λ) / A E,old (λ) / A S,old (λ) / A C,old (λ) / A L,old (λ) / A U,old (λ), add the attenuation adjustment ΔA of the corresponding band to the current channel attenuation value of the WSS to obtain the new target channel attenuation value A. O,new (λ) / A E,new (λ) / A S,new (λ) / A C,new (λ) / A L,new (λ) / A U,new (λ), as shown in the following formula, and configure the target channel attenuation value to the WSS at the transmitter end of the optical multiplex section.

[0145] Understandably, the aforementioned channel-level adjustment does not require checking whether certain conditions are met; one adjustment is sufficient. However, cross-band loss adjustment, inter-band adjustment, and intra-band adjustment all require iterative checks to determine whether the corresponding conditions are met after adjustment. This is because any adjustment of any of the three may cause changes in the power transfer due to the SRS effect within the optical multiplexing section. Therefore, if the first condition is met but the second or third condition is not, the control system reacquires the output power of the OBA, OLA, and OPA for each band and readjusts the amplification gain of the OLA and OPA for each band based on the output power of the OBA, OLA, and OPA for each band to meet the first condition. Afterward, the control system reacquires the OSNR of the output end of the OPA for each band and checks again whether the second or third condition is met simultaneously, until the first, second, and third conditions are met simultaneously under the current configuration parameters, and then enters channel-level adjustment.

[0146] In summary, this embodiment of the application suppresses power transfer caused by the SRS effect in a multi-band system through four adjustment stages: cross-band loss adjustment, inter-band adjustment, intra-band adjustment, and channel-level adjustment. First, the amplification gain of the OLA and OPA in each band is adjusted by the output power of the OBA, OLA, and OPA in each band to meet the first condition. Under the premise of meeting the first condition, the amplification gain of the OBA in each band is adjusted by the optical signal-to-noise ratio (OSNR) of the OPA in each band to meet the second condition, and the gain slope of the OBA in each band is adjusted to meet the third condition. The simultaneous satisfaction of the above three conditions after adjustment indicates that the current multi-band system has completed the three stages of cross-band loss adjustment, inter-band adjustment, and intra-band adjustment, and the OSNR unevenness caused by the SRS effect is suppressed. Finally, the channel attenuation value of the WSS at the optical input end is adjusted by the OSNR of the OPA in each band to complete the channel attenuation adjustment. The entire process ultimately achieves the required flatness of the OSNR between bands after the light is transmitted in the multi-wavelength system, ensuring the stability and reliability of network operation.

[0147] The optical signal-to-noise ratio equalization method of this application will be explained in detail below with an example.

[0148] The OSNR equalization process for an ultra-wideband O+E+S+C+L+U multi-band optical transmission system is shown in Figure 15, and includes four adjustment steps: cross-segment loss adjustment, inter-band adjustment, intra-band adjustment, and channel-level adjustment. Taking a single optical multiplexing segment in Figure 1 as an example, the optical signal-to-noise ratio equalization method is applied in detail below:

[0149] Step 1: Cross-segment loss adjustment

[0150] To compensate for cross-band losses in the O / E / S / C / L / U bands, the amplification gain of the OLA / OPA needs to be adjusted. The input parameters required for the control system to perform cross-band loss adjustment include the output power of the OBA, OLA, and OPA for each band, as well as the current amplification gain of the OLA and the current amplification gain of the OPA. The output parameters include the target amplification gain of the OLA and the target amplification gain of the OPA.

[0151] Step 1.1: The control system reads the output power of the OBA, OLA at each level, and OPA in the O / E / S / C / L / U bands. The subscript n represents the nth OLA, where n is a positive integer. The difference between the output power of each OLA and OPA in the O / E / S / C / L / U band and the output power of the OBA is calculated as shown in Equation (1). Since the total power difference ΔP reflects the difference between the amplification gain and cross-band loss currently set for each OLA and OPA in each band, the difference ΔP calculated by Equation (1) is used as the gain to be adjusted for the OLA and OPA.

[0152] Determine whether the maximum value of the difference ΔP satisfies the set threshold Th1, i.e., ΔP max =max{ΔP}≤Th1. If ΔP max If the power is less than the preset power threshold Th1, then it directly enters inter-band adjustment and intra-band adjustment. If ΔP max If the power exceeds the preset power threshold Th1, then proceed to step 1.2.

[0153] Step 1.2: Read the current amplification gain of each OLA / OPA level in the O / E / S / C / L / U bands. The gain to be adjusted, ΔP, is added to the current amplification gain of each OLA / OPA level to obtain the new target amplification gain, as shown in Equation (2), and the target amplification gain is configured to each OLA / OPA level.

[0154] Repeat the steps from step 1.1 to step 1.2 until ΔP is satisfied. max Less than the preset power threshold Th1.

[0155] Step 2: Inter-band adjustment

[0156] Under the influence of the SRS effect, shortwave power shifts to longwave power in multi-band systems, specifically from O-band to E-band, E-band to S-band, S-band to C-band, C-band to L-band, and L-band to U-band. This results in the lowest average power in the O-band and the highest average power in the U-band after transmission through optical fiber, with significant differences in power between bands. In addition, the noise figures of amplifiers in each band are not the same, ultimately leading to large differences in the average OSNR between bands.

[0157] Accordingly, the OSNR of each band is detected at the end of the optical multiplexing section (or the receiving end, optical output end). Then, the difference between the mean OSNR of each band and the mean OSNR of the entire band is calculated. At the transmitting end of the optical multiplexing section (or the transmitting end, optical input end), the amplification gain of the OBA in each band is adjusted to ensure that the difference in the mean OSNR of each band at the end of the optical multiplexing section after adjustment is less than or equal to a preset OSNR threshold. The input parameters required for the control system to perform inter-band adjustment include: the OSNR spectrum at the OPA output end and the current amplification gain of the OBA. The output parameters include: the target amplification gain of the OBA.

[0158] Step 2.1: Read the OSNR spectrum of the O / E / S / C / L / U bands at the end of the optical multiplexer output. O (λ) / OSNR E(λ) / OSNR S (λ) / OSNR C (λ) / OSNR L (λ) / OSNR U (λ), calculate the mean OSNR of each band and the mean OSNR of the entire band, as shown in equation (3), where N O / N E / N S / N C / N L / N U This represents the number of channels in each band.

[0159] Then, the difference ΔOSNR between the mean OSNR of each band and the mean OSNR of the entire band is calculated, as shown in equation (4) below. This difference ΔOSNR reflects the level of OSNR difference between bands. According to the basic formula for calculating OSNR, the OSNR difference between bands can be made up by adjusting the output power (i.e., input power) of the OBA of each band at the transmitting end of the optical multiplexing section. Therefore, ΔOSNR can be used as the gain adjustment amount of the OBA.

[0160] Then determine whether the maximum value of ΔOSNR meets the set threshold Th2, i.e., ΔOSNR max =max{ΔOSNR}≤Th2. If ΔOSNR max If the OSNR is less than the preset OSNR threshold Th2, it is necessary to determine whether the intra-band adjustment criteria in step 3 are met. If the criteria in step 3 are also met, channel-level adjustment can proceed. If ΔOSNR max If the value is greater than the preset OSNR threshold Th2, then proceed to step 2.2.

[0161] Step 2.2: Read the current amplification gain of the OBA for each band (O / E / S / C / L / U). The ΔOSNR of each band is added as an adjustment to the current amplification gain of the OBA of each band, as shown in Equation (5), to obtain the new target amplification gain, and the target amplification gain is configured to the OBA of each band.

[0162] Since both inter-band and intra-band adjustments affect the SRS transfer between bands, and consequently, cross-band loss, inter-band adjustment is performed directly after intra-band adjustment, followed by cross-band loss adjustment. This process of inter-band adjustment, intra-band adjustment, and cross-band loss adjustment is repeated cyclically until all threshold conditions in steps 1, 2, and 3 are met, at which point step 4, channel-level adjustment, is initiated.

[0163] Step 3: Intra-band adjustment

[0164] The SRS effect not only affects power differences between bands but also causes power differences between different channels within a band. Therefore, due to the SRS transfer effect between channels, the OSNR at the optical output end is not flat across bands. Thus, it is necessary to adjust the gain slope of each band amplifier, i.e., by preset a certain slope at the optical input end to achieve a flat OSNR at the optical output end. The input parameters required for the control system to perform intra-band adjustment include: the OSNR spectrum at the OPA output end, and the current gain slope of the OBA / OLA / OPA. The output parameters include: the target gain slope of the OBA.

[0165] Step 3.1: Read the OSNR spectrum of the O / E / S / C / L / U bands at the output of the OPA. O (λ) / OSNR E (λ) / OSNR S (λ) / OSNR C (λ) / OSNR L (λ) / OSNR U (λ), and perform linear fitting on its OSNR spectrum to obtain the fitting gain slope T. O,Fit / T E,Fit / T s,Fit / T C,Fit / T L,Fit / T U,Fit Calculate the adjustment amount of the gain slope of OBA, OLA and OPA in each band according to the following formula (6), where N is the number of fiber spans in the optical multiplexing section, α is the slope distribution ratio of OBA and OPA, and α can be set as needed according to the scenario.

[0166] Determine whether the maximum value of the gain slope adjustment ΔT satisfies the set threshold Th3, i.e., ΔT max =max{ΔT}≤Th3. If ΔT max It is less than the preset adjustment amount Th3, and simultaneously satisfies ΔOSNR in step 2. max If the OSNR is less than the preset threshold Th2, proceed to channel-level adjustment step 4. If ΔT max If the value is greater than the preset adjustment amount Th3, then proceed to step 3.2.

[0167] Step 3.2: Read the current gain slope of OBA / OLA / OPA for each band. The adjustment amount ΔT of the gain slope is added to the current gain slope, as shown in Equation (7), to obtain the new target gain slope, and the target gain slope is assigned to each band OBA / OLA / OPA.

[0168] Since inter-band and intra-band adjustments affect inter-band SRS transfer and thus cross-band loss, after step 3.2 is completed, step 1 is executed again to adjust the cross-band loss until the ΔOSNR in step 2 is simultaneously satisfied. max Less than the preset OSNR threshold Th2 and ΔT in step 3 max Once the threshold of less than the preset adjustment amount Th3 is met, proceed to step 4.

[0169] Step 4: Channel-level adjustment

[0170] After inter-band and intra-band adjustments, the unevenness caused by the SRS effect is largely suppressed. However, residual wavelength-dependent loss and OA ripple remain, collectively referred to as channel loss ripple. This ripple cannot be compensated for by adjusting the OA gain and slope. Therefore, there are certain differences in OSNR among the channels after inter-band and intra-band adjustments. This can be suppressed by adjusting the attenuation parameter of the WSS at the transmitter end of the optical multiplexing section, ensuring a flat OSNR at the output of the optical multiplexing section. The input parameters required for the control system to perform channel-level adjustments include: the OSNR spectrum at the OPA output and the current channel attenuation value of the WSS at the transmitter end. The output parameters include: the target channel attenuation value of the WSS at the transmitter end.

[0171] Step 4.1: Read the OSNR spectrum of the O / E / S / C / L / U bands at the OPA output. O (λ) / OSNR E (λ) / OSNR S (λ) / OSNR C (λ) / OSNR L (λ) / OSNR U (λ), and perform linear fitting on its OSNR spectrum to obtain the fitted OSNR spectrum for each band. O,Fit (λ) / OSNR E,Fit (λ) / OSNR S,Fit (λ) / OSNR C,Fit (λ) / OSNR L,Fit (λ) / OSNR U,Fit (λ), calculate the attenuation adjustment amount ΔA of the WSS on the transmitting end according to Equation (8).

[0172] Step 4.2: Read the current channel attenuation value A of the WSS on the O / E / S / C / L / U band transmitter. O,old (λ) / A E,old (λ) / A S,old (λ) / AC,old (λ) / A L,old (λ) / A U,old (λ), and then the attenuation adjustment amount ΔA of the WSS on the transmitting end. O (λ) / ΔA E (λ) / ΔA S (λ) / ΔA C (λ) / ΔA L (λ) / ΔA U (λ) is added to the current channel attenuation value, as shown in equation (9) below, to obtain the new target channel attenuation value, and the target channel attenuation value is configured to the WSS on the transmitting end.

[0173] The channel-level adjustments in step 4 do not need to be executed repeatedly.

[0174] In summary, during the optical network planning phase, the method described in this example can be used to quickly evaluate the transmission OSNR performance of a multi-band system, and calculate the OSNR system margin and the corresponding maximum transmission distance without electrical repeaters based on the OSNR performance after transmission.

[0175] During the initial deployment phase of an optical network, the method described in this example can be used to quickly and automatically level the performance of a multi-band system, avoiding the slow speed and error-prone nature of manual adjustments, thus accelerating the deployment process and enabling rapid delivery.

[0176] During the expansion phase of an optical network, the method described in this example can be used to predict the post-transmission performance of new service waves in advance, ensuring the stable and smooth commissioning of services during the expansion phase.

[0177] During the operation and maintenance phase of optical networks, as the network operating time increases, various devices will experience aging and performance fluctuations, such as increased fiber optic segment loss and OA gain drift. The method in this example can be used to effectively adjust and suppress these problems, ensuring the stability and reliability of network operation.

[0178] This application also provides a controller, including at least one processor and a memory for communicatively connecting to the at least one processor; the memory stores instructions executable by the at least one processor, which, when executed by the at least one processor, enable the at least one processor to perform the optical signal-to-noise ratio equalization method of the foregoing embodiments.

[0179] Referring to Figure 16, an example is taken where the processor 1001 and memory 1002 in the controller 1000 can be connected via a bus. The memory 1002, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, the memory 1002 may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 1002 may include memory remotely located relative to the processor 1001, and these remote memories can be connected to the controller 1000 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0180] Those skilled in the art will understand that the device structure shown in FIG16 does not constitute a limitation on the controller 1000, and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0181] This application also provides a computer-readable storage medium storing computer-executable instructions that are executed by one or more processors, for example, by one of the processors 1001 in FIG16, which can cause the one or more processors to perform the optical signal-to-noise ratio equalization method in the above method embodiment.

[0182] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0183] This application embodiment also provides a control system, including the above-mentioned controller 1000. The controller 1000 is connected to OBA, OLA and OPA in a multi-band transmission system. The controller 1000 can also be connected to WSS in the multi-band transmission system.

[0184] This application provides an optical signal-to-noise ratio (OSNR) equalization method, controller, and management system for multi-band systems. This system effectively adjusts the OSNR of multi-band optical transmission systems, ensuring network stability and reliability. The OSNR equalization method, controller, and management system provided in this application achieve OSNR equalization through three conditions and corresponding adjustment methods. First, the amplification gain of the OLA and OPA in each band is adjusted by controlling the output power of the OBA, OLA, and OPA to meet the first condition. Under the premise of meeting the first condition, the amplification gain of the OBA in each band is adjusted by controlling the OSNR of the OPA in each band to meet the second condition, and the gain slope of the OBA in each band is adjusted to meet the third condition. When all three conditions are met after adjustment, it indicates that the multi-band system has completed the three stages of cross-band loss adjustment, inter-band adjustment, and intra-band adjustment. The OSNR unevenness caused by the SRS effect is suppressed. The entire process ultimately achieves the required OSNR flatness between bands after light transmission in the multi-wavelength system, ensuring network stability and reliability.

[0185] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0186] The above describes some implementations of this application, but this application is not limited to the above-described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method of optical signal-to-noise ratio equalization for a multi-band system, wherein, The transmission path from the optical input to the optical output of the multi-band system is sequentially equipped with optical power amplifiers (OBA), preamplifiers (OPA), and optical line amplifiers (OLA) corresponding to each band; the optical signal-to-noise ratio equalization method includes: Obtain the output power of the OBA, OLA and OPA in each band, and adjust the amplification gain of the OLA and OPA in each band according to the output power of the OBA, OLA and OPA in each band to meet the first condition; The optical signal-to-noise ratio (OSNR) of the OPA in each band is obtained, the amplification gain of the OBA in each band is adjusted according to the OSNR of the OPA in each band to satisfy the second condition, and the gain slope of the OBA in each band is adjusted according to the OSNR of the OPA in each band to satisfy the third condition. in, The first condition is that the power difference between the output power of the OLA in each band and the output power of the OBA in each band, and the power difference between the output power of the OPA in each band and the output power of the OBA in each band, are all not greater than a preset power threshold. The second condition is that the difference between the OSNR of the OPA in each band and the mean OSNR of the entire band is not greater than a preset OSNR threshold. The third condition is that the adjustment amount of the gain slope of the OBA, OLA and OPA in each band is not greater than the preset adjustment amount.

2. The method of claim 1, wherein, The step of adjusting the amplification gain of the OLA and OPA in each band according to the output power of the OBA, OLA and OPA in each band to satisfy the first condition includes: The difference between the output power of the OLA in each band and the output power of the OBA in each band is determined as the first power difference value, and the difference between the output power of the OPA in each band and the output power of the OBA in each band is determined as the second power difference value. If the first power difference and the second power difference do not meet the first condition, adjust the amplification gain of the OLA in each band according to the first power difference, and / or adjust the amplification gain of the OPA in each band according to the second power difference; Then, determine again whether the first power difference and the second power difference obtained after adjusting the amplification gain satisfy the first condition.

3. The method of claim 2, wherein, The step of adjusting the amplification gain of the OLA in each band according to the first power difference includes: Obtain the current amplification gain value of the OLA in each band, and determine the first target amplification gain value of each band based on the current amplification gain value of the OLA in each band and the first power difference. Configure the first target amplification gain value of each band to the corresponding OLA; The step of adjusting the amplification gain of the OPA in each band according to the second power difference includes: Obtain the current amplification gain value of the OPA in each band, and determine the second target amplification gain value of each band based on the current amplification gain value of the OPA in each band and the second power difference; Configure the second target amplification gain value of each band to the corresponding OPA of the band.

4. The method of claim 2, wherein, The method for determining the first condition is as follows: The maximum power difference is determined based on the absolute value of the first power difference for each band and the absolute value of the second power difference for each band. If the maximum power difference is less than the preset power threshold, it is determined that the first condition is met; If the maximum power difference is greater than the preset power threshold, it is determined that the first condition is not met.

5. The method of claim 1, wherein, The step of adjusting the amplification gain of the OBA in each band according to the OSNR of the OBA in each band to satisfy the second condition includes: The mean OSNR of the entire band is determined based on the OSNR of the output terminal of the OPA in each band, and the difference between the OSNR of the output terminal of the OPA in each band and the mean OSNR of the entire band is determined as the first OSNR difference. If the first OSNR difference does not meet the second condition, adjust the amplification gain of the OBA for each band according to the first OSNR difference; Then, determine again whether the first OSNR difference obtained after adjusting the amplification gain satisfies the second condition.

6. The method of claim 5, wherein, The step of adjusting the amplification gain of the OBA in each band according to the first OSNR difference includes: Obtain the current amplification gain value of the OBA for each band, and determine the third target amplification gain value for each band based on the current amplification gain value of the OBA for each band and the first OSNR difference. Configure the third target amplification gain value of each band to the corresponding OBA of the band.

7. The method of claim 5, wherein, The second condition is determined as follows: For each band at the output end of the OPA, the average OSNR of all channels within the same band is determined as the OSNR within the band. The mean OSNR of the entire band is determined based on the OSNR within each band. Determine the difference between the OSNR within each band and the mean OSNR of the entire band, and determine the maximum value of the difference as the maximum OSNR difference; If the maximum OSNR difference is less than the preset OSNR threshold, it is determined that the second condition is met; If the maximum OSNR difference is greater than the preset OSNR threshold, it is determined that the second condition is not met.

8. The method of claim 1, wherein, The step of adjusting the gain slope of the OBA in each band according to the OSNR of the OBA in each band to satisfy the third condition includes: The fitting gain slope of each band is obtained by fitting the OSNR of the output terminal of the OPA of each band. The adjustment amount of the gain slope of the OBA, the OLA and the OPA in each band is determined based on the fitted gain slope of each band. If the adjustment amount of the gain slope does not meet the third condition, adjust the gain slope of the OBA, the OLA and the OPA of each band according to the adjustment amount of the gain slope; Next, determine whether the adjustment amount of the gain slope obtained after adjusting the gain slope satisfies the third condition.

9. The method of claim 8, wherein, The adjustment of the gain slope of the OBA, OLA, and OPA in each band according to the adjustment amount of the gain slope includes: Obtain the current gain slope of the OBA, OLA and OPA for each band, and determine the target gain slope of the OBA, OLA and OPA for each band based on the current gain slope of the OBA, OLA and OPA for each band and the adjustment amount of the gain slope; Configure the target gain slope of the OBA, OLA and OPA of each band to the OBA, OLA and OPA of the corresponding band.

10. The method of claim 8, wherein, The method for determining the third condition is as follows: Based on the fitted gain slope of each band, the preset gain slope allocation ratio, and the number of fiber optic spans in the transmission path, determine the adjustment amount of the gain slope of the OBA, the OLA, and the OPA in each band. The maximum value among the adjustment amounts of the gain slope is determined as the maximum gain slope adjustment amount; If the maximum gain slope adjustment is less than the preset adjustment, it is determined that the third condition is met; if the maximum gain slope adjustment is greater than the preset adjustment, it is determined that the third condition is not met.

11. The method of claim 1, wherein, The optical signal-to-noise ratio equalization method further includes: If the first condition, the second condition, and the third condition are met simultaneously, the channel attenuation value of the wavelength selection switch WSS at the optical input terminal is adjusted according to the OSNR of the OPA in each band.

12. The method of claim 11, wherein, The step of adjusting the channel attenuation value of the wavelength selection switch (WSS) at the optical input terminal according to the OSNR of the OPA in each band includes: The fitted OSNR for each band is obtained by fitting the OSNR at the output of the OPA for each band. The attenuation adjustment amount of WSS at the optical input terminal is determined based on the OSNR at the output terminal of the OPA in each band and the fitted OSNR in each band. Obtain the current channel attenuation value of the WSS at the optical input end, and determine the target channel attenuation value based on the current channel attenuation value and the attenuation adjustment amount; Configure the target channel attenuation value at the optical input terminal WSS.

13. The method of claim 1, wherein, The method further includes: If the first condition is met but the second or third condition is not met, the output power of the OBA, OLA and OPA of each band is reacquired, and the amplification gain of the OLA and OPA of each band is readjusted according to the output power of the OBA, OLA and OPA of each band to meet the first condition. Reacquire the optical signal-to-noise ratio (OSNR) of the OPA for each band, and determine again whether the second condition or the third condition is met simultaneously.

14. The method of claim 1, wherein, The multi-band system transmits two or more of the following bands: O-band, E-band, S-band, C-band, L-band, and U-band.

15. A controller comprising at least one processor and a memory for communicatively connecting to the at least one processor; the memory storing instructions executable by the at least one processor to enable the at least one processor to perform the optical signal-to-noise ratio equalization method as claimed in any one of claims 1 to 14.

16. A management system comprising the controller of claim 15, the controller connected to the OBA, the OLA, and the OPA.

17. A computer readable storage medium storing computer executable instructions for causing a computer to perform the optical signal-to-noise ratio equalization method of any one of claims 1 to 14.

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