A method and device for controlling transient performance of cascaded erbium-doped fiber amplifiers

Abstract

The present invention relates to the field of optical communication technology, and in particular to a method and device for controlling the transient performance of a cascaded erbium-doped fiber amplifier. The method mainly includes: synchronizing the optical power detection branches at both ends of the pump and the adjustable optical power attenuator involved in feedback control, calibrating the feedforward values of different pump currents under different gain and input optical power conditions; debugging the PID reference parameters and roughly adjusting the PID overshoot parameters; in the cascade state, debugging the starting point and end point of the overshoot window, wherein the range of the overshoot window covers the oscillation duration and overshoot / undershoot peak position in the cascade transient effect; fine-tuning the delay parameters and PID correction parameters in the up-wave and down-wave states respectively; traversing the required gain range, wavelength range, and power range, and measuring and judging whether the transient indicators meet the expected requirements. The present invention solves the problem of optical surge impact caused by transients of multi-stage cascaded EDFAs in optical networks and improves the stability of optical transmission networks.

Description

Technical field

[0001] The present invention relates to the field of optical communication technology, and in particular to a method and device for controlling the transient performance of an erbium-doped fiber amplifier cascade. [Background Technology]

[0002] Erbium-doped fiber amplifiers (EDFAs) have greatly accelerated the development of optical communications. They offer advantages such as transparency to data formats and rates, high gain and low noise, the absence of electrical regeneration repeaters, and a wide gain bandwidth. EDFAs are essential components in dense wavelength division multiplexing (DWDM) systems. In DWDM systems, as traffic volume increases, the number of channels requiring add / drop optical paths and the channel power also increase rapidly. This change in the number of channels causes changes in the EDFA input optical power, resulting in transient effects. These EDFA transient effects have a significant impact on DWDM systems. When the optical signal strength input to the EDFA experiences a 20.8dB dropout or gain, and the transient duration is in the microsecond range, the energy in the erbium fiber is instantly transferred to the remaining signal wavelength, causing the remaining signal wavelength to produce a large overshoot or undershoot. Multi-stage cascaded EDFAs are widely used in long-distance optical network systems. In cascaded EDFA systems, this overshoot or undershoot can seriously affect network stability. Therefore, effectively suppressing the EDFA transient effect can improve the stability of data transmission in the network and build a more robust and reliable optical transmission network.

[0003] Patent application publication number 103560834, entitled "Device and Method for Suppressing Transient Effects in Multi-Stage EDFAs," introduces a shared controller into a multi-stage EDFA. This controller is sequentially connected in the optical path, with the output of the preceding stage serving as the input to the succeeding stage. This controller can detect the delay time of the intermediate stage between two stages and preemptively control the pump power of the succeeding EDFA, thereby suppressing EDFA transient effects. This invention calculates the delay time between two stages in a multi-stage EDFA, generates a transient decision signal based on the input signal of the preceding EDFA, and suppresses transient effects in the multi-stage EDFA based on the delay time and the transient decision signal. However, this method lacks consideration for the feasibility of using a shared controller for multi-stage cascaded EDFAs in long-haul optical network systems. It also fails to address the problem of post-cascade optical power oscillation caused by transient effects in cascaded EDFA systems and its mitigation measures.

[0004] Patent Publication No. 102098109, entitled "EDFA Transient Effect Suppression Method," captures light intensity variations through an analog-to-digital converter (ADC), obtains the values of a dedicated difference data register between adjacent cycles, and combines the status of two timers to determine whether the EDFA is in normal phase mode, pre-modulation phase mode, or overmodulation phase mode. When the predetermined judgment conditions are met, the EDFA enters overmodulation phase mode, rapidly adjusting the pump laser current in response to sudden changes in light intensity to suppress transient effects. However, this method's shortcomings include its failure to consider overmodulation methods other than PID to suppress transients; its failure to consider the reliability of overmodulation methods and conditions in a cascaded EDFA system; and its failure to address transient-induced optical power oscillations in a cascaded EDFA system and its mitigation measures.

[0005] In view of this, how to overcome the defects of the existing technology and solve the phenomenon of optical power oscillation caused by transient effects in the cascaded EDFA system in the existing technical solution is a problem to be solved in this technical field. [Summary of the invention]

[0006] In view of the above defects or improvement needs of the prior art, the present invention solves the problem of optical power oscillation caused by transient effects in a mid-cascade EDFA system.

[0007] The embodiment of the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for controlling the transient performance of a cascaded erbium-doped fiber amplifier, specifically comprising: synchronizing the optical power detection branches at both ends of the pump and the adjustable optical power attenuator involved in feedback control, and calibrating the feedforward values of different pump currents under different gain and different input optical power conditions; debugging the PID reference parameters and coarsely adjusting the PID overshoot parameters under the extreme transient conditions of a single-stage module; debugging the starting point and end point of the overshoot window in the cascade state, wherein the range of the overshoot window covers the oscillation duration and overshoot and undershoot peak positions in the cascade transient effect; fine-tuning the delay parameters and PID correction parameters in the up-wave and down-wave states respectively in combination with the influence of the modified overshoot window on the transient; traversing the required gain range, wavelength range, and power range, and respectively measuring and judging whether the transient indicators meet the expected requirements.

[0009] Preferably, calibrating the feedforward values of different pump currents under different gains and different input optical powers specifically includes: adjusting the current ratio of each pump in the first-stage multi-pump and the current bias of each pump to achieve a preliminary balance between the EDFA's ultimate noise figure under low input light conditions and the ultimate transient performance under high input light conditions; calibrating the feedforward current parameters of each pump according to the current ratio of each stage of pumps under different gains; and calibrating the feedforward values of different pump currents under different gains and different input optical powers.

[0010] Preferably, debugging the PID reference parameters specifically includes: adjusting the PID reference parameters at minimum gain to achieve the optimal ultimate transient performance of the current state; adjusting the power scaling factor in the PID according to the expected output power to achieve the optimal ultimate transient performance of the current state; at maximum gain, adjusting the gain scaling factor in the PID to achieve the optimal ultimate transient performance of the current state.

[0011] Preferably, the coarse adjustment of the PID overshoot parameter specifically includes: in the up-wave state, adjusting the delay overshoot parameter so that the extreme transient performance of the up-wave state reaches the preset up-wave performance index; in the down-wave state, adjusting the delay overshoot parameter so that the extreme transient performance of the down-wave state reaches the preset down-wave performance index.

[0012] Preferably, the starting point and the ending point of the overshoot window are debugged, specifically including: adjusting the initialization window period parameters according to the duration of the oscillation caused by the cascade transient, extending the overshoot window, and shifting the overshoot time window backward so that the ending time point of the overshoot time window covers the time period of the cascade oscillation; adjusting the initialization window period parameters and the overshoot and undershoot judgment initialization threshold according to the moment when the overshoot and undershoot peaks appear in the cascade transient performance, and shifting the overshoot window forward so that the starting time of the overshoot time window covers the time point of the overshoot and undershoot peaks.

[0013] Preferably, the delay parameters and PID correction parameters in the up-wave and down-wave states are fine-tuned respectively, specifically including: in the up-wave state, fine-tuning the delay over-adjustment parameter and the PID correction parameter to optimize the extreme cascade transient performance of the up-wave state; in the down-wave state, fine-tuning the delay over-adjustment parameter and the PID correction parameter to optimize the extreme cascade transient performance of the down-wave state.

[0014] On the other hand, the present invention provides a device for controlling the transient performance of a cascaded erbium-doped fiber amplifier, specifically comprising an input / output optical power sampling module 1, a transient judgment and control module 2, an input / output delay control module 3, a PID parameter correction module 4, and a pump current driving module 5. Specifically, the input / output optical power sampling module 1 is used to receive and cache the sampling data of the input and output optical powers, and update them in real time according to the first-in-first-out order; the transient judgment and control module 2 is connected to the input / output optical power sampling module 1 and is used to process the cached input optical power sampling data; the input / output delay control module 3 is used to process the cached input optical power sampling data according to the received overmodulation state and the configured The delay amount is used to delay the input and output sampling values respectively according to the method provided in the first aspect, thereby providing an advanced or lagging data source for the pump current calculation module; the PID parameter correction module 4 corrects the PID control parameters in the overmodulation window period according to the method provided in the first aspect based on the received overmodulation state and the configured PID parameter correction amount and scaling ratio; the pump current driving module 5 calculates the PID output current value in the overmodulation state according to the overmodulation parameters and data source provided by the input / output delay control module 3 and the PID parameter correction module 4, and continues to operate in this state according to the overmodulation window period controlled by the transient judgment and control module 2 until leaving the overmodulation state.

[0015] Preferably, the transient judgment and control module 2 specifically includes:

[0016] The slope of the input optical power is estimated based on the continuously sampled input optical power and the least squares method, and based on this, it is determined whether there are up and down waves in the optical path; when it is determined that there are up and down waves, the transient judgment and control module 2 outputs an up and down wave state indication signal and the shortest time interval before exiting overmodulation, wherein the up and down wave state indication signal includes an up wave overmodulation state and a down wave overmodulation state; according to the hysteresis time for entering the overmodulation state and the hysteresis time for exiting the overmodulation state, the delay time for entering the overmodulation state and the shortest time interval for maintaining the overmodulation state are constrained.

[0017] Preferably, the PID parameter correction module 4 specifically includes: calculating the target output power value under the real-time input optical power, and correcting the P, I and D parameters in the scaled PID parameters in the up-wave state and down-wave state according to the up-wave state indication signal and the configured PID correction parameters output by the transient judgment and control module 2, and outputting the corrected P, I and D parameters.

[0018] Preferably, the input / output delay control module 3 specifically includes: caching the sampling value output by the input / output optical power sampling module 1 in a shift register of size W×L, wherein W is the bit width length of the sampling data, and L is the depth of the input / output buffer area; when the upper wave status indication signal output by the transient judgment and control module 2 appears and there is no lower wave status indication signal, adjusting the interception position of the output or input shift register according to the positive or negative value of the upper wave delay control parameter; when the lower wave status indication signal output by the transient judgment and control module 2 appears and there is no upper wave status indication signal, adjusting the interception position of the input or output shift register according to the positive or negative value of the lower wave delay control parameter.

[0019] Compared with the prior art, the beneficial effects of the embodiments of the present invention are: by adjusting parameters such as the starting point of the overmodulation effect, the overmodulation time period, the PID parameter correction value, the input and output sampling value delay, etc., the transient performance of the multi-stage cascaded EDFA is optimized, the optical surge impact problem caused by the transient of the multi-stage cascaded EDFA in the optical network is solved, and the stability of the optical transmission network is improved.

Brief Description of the Drawings

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0021] Figure 1 A flow chart of a method for controlling transient performance of cascaded erbium-doped fiber amplifiers provided in an embodiment of the present invention;

[0022] Figure 2 A flow chart of another method for controlling transient performance of cascaded erbium-doped fiber amplifiers provided in an embodiment of the present invention;

[0023] Figure 3 A flow chart of another method for controlling transient performance of cascaded erbium-doped fiber amplifiers provided in an embodiment of the present invention;

[0024] Figure 4 A flow chart of another method for controlling transient performance of cascaded erbium-doped fiber amplifiers provided in an embodiment of the present invention;

[0025] Figure 5 A flow chart of another method for controlling transient performance of cascaded erbium-doped fiber amplifiers provided in an embodiment of the present invention;

[0026] Figure 6 A flow chart of another method for controlling transient performance of cascaded erbium-doped fiber amplifiers provided in an embodiment of the present invention;

[0027] Figure 7 A schematic diagram of the system structure of a device for controlling the transient performance of cascaded erbium-doped fiber amplifiers provided in an embodiment of the present invention;

[0028] Figure 8 A flowchart of the actions executed by the transient judgment and control module 2 in a device for controlling transient performance of cascaded erbium-doped fiber amplifiers provided in an embodiment of the present invention;

[0029] Figure 9 A flowchart of the actions executed by the input / output delay control module 3 in a device for controlling transient performance of cascaded erbium-doped fiber amplifiers provided in an embodiment of the present invention;

[0030] Figure 10 A schematic diagram of the complete linkage and feedback process between modules of a device for controlling the transient performance of cascaded erbium-doped fiber amplifiers provided by an embodiment of the present invention;

[0031] The accompanying drawings are numerals as follows:

[0032] 1: Input / output optical power sampling module, 2: Transient judgment and control module, 3: Input / output delay control module, 4: PID parameter correction module, 5: Pump current drive module. [Specific implementation method]

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] The present invention is an architecture of a specific functional system. Therefore, the specific embodiments mainly illustrate the functional logical relationship between the various structural modules, and do not limit the specific software and hardware implementation methods.

[0035] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0036] Example 1:

[0037] Prior art techniques have not considered transient suppression using overmodulation methods other than PID, nor have they considered optical power oscillations caused by transient effects in cascaded EDFA systems and their countermeasures. Furthermore, they have not addressed the technical issues of ensuring the reliability of the overmodulation method and conditions in cascaded EDFA systems. To address these issues and optimize the transient performance of cascaded EDFAs, this embodiment provides a method for controlling the transient performance of cascaded erbium-doped fiber amplifiers. By adjusting the overmodulation starting point, the overmodulation time period, the PID parameter correction value, and the input and output sampling delay, the transient performance of multi-stage cascaded EDFAs is optimized.

[0038] like Figure 1 As shown, the specific steps of the method for controlling transient performance of cascaded erbium-doped fiber amplifiers provided in the embodiment of the present invention are as follows.

[0039] Step 101: Synchronize the optical power detection branches at both ends of the pump and the adjustable optical power attenuator involved in feedback control, and calibrate the feedforward values of different pump currents under different gains and different input optical powers.

[0040] To control the EDFA, parameter initialization is first required. In practice, these parameters include the baseline PID initialization parameters (pid_p, pid_i, pid_d, ratio_p, ratio_g), the power scaling factor (ratio_p), and the gain scaling factor (ratio_g). To adjust the overshoot and undershoot amplitudes, the overshoot and undershoot thresholds (add_thr and drop_thr) and the corresponding initialization window parameters (enter_window and exit_window) must be set. The delay overshoot parameters (add_dly and drop_dly) and PID correction parameters (add_P_delta, add_I_delta, add_D_delta, drop_P_delta, drop_I_delta, and drop_D_delta) must also be set to 0.

[0041] After completing the initialization parameter settings, adjust the synchronization of input and output. Adjust the sampling circuit, interface driver, shift mode, filtering mode, and conversion mode separately. Synchronize the optical power detection branches at both ends of the pump and the adjustable optical power attenuator involved in feedback control to avoid misadjustments in subsequent steps due to input and output asynchrony.

[0042] After completing the parameter setting, it is necessary to calibrate the pump current feedforward value under different gains and different input optical powers by adjusting the current ratio and current bias of each pump.

[0043] Step 102: Under the extreme transient conditions of the single-stage module, debug the PID reference parameters and roughly adjust the PID overshoot parameters.

[0044] When a transient event occurs, each EDFA module independently overmodulates to suppress transient overshoot and undershoot in the multi-stage EDFA under extreme transient conditions of a single-stage module. Overmodulation parameters can be adjusted based on the PID control, including adjusting the PID reference parameters pid_p, pid_i, and pid_d, as well as the power scaling factor ratio_p and the gain scaling factor ratio_g.

[0045] In a specific implementation, whether a transient event occurs can be determined by detecting the rate of change of the input optical power in a single-stage EDFA.

[0046] Step 103: In the cascade state, adjust the start point and the end point of the overshoot window, wherein the range of the overshoot window covers the oscillation duration and the overshoot and undershoot peak positions in the cascade transient effect.

[0047] In cascade mode, adjust the overmodulation window's starting and ending points to cover the oscillation duration and overshoot / undershoot peak locations in cascade transient effects. By adjusting the overmodulation detection threshold, detection window, and overmodulation cutoff point, delaying or advancing the overmodulation event's starting point and controlling the overmodulation duration, the amplitude of optical power oscillations that occur after cascading can be suppressed.

[0048] Step 104: Based on the influence of the modified overshoot window on the transient state, fine-tune the delay parameters and PID correction parameters in the up-wave and down-wave states respectively.

[0049] After coarsely adjusting the overshoot parameters, further fine-tuning is required. Taking into account the impact of the modified overshoot window on transients, fine-tune the delay parameters and PID correction parameters for both the rising and falling wave states. By using the PID correction parameter values during the overshoot period and introducing additional input and output sampling delays, the PID lock to the target power is accelerated, enhancing overshoot and undershoot suppression capabilities and suppressing overshoot, undershoot, or oscillation in the output optical power of single-stage or multi-stage cascaded EDFA modules.

[0050] Step 105: Traverse the required gain range, wavelength range, and power range, and measure and determine whether the transient indicators meet the expected requirements.

[0051] After adjusting all parameters, the EDFA's transient performance can be comprehensively evaluated to determine whether the existing parameter combination can achieve the required transient performance. Specifically, the required gain range, wavelength range, and power range are traversed, and the transient indicators are measured and determined to determine whether they meet the expected requirements.

[0052] After steps 101 to 105 provided in this embodiment, a parameter combination that achieves the expected transient performance requirements can be obtained. If the judgment result indicates that the transient performance achieved by the current parameter combination does not meet the expected requirements, the current parameter combination can be used as the initialization parameter in step 101, and adjustments can be repeated one or more times starting from step 102 until the expected requirements are met.

[0053] like Figure 2 As shown, in step 101, calibrating the feedforward values of different pump currents under different gains and different input optical powers can be accomplished using the following steps.

[0054] Step 201: Adjust the current ratio (pump_i_ratio) and the current bias (pump_i_offset) of each pump in the first-stage multi-pump to achieve a preliminary balance between the EDFA's ultimate noise figure under low input light conditions and the ultimate transient performance under high input light conditions.

[0055] Step 202: Calibrate the feedforward current parameters of each pump according to the current ratio of each pump stage at different gains.

[0056] Step 203: calibrating feedforward values of different pump currents under different gain and input optical power conditions.

[0057] After steps 201 to 203, the current ratio and current bias of each pump are first adjusted to obtain a preliminary balance of the extreme transient performance under low output light and high output light conditions, and then the feedforward current value of each pump is adjusted and calibrated under different gain and different input optical power conditions.

[0058] like Figure 3 As shown, in step 102, debugging the PID reference parameters can be completed using the following steps.

[0059] Step 301: At the minimum gain, adjust the PID reference parameters pid_p, pid_i, and pid_d to achieve the optimal extreme transient performance of the current state.

[0060] Step 302: According to the expected output power, adjust the power scaling factor ratio_p in the PID to achieve the optimal extreme transient performance in the current state.

[0061] Step 303: At the maximum gain, adjust the gain scaling factor ratio_g in the PID to achieve the optimal extreme transient performance in the current state.

[0062] After steps 301 to 303, the PID reference parameters, as well as the power scaling factor and gain scaling factor in the PID are adjusted according to the expected output power, achieving the ultimate transient optimal performance of the current state and completing the debugging of the PID reference parameters.

[0063] like Figure 4 As shown, in step 102, the PID overshoot parameter is roughly adjusted, which can be completed using the following steps.

[0064] Step 401: In the wave-up state, adjust the delay overshoot parameter so that the extreme transient performance of the wave-up state reaches a preset wave-up performance index.

[0065] In the rising wave state, the delay overshoot parameter add_dly is adjusted so that the extreme transient performance of the rising wave state meets the requirements. If the delay overshoot parameter add_dly meets the requirements, step 402 is executed. Otherwise, the PID correction parameters add_P_delta, add_I_delta, and add_D_delta are debugged so that the extreme transient performance of the rising wave state meets the requirements.

[0066] Step 402: In the wave-dropping state, adjust the delay overshoot parameter so that the extreme transient performance of the wave-dropping state reaches a preset wave-dropping performance index.

[0067] In the falling wave state, the delay overshoot parameter drop_dly is adjusted so that the extreme transient performance of the falling wave state meets the requirements. If the adjustment parameter drop_dly meets the requirements, the process continues with step 103. Otherwise, the PID correction parameters drop_P_delta, drop_I_delta, and drop_D_delta are adjusted so that the extreme transient performance of the falling wave state meets the requirements.

[0068] After step 401 and step 402, the delay overshoot parameter and the PID correction parameter are adjusted so that the extreme transient performance in the up-wave and down-wave states reaches the expected index.

[0069] like Figure 5 As shown, in step 103, the start point and the end point of the overshoot window are debugged, which can be completed using the following steps.

[0070] Step 501: According to the oscillation duration caused by the cascade transient, adjust the initialization window parameter exit_window, extend the overmodulation window, and shift the overmodulation time window backward so that the end time point of the overmodulation time window covers the duration of the cascade oscillation.

[0071] Step 502: According to the time when the overshoot and undershoot peak values appear in the cascade transient performance, adjust the initialization window parameter enter_window and the overshoot and undershoot judgment initialization thresholds add_thr and drop_thr to move the overshoot window forward so that the start time of the overshoot time window covers the time point of the overshoot and undershoot peak values.

[0072] After step 501 and step 502, by adjusting the initialization window period parameters and the overshoot / undershoot judgment initialization threshold, the range of the overshoot window is made to cover the oscillation duration and overshoot / undershoot peak position in the cascade transient effect.

[0073] like Figure 6 As shown, in step 104, the delay parameters and PID correction parameters in the up-wave and down-wave states are fine-tuned respectively, which can be accomplished using the following steps.

[0074] Step 601: In the rising wave state, fine-tune the delay overshoot parameter add_dly and the PID correction parameters add_P_delta, add_I_delta and add_D_delta to optimize the extreme cascade transient performance in the rising wave state.

[0075] Step 602: In the falling wave state, fine-tune the delay overshoot parameter drop_dly and the PID correction parameters drop_P_delta, drop_I_delta, and drop_D_delta to optimize the extreme cascade transient performance in the falling wave state.

[0076] After step 601 and step 602, the delay parameters and PID correction parameters are fine-tuned in the up-wave and down-wave states, and the optimized extreme cascade transient performance is finally achieved.

[0077] This embodiment provides a method for controlling the transient performance of a cascaded erbium-doped fiber amplifier (EDFA). This method detects the rate of change of the input optical power in a single-stage EDFA to determine whether a transient event has occurred. When a transient event occurs, each EDFA module independently overmodulates to suppress transient overshoots and undershoots in the multi-stage EDFA. By adjusting the overmodulation detection threshold, detection window, and overmodulation cutoff point, the overmodulation start point is delayed or advanced, and the overmodulation time period is controlled, thereby suppressing the amplitude of optical power oscillations that occur after the cascade. By using PID correction parameters during the overmodulation period and introducing additional input and output sampling delays, the PID lock-on to the target power is accelerated, enhancing overshoot and undershoot suppression capabilities and suppressing the overshoot, undershoot, or oscillation amplitude of the output optical power of the cascaded single-stage or multi-stage EDFA modules. By adjusting the overmodulation start point, overmodulation time period, PID parameter correction values, and input and output sampling delays, the transient performance of the multi-stage cascaded EDFA is optimized, addressing the optical surge impact caused by transients in the multi-stage cascaded EDFA in optical networks and improving the stability of optical transmission networks.

[0078] Example 2:

[0079] Based on the method for controlling the transient performance of cascaded erbium-doped fiber amplifiers provided in the above embodiment 1, the present invention further provides a device for controlling the transient performance of cascaded erbium-doped fiber amplifiers that can be used to implement the above method.

[0080] like Figure 7 FIG2 is a schematic diagram of the device architecture of an embodiment of the present invention, which includes an input / output optical power sampling module 1, a transient judgment and control module 2, an input / output delay control module 3, a PID parameter correction module 4, and a pump current driving module 5.

[0081] The input / output optical power sampling module 1 receives and caches input and output optical power sampling data, updating it in real time in a first-in, first-out order. It provides a data source for the transient judgment and control module 2, the input / output delay control module 3, and the pump current driver module 5. It utilizes two parallel analog-to-digital converters to drive and receive the input and output optical power sampling values in parallel.

[0082] Transient judgment and control module 2, connected to input / output optical power sampling module 1, processes the cached input optical power sampling data. It estimates the slope of the input optical power based on the continuously sampled input optical power and the least squares method, and uses this to determine whether up and down waves exist in the optical path. If up and down waves are detected, the module outputs an up and down wave status indication signal, which includes both up and down wave overmodulation states, as well as the minimum time interval before exiting overmodulation. This signal is associated with the initialization window parameters enter_window and exit_window.

[0083] Input / output delay control module 3, based on the received overshoot status and configured delay amount, performs delay control on the input and output sample values according to the method provided in Example 1, providing an advance or lag data source for the pump current calculation module, thereby introducing a larger overshoot control variable. This module is associated with the delay overshoot parameters add_dly and drop_dly.

[0084] PID parameter correction module 4, based on the received overshoot status and the configured PID parameter correction amount and scaling ratio, corrects the PID control parameters during the overshoot window according to the method provided in Example 1, thereby introducing a larger overshoot parameter. This module is associated with the PID correction parameters add_P_delta, add_I_delta, add_D_delta, drop_P_delta, drop_I_delta, and drop_D_delta.

[0085] The pump current driving module 5 calculates the PID output current value in the overmodulation state according to the overmodulation parameters and data source provided by the input / output delay control module 3 and the PID parameter correction module 4, and continues to operate in this state according to the overmodulation window period controlled by the transient judgment and control module 2 until leaving the overmodulation state, thereby driving the pump current to generate a corresponding working current.

[0086] By combining the above modules and independently determining transient and overshoot parameters using a single-stage EDFA module, the least squares method is used to estimate the slope of the input optical power change. The slope threshold and hysteresis window are then combined to determine in real time whether there are up and down waves in the optical path. During the transient time period, the transient overshoot time, overshoot threshold, overshoot parameters, and input and output sampling delays are controlled. By combining the single-stage transient performance with the overshoot and undershoot oscillation phenomenon caused by cascading, parameter correction is iteratively performed to effectively suppress transient overshoots and undershoots in the cascaded system, solving the optical surge impact problem caused by transients in the cascaded EDFA.

[0087] In a specific implementation, combined with the control method in Example 1, each module can complete its own preset function by executing specific corresponding actions.

[0088] like Figure 8 As shown, the actions performed by the transient judgment and control module 2 are as follows.

[0089] Step 701: Estimate the slope of the input optical power based on the continuously sampled input optical power and the least square method, and determine whether there are up and down waves in the optical path.

[0090] Step 702: When it is determined that there are up and down waves, the transient judgment and control module 2 outputs an up and down wave state indication signal and the shortest time interval before exiting overmodulation, wherein the up and down wave state indication signal includes an up wave overmodulation state and a down wave overmodulation state.

[0091] Step 703: According to the hysteresis time for entering the overmodulation state and the hysteresis time for exiting the overmodulation state, constrain the delay time for entering the overmodulation state and the shortest time interval for maintaining the overmodulation state.

[0092] In steps 701 to 703, the transient judgment and control module 2 shifts the input cache signal by N levels so that it meets the minimum number of levels required for reliable slope estimation based on the least squares method. The slope k of the optical power change is estimated based on the input optical power of the N-level cache and the least squares calculation formula. The calculation formula is as follows.

[0093]

[0094] Where k is the estimated slope, X i is the i-th serial number of the input optical power value, Y iis the ith input optical power calibration value, and n is the number of sampling samples used for estimation.

[0095] According to the above formula, when n is 8, the transient judgment and control module 2 performs the least square method on the input optical power to estimate the slope k of the optical power change, and the calculation result is as follows.

[0096]

[0097] Each X i and Y i After substituting the actual value of into the calculation, the estimated slope k is compared with the configured upper wave transient decision threshold (add_thr) and lower wave transient decision threshold (drop_thr), and a judgment is output to determine whether the current state is an upper or lower wave state indication signal, where the upper or lower wave state indication signal includes the upper wave overmodulation state and the lower wave overmodulation state. The configured overmodulation state entry hysteresis time (enter_window) and exit overmodulation state hysteresis time (exit_window) constrain the delay time for entering the overmodulation state and the minimum time interval for maintaining the overmodulation state.

[0098] The actions performed by the PID parameter correction module 4 specifically include: calculating the target output power value under the real-time input optical power, and correcting the P, I and D parameters in the scaled PID parameters in the up-wave state and down-wave state according to the up-wave state indication signal and the configured PID correction parameters output by the transient judgment and control module 2, and outputting the corrected P, I and D parameters.

[0099] During this process, the PID parameter correction module 4 calculates the target output power value P under the input optical power in real time. expect =P input +G set , where P input Input optical power value in real time, G set is the current gain setting; according to P expect Reduce or enlarge the original PID. expect When the output power value is increased by 3dB compared with the reference value, the PID parameter is reduced by half compared with the reference setting value; similarly, when P expect When the output power is 3dB lower than the reference output power, the PID parameters are doubled compared to the reference setting value. Based on the up / down wave state indication signal output by the transient judgment and control module 2 and the configured PID correction parameters, the P, I, and D parameters in the scaled PID parameters are corrected in the up / down wave state and the down / up wave state, and the corrected P, I, and D parameters are output.

[0100] like Figure 9 As shown, the actions performed by the input / output delay control module 3 are as follows.

[0101] Step 801: Buffer the sampled values output by the input / output optical power sampling module 1 in a shift register of size W×L, where W is the bit width of the sampled data and L is the depth of the input / output buffer.

[0102] Step 802: When the up-wave state indication signal output by the transient judgment and control module 2 appears and there is no down-wave state indication signal, the interception position of the output or input shift register is adjusted according to the positive or negative value of the up-wave delay control parameter.

[0103] Step 803: When the transient judgment and control module 2 outputs a lower wave state indication signal and no upper wave state indication signal, the interception position of the input or output shift register is adjusted according to the positive or negative value of the lower wave delay control parameter.

[0104] In steps 801-803, when the upper wave state indication signal appears and there is no lower wave state indication signal, the input / output delay control module 3 adjusts the interception position of the output or input shift register according to the positive or negative value of the upper wave delay control parameter add_dly: when add_dly>=0, the corresponding delay value of the output shift register is intercepted and output; when add_dly<0, the corresponding delay value of the input shift register is intercepted and output. When the lower wave state indication signal appears and there is no upper wave state indication signal, the input / output delay control module 3 adjusts the interception position of the input or output shift register according to the positive or negative value of the lower wave delay control parameter drop_dly: when drop_dly>=0, the corresponding delay value of the input shift register is intercepted and output; when drop_dly<0, the corresponding delay value of the output shift register is intercepted and output.

[0105] The pump current driving module 5 performs the following actions: according to the input optical power after delay control outputted by the input / output delay control module 3 and the set gain value, calculates the expected output power value P' after delay. expect =P input_dly +G set , where P input_dly is the input optical power value after delay control, G set =The current gain value. According to the expected output power value after delay and the output optical power after delay control P output_dly , calculate the current PID deviation Error delay =P' expect -P output_dly The PID output current value in the over-modulation state is calculated using the PID deviation and the corrected PID over-modulation parameter output by the PID parameter correction module 4. Based on the above PID output current value and the pre-calibrated feedforward value, the output drives the digital-to-analog conversion chip to generate a pump current corresponding to the digital signal.

[0106] According to the actions performed by the above modules, combined with the method in Example 1, Figure 10 Figure 1 shows a schematic diagram of the complete linkage and feedback process between the various modules of the device provided in this embodiment. To clarify the correspondence between actions and modules, multiple input / output delay control modules 3 and PID parameter correction modules 4 are implemented, corresponding to the different parameters corresponding to different actions. In actual implementation, the number of modules will be determined based on the actual determination accuracy, processing difficulty, and processing cost.

[0107] The EDFA control device for optimizing cascade transient performance provided by this embodiment has the following advantages.

[0108] 1. The single-stage EDFA module is used to independently determine the transient and overshoot parameters. No additional controller is required to assist in correcting transient overshoot, which facilitates project implementation and subsequent maintenance.

[0109] 2. The least squares method is used to estimate the slope of the input optical power change, and the slope threshold and hysteresis window are combined to determine in real time whether there are up and down waves in the optical path. Compared with judging up and down waves based on adjacent power jumps, this method is more stable and reliable, avoids the optical path instability that may be introduced by using overmodulation, and improves system stability.

[0110] 3. By controlling the transient overshoot time, overshoot threshold, overshoot parameters and input and output sampling delay, and combining the single-stage transient performance and the overshoot oscillation phenomenon caused by cascading, the parameters are iteratively corrected to effectively suppress the transient overshoot and undershoot of the cascaded system and solve the optical surge impact problem caused by the transient of the cascaded EDFA.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for controlling transient performance of cascaded erbium-doped fiber amplifiers, characterized in that: Specifically include: Synchronize the optical power detection branches at both ends of the pump and the adjustable optical power attenuator involved in feedback control to calibrate the feedforward values of different pump currents under different gain and input optical power conditions; Under the extreme transient conditions of a single-stage module, debug the PID baseline parameters and roughly adjust the PID overshoot parameters; In the cascade state, debugging the starting point and the ending point of the overshoot window, wherein the range of the overshoot window covers the oscillation duration and the overshoot and undershoot peak positions in the cascade transient effect; Based on the impact of the modified overshoot window on transients, fine-tune the delay parameters and PID correction parameters in the up-wave and down-wave states respectively; Traverse the required gain range, wavelength range and power range, and measure and judge whether the transient indicators meet the expected requirements.

2. The method for controlling transient performance of cascaded erbium-doped fiber amplifiers according to claim 1, characterized in that: The calibrating the feedforward values of different pump currents under different gain and input optical power conditions specifically includes: Adjust the current ratio and current bias of each pump in the first-stage multi-pump to achieve a preliminary balance between the EDFA's ultimate noise figure under low input light conditions and its ultimate transient performance under high input light conditions; According to the current ratio of each pump at different gains, the feedforward current parameters of each pump are calibrated; The feedforward values of different pump currents are calibrated under different gain and input optical power conditions.

3. The method for controlling transient performance of cascaded erbium-doped fiber amplifiers according to claim 1, wherein: The debugging PID reference parameters specifically include: At minimum gain, adjust the PID reference parameters to achieve the optimal extreme transient performance of the current state; According to the expected output power, the power scaling factor in the PID is adjusted to achieve the optimal extreme transient performance of the current state; At maximum gain, the gain scaling factor in the PID is adjusted to achieve the optimal extreme transient performance for the current state.

4. The method for controlling transient performance of cascaded erbium-doped fiber amplifiers according to claim 1, wherein: The coarse adjustment PID overshoot parameter specifically includes: In the wave-up state, adjust the delay overshoot parameter to make the extreme transient performance of the wave-up state reach the preset wave-up performance index; In the wave-drop state, the delay overshoot parameter is adjusted so that the extreme transient performance of the wave-drop state reaches the preset wave-drop performance index.

5. The method for controlling transient performance of cascaded erbium-doped fiber amplifiers according to claim 1, wherein: The starting point and ending point of the debugging overshoot window specifically include: According to the duration of oscillation caused by the cascade transient, adjust the initialization window parameters, extend the overmodulation window, and shift the overmodulation time window back so that the end time point of the overmodulation time window covers the duration of the cascade oscillation. According to the time when the overshoot and undershoot peak values appear in the cascade transient performance, the initialization window parameters and the overshoot and undershoot judgment initialization threshold are adjusted to move the overshoot window forward so that the start time of the overshoot time window covers the time point of the overshoot and undershoot peak values.

6. The method for controlling transient performance of cascaded erbium-doped fiber amplifiers according to claim 1, wherein: The fine-tuning of the delay parameters and PID correction parameters in the up-wave and down-wave states specifically includes: In the up-wave state, fine-tune the delay overshoot parameters and PID correction parameters to optimize the extreme cascade transient performance of the up-wave state; In the down-wave state, fine-tune the delay overshoot parameters and PID correction parameters to optimize the extreme cascade transient performance in the down-wave state.

7. A device for controlling transient performance of cascaded erbium-doped fiber amplifiers, characterized in that: The system comprises an input / output optical power sampling module (1), a transient judgment and control module (2), an input / output delay control module (3), a PID parameter correction module (4), and a pump current driving module (5), specifically: The input / output optical power sampling module (1) is used to receive and cache the sampling data of the input and output optical powers, and update them in real time according to the first-in-first-out order; The transient judgment and control module (2) is connected to the input / output optical power sampling module (1) and is used to process the buffered input optical power sampling data; the transient judgment and control module (2) specifically includes: estimating the slope of the input optical power based on the continuously sampled input optical power and the least square method, and judging whether there are up and down waves in the optical path based on the slope; when it is judged that there are up and down waves, the transient judgment and control module (2) outputs an up and down wave state indication signal, wherein the up and down wave state indication signal includes an up wave overmodulation state and a down wave overmodulation state; The input / output delay control module (3) performs delay control on the input and output sample values according to the received overmodulation state and the configured delay amount according to the method provided in any one of claims 1 to 6, thereby providing an advance or lag data source for the pump current calculation module; The PID parameter correction module (4) corrects the PID control parameters during the overshoot window period according to the received overshoot state and the configured PID parameter correction amount and scaling ratio according to the method provided in any one of claims 1 to 6; The pump current driving module (5) calculates the PID output current value in the overmodulation state according to the overmodulation parameter and data source provided by the input / output delay control module (3) and the PID parameter correction module (4), and continues to operate in this state according to the overmodulation window period controlled by the transient judgment and control module (2) until leaving the overmodulation state.

8. The device for controlling transient performance of cascaded erbium-doped fiber amplifiers according to claim 7, characterized in that: The transient judgment and control module (2) specifically includes: When it is determined that there are up and down waves, the transient judgment and control module (2) also outputs the shortest time interval before exiting overmodulation; The delay time for entering the overmodulation state and the minimum time interval for maintaining the overmodulation state are constrained based on the hysteresis time for entering the overmodulation state and the hysteresis time for exiting the overmodulation state.

9. The device for controlling transient performance of cascaded erbium-doped fiber amplifiers according to claim 7, characterized in that: The PID parameter correction module (4) specifically includes: The target output power value under the real-time input optical power is calculated, and according to the up-down wave state indication signal output by the transient judgment and control module (2) and the configured PID correction parameters, the P, I and D parameters in the scaled PID parameters are corrected in the up-down wave state and the down-down wave state respectively, and the corrected P, I and D parameters are output.

10. The device for controlling transient performance of cascaded erbium-doped fiber amplifiers according to claim 7, characterized in that: The input / output delay control module (3) specifically includes: The sampling value output by the input / output optical power sampling module (1) is buffered in a shift register of size W×L, wherein W is the bit width length of the sampling data and L is the depth of the input / output buffer area; When the upper wave state indication signal output by the transient judgment and control module (2) appears and there is no lower wave state indication signal, the interception position of the output or input shift register is adjusted according to the positive or negative value of the upper wave delay control parameter; When the lower wave state indication signal output by the transient judgment and control module (2) appears and there is no upper wave state indication signal, the interception position of the input or output shift register is adjusted according to the positive or negative value of the lower wave delay control parameter.

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