Method and system for controlling Raman fiber amplifier

Patent metadata

Field	Value
Publication number	US-12294195-B2
Application number	US-201917434502-A
Country	US
Kind code	B2
Filing date	Dec 13, 2019
Priority date	Feb 27, 2019
Publication date	May 6, 2025
Grant date	May 6, 2025

Abstract

Provided are a method and system for controlling a Raman fiber amplifier. The method comprises: according to a target gain and a tilt, calculating an expected output power of a pump by using a feedforward formula, and obtaining an actual output power of the pump through detection ( 201 ); locking the actual output power of the pump to the expected output power through first-stage feedback control ( 202 ); according to the target gain and the tilt, calculating an expected ASE power of the pump by using an ASE formula, and obtaining an actual out-of-band ASE power of the pump through detection ( 203 ); if the out-of-band ASE is not locked, determining gain compensation and tilt compensation of the pump through second-stage feedback control, and feeding the compensation back to the feedforward formula and the ASE formula for recalculation ( 204 ); and repeatedly performing the first-stage feedback control and the second-stage feedback control until the gain and the tilt are locked ( 205 ). In the system, a combination of feedforward and multi-closed loop feedback control is used to realize rapid locking of a pump power and locking of the gain and the tilt compensation, which improves the control precision of the gain and the tilt and accelerates a response speed.

First claim

What is claimed is:

1. A method for controlling a Raman fiber amplifier, characterized in comprising:
according to a set target gain and a set target tilt, calculating expected output power of each pump by using a feedforward formula, and obtaining actual output power of each pump through PD detection;
locking the actual output power of each pump to the corresponding expected output power through first-stage feedback control;
according to the set target gain and the set target tilt, calculating expected out-of-band ASE power of each pump by using an ASE formula, and obtaining actual out-of-band ASE power of each pump through PD detection;
in a case where the out-of-band ASE power of a pump is not locked, determining gain compensation and tilt compensation of the pump through second-stage feedback control, and feeding the compensation back to the feedforward formula and the ASE formula for recalculation; and
repeatedly performing the first-stage feedback control and the second-stage feedback control to each pump, until the actual out-of-band ASE power of the pump is locked to the corresponding expected out-of-band ASE power to realize the locking of the gain and the tilt.

2. The method for controlling the Raman fiber amplifier of claim 1 , characterized in that, before calculating the expected output power of each pump by using the feedforward formula, the method further comprises: outputting one power to the corresponding pump in a case where each pump is turned on, and calculating an insertion loss of optical fiber currently accessing each pump according to the detected actual out-of-band ASE power;
then after the expected output power of each pump is calculated by using the feedforward formula, the method further comprises: compensating the corresponding calculated insertion loss to the expected output power of each pump as the expected output power for subsequent use.

3. The method for controlling the Raman fiber amplifier of claim 1 , characterized in that, for each pump, in a case of where setting the target gain and the target tilt, performing regulation in a stepping manner for the both, thus gradually modulating the gain from zero to the target gain, and gradually modulating the tilt from zero to the target tilt.

4. The method for controlling the Raman fiber amplifier of claim 1 , characterized in that, for each pump, the process of the first-stage feedback control is:
setting a reasonable proportional parameter and a reasonable differential parameter through a PID controller, and regulating pump output DAC so as to regulate a pump driving current without shaking, thereby locking the actual output power of the pump to the corresponding expected output power.

5. The method for controlling the Raman fiber amplifier of claim 1 , characterized in that, before calculating the expected output power of each pump by using the feedforward formula according to the set target gain and target tilt, the method further comprises:
setting N fixed gain points in an AGC mode, respectively calculating a difference between unamplified input optical power at each fixed gain point and input optical power in a case where the pump is turned off, and performing curve fitting on the differences and gains, so as to obtain an error fitting curve of different gain points, wherein N≥3;
then after the set target gain is provided, determining a gain compensation amount corresponding to the gain point currently set according to the error fitting curve, and performing compensation to the target gain currently set by the gain compensation amount, so as to be subsequently used in the feedforward formula and the ASE formula.

6. The method for controlling the Raman fiber amplifier of claim 1 , characterized in that, for each pump, the feedforward formula needs to be calibrated according to the tilt in advance, which is as follows:
under the current tilt, determining output power of each pump under different gains, and then performing curve fitting; determining a relevant parameter in the feedforward formula corresponding to each pump according to a fitting curve, and then completing a calibration of the feedforward formula.

7. The method for controlling the Raman fiber amplifier of claim 1 , characterized in that, for each pump, the ASE formula needs to be calibrated according to the tilt in advance, which is as follows:
under the current tilt, determining a leakage factor and out-of-band ASE power of each pump under different gains, and then performing curve fitting; and determining a relevant parameter in the ASE formula corresponding to each pump according to a fitting curve, and then completing a calibration of the ASE formula.

8. The method for controlling the Raman fiber amplifier of claim 1 , characterized in that, for each pump, the first-stage feedback control needs to be calibrated in advance, which is as follows:
entering a APC mode, setting the expected output power of each pump, regulating a proportional parameter, differential parameter and regulation period of a PID feedback algorithm in the first-stage feedback control, so that the output of each pump can be stably locked to target power, thereby making the first-stage feedback control effective.

9. The method for controlling the Raman fiber amplifier of claim 1 , characterized in that, for each pump, the second-stage feedback control needs to be calibrated in advance, which is as follows:
entering a AGC mode, setting an expected gain and an expected tilt of ease pump, regulating a proportional parameter, differential parameter and regulation period of a PID feedback algorithm in the second-stage feedback control, so that the out-of-band ASE power of each pump can steadily approach a target value through feedback regulation, thereby realizing the lock of the out-of-band ASE power through the gain compensation and the tilt compensation.

10. A system for controlling a Raman fiber amplifier, characterized in comprising: a feedforward calculation module, a pump power calculation module, a first-stage feedback control module, an expected out-of-band ASE calculation module, an actual out-of-band ASE calculation module, a second-stage feedback control module, and one or more pumps;
wherein the feedforward calculation module is used for calculating expected output power of each pump according to a currently set gain and a currently set tilt;
the pump power calculation module is used for calculating actual output power of each pump according to PD detection;
the first-stage feedback control module is used for locking the actual output power of each pump to the expected output power through a feedback algorithm;
the expected out-of-band ASE calculation module is used for calculating expected out-of-band ASE power of each pump according to the currently set gain and the currently set tilt;
the actual out-of-band ASE calculation module is used for calculating actual out-of-band ASE power of each pump according to the PD detection; and
the second-stage feedback control module is used for determining gain compensation and tilt compensation of each pump through a feedback algorithm, and feeding them back to the feedforward calculation module and the expected out-of-band ASE calculation module.

Assignees

• Accelink Tech Co Ltd

Inventors

• Zhang Hao
• Fu Chengpeng
• Tao Jintao
• Cheng Lijing
• Zeng Bingmei
• Fan Jingyang

Classifications

• H01S2301/02

  ASE (amplified spontaneous emission), noise; Reduction thereof · CPC title

• H01S3/302

  in an optical fibre · CPC title

• H01S3/1301

  in optical amplifiers · CPC title

• H01S3/06754

  Fibre amplifiers (H01S3/06708 takes precedence) · CPC title

• H01S3/1312

  by controlling the optical pumping · CPC title