Method for realizing precise target gain control for hybrid fibre amplifier, and hybrid fibre amplifier

Patent metadata

Field	Value
Publication number	US-11239628-B2
Application number	US-201616089929-A
Country	US
Kind code	B2
Filing date	Dec 19, 2016
Priority date	Mar 30, 2016
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

A method for realizing precise gain control for a hybrid fibre amplifier, and a hybrid fibre amplifier, in which by an erbium-doped fibre amplifier firstly outputting a constant power, a comparable source signal optical power is provided for a raman fibre amplifier of a next stage. A feedback for the gain control may be formed by comparing a source signal optical power calculated after starting pumping of the Raman fibre amplifier and a source signal optical power detected after pumping stops, thereby greatly improving gain control precision of the Raman fibre amplifier. Moreover, the erbium-doped fibre amplifier parts of all the hybrid fibre amplifiers may simultaneously output a constant optical power, and the Raman amplifier parts of all the hybrid fibre amplifiers may simultaneously start calibration, so that the time for starting operation of the entire system may be improved greatly.

First claim

What is claimed is:

1. A method for realizing precise target gain control of a hybrid fibre amplifier, being characterized in comprising the following steps:
Step 1: controlling an erbium-doped fibre amplifier of the hybrid fibre amplifier firstly to output light with a constant power P1 when the hybrid fibre amplifier starts pumping;
Step 2: after the erbium-doped fibre amplifier outputs the constant power for a period of time t1, controlling a Raman fibre amplifier of the hybrid fibre amplifier to detect a source signal optical power S1 and an out-of-band ASE power Source_ASE1 contained in the source signal light;
Step 3: reading a target gain G1 from a control unit part and a relationship between the gain and the out-of-band ASE obtained by calibration to calculate a target ASE power P G1 _ASE1, and calculating a target out-of-band ASE power Target_ASE_1 compensated by the source ASE: Target_ASE_1=P G1 _ASE1+Source_ASE1*G1;
Step 4: controlling the Raman fibre amplifier to start pumping when it is determined that the source signal optical power S1 detected by the Raman fibre amplifier becomes stable, and reading a detection value of the out-of-band ASE power in real-time;
Step 5: comparing the detection value of the out-of-band ASE power read in Step 4 with the Target_ASE_1, and stopping adjustment of the pumping power when the two values are equal to each other;
Step 6: when the pumping power of the Raman fibre amplifier becomes stable, calculating a source signal optical power S2 after starting pumping, and comparing S1 with S2 to calculate a delta Gain ΔG=S2−S1; if the delta Gain meets an accuracy requirement, proceeding to Step 8 directly; and if the delta Gain does not meet the accuracy requirement, proceeding to Step 7;
Step 7: compensating the delta Gain to the target gain to obtain G2=G1−ΔG; repeating Step 3 to calculate a new target out-of-band ASE power ASE3; and repeating Step 4, Step 5 and Step 6 in this order;
Step 8: controlling the erbium-doped fibre amplifier to start pumping according to a preset gain requirement so as to achieve a rated control gain of the hybrid fibre amplifier when the pumping power of the Raman fibre amplifier becomes stable.

2. A hybrid fibre amplifier for realizing a precise target gain control, being characterized in comprising a Raman fibre amplifier part ( 1 ), an erbium-doped fibre amplifier part ( 9 ), and a control unit part ( 10 ); the Raman fibre amplifier part including a pump signal combiner ( 2 ), a Raman pump laser bank ( 11 ) connected to a pumping input end of the pump signal combiner ( 2 ), a first optical splitting coupler ( 3 ) connected to a signal output end of the pump signal combiner ( 2 ), a first photodetector ( 4 ) connected to a low transmission end of the first optical splitting coupler ( 3 ), an out-of-band ASE filter ( 5 ) connected to a high transmission end of the first optical coupler ( 3 ), a second photodetector ( 6 ) connected to an out-of-band light output end of the out-of-band ASE filter ( 5 ), a second optical splitting coupler ( 7 ) connected to a signal light output end of the out-of-band ASE filter ( 5 ), a third photodetector ( 8 ) connected to a low transmission end of the second optical splitting coupler ( 7 ), a high transmission end of the second optical splitting coupler ( 7 ) serving as an output end of the Raman fibre amplifier part, and the output end of the Raman fibre amplifier part being connected with an input end of the erbium-doped fibre amplifier part ( 9 ); wherein the low transmission end for the first coupler and the second coupler is tap output with low transmission, and the high transmission end for the first coupler and the second coupler is tap output with high transmission as compared to the low transmission end;
the control unit part ( 10 ) being connected with the Raman pump laser bank ( 11 ), the first photodetector ( 4 ), the second photodetector ( 6 ), the third photodetector ( 8 ), and the erbium-doped fibre amplifier part ( 9 ), respectively,
wherein the first photodetector of the Raman fibre amplifier is used for detecting a source signal optical power S1 and an out-of-band ASE power Source ASE1 contained in the source signal light when the Raman stops pumping.

3. The hybrid fibre amplifier for realizing a precise target gain control according to claim 2 , being characterized in that:
the control unit part ( 10 ) includes a pump laser output control unit ( 20 ), a signal light and out-of-band ASE detecting and storing unit ( 21 ), a gain and out-of-band ASE calculating unit ( 22 ), and an erbium-doped fibre amplifier gain control unit ( 23 ).

Assignees

• Accelink Tech Co Ltd

Inventors

• Tao Jintao
• Fu Chengpeng
• Zhang Cuihong
• Cai Fei
• Xiong Tao
• Jing Yunyu
• Bu Qinlian
• Yu Chunping

Classifications

• H04B10/293 Primary

  Signal power control · CPC title

• H04B10/2916

  using Raman or Brillouin amplifiers · CPC title

• H01S3/2375

  Hybrid lasers (H01S3/07 takes precedence) · CPC title

• H01S3/1608

  erbium · CPC title

• H01S3/06758

  Tandem amplifiers · CPC title