| 摘要 |
PROBLEM TO BE SOLVED: To obtain a stable output level even in the case where the level of an input signal greatly varies, by estimating the degree of contribution by a plurality of excitation semiconductor lasers to output power of an optical fiber amplifier, and controlling the power of the excitation semiconductor lasers based on the estimated values. SOLUTION: An output signal from an excitation semiconductor laser 10 is inputted into a WDM coupler 3, and inputted into a rare-earth element doped fiber 5. A CPU 12 detects the signal by an input signal light monitor 6, optical monitors 8 and 9 for excitation semiconductor laser output, and an output signal light monitor 11. Then, based on the detection values, the CPU 12 controls the excitation semiconductor lasers 7 and 10 while feedback-controlling the power from the output signal light monitor 11, outputted from the rare-earth dope fiber 5 and branched from an output signal monitor coupler 4 via the WDM coupler 3, to the input side. By this control, even when the level of the input signal greatly varies, a constant output level can be obtained. |
