| 摘要 |
PROBLEM TO BE SOLVED: To dispense with the need for manual control of ASE dummy optical power, when a signal wavelength is added. SOLUTION: Signal light output devices 12-1 to 12-4 respectively output signal beams of mutually different wavelength to optical amplifiers 14-1 to 14-4. Each of optical amplifiers 14-1 to 14-4 amplifies the input signal light, so that the optical power becomes a fixed value. An ASE light source 16 outputs ASE dummy light of wavelengths λa and λb lying outside the signal wavelength band. An optical multiplexer 20 multiplexes the output beams of the ASE light sources 16 and 18, and an optical amplifier 22 amplifies the output light of the optical multiplexer 20 with a gain corresponding to a control signal from a control circuit 32. An optical multiplexer 24 multiplexes the output light of the optical amplifiers 14-1 to 14-4 and 22, and a demultiplexer 26 supplies almost all of the output light of the optical multiplexer 24 to an optical amplifier 28 and supplies the remaining light to a photodetector 30. The photodetector 30 converts the light signal from the demultiplexer 26 into an electrical signal. In accordance with the output of the photodetector 30, the control circuit 32 controls the gain of the optical amplifier 22, the total optical power of the optical multiplexer 24 becomes equal to the total optical power when the entire wavelength band is used. |
