| 摘要 |
PROBLEM TO BE SOLVED: To amplify optical signals by an optical receiver and to prevent the degradation of reception sensitivity at the time of receiving the transmitted optical signals, by reducing noise characteristics regardless of the level of the intensity of signal light impressed to an optical fiber amplifier. SOLUTION: An amplifier is provided with a third optical fiber medium 470 for amplifying the signal light by using pump light not used in a first optical fiber medium 430; a second wavelength selective coupler 440 for separating light outputted from the first optical fiber medium 430 into the signal light and the pump light, and for impressing the signal light to a second optical fiber medium 450 so as to interrupt impression to the second optical fiber medium 450 by the pump light not used in the first optical fiber medium 430; and a third wavelength selective coupler 460 for coupling the pump light separated by the second wavelength selective coupler 440, and the signal light whose amplification degree is reduced by the second optical fiber medium 450 by one optical fiber and impressing them to the third optical fiber medium 470. |
