| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rare-earth element-doped optical fiber amplifier which is provided with a signal generation function and which reduces a noise accumulation effect in a multistage cascade connection at a time when light is amplified and relayed by a method wherein an original signal is self-extracted, the signal is processed in such a way that its waveform is shaped or that its timing is adjusted and exciting signal light is modulated so as to be amplified in synchronization with the injection of signal light to be amplified. SOLUTION: A part of a light signal is taken out by an optical branching filter 30, and it is received with high sensitivity by a light-signal reception means 4 so as to be photoelectrically converted. The received signal which has been converted into an electric signal is timing-regenerated or waveform-shaped through an input drive-type timing filter 33 so as to be returned to the original signal. Exciting light from an exciting light source is modulated by the original signal. The modulated exciting light is multiplexed with the light signal by an optical multiplexer 12, and their multiplexed light is amplified through a rare-earth element-doped optical fiber 15 in synchronization with the injection of the light signal. When the light signal is multiplexed by the optical multiplexer 12, the timing of both is different. As a result, an optical delay circuit 31 is inserted into a light signal line so as to make the timing agree. |
