| 摘要 |
PURPOSE:To improve reliability for a long term and time stability by branching inputted signal light, supplying each to an input terminal of one of plural optical amplifiers so as to vary the amplifier gain of each optical amplifier in response to a monitored output. CONSTITUTION:A signal light sent from an optical fiber 61 is divided into two equally by a fiber coupler 11 and made incident in semiconductor laser amplifiers 21, 22. Then, the two optical amplifiers 21, 22 are used, amplify the light and synthesize it again and a monitor output is used to control the amplification gain of the optical amplifiers 21, 22. Thus, the level of the output signal after re-synthesis is kept constant by controlling the amplification gain of other optical amplifier even when the amplification gain of an optical amplifier depending on the change in the polarized state of the input signal light or the change in ambient temperature. Thus, the reliability for a long term and the timewise stability are improved. |
