| 摘要 |
PURPOSE:To obtain an optical amplifier which produces no much noise and can respond at a high speed by constituting the optical amplifier of on fiber amplifier cascade-connected in multiple stages and semiconductor laser amplifier and amplifying the optical signal inputted to the optical amplifier by means of the first-stage fiber amplifier. CONSTITUTION:The title optical amplifier is constituted so that the signal light inputted to the title optical amplifier can be first amplified by means of an amplifier 1 composed of a rare-earths doped optical fiber and again amplified by means of a semiconductor laser amplifier 2. A monitor section 7 monitors the gain or signal output of the optical amplifier and a control circuit 8 controls the gain or signal output of the optical amplifier by driving the exciting light source 4 of the amplifier 1 and current device circuit 6 of the amplifier 2 based on monitored values outputted from the section 7. |
