| 摘要 |
PURPOSE:To obtain a light-amplifying device with automatic output control system having simple configuration and without requiring a light branching circuit by providing a light acceptor for receiving naturally radiated light transmitted by a light amplifier and a feedback circuit for controlling DC bias applied to the light amplifier so that the output from the acceptor may be constant by an electrical circuit. CONSTITUTION:A semiconductor double hetero construction light amplifier 1, an electrical circuit 4 applying DC bias to the light amplifier 1, means 18 for inputting light signal to the above light amplifier 1, means 19 for outputting optic signal amplified by the optic amplifier 1 are provided. Furthermore, a light acceptor 3 for receiving naturally radiated light emitted by the light amplifier 1 and a feedback circuit 5 for controlling DC bias applied to the light amplifier 1 so that the output from the optic 3 may be constant are provided. For example, an InGaAs-PIN photo detector of large optical diameter is placed near the side surface of the light amplifier 1 as the light acceptor 3 to enable naturally radiated light level from the light amplifier 1 to be monitored. |
