| 摘要 |
PURPOSE:To form an optical AGC circuit which can take high reception sensitivity by providing a waveguide having a light amplifying function in front of an optical receiver and controlling the gain of the waveguide. CONSTITUTION:One end of an Er dope optical fiber 1 is coupled with an optical fiber 21 through an optical fiber type directional coupler 2, and the other end is coupled with an APD 8 through an optical fiber type directional coupler 3. Also, to the coupler 2, an excitating light source 4 is connected. An optical signal 61 from the fiber 21 is propagated through the inside of the coupler 2, the optical fiber 1 and the coupler 3 and light-received by the APD 8, and its optical received power is converted to an electric signal. The converted electric signal is amplified by an amplifier 10, and its signal output 11 is fed back to the driving circuit 5 of the excitating light source 4 through a peak detecting circuit 12 and a comparator 13. |
