| 摘要 |
PROBLEM TO BE SOLVED: To absorb usual level fluctuations and momentary level fluctuations of an input optical signal while preventing production of light surge with respect to the optical receiver that receives a transmitted optical signal via an optical fiber. SOLUTION: The receiver is provided with an optical fiber amplifier 12 that amplifies an input optical signal, with a photo diode 16 that converts an output light of the optical fiber amplifier 12 into an electric signal, a variable amplification factor electric amplifier 22 that amplifies the electric signal outputted from the photo diode 16, a 1st level detection circuit 20 that generates a 1st control signal S1 based on an output signal from the variable amplification factor electric amplifier 22 and with a 1st level conversion circuit 24 that generates a 2nd control signal S2 based on the control signal S1. The optical fiber amplifier 12 and the variable amplification factor electric amplifier 22 execute feedback control based on the signal S1 or S2 respectively. |
