| 摘要 |
PURPOSE: To provide the receiver of optical signals provided with a wide dynamic region. CONSTITUTION: A preamplifier 11 is an optical amplifier, provided with automatic gain control, and the optical output of the preamplifier 11 supplied to the input of this receiver 13 is maintained fixed. For the automatic gain control, before the optical output of the preamplifier 11 is connected via a filter 12 to the receiver 13, a part of it is taken out by a photocoupler 14, detected in a monitoring photodiode 15 and feedback-controlled by an AGC circuit 16, and the output of a pumped erbium fiber amplifier 11 is held fixed. |
