OPTICAL REPEATER

摘要

PURPOSE:To provide the constant gain of the input and output of the optical repeater by modulating the bias current of a pumping light source of an optical fiber amplifier by a low frequency and automatically controlling the gain of the optical fiber amplifier in accordance with the output amplitude of the low-frequency component thereof. CONSTITUTION:An oscillator 4 modulates the bias current of the pumping light source of the optical fiber amplifier 10. A photodetector (photodiode) 6 detects one of the output light signals of a 1st optical multiplexer 5 connected to the output of the optical fiber amplifier 10 and converts the signal to an electric signal. A band pass filter 8 allows the passage of the same frequency as the output frequency of the oscillator 4 among the output signals of the detector 6. An automatic gain control circuit 7 adjusts the bias current of the pumping power source in accordance with the output signal of the band-pass filter and controls the gain of the optical fiber amplifier so as to have the constant gain. The constant gain of the input and output of the optical repeater is obtd. in this way.