| 摘要 |
PROBLEM TO BE SOLVED: To provide a system that can quickly detect a fault caused in a pre-optical amplifier, a booster optical amplifier and an optical transmission line so as to be recovered quickly. SOLUTION: The system consists of an optical transmission terminal station, an optical reception terminal station and an optical cable interconnecting both the terminal stations, and the optical transmission terminal station provided with optical transmitters that transmit signal lights, an optical multiplier that applies wavelength multiplexing to the signal lights, an optical branching unit that branches the wavelength multiplexed signal light, and two booster optical amplifiers that respectively apply optical amplification to both the branched signal lights to provide an output of the amplified lights to 1st and 2nd optical transmission lines. The optical reception terminal station, is however, provided with 1st and 2nd pre-optical amplifiers that apply optical amplification to the signal lights outputted from both the optical transmission lines, whose optical switching circuit selects either of both the signal lights. The signal light, outputted from the optical switching circuit, is branched to each signal light and each optical receiver converts the signal light into an electrical signal. An optical coupler is placed in place of the optical switching circuit and may be controlled through the operation of the pre-optical amplifier. |
