| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-way optical transmission system, capable of bidirectionally distributing supervisory light and high in reliability by introducing or leading the supervisory light having wavelength different from signal light and also different from each other to a transmission line. SOLUTION: Signal light is bidirectionally transmitted from an optical transmitter 21 to an optical receiver 42 and also from an optical transmitter 22 to an optical receiver 41 . In a line state, optical supervisory multiplexers 91 to 96 multiplexes supervisory light that is sent from optical supervisory transmitters 81 to 86 to transmission lines 71 to 73 , and optical supervisory demultiplexers 101 to 106 transmit separated supervisory light to optical supervisory receivers 111 to 116 in terminal station relaying devices 51 and 52 , which adjoin the lines 71 to 73 or intermediate relaying devices 61 and 62 . As a result, line supervision or information communication is performed. Supervisory light is also transmitted in a reverse direction of the lines 71 to 73 . Back scattered light can be separated from supervisory light to be received through the demultiplexers 101 to 106 , by making the supervisory light distributed bidirectionally of different wavelength respectively. |
