TRANSMITTING SYSTEM OF OPTICAL LOOP NETWORK

PURPOSE:To constitute an optical loop network having simple constitution and high reliability, by using optical signals of different waveforms for communication and by-pass. CONSTITUTION:Each optical terminal station device connected mutually in a loop consists of a demultiplexer 6 separating optical signals from a transmission line with the wavelength, an optical reception section 2, an optical transmission section 7 generating two kinds of wavelength of optical signals, and an optical coupler 5. In the normal operation, the optical transmission section 7 of each terminal station device performs transmission of a light source of a wavelength receivable at the section 2 of the next optical terminal station device. If a failure takes place in a specific optical terminal station device in a loop network, the section 7 of the optical terminal station device of the preceding stage transmits signals from the light source of wavelength different from the normal state. Thus, the optical demultiplexer 6 of the optical terminal station device having a failure by-passes this optical signal and transmits the signal to the next optical terminal station device.