| 摘要 |
PURPOSE:To provide an optical communications system, in which no problem occurs even when inserting an optical amplifier, by hardly turning reflected light into noises, reducing the passed light loss of a node while using a single mode optical fiber, and connecting a lot of nodes. CONSTITUTION:This system is provided with optical fibers 1 and 2 provided in the shape of a ring through the plural nodes, optical amplifiers 4 and 5 inserted to the optical fibers so as to respectively turn optical signals in a clock-wise direction and a half clock-wise direction, optical switches 41-44 respectively inserted to the optical fibers at the respective nodes, optical transmitters 11-13, optical receivers 14-16 and photocouplers 6-10. In a normal state, the optical amplifiers are not operated but the transmitted optical signals from the respective nodes are absorbed, when the optical fibers are discontinued, the optical amplifiers are operated so as to restart communication and when only one core of optical fibers is discontinued, one of optical switches is turned off while specifying the discontinued position, the state of discontinued two cores is provided, and the optical amplifiers are operated later. |
