| 摘要 |
PURPOSE: A retrieval method after recovery of a WDM(Wave Division Multiplexing) system of a ring-type optical communication network is provided to make two nodes, directly connected with a failed optical fiber, form a closed-loop when recovering the optical fiber, and to make a gain of the closed loop exceed 1 to lead lasing, so that optical signals under transmission with a standby optical fiber can be transferred to an operating optical fiber. CONSTITUTION: If multiple nodes(14a-14d) are connected through an operating optical fiber(10) and a standby optical fiber(12) and a failure is generated while optical signals are transmitted with the operating optical fiber(10) in a normal state, the failure is detected using light receiving elements inside the nodes(14a-14d). Space switches configuring nodes(14c,14d) adjacent to a failure generating block is controlled. A signal passing the failure generating block is transferred to the standby optical fiber(12). The failed operating optical fiber(10) is recovered, to form a closed loop(20) by the operating optical fiber(10), the standby optical fiber(12) and the adjacent nodes(14c,14d). A loop gain of the closed loop(20) is made to be larger than 1(one), to lead lasing in the closed loop(20). The nodes(14c,14d) monitor an optical strength of the failure generating block, to control a switch(SW) and recover an optical communication network to a normal state if the optical strength exceeds a predetermined value.
|
