| 摘要 |
PURPOSE:To simplify the restoring work by performing restoration from a fault without cutting an optical fiber. CONSTITUTION:Optical transmission lines 30 and 50 are halfway branched by tree type optical couplers C1 to C4 and are formed like a tree. Tree type optical couplers C1 to C4 have two ports P11 and P12, two ports P21 and P22, two ports P31 and P32, and P41 and P42 for input or output of optical signals respectively on the start point side of the tree. Normally, only one ports P11, P21, P31, and P41 are used and the other ports are spare. If a fault occurs in any place, a cable for emergency is connected to spare ports P12, P22, P32, and P42 to form a transmission line bypassing this place where the fault occurs. |
