| 摘要 |
PROBLEM TO BE SOLVED: To provide a branching device with which the transmission characteristic deterioration of main transmission line can be prevented in the case fault occurred on a branch station side transmission line. SOLUTION: The internal configuration of an optical add drop multiplexer/ wavelength multiplexing element) 1 is composed of an optical circulator 14a connected to the input of main signal transmission line, fiber black grating(FBG) 13a for inputting the output of optical circulator 14a, optical isolator 12 for inputting the output of FBG 13a, FBG 13b for inputting the output of optical isolator 12, and optical circulator 14b for inputting the output of FBG 13b. Thus, it is detected an optical Amp 4 is disconnected by any fault on the branch transmission line and even when the bypass of light branched by the optical circulator is formed, this light is shielded by the optical isolator 12 so that any loop is not formed at the time of branch signal bypass and the transmission characteristic deterioration of main transmission line can be prevented. |
