OPTICAL AMPLIFIER, OPTICAL FIBER RAMAN OPTICAL AMPLIFIER AND OPTICAL SYSTEM

摘要

PROBLEM TO BE SOLVED: To prevent malfunction of a breaking circuit of an optical amplifier caused by a Raman exciting light. SOLUTION: Exciting light removing filters are placed at the front of an input light detector and a reflected light detector constituting the optical amplifier. A residual component of the Raman exciting light transmitted from lower reaches of an optical fiber transmission path is removed. Only signal component is detected and a breaking operation is performed. A determining threshold for breaking is changed depending on an on or off state of the exciting light. Or Raman exciting light is used for detecting of an output release.