公开(公告)号：US5179604A

公开(公告)日：1993-01-12

申请号：US813968

申请日：1991-12-24

申请人： Hisaharu Yanagawa ,  Takeo Shimizu ,  Shiro Nakamura ,  Isao Oyama

发明人： Hisaharu Yanagawa ,  Takeo Shimizu ,  Shiro Nakamura ,  Isao Oyama

IPC分类号： G02B6/122 ,  G02B6/28 ,  G02B6/34

CPC分类号： G02B6/2804 ,  G02B6/29361

摘要： A 2-input/2-output directional coupler is arranged as an element coupler/splitter for a first stage, and 1-input/2-output coupler/splitters are used as element coupler/splitters for a second stage and subsequent stages. Output ports of these element coupler/splitters are concatenated with input ports of other element coupler/splitters to form a 2-input/multi-output coupler/splitter. An optical signal can be inputted through one input port of the first-stage 2-input/2-output directional coupler, and an optical signal for optical line monitoring can be inputted through the other input port. It is unnecessary, therefore, to use an optical wavelength division multiplexer/demultiplexer or other optical part which conventionally is connected at the time of optical line monitoring.