Coherent detection loop distribution system

Abstract From the Canadian patent

An optical fiber point-to-multipoint communications network is disclosed of the type having a bus topology. The broadcasting terminal (101) of the network includes an information transmitting laser (102) and a local oscillator laser (103) the signals of which are launched onto opposite ends of an optical fiber bus (104) to counter-propagate thereon. At each of the M stations (105-1 - 105-M) connected to the bus a wideband, directional coupler (106-1 - 106-M) couples portions of each of the counter-propagating signals to a balanced coherent detector (107-1 - 107-M). The effective total power input to the balanced coherent detector at each of the stations is equal regardless of the location …