Image Number 3 for United States Patent #4956834.
A transmitter includes a coupler having N input prots and N output ports, N being the number of input signals to be multiplexed. The coupler has a unitary coupling matrix, and receives N input signals at its input ports to produce N intermediate transmitting signals at its output ports. The intermediate transmitter signals are subjected to different time delays and then combined into a composite optical signal launched onto an optical bus. At the receiver, the composite signal is divided into N intermediate receiver signals, the intermediate receiver signals are time delayed in the same manner as in the transmitter, and then coupled to input ports of a receiver coupler that has a coupling matrix equal to the transpose of the transmitter's coupling matrix. The output port signals may then be detected and processed to decouple the N data channels.