In a recent publication (Delisle and Cielo) a method of communication by optical waves, based on the variation of fringe interval in the channelled spectrum from a broad band source, was presented. The purpose of the present paper is to show, both theoretically and experimentally, how to construct a multiplex communication system based on this principle, which allows a simultaneous transmitting and receiving of several messages. Within the framework of studying several variables of the system, particular attention is given to the choice of path-length differences in the emitting interferometers. This choice must be within certain constraints in order to avoid crosstalk or reduce it to a negligible level. A slightly different approach is also described, multiplexing by frequency, which presents certain advantages over the first method, multiplexing by wavelength difference, especially where it concerns the intensity of the transmitted light beam as a function of the number of emission sources.[Journal translation]