an optical fiber communication system comprises a bus to which are connected two or more individual stations with inputs from the bus and outputs to the bus . each station includes an optical coupler , folded by means of a partially transmissive mirror , wherein the inputs and outputs are optically coupled . a light energy source applies optical energy to the bus which passes through each station by means of the optical coupler associated therewith . each station includes means for modulating the light energy on the bus by varying the optical coupling , and each station has detector means for receiving optical energy passing through the mirror and detecting the presence or absence of modulated signals on the bus . control means at each station initiates operating commands on the basis of the energy detected by the detector means .