A new light communication system is proposed, which makes possible to do mutual communi-cation between two separate stations using only one laser transmitter. Light from a gas laser set in a station A is modulated by a modulator K2 and propagated to the other station B. A part of the modulated light is demodulated by the detector in the station B. A new signal is superposed by the modulator K2 in the station B on the rest of the modulated light which is folded back to the station A. The azimuthes of the optical components are selected so as to eliminate the mutual interference of the two modulated signals transmitted through the going and the coming back path. The optimum conditions obtained by use of Jones matrices were examined by telephone call experiments using ADP pockels modulators.
