The folded-back light communication system utilizing polarization characteristics

An optical communication system based on the polarization characteristics of a single laser source is proposed. The return path is produced through mirror reflection and the mutual interference of each modulation signal transmitted between the two stations is eliminated by choosing the relative axial relations among the modulator crystals and the optical components contained in the system. The results were confirmed by telephone call experiments using ADP Pockels modulators. It was found that no mixing of signals occurred if we took the axial relations among the optical components and the modulator crystal as predicted by the theoretical results.