Transmission of encoded information based on antiphase dynamics

We propose a method for secure information encoding and transmission that exploits (i) the sensitivity of antiphase dynamics to the relative phase of time-dependent intensities in multimode free-running Fabry-Perot lasers and (ii) the nonreciprocal independence of antiphased states oscillating in orthogonal polarizations. The logical states are chaotic attractors. The signal sent by the transmitter is only part of the key. The total key is the signal plus the receiver. The signal generates the message only in the correct receiver. (C) 1997 Optical Society of America.