Secure communication based on chaos have been investigated for several years, specially in the area of radiofrecuency transmissions. Signal decoding and decoding is then generaly achieved using a RF carrier whose amplitede fluctuates chaotically. Recent advances have also been reported in the field of optical communications. Signal encryption using chaos has been carried out especially using the idea of synchronized  chaos developed by Pecora and Carroll. We perform experiments in which chaos in wavelength, in the range of 1540 nm, is used to encrypt signals.  Decoding makes use of another generator of chaos operating as a local oscillator synchronized on the first one.

We report a specific implementation of a high dimensional chaotic system for optically encoded communications. It is achieved with a delayed feedback chaotic generator, which is known to produce high dimensinal chaos. Since there is no rigorous analysis for synchronization of delay-differential equations, we used a way different from Pecora-Carroll. Another originality of the method is thatthe method is based on chaos in wavelength, in contrast with previous systems, which make use of chaos intensity. The advantage is that the chaotic regime can be controlled very easily using non-linearity in wave