Optical communications using synchronized hyperchaos

We report experiments in which chaos in wavelength, rather than in intensity, is advantageously used to encrypt signals. The latter are encrypted as chaotic fluctuations of the wavelength of a tunable semiconductor laser driven by a generator of chaos. Decoding makes use of another generator of chaos operating as a local oscillator synchronized on the first one. The first results are reported in the wavelength range of 1550 nm. 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 dimensional chaos. Since there is no rigorous analysis for synchronization of delay-differential equations, we used a way different from Pecora and Carroll (1991). Another originality of the method is that the method is based on chaos in wavelength, in contrast with previous systems which make use of chaos in intensity. The advantage is that the chaotic regime can be controlled very easily using a nonlinearity in wavelength rather than in power