STOCHASTIC RESONANCE IN A CHAOTIC SEMICONDUCTOR LASER

We report the experimental evidence of stochastic and coherence resonance in a chaotic semiconductor laser with optoelectronics feedback. Gaussian white noise has been applied to the laser chaotic output. The chaotic system becomes regular under a moderate noise level. In stochastic resonance, the noise serves to enhance the nonlinear system response to a weak regular perturbation. We have checked the feasibility of detection of weak periodic signals of different frequencies where the stochastic resonance is realized. In particular, we observed that the noise level should be increased when the modulating frequency is high. Results show that what plays a key role is the amplification of the modulating (perturbation) signal. In particular, this offers the ability to extract the periodic signal without synchronization in chaos communications. This fact opens new perspectives in chaos communications when the synchronization will not be required.