Effect of control parameters on chaos synchronization by means of optical feedback

An optical communication scheme based on the synchronization of two chaotic semiconductor lasers is investigated experimentally. Two schemes of optical feedback injection, bidirectional and unidirectional, have been used. Synchronization of the chaos is achieved by coupling a fraction of the transmitter's output power to the driving current of the receiver. We present experimental results on the different routes of chaos synchronization. First is by using different current densities from master to slave-making synchronization, second is to apply different frequencies with fixed amplitude by using an external perturbation, and third is by applying a different amplitude white noises signals. Our results show that the third route has perfect results of synchronization. The last two routes are new methods and their experimental results are presented for the first time in making chaos synchronization. Finally, the quality of the synchronization was studied by different methods such as a Cross-Correlation Coefficient and Residual Chaos.