On/Off phase shift keying encryption method of semiconductor lasers with an air gap

Abstract

We discuss the dynamical behaviour of a single mode semiconductor laser with an air gap under the influence of multiple optical feedbacks. It is shown that the system displays, under certain conditions, chaotic behaviours appropriate for chaos based communications. The synchronization of two unidirectional coupled (master-slave) systems is also studied. Finally, the conditions for message encoding by using the on/off phase shift keying encryption method are identified and examples of message encoding/decoding are presented.