Secure Optical Communication Systems based on Chaotic Carriers

Abstract. In this Thesis, the generation of a chaotic carrier by semiconductor lasers is theoretically studied. Three different encoding techniques are employed and the performance of an optical chaotic communications system for different receiver configurations is evaluated. It is proved that chaotic carriers allow the successful encoding and decoding of messages with up to 10 Gb/s bit rate. Focusing on the Chaotic Modulation encoding method it is shown that the normalized decoding method provides significantly different results in the estimation of the system’s performance compared to the method of photocurrent subtraction, proposed in this study. Finally, the effects of transmission in optical fiber are studied for a chaotic communications system when CM and CSK encoding techniques are employed for various message bit-rates. The downgrading of the system’s performance due to fiber transmission impairments is confronted by the employment of various dispersion management techniques