Performance of Synchronized Chaotic Optical Communication Systems

Abstract

Chaotic optical communication is a novel communication scheme that utilizes optical chaotic waveform to transmit messages at a high bit rate. Its potential applications include secure communications and spread-spectrum communications. In a chaotic optical communication system, a nonlinear dynamical system is used to generate the optical chaotic waveform for message transmission. Messages are encoded through chaos encryption where the messages are mixed with the chaotic waveform. Message recovery is achieved by comparing the received signal with a reproduced chaotic waveform which synchronizes with the chaotic waveform from the transmitter. Details are discussed in this chapter regarding each of the above basic issues. Furthermore, we also review the experiment of chaotic optical communication at 2.5 Gb/s, which has the highest bit rate in any chaotic communication systems ever reported in the literature. This system uses semiconductor lasers with delayed optoelectronic feedback to generate chaotic pulses. Three major encoding and decoding schemes, namely, chaos masking, chaos shift keying, and chaos modulation, are implemented and compared in this 2.5 Gb/s chaotic optical communication system. The chaos modulation scheme is found to have the best performance. To investigate the potential applications of chaotic optical communications at an even higher bit rate, numerical simulations are carried out on chaotic optical communication systems operating at 10 Gb/s. In this numerical study, three different systems using semiconductor lasers with optical injection, optical feedback, or optoelectronic feedback, respectively are investigated. It is shown that chaotic optical communication at 10 Gb/s is feasible with high-speed semiconductor lasers.