Chaotic Architectures for Secure Free-Space Optical Communication

Free-Space Optical (FSO) communication provides very large bandwidth, relatively low cost, low power, low mass of implementation, and improved security when compared to conventional Free-Space Radio-Frequency systems. Secure FSO communications has usually been proposed through the use of laser N-slit-interferometers. This technique, however, works over relatively short propagation distances, particularly for deep-space communication. In this paper, we propose the use of chaotic systems combined with FSO in order to achieve robust longer-range communication while maintaining the inherent security in chaotic systems targeting both space and terrestrial applications. Chaotic systems show particular characteristics such as broadband noise-like signals with multi-path fading resistance, unpredictability, and sensitivity to initial conditions which make it difficult for unintentional receivers to synchronize to the chaotic signal. We also propose the use of FPGAs as the implementation technology that could meet the demanding real-time requirements of FSO communications. The experimental results show favorable characteristics of our approach.