Optical chaotic secure bidirectional communication based on optical injected electro-optical phase delay feedback loop

Abstract

To enhance chaotic complexity and conceal time-delay signatures, we propose an optically chaotic secure communication system. The system combines chaotic intensity signals from an amplified spontaneous emission (ASE) noise source with an electro-optical phase delay oscillating feedback loop through optical injection. It integrates all-optical intensity chaos and electro-optical feedback to produce complex chaotic signals. ASE noise acts as an entropy source, while a fiber Bragg grating (FBG) enhances signal complexity by leveraging its dispersion properties. This approach significantly expands the system’s key space. The transmitted information is nonlinearly coupled with the chaotic carrier via phase modulation, contributing to the chaotic carrier’s generation. At the receiver, optical chaotic synchronization decrypts the transmitted signals. Performance analysis shows that the system effectively hides time-delay signatures, increases chaotic complexity, and exhibits strong resistance to parameter mismatches. These results demonstrate its high security for physical-layer communication.