Secure optical communication using dual-feedback chaotic lasers with adaptively controlled time delay feedback

Abstract We propose and numerically demonstrate a secure optical communication scheme based on a variable-parameter electro-optical time delay system driven by dual-feedback chaotic input. In this scheme, chaos generated via a dual-feedback mechanism serves as the input to an electro-optical time delay feedback system. This input dynamically modulates the feedback strength and expands the number of hardware security parameters. This approach effectively conceals delay characteristics, significantly enhancing system security. Numerical simulation results confirm the successful transmission of 20 Gb s −1 4-level pulse amplitude modulation (PAM4) data over a 150 km fiber link. At the legitimate receiver, chaotic synchronization and decryption are achieved using an open-loop symmetric structure, yielding a bit error rate (BER) of 1.34 × 10 −3 . The results demonstrate that the scheme offers a robust and promising solution for high-speed, long-haul optical communication systems with improved security.