Chaotic secure communication based on optoelectronic differential coupling phase feedback

Addressing the issue of increasingly complex structures in current optoelectronic feedback chaotic secure communication systems designed to suppress time-delay characteristics, we propose a chaotic secure communication system based on optoelectronic differential coupling phase feedback, which holds promise for overcoming the aforementioned limitations. In this system, all-optical chaos is injected into the classical optoelectronic phase feedback loop through optoelectronic conversion, and it is differentially coupled with the chaotic signal of the feedback loop, enhancing the complexity of the system’s chaotic carrier and effectively masking the delay characteristics of the optoelectronic phase feedback loop. The simulation results show that when the feedback gain is less than 1 based on the optoelectronic differential coupling phase feedback system, a delay-free chaotic output can be realized, which can effectively prevent the eavesdropper from cracking the encrypted information. When the system feedback parameter β=5 and the mismatch range of the time-delay T2 in the all-optical chaotic branch are within 30 ps, the cross-correlation function value can still remain above 0.9, and its change with the feedback parameter is not significant. In addition, when the mismatch of the delay parameters T1 and δT in the optoelectronic phase feedback loop exceeds 10 ps, the cross-correlation function value drops below 0.6 and varies significantly with changes in the feedback parameters. This indicates that introducing all-optical chaos has a little impact on system synchronization while effectively concealing the delay parameters of the optoelectronic feedback loop, offering high robustness and security.