Bidirectional communication with time-delay concealment in a system combining all-optical intensity and electrooptical phase chaos

Abstract

In this paper, we propose and study theoretically a novel architecture, which combines all-optical intensity chaos and electrooptical-phase chaos generator, allows for bidirectional secure communication. The configuration includes three all-optical chaotic semiconductor lasers and two identical phase-chaos electrooptic delayed oscillators in the optic-fiber link. We investigate the complexity degree of this chaotic time trace generated in this system and the concealment of the time delay signature (TDS), and systematically analyze the influence of the parameter mismatch on synchronization performance , We demonstrate that the system can generate the chaos with high complexity degree through a calculation of the largest Lyapunov exponent (LLE), Lempel–Ziv complexity (LZC), permutation entropy (PE) and fractal box-counting dimension (FBCD); the TDS of an electro-optical delayed oscillator is concealed by calculating the autocorrelation function (ACF) and the delayed mutual information (DMI); the parameter mismatches, such as the TDS, the bias current, the line width enhancement factor (LWEF), etc., have the influence on the synchronization performance; the changes of the bit rate and the modulation index have the influence on Q-factor of the system. Moreover, our numerical simulations also reveal that, under the parameter match condition the delayed chaotic dynamics can be identically synchronized and the synchronization solution is robust. At last, we successfully achieve the simultaneously bidirectional exchange of the messages introduced on the two sides of a link.