Time Delay Concealment in Feedback Chaotic Systems With Dispersion in Loop

• Published in: IEEE photonics journal Vol. 9; no. 2; pp. 1 - 8
• Main Authors: Ke, Junxiang, Yi, Lilin, Hou, Tongtong, Hu, Ye, Xia, Guangqiong, Hu, Weisheng
• Format: Journal Article
• Language: English
• Published: IEEE 01.04.2017
• Subjects: Cavity resonators; Chaotic communication; Dispersion; Fiber non-linear optics; nonlinear optical effects in semiconductors; Optical attenuators; Optical feedback; Optical fibers; Optical filters
• ISSN: 1943-0655; 1943-0647
• DOI: 10.1109/JPHOT.2017.2664341

The concealment of time delay signature is one of the most critical issues in delayed-feedback optical chaotic systems. In this paper, we present a method to address this problem without significantly complicating the original architecture. By properly introducing a dispersion module into the feedback loop, a different frequency component of chaotic spectrum will be subject to different time delay in feedback loop, thus destroying the generation mechanism of time delay signature (TDS). The concealment performance is verified by both time-domain and spectrum analysis methods. The relation between the amplitude of TDS and cavity dispersion value is evaluated in detail. Since the dispersion module has no filtering effect, the chaotic bandwidth will not be affected during the TDS concealment process. This proposal solves the security problem of feedback chaotic systems without introducing much extra effort in implementation, and the underlying principle is not restricted to all-optical chaotic systems but applies for other optelectrical chaotic dynamics, which include a feedback cavity.