在混沌通信系统中,混沌载波的时延特征直接影响着通信系统的安全性,因此隐藏混沌载波的时延特征信息十分重要。本文基于外腔反馈式半导体激光器(ECSL)的单光注入结构,引入激光器参数失配,详细阐述了一种通过主从激光器参数失配来消除混沌信号时延特征的方法。利用自相关函数作为量化工具,对混沌信号的时延隐藏效果进行量化分析,数值研究了主从激光器间的参数失配对混沌信号时延消除的影响,并结合注入强度与频率失谐开展了进一步综合研究。研究结果表明:引入激光器参数失配对时延隐藏的效果影响显著,参数失配率在-0.4～0范围时有助于在从激光器混沌输出中隐藏主激光器外腔引入的反馈时延;而且,当主激光器注入强度在10 ns-1～20 ns-1范围内,主从激光器频率失谐控制在-20 GHz附近时,信号时延隐藏效果最佳。因此,由此单混沌光注入系统产生的混沌信号可显著提高混沌载波的安全性,进而增强其潜在应用的性能。

In chaos-based communications, time delay signature of the chaotic carrier has a direct impact on the security of the system, and thus it is of great importance to conceal this kind of delay signature. Based on the structure of single chaotic optical injection, a method to conceal time delay signature by introducing parameter mismatch to semiconductor lasers is established. The effect of parameter mismatch between the master and slave lasers on the concealment of time delay signature is investigated numerically, in terms of autocorrelation function, as well as the combined effect of parameter mismatch, injection strength and frequency detuning. It is shown that, the parameter mismatch is helpful in concealing time delay signature. In particular, when the parameter mismatch value is within the range of-0.4～0, the injection strength is limited to 10 ns-1～20 ns-1 and the frequency detuning between the two lasers is controlled around-20 GHz, the time delay signature can be more effectively concealed. Therefore, the chaotic signals generated by semiconductor lasers subject to single chaotic optical injection can enhance security of chaotic carrier significantly.