摘要:
基于光反馈半导体激光器(SL)速率方程模型,理论仿真研究了高斯切趾型光纤布拉格光栅(GAFBG)反馈SL(GAFBGF-SL)混沌输出的延时特征(TDS)以及混沌带宽特性.结果表明:随着反馈强度的增加,GAFBGF-SL表现出由准周期进入混沌的动力学演化路径;通过合理选择GAFBG布拉格频率与SL中心频率之间的频率失谐及反馈强度,GAFBGF-SL混沌输出的TDS能得到有效抑制(低于0.02);通过进一步绘制混沌信号TDS及带宽在GAFBG布拉格频率与SL中心频率之间的频率失谐和反馈强度构成的参量空间中的分布图,确定了获取弱TDS、宽带宽光混沌信号的参数范围.
Abstract:
Optical chaos based on semiconductor laser (SL) has some vital applications such as optical chaos secure commu-nication, high-speed physical random number generation, chaos lidar, etc. Among various schemes to drive an SL into chaos, the introduction of external cavity feedback is one of the most popular techniques, which can generate chaos signals with high dimension and complexity. For the chaos output from an external cavity feedback SL, a time-delay signature (TDS) and bandwidth are two key indexes to assess the chaos signal quality. In this work, according to the rate-equation model of an optical feedback SL, we theoretically investigate the characteristics of TDS and effective band-width (EWB) of chaotic output from a Gaussian apodized fiber Bragg grating (GAFBG) feedback SL (GAFBGF-SL). The results show that with the increase of feedback strength, the GAFBGF-SL experiences a quasi-periodic route to chaos. Through selecting the suitable feedback strength and the frequency detuning between the Bragg frequency of the GAFBG and the peak frequency of the free-running SL, the TDS of chaotic output from the GAFBGF-SL can be efficiently suppressed to a level below 0.02. Furthermore, by mapping the TDS and EWB in the parameter space of the feedback strength and the frequency detuning between the Bragg frequency of the GAFBG and the peak frequency of the free-running SL, the optimized parameter region, which is suitable for achieving chaotic signal with weak TDS and wide bandwidth, can be determined. We believe that this work will be helpful in acquiring the high quality chaotic signals and relevant applications.
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