一种可产生高带宽混沌的外腔半导体激光器的设计及其动态特性

Design and Dynamic Characteristics of an External-Cavity Semiconductor Laser Generating Wide Bandwidth Chaos

设计一种新型的可产生高带宽混沌的面向蝶形封装的外腔半导体激光器,并在理论上研究了反馈率、注入电流比和载流子寿命对其动态特性的影响。数值仿真结果表明,调节反馈率或增加注入电流比时,该结构的输出光经历从稳定状态、准周期状态、混沌状态再到稳定状态的周期演化。增大注入电流比或减小载流子寿命时,外腔激光器的弛豫振荡频率增大。在大弛豫振荡频率和大外腔振荡频率下,能够生成有效带宽高达70GHz的混沌。分析了这种高带宽混沌生成的机理,也为高速随机数的生成提供了新的熵源。此外,在弱光反馈下,尝试利用激光器的弛豫振荡来掩盖反馈的时延特征,并分析了时延对外腔振荡频率的影响。

A novel external-cavity semiconductor laser faced to butterfly packaging which can generate wide bandwidth chaos is designed, and the influences of feedback ratio, injection current ratio and carrier lifetime on dynamic performance of the designed structure are investigated. Numerical simulation results demonstrate that diversely dynamical states including the stable state, as well as the so-called period-one, and chaotic states can be observed when the feedback ratio is adjusted or the injection current ratio is increased. The relaxation oscillation frequency of the external-cavity semiconductor laser rises with the increasing injection current ratio or the decreasing carrier lifetime. So it is much easier to generate chaotic signal with effective bandwidth of 70 GHz when the relaxation oscillation frequency and oscillation frequency of the external-cavity are at high level. The mechanism to generate such a chaos with wide bandwidth is analyzed, which provides a new source of entropy for the generation of random number. In addition, we use the relaxation oscillation of laser to cover time delay characteristics of feedback when the feedback is weak, and analyze the influence of feedback time delay on the dynamics of oscillation frequency of the external-cavity.