考虑激光器外有多个反射体时所产生的自混合干涉现象,运用薄膜干涉理论,对弱光反馈条件下的多外腔自混合干涉理论进行了研究。基于复合腔激光器结构,建立了理论模型。理论分析构造了一个含有五个反射面的自混合干涉模型,模型是由三个外腔构成的多外腔自混合干涉。对模型进行了理论分析及数值仿真,得出在弱光反馈条件下,多外腔自混合干涉信号类似于传统的自混合干涉信号,为一类正弦波(外部反射率较小时)或类锯齿波(外部反射率较大时)。设计了实验系统,给出了实验结果并进行了验证。如果忽略多外腔的结构,理论所得结果与简单的三镜腔自混合干涉结构所得结果一致。

This paper analyzes the self-mixing interference effect in the laser diode (LD) with multiple external reflectors and presents the analysis based on the compound cavity effect in lasers. Each external cavity is considered to be an optical thin film, and the reflectance ratio can be get from the theory of the thin film optics. The general expression of the threshold gain and frequency in the compound laser cavity are deduced and some simulation analysis is made at different conditions. A self-mixing interference experiment system is build with multiple external reflectors. And some experiment results are presented. It is found from the simulation and experiment that the output of the self-mixing interference system with multiple external reflectors is sinusiodal or saw-toothed waves which is similar with the three-mirror Fabry-Perot cavity system. The simulating and experimental results demonstrate the validity of the principle. This principle can be used to analyze the fiber-coupled self-mixing system and the simulation is accordant with experimental results.