浅析元件参数对外腔半导体激光器输出谱宽影响

半导体抽运碱金属蒸气激光器（DPAL）需大功率窄线宽泵浦源，但市售半导体激光器输出线宽远远大于碱金属原子吸收谱宽，难以实现有效泵浦，因此需采用Littrow 外腔法压窄半导体激光器输出谱宽。Littrow 外腔系统中元件参数的选择直接影响大功率半导体激光器输出谱宽。为此文中沿入射光线方向构建外腔压窄模型，利用球面镜替代柱面镜，分析了微柱透镜阵列、光学系统和光栅元件对外腔输出谱宽的影响，模拟结果为微柱透镜阵列焦距越小、光栅刻线越密、球面镜焦距越大，外腔输出谱宽越窄，实验结果符合理论模型。

Influencing factors on spectral linewidth of external cavity diode laser

High power narrowed linewidth pump source is needed with diode pumped alkali laser developed. But the linewidth of the commercial diode laser is far exceed the absorption linewidth of the alkali atom. So the Littrow external cavity is used to narrowed the spectrum of high power diode laser array. The linewidth of high power diode laser array is directly affected by the parameters of elements in Littrow external cavity. In this paper, the model of external cavity diode laser was set up by using ray tracing method. By replacing cylindrical lens with sphere lens, the influence of micro-cylindrical lens array, beam shaping optics and grating were analysed. The resutls show that, to obtain narrower output laser linewidth, the focal length of micro-cylindrical lens array should be smaller, the grating grooves is denser, and the focal of spherical lens is larger. And the theoretical conclusions is demonstrated by experimental results.