研究了利特罗(Littrow)结构外腔半导体激光器的结构参量对激光连续可调范围的影响。给出了反射镜转轴等处的机械加工误差对激光波长连续可调范围所造成的影响的数值计算结果。介绍了半导体激光器外腔结构设计的具体细节要点。利用该设计制作的外腔只需要配合商用半导体激光管便可以得到优质的780 nm激光输出,经测量其线宽小于1 MHz,连续可调谐范围大于3 GHz。利用腔外Rb饱和吸收谱的三、五次谐波稳频方法对半导体激光器进行了稳频。其中提出了优化激光频率短期稳定度的方法,并对调制深度的选择给出了详细的理论解释。根据该优化方法设计出稳频系统对半导体激光器进行稳频,得到了稳定度达到10-12量级的半导体激光输出。

The influence of structural parameters on laser wavelength continuous tuning range in external cavity semiconductor laser with Littrow configuration is studied. The influence of allowed machining errors at the key points such as the mirror rotation axis on laser wavelength continuous tuning range is calculated. The details of designing external cavity semiconductor laser are presented. An external cavity semiconductor laser is designed, and with a commercial semiconductor laser tube it can produce qualified 780 nm laser, with line width less than 1 MHz and wavelength continuous tuning range of 3 GHz. The semiconductor laser is frequency stabilized by use of the third and fifth harmonics of Rb saturated absorption spectra. The method for optimizing the laser frequency short-term stability is proposed, and the choice of modulating depth is explained theoretically in detail. With the proposed frequency stabilizing method, the stability of laser reaches 10-12 at 780 nm wavelength.