基于液晶相位可变延迟器频率调谐外腔半导体激光器

Frequency tuning of external-cavity diode laser with liquid crystal variable retarder

利用液晶相位可变延迟器慢轴折射率随外加电压变化的特性,研制了一台用液晶进行频率调谐的分布反馈(DFB,distributed feedback)外腔半导体激光器。液晶DFB外腔激光器输出激光线宽为475 kHz,液晶电压变化1.6 V(0.5～2.1 V)时,激光频率变化为7 GHz,覆盖了Cs原子D2线的全部饱和吸收谱线。在实现外腔半导体激光器方法中,应用液晶调相较应用压电陶瓷(PZT)改变腔长,其具有调谐电压低,回程误差小,并可以消除机械稳定性差等特点。

We report a frequency tunable external-cavity DFB laser, using the feature that the extraordinary refraction index of a liquid crystal variable retarder（LCVR） would change as a function of the voltage applied on the liquid crystal. The output laser linewidth of this LCVR external-cavity diode is 475 kHz, the laser frequency range can span 7 GHz when the bias voltage varies 1.6 V（0.5-2.1 V）, covers all the saturated absorption spectroscopy of the Cs D2 line. Compared with the PZT driven tunable diode laser, frequency tuning with liquid crystal is advantageous regarding the low bias voltage, small retrace error, and high mechanical stability.