基于BGSe晶体的电控可调谐中红外激光器设计

Design of Electrically Controlled Tunable Mid Infrared Laser Based on BGSe Crystal

光学参量振荡器(OPO)是一种简单有效的产生理想特定波长的方法。报道一种电动控制的光学参量振荡器,该可调谐激光器体积小,方便携带外出试验,效率较高,阈值低,调谐精度高,可在室温下工作,水冷控温于25℃。以BaGa4Se7晶体为核心,由脉宽10 ns、波长1.06μm电光调Q的Nd:YAG激光器泵浦。输出的中红外空闲波可以实现2.97μm到6.35μm宽范围调谐,在3.8μm处脉冲能量高达1.97 mJ,可以提高泵浦功率使其达到更高水平。转台的机械转角为0°时,有中心波长为4.66μm,闲频光通过电机控制转动晶体的旋转角度来调谐。电动连续转台结构紧凑,精度高,最小旋转步长为0.002 5°,从而微调相位匹配角度和输出波长。

The optical parametric oscillator(OPO) is a simple and effective method to generate desirable and specific wavelength. The OPO laser is small, portable and has high efficiency, low threshold and can be operated at room temperature. In this paper, we report an electrically controlled tunable optical parametric oscillator operating from wavelength of 2.97 to 6.35 μm. The nanosecond OPO is based on BaGa4Se7 crystal and pumped by a 10 ns 1.06 μm electro-optic Q-switched Nd: YAG laser. The output mid-infrared idler wave can be tuned from 2.97 μm to 6.35 μm with pulse energy as high as 1.97 mJ at 3.8 μm and can be even increased with more pump power. The central idler wavelength is 4.66 μm(rotation angle is 0°). The output idler wavelength can be tuned by turning the rotation angle of the crystal, which is controlled by an electronic motor. The motorized continuous rotation stage is compact and highly precise with minimum rotation step of 0.002 5°. This enables the fine tuning of the phase-matching angel and the resulting output wavelength.