介O437绍了高重复频率、高平均功率的2 μm激光器的应用前景和产生方式,从KTP晶体的折射率椭球和Sellmeier方程出发,分析了当用1.064 μm连续Nd:YAG激光抽运Ⅱ类相位匹配的KTP晶体,发生光参量作用时,晶体绕切割角θ的调谐特性,并计算了θ角调谐曲线。结果表明,当θ角等于52.6°时,信号光和空闲光刚好在2.128 μm处简并输出。为了抑制KTP晶体的走离效应,综合了内腔式光学参量振荡器(OPO)和短晶体级联外腔式OPO的优点,设计了一套采取两块短晶体级联内腔式OPO的实验装置,该装置在声光调Q下可实现高重复频率2 μm的激光输出。并对该实验装置的抽运振荡阈值,转换效率,KTP晶体走离长度,线宽等进行了数值模拟计算。

The application prospect and production methods of the high-repetition-rate, high average power 2 μm laser were reported. With the KTP crystal refractive index ellipse and the Sellmeier equations, the tuning characteristic of the crystal about the cutting angle was analyzed when the 1.064 μm continuous Nd:YAG laser pumped the type Ⅱ phase matching KTP crystal. The cutting angle tuning curve was also calculated. As a result, when the cutting angle was 52.6°, the signal and the idler were degenerated at 2.128 μm with perpendicular polarization. To restrain the dispersion effect, the authors combined the intracavity optical parametric oscillator (OPO) with the short crystals connecting external OPO and designed an experimental set of intracavity doubly resonant optical parametric oscillator with two short KTP crystals connecting, with which high-repetition-rate 2 μm laser output was readized with acoustic-optic Q-switch. Finally, the threshold, the converting efficiency, the crystal dispersion length and the linewidth were numerically simulated.