为了验证KTiOAsO4(KTA)晶体用于光参变振荡产生2 μm激光的可行性,设计了脉冲式2 μm KTA光参变振荡器,采用θ=49°切割的KTA晶体作为光参变振荡晶体,实现了2 μm激光的输出;计算了该系统在双谐振情况下的起振阈值,在实验中测得输出的信号光、闲频光波长在2.16 μm和2.09 μm附近,与理论计算基本吻合,并测量了脉冲宽度。同时选用了对信闲光透过率分别为60％、70％、90％的镜片作为光参变振荡器(OPO)输出镜,测得了三种情况下的输出能量及电光效率的数值;测得了在380 V电压下,输出镜透过率一定时输出能量与光参变振荡器腔长之间的关系曲线,从而验证了KTA晶体用于光参变振荡产生2 μm激光的可行性,为下一步的研究工作打下了基础。

In order to confirm that KTiOAsO4 can be used in optical parametric oscillator (OPO) to generate 2 μm laser, the pulsed 2 μm KTA OPO which uses θ=49°-cut KTA as a nonlinear crystal to generate 2 μm laser light is designed. The oscillation threshold of the OPO is calculated. The signal and idle wavelengths are measured near 2.16 μm and 2.09 μm which are in agreement with theoretical value. And the pulse width is also measured. By using the mirrors whose transmittance are 60%,70％,90％ respectively as the output mirrors of OPO, the output energy and the electro-optic efficiency are detected. And the impact of the reflectivity of output mirror on output energy is tested and the relationship between the output energy and OPO cavity length is got. So the fesibility of using KTA crystal in OPO to generate 2 μm laser light is demonstrated, which can be the theoretical basis for the next research work.