为了研究如何产生2μm激光，提出将KTA晶体用于光参变振荡来产生2μm激光的方法，通过对比KTA与KTP晶体的非线性性能，从理论上论证了该方法的可行性；并从光学频率变换所遵循的能量守恒与动量守恒出发，利用KTA晶体的Sellmeier方程、根据折射率椭球方程计算出了晶体的切割角度，绘制出了角度调谐和波长的关系曲线图；比较了两种切割方式下的晶体有效非线性系数的大小，通过比较，得出Φ=0°，θ=48．37。切割的晶体具有更好的非线性特性的结论；并对该晶体的走离角、允许角、可接受带宽进行了计算，解决了KTA－OPO设计的最基本问题，为下一步的试验工作开展打下了基础。

In order to generate 2μm laser,a novel method was presented with kalium titanyl arsenate(KTA)as a nonlinear crystal in optical parametric oscillators. It was proved feasible by comparing the nonlinear parameters between KTA and KTP crystal. The graph of the relationship between the wavelength and the tunable-angle was drawn based on Sellmeier equation and refractive index ellipsoid of KTA. After compareson it was found that the crystal has better nonlinear characteristic at cut angles of φ =0°,θ=48.37°. Then the walk-off angle,acceptance angle and bandwidth were calculated. The basic problems on the design of KTA-OPO were solved and the study foundation was built up for the future experiments.