三阶非线性效应对三次谐波振荡转换的影响  

The Effect of Third-Order Nonlinear Interaction on High-Efficiency Third Harmonic Generation Conversion

作　　者：赵华君[1] 杨李茗[2] 冯国英[1] 张清泉[3] 朱启华[3] 陈建国[1] 

机构地区：[1]四川大学电子信息学院,成都610064 [2]成都精密光学工程研究中心,成都610041 [3]中国工程物理研究院激光聚变研究中心,绵阳621900

出　　处：《光学学报》2005年第3期387-391,共5页Acta Optica Sinica

基　　金：中国工程物理研究院与国家自然科学基金会联合基金(10176019)资助课题

摘　　要：使用快速傅里叶变换和四阶龙格库塔法,对KDP晶体内以Ⅰ/Ⅱ类角度失谐设置方式的高强度激光三次谐波振荡转换进行了研究,考虑了谐波转换过程中的三阶非线性χ(3)、衍射、离散等效应,并着重研究了KDP晶体的三阶非线性效应对高强度激光三次谐波转换的影响。研究表明,三阶非线性效应降低了三次谐波振荡转换效率,增大了相位扰动对3ω光束的强度调制,然而通过增加二倍频的失谐角Δθs,可以避免三阶非线性效应对三次谐波振荡转换带来的不利影响。A theoretical analysis is presented for conversion of third-harmonic generation (THG) in KDP crystal for type Ⅰ/Ⅱ angle-detuning scheme of high-intensity laser. Taking into account the the third-order nonlinear effects, transverse walk-off and diffraction, mostly the effects of third-order nonlinear χ (3) interactions on the frequency conversion and the phase matching condition are discussed. A split-step algorithm based on the fast Fourier transform (FFT) and a Runge-Kutta (R-K) integrator is used. The results show that the third-order nonlinear effect decreases the tripling efficiencies and increases the modulate depth of the output intensity of 3ω radiation. However, adjusting the angular detuning (Δθ_s) can avoid effectively the third-order nonlinear effects.

关 键 词：非线性光学 三次谐波振荡 三阶非线性 KDP晶体 Ⅰ/Ⅱ类角度失谐 失谐角 

分 类 号：O437.1[机械工程—光学工程]