高强度飞秒脉冲单块BBO晶体三倍频实验  

Third Harmonic Generation Experiment of Super Intense Femtosecond Laser with a Single BBO Crystal

作　　者：李琨[1] 张彬[1] 刁煦[1] 李恪宇[2] 

机构地区：[1]四川大学电子信息学院 [2]中国工程物理研究院激光聚变研究中心,四川绵阳621900

出　　处：《中国激光》2008年第7期976-981,共6页Chinese Journal of Lasers

基　　金：四川省青年科技基金(05ZQ026-013);超强超短脉冲激光应用基础研究实验室开放课题(CD200508)资助项目

摘　　要：针对脉冲宽度100fs，带宽25nm，能量6mJ左右的超短脉冲基频光（经过透镜缩束后峰值光强为200～900GW／cm^2），采用单块厚度为1.5mm的BBO晶体进行了三倍频实验研究。在入射基频光强度约300GW／cm^2时，得到的三倍频转换效率约0．8％。采用分步傅里叶变换及四阶龙格一库塔算法，对描述飞秒脉冲单块晶体三倍频的耦合波方程组进行了数值计算。研究结果表明，三倍频光主要是由三阶非线性效应产生的；基频光带宽较大是限制三倍频转换效率的主要因素之一；对基频光的入射角度及方位角进行优化，可较好地补偿非线性相位失配，提高单块晶体三倍频转换效率。Third harmonic generation （THG） experiment of supper intense femtosecond laser with a single BBO crystal of 1.5 mm was carried out. The pulse width of the input fundamental field is about 100 fs, the bandwidth is about 25 nm, the energy is about 6 mJ, and the maximum intensity is 200-900 GW/cm^2 after focusing by a lens. The conversion efficiency was 0.8% with the intensity of the input fundamental field of about 300 GW/cm^2. Based on the numerical techniques such as split-step Fourier transformation and fourth-order Runge-Kutta method, theoretical analysis was presented and the results show that the third harmonic field is mainly produced by the thirdorder nonlinear effect; the large bandwidth of the fundamental field is one of the chief reasons that limit the conversion efficiency; the nonlinear phase-mismatching and the conversion efficiency could be compensated well after optimizing the incidence angle and the azimuth angle of the fundamental field.

关 键 词：非线性光学 三阶非线性效应 单块晶体三倍频 飞秒脉冲 群速度失配 

分 类 号：O437.1[机械工程—光学工程]