正交偏振双色激光场作用下高次谐波的椭偏特性研究  

The ellipticity in high-order harmonic generation in an orthogonally polarized two-color laser field

作　　者：张军 刘学深[1] ZHANG Jun;LIU Xue-Shen(Institute of Atomic and Molecular Physics,Jilin University,Changchun 130012,China)

机构地区：[1]吉林大学原子与分子物理研究所,长春130012

出　　处：《原子与分子物理学报》2020年第6期928-934,共7页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(11904122,61575077);吉林省科技发展计划资助项目(20180101225JC);中国博士后基金(2018M641766,2019T120232)。

摘　　要：通过数值求解二维含时薛定谔方程,理论研究了正交偏振双色激光场作用下H2+分子高次谐波发射和孤立阿秒脉冲的产生.数值结果显示,改变激光场的强度比,可以调控高次谐波强度以及谐波椭偏率.结果表明随着场强比的增加,y方向的谐波强度不断提高.当场强比为1:2.5时,x方向和y方向分别仅有奇次谐波和偶次谐波产生,并且偶次谐波的强度比奇次谐波强度高2-3个数量级.此时,奇次谐波的椭偏率最大可以达到0.3,偶次谐波的椭偏率接近于0.此外,通过改变分子的准直角可以控制谐波的椭偏率,基于这一现象,利用椭圆偏振高次谐波的平台区合成了椭偏率为0.05的椭圆偏振阿秒脉冲链.We investigate the high-order harmonic generation(HHG)and single isolated attosecond pulses from H2+molecule in the orthogonally polarized two-color(OTC)laser field by numerically solving the two-dimensional(2 D)time-dependent Schr?dinger equation(TDSE).The intensity and the ellipticity of HHG can be controlled by changing the laser intensity ratio.The results show that,with the increase of the laser intensity ratio,the harmonic intensity in the y direction increases continuously.When the laser intensity ratio is 1:2.5,only odd order harmonics are generated in the x direction and even order harmonics are generated in the y direction.And the intensity of even order harmonics is two or three orders of magnitude higher than the intensity of odd order harmonics.In this case,the ellipticity of odd order harmonics can reach 0.3,and the ellipticity of the even order harmonics is close to 0.Furthermore,we find that the molecule alignment angle can be used to control the ellipticity of the harmonics.According to this phenomenon,the elliptically polarized attosecond pulse train with an ellipticity of 0.05 is synthesized by superposing the high-energy region of elliptically polarized HHG.

关 键 词：正交偏振双色激光场 含时薛定谔方程 高次谐波发射 阿秒脉冲 

分 类 号：O562.4[理学—原子与分子物理]