椭圆偏振非均匀激光场中氩离子团簇高次谐波发射及孤立阿秒的产生

The High-order Harmonic and Isolated Attosecond Pulse Generation of an Ar + Cluster in a Elliptically Polarized Inhomogeneous Laser Fields

通过数值求解二维含时Schrodinger方程,研究了氩离子团簇在椭圆偏振空间均匀和非均匀激光场作用下的高次谐波发射及孤立阿秒脉冲的产生.在空间均匀场下,随着氩离子团簇离子数目的增加,氩离子团簇的高次谐波谱的特性发生变化,即谐波谱平台区被延展,谐波谱转换效率增强,并且当变化椭圆率时,椭圆率越大谐波谱平台区的截止位置越小;在空间非均匀激光场下,随着空间非均匀参数的增大,氩离子团簇的高次谐波谱平台区延展越大,且谐波效率越高,因此能够得到超宽的连续谐波谱,获得孤立阿秒脉冲.本文叠加了椭圆率为0.3、非均匀参数为0.004时的高次谐波谱平台截止区内的谐波谱,获得了79 as的孤立阿秒脉冲.通过以上计算,在理论上可以通过非均匀参数以及椭偏率的变化对高次谐波谱的特性进行研究.

We theoretically investigate the high-order harmonic generation(HHG)and the generation of isolated attosecond pulses by solving a two-dimensional time-dependent Schr dinger equation for a two-dimensional model of an Ar+cluster driven by homogeneous and inhomogeneous elliptically polarized laser fields.In the space homogeneous laser fields,with the increase of the number of ions in the Argon ion cluster,the characteristics of the high-order harmonic spectrum of the Argon ion cluster are changed,the plateau region of the harmonic spectrum is extended,the conversion efficiency of the harmonic spectrum is enhanced,and when the ellipticity changes,the larger the ellipticity,the smaller the cut-off position of the plateau region of the harmonic spectrum.In the inhomogeneous laser fields,the larger the spatial inhomogeneous parameter,the larger the platform area of the high-order harmonic spectrum is extended,and the higher the harmonic spectrum efficiency,so the ultra-wide continuous harmonic spectrum and isolated attosecond pulse can be obtained.In this paper,79 as isolated attosecond pulses are obtained by superimposing the harmonic spectrum in the cutoff region of the high-order harmonic spectrum platform with an ellipticity of 0.3 and a nonuniform parameter of 0.004.Through the above calculation,we can theoretically study the characteristics of high order harmonic spectrum through the variation of nonuniform parameters and ellipticity.