双色反向旋转椭圆偏振激光场下氩原子的高次谐波发射的选择定则的验证

The Verification of Selection Rule for High-Order Harmonic Generation of Ar Atom Driven by Bichromatic CounterRotating Elliptically Polarized Laser Fields

通过数值求解二维含时薛定谔方程,研究了氩原子在双色反向旋转椭圆偏振激光场作用下的高次谐波发射,双色反向旋转椭圆偏振激光场是由2个共面的频率为rω和sω(r=1,s=2,3,4,ω是圆偏振的基频)时的激光脉冲组成.通过理论计算我们发现在不同椭偏率下的氩原子的高次谐波谱的特性与2015年Milo evi Ac'[26]提出的选择定则一致.倍频场为2倍频,驱动激光场为反向旋转圆偏振激光脉冲时,高次谐波谱的3 q阶次谐波被抑制,驱动激光场为反向旋转椭圆偏振激光脉冲时,高次谐波谱中被抑制的3 q阶次谐波增强;倍频场为3倍频,驱动激光场为反向旋转圆偏振和椭圆偏振激光脉冲时,高次谐波谱的偶数阶次谐波被抑制;倍频场为4倍频,高次谐波谱中与5 q阶次相邻的谐波阶次产生,其余谐波阶次被抑制,驱动激光场为反向旋转椭圆偏振激光脉冲时,被抑制的谐波阶次增强.我们计算了相对应激光场下的Lissajou s图形,从图中可以看到随着椭偏率的变化,Lissajou s图形的对称性被破坏,相应的高次谐波谱的特性发生变化;Lissajou s图形的对称性不变化,相应的高次谐波谱的特性不发生改变.

We investigate the harmonic spectra of Ar atom with the bichromatic counter-rotating elliptically polarized laser fields which consists of two coplanar components having the frequencies rωand sω(r=1,s=2,3,4,ωis the fundamental frequency)by numerically solving the Time-Dependent Schr dinger Equation(TDSE).We demonstrate that the high harmonic spectrum is consistent with the selection rule reported by Milo evi Ac'2015.When the harmonic pulse is the second harmonic,the 3 q order is suppressed in the bichromatic counter-rotating circularly polarized laser field,while the 3 q order is enhanced in the bichromatic counter-rotating elliptically polarized laser fields.When the harmonic pulse is the third harmonic,the even order high-order harmonic is suppressed in the bichromatic counter-rotating circularly and elliptically polarized laser fields.When the harmonic pulse is the fouth harmonic,the high-order harmonic spectra which next to the 5 q order is emission and others are suppressed in the bichromatic counter-rotating circularly polarized laser field,while the suppressed orders are enhanced in the bichromatic counter-rotating elliptically polarized laser field.We also investigate the Lissajou s curves in different ellipticity,we can see the character of the high-order harmonic spectra is changed with the symmetry of the Lissajou s curves.