光学学报, 2019, 39 (6): 0602001, 网络出版: 2019-06-17
由动态Stark效应诱导的氢原子涡旋动量分布 下载: 1072次
Dynamic-Stark-Effect Induced Distortion of Vortex Momentum Distributions of Hydrogen Atoms
原子与分子物理学 原子光电离 强场近似 氢原子 超短脉冲 数值模拟 atomic and molecular physics atomic photoionization strong field approximation hydrogen atom ultrashort laser pulse numerical simulation
摘要
采用强场近似方法,对处于两个具有时间延迟的圆偏振激光场中氢原子的涡旋状光电子动量分布进行了数值模拟。在两个延时激光脉冲的作用下,电子吸收光子后克服电离阈值,从基态经由两个不同的通道跃迁到连续态,产生的电子波包之间会发生干涉。模拟结果表明,所产生的光电子动量涡旋的旋向与两脉冲的偏振方向有关,涡旋臂的数目与激光载波频率有关。动态Stark效应是一种典型的强场现象。若在电离发生的同时考虑动态Stark效应,将会观察到动量涡旋的扭曲。对顺时针的动量涡旋及其扭曲进行分析,发现扭曲现象是由动态Stark效应引入的附加相位的时间非线性特性引起的。
Abstract
In this study, the vortex-shaped photoelectron momentum distributions of a hydrogen atom ionized by two time-delayed circularly polarized laser fields are numerically simulated based on the strong field approximation (SFA) theory. Under the action of two time-delayed laser pulses, the electron absorbs photons to overcome the ionization threshold and undergoes photoionization via two different transition channels to reach the continuum states for electron wave-packet interference. The simulation results show that the orientation of the photoelectron momentum vortices is observed to be related with the polarization directions of the two pulses, whereas the number of vortex arms is related with the carrier frequencies. Furthermore, the dynamic Stark effect is a ubiquitous strong field process, which would result in the distortion of the vortex-shaped momentum distributions when considered. On this basis, the clockwise momentum vortices and their distortion are specifically investigated, revealing that the distortion is attributed to the nonlinear properties of the phase associated with the dynamic Stark effect.
孔雪莲, 张贵忠, 汪天庆, 丁欣, 姚建铨. 由动态Stark效应诱导的氢原子涡旋动量分布[J]. 光学学报, 2019, 39(6): 0602001. Xuelian Kong, Guizhong Zhang, Tianqing Wang, Xin Ding, Jianquan Yao. Dynamic-Stark-Effect Induced Distortion of Vortex Momentum Distributions of Hydrogen Atoms[J]. Acta Optica Sinica, 2019, 39(6): 0602001.