1 天津大学精密仪器与光电子工程学院，天津 300072
2 教育部光电信息技术重点实验室，天津 300072
报道了强激光脉冲电离氢原子诱导的花篮状动量谱（PMDs）的数值模拟研究。采用强场近似理论（SFA）和鞍点近似算法模拟计算了不同激光强度条件下的花篮状动量谱。数值模拟结果表明，花篮状干涉结构电子动量谱源于三种干涉条纹的相互干涉叠加，这三种干涉条纹分别是半圆状阈上电离（ATI）干涉条纹和两种左右对称的周期内干涉（ICI）条纹。后者的干涉条纹随着激光强度的增加而单调变密。依据经典作用相位，深入研究了阈上电离干涉结构和周期内干涉结构的特点，提出了定量描述这两类干涉条纹结构的解析式，所提解析式可以很好地刻画干涉条纹的性质。此外，类比于传统坐标空间的多缝干涉，本文给出了动量空间三缝干涉诱导花篮状动量谱的直观物理图像，该图像有助于理解电子波包干涉的微观机理。
非线性光学 光电子全息 花篮状干涉动量谱 阈上电离 周期内干涉
天津大学精密仪器与光电子工程学院，天津 300072
报道了强激光脉冲电离氢原子诱导的蜘蛛状干涉光电子动量谱（PMD）的数值探究结果。标准的半经典回碰模型（SRM）虽然简化了电子行为，但是忽略了难以处理的库仑作用。与以往的数值修正不同，对电离过程的库仑作用进行解析近似处理，并将其引入到SRM中，成功构建了解析修正的SRM（AC-SRM）。运用该模型数值模拟计算了蜘蛛状PMD和库仑作用引起的干涉图样的系统性位移。用经典相位、含时薛定谔方程（TDSE）和电子轨迹等方法，对这种位移现象进行了定量分析和机理探究。结果发现，所提的经典相位方法对PMD中蜘蛛状干涉结构的库仑作用最敏感，对第一干涉极小值尤为突出。精确的TDSE数值结果也证实了由AC-SRM所得到的模拟结果的正确性。
原子与分子物理学 原子光电离 光电子全息 库仑作用 数值模拟 光学学报
2022, 42(21): 2102001
Author Affiliations
Abstract
1 Huazhong University of Science and Technology, School of Physics and Wuhan National Laboratory for Optoelectronics, Wuhan, China
2 Wuhan Institute of Technology, Hubei Key Laboratory of Optical Information and Pattern Recognition, Wuhan, China
Tunneling ionization of atoms and molecules induced by intense laser pulses contains the contributions of numerous quantum orbits. Identifying the contributions of these orbits is crucial for exploring the application of tunneling and for understanding various tunneling-triggered strong-field phenomena. We perform a combined experimental and theoretical study to identify the relative contributions of the quantum orbits corresponding to the electrons tunneling ionized during the adjacent rising and falling quarter cycles of the electric field of the laser pulse. In our scheme, a perturbative second-harmonic field is added to the fundamental driving field. By analyzing the relative phase dependence of the signal in the photoelectron momentum distribution, the relative contributions of these two orbits are unambiguously determined. Our results show that their relative contributions sensitively depend on the longitudinal momentum and modulate with the transverse momentum of the photoelectron, which is attributed to the interference of the electron wave packets of the long orbit. The relative contributions of these orbits resolved here are important for the application of strong-field tunneling ionization as a photoelectron spectroscopy for attosecond time-resolved measurements.
tunneling ionization quantum orbits photoelectron holography attosecond electron dynamics Advanced Photonics
2021, 3(3): 035001
天津大学精密仪器与光电子工程学院光电信息技术教育部重点实验室, 天津 300072
采用半经典回碰模型(semiclassical rescattering model, SRM)和含时薛定谔方程(time-dependent Schr?dinger equation, TDSE),对线偏振激光场中氢原子的蜘蛛型光电子动量谱进行了数值模拟,重点研究了散射振幅相位的提取。基于前人的研究成果,依据SRM理论和鞍点理论,得到时间参数近似相等的结论,并提出了一种相位提取的新方法。构建了两个一级近似公式,解析表达了散射振幅相位。由所提方法获得的相位与纵向动量和横向动量有关。新方法尽管增加了计算量,但是相位提取精度有显著提高。
原子与分子物理学 原子光电离 氢原子 强场光电子全息 数值模拟 光学学报
2021, 41(10): 1002001
Author Affiliations
Abstract
College of Precision Instrument and Optoelectronics Engineering, Tianjin University; Key Laboratory of Optoelectronic Information Technology, Ministry of Education, Tianjin 300072, China
The spiderlike structures in the photoelectron momentum distributions of ionized electrons from the hydrogen atom are numerically simulated by using a semiclassical rescattering model (SRM) and solving the time-dependent Schr?dinger equation (TDSE), focusing on the role of the phase of the scattering amplitude. With the SRM, we find that the spiderlike legs shift to positions with smaller transverse momentum values while increasing the phase. The spiderlike patterns obtained by SRM and TDSE are in good agreement upon considering this phase. In addition, the time differences in electron ionization and rescattering calculated by SRM and the saddle-point equations are either in agreement or show very similar laws of variation, which further corroborates the significance of the phase of the scattering amplitude.
photoelectron holography semiclassical rescattering model spiderlike structure Chinese Optics Letters
2021, 19(7): 073201
