Tunneling ionization in ultrashort laser pulses: edge-effect and remedy

TL;DR

This paper investigates the edge-effect in tunneling ionization under ultrashort laser pulses, proposes a method to remove it, and demonstrates its effectiveness in both 1D and 3D scenarios, enabling clearer analysis of nonadiabatic electron dynamics.

Contribution

It introduces an efficient method to eliminate the edge-effect in photoelectron momentum distributions, improving the analysis of nonadiabatic ionization dynamics.

Findings

The edge-effect causes fast oscillations in the PMD that obscure physical features.

The proposed method effectively removes the edge-effect in both 1D and 3D models.

Validation shows the method aligns well with analytical and numerical solutions.

Abstract

Tunneling ionization of an atom in ultrashort laser pulses is considered. When the driving laser pulse is switched-on and -off with a steep slope, the photoelectron momentum distribution (PMD) shows an edge-effect because of the photoelectron diffraction by the time-slit of the pulse. The trivial diffraction pattern of the edge effect consisting of fast oscillations in the PMD disguises in the deep nonadiabatic regime the physically more interesting features in the spectrum which originate from the photoelectron dynamics. We point out the precise conditions how to avoid this scenario experimentally and if unavoidable in theory we put forward an efficient method to remove the edge-effect in the PMD. This allows to highlight the nonadiabatic dynamical features of the PMD, which is indispensable for their further investigation in complex computationally demanding scenarios. The method is firstly demonstrated on a one-dimensional problem, and further applied in three-dimensions for the attoclock. The method is validated by a comparison of analytical results via the strong-field approximation with numerical solutions of the time-dependent Schr\"odinger equation.