Laser-induced electron Fresnel diffraction in the tunneling and over-barrier ionization

TL;DR

This paper demonstrates that laser-induced electron Fresnel diffraction influences the low-energy interference structures in strong-field ionization, applicable across different ionization regimes and confirmed by quantum and semiclassical models.

Contribution

It extends the understanding of electron diffraction phenomena to tunneling and over-barrier ionization regimes, showing the mechanism's universality across different laser pulse conditions.

Findings

Fresnel diffraction explains low-energy interference in tunneling and over-barrier ionization.

Quantum and semiclassical models agree with numerical solutions.

Electron displacement by the electric field governs the diffraction pattern.

Abstract

The photoelectron momentum distribution in the strong-field ionization has a variety of structures that reveal the complicated dynamics of this process. Recently, we identified a low-energy interference structure in the case of a super-intense extreme ultraviolet (XUV) laser pulse and attributed it to the laser-induced electron Fresnel diffraction. This structure is determined by the laser-induced electron displacement [Geng L et al. 2021 Phys. Rev. A 104(2) L021102]. In the present work, we find that the Fresnel diffraction picture is also present in the tunneling and over-barrier regime of ionization by short pulses. However, the electron displacement is now induced by the electric field component of the laser pulse, instead of by the magnetic field component in the case of the superintense XUV pulse. After corresponding modifications to our quantum and semiclassical models, we find the same physical mechanism of the Fresnel diffraction governs the low-energy interference structures along the laser polarization. The results predicted by the two models agree well with the accurate results from the numerical solution to the time-dependent Schrodinger equation.