Sub-Cycle Interference upon Tunnel-Ionization by Counterrotating Two-Color Fields

TL;DR

This paper investigates the effects of counterrotating two-color laser fields on helium ionization, revealing sub-cycle interference patterns and low energy structures through experimental and numerical methods.

Contribution

It demonstrates the observation and numerical reproduction of sub-cycle interference and low energy structures in 3D electron momentum distributions caused by counterrotating two-color fields.

Findings

Observation of pronounced 3D low energy structures.

Experimental and numerical agreement on sub-cycle interference.

Verification of structure orientation via Schrödinger equation simulations.

Abstract

We report on three-dimensional (3D) electron momentum distributions from single ionization of helium by a laser pulse consisting of two counterrotating circularly polarized fields (390 nm and 780 nm). A pronounced 3D low energy structure and sub-cycle interferences are observed experimentally and reproduced numerically using a trajectory based semi-classical simulation. The orientation of the low energy structure in the polarization plane is verified by numerical simulations solving the time dependent Schr\"odinger equation.