Below threshold nonsequential double ionization with linearly polarized two-color fields I: symmetry and dominance

TL;DR

This paper studies how bichromatic linearly polarized laser fields influence nonsequential double ionization, revealing how field symmetry and parameters control electron momentum distributions and ionization event dominance.

Contribution

It demonstrates how manipulating bichromatic field parameters affects the symmetry and dominance of RESI mechanisms in double ionization.

Findings

Electron momentum distributions are shifted away from zero in bichromatic fields.

Multiple ionization events can occur per half cycle.

Field parameters can be tuned to confine RESI distributions to specific momentum regions.

Abstract

We investigate laser-induced nonsequential double ionization with linearly polarized bichromatic fields, focusing on the recollision-excitation with subsequent ionization (RESI) mechanism. Using the strong-field approximation, we assess how the symmetries of the field influence the dominant events. Furthermore, we show that, by manipulating the field parameters such as the field frequencies and relative phase between the two driving waves, one can influence the correlated electron-momentum distributions. Specific features of a linearly polarized bichromatic field are that the momentum distributions of the second electron are no longer centered around vanishing momenta and that there may be more than one ionization event per half cycle. This can be used to confine the RESI distributions to specific momentum regions and to determine a hierarchy of parameters that make an event dominant.