Nonsequential Double Ionization with Polarization-gated Pulses

TL;DR

This paper explores how polarization-gated laser pulses influence nonsequential double ionization, revealing asymmetries in electron momentum distributions that depend on pulse delay and phase, offering insights into ultrafast electron dynamics.

Contribution

It demonstrates that polarization gating can control electron momentum asymmetries in NSDI without using few-cycle pulses, using a classical trajectory model to mimic quantum behavior.

Findings

Electron momentum distributions are highly asymmetric when delay T_d is comparable to pulse length.

As T_d decreases, the asymmetry in distributions diminishes.

Polarization gating can effectively study NSDI dynamics in the single-cycle limit.

Abstract

We investigate laser-induced nonsequential double ionization by a polarization-gated laser pulse, constructed employing two counter-rotating circularly polarized few cycle pulses with a time delay $T_{d}$. We address the problem within a classical framework, and mimic the behavior of the quantum-mechanical electronic wave packet by means of an ensemble of classical electron trajectories. These trajectories are initially weighted with the quasi-static tunneling rate, and with suitably chosen distributions for the momentum components parallel and perpendicular to the laser-field polarization, in the temporal region for which it is nearly linearly polarized. We show that, if the time delay $T_{d}$ is of the order of the pulse length, the electron-momentum distributions, as functions of the parallel momentum components, are highly asymmetric and dependent on the carrier-envelope (CE) phase. As this delay is decreased, this asymmetry gradually vanishes. We explain this behavior in terms of the available phase space, the quasi-static tunneling rate and the recollision rate for the first electron, for different sets of trajectories. Our results show that polarization-gating technique may provide an efficient way to study the NSDI dynamics in the single-cycle limit, without employing few-cycle pulses.