Femtosecond laser pulse shaping for enhanced ionization

TL;DR

This paper presents a method to optimize femtosecond laser pulse shapes to maximize atomic and molecular ionization, using a direct-optimization scheme combined with solving the time-dependent Schrödinger equation.

Contribution

It introduces a novel pulse shaping optimization technique that enhances ionization by adjusting pulse shape and frequency within constraints.

Findings

Optimized pulses increase ionization yields for H2+ molecules.

The method maintains total pulse energy while modifying shape and frequency.

Enhanced ionization is achieved with short, high-intensity laser pulses.

Abstract

We demonstrate how the shape of femtosecond laser pulses can be tailored in order to obtain maximal ionization of atoms or molecules. For that purpose, we have overlayed a direct-optimization scheme on top of a fully unconstrained computation of the three-dimensional time-dependent Schrodinger equation. The procedure looks for pulses that maintain the same total length and integrated intensity or fluence as a given pulse that serves as an initial guess. It allows, however, for changes in frequencies -- within a certain, predefined range -- and overall shape, leading to enhanced ionization. We illustrate the scheme by calculating ionization yields for the H2+ molecule when irradiated with short (~5 fs), high-intensity laser pulses.