Spectral Phase Effects in High-Order Above Threshold Ionization of Noble Gas Atoms

TL;DR

This study investigates how spectral phase shaping of laser pulses, especially using Airy pulses, influences high-order above threshold ionization in noble gases, revealing shifts in energy cutoffs and rescattering dynamics.

Contribution

It provides the first detailed theoretical analysis of spectral phase effects, particularly third-order phase, on ATI spectra using sculpted laser pulses.

Findings

Airy pulses shift the ATI cutoff to lower energies.

Spectral phase affects electron rescattering timing and dynamics.

Different spectral phases produce distinct photoelectron momentum distributions.

Abstract

We present theoretical studies of above threshold ionization (ATI) using sculpted laser pulses for noble gas atoms. The time-dependent Schroedinger equation is solved to calculate the ATI energy and momentum spectra, and a qualitative understanding of the electron motion after ionization is explored using a classical model that solves Newton's equation of motion. Results are presented for Gaussian and Airy laser pulses with identical power spectra, but differing spectral phases. The simulations show that the third order spectral phase of the Airy pulse, which can alter the temporal envelope of the electric field, causes changes to the timing of ionization and the dynamics of the rescattering process. Specifically, the use of Airy pulses in the ATI process results in a shift of the Keldysh plateau cutoff to lower energy due to a decreased pondermotive energy of the electron in the laser field. Additionally, the side lobes of the Airy laser pulse change the number and timing of rescattering events, which results in changes to the high-order ATI plateau. Our results also show that laser pulses with identical carrier envelope phases and nearly identical envelopes yield different photoelectron momentum densities, which are a direct result of the pulse's spectral phase.