Coulomb effects in the high-energy part of above-threshold-ionization spectra in intense bicircular laser fields

Abstract

Coulomb effects in the high-energy part of photoelectron spectra produced through the above-threshold ionization of an atom subject to intense short laser pulses are analyzed. The analysis is carried out for linearly polarized and tailored bicircular laser pulses consisting of the fundamental and the second-harmonic components. We include the Coulomb effects in the analytic semiclassical description of the photoelectron rescattering plateau using the recently developed adiabatic approach [Phys. Rev. A 104, 033109 (2021)] and the expression for the Coulomb phase derived for description of the high harmonic generation [J. Phys. B: At., Mol. Opt. Phys. 51, 144006 (2018)]. Comparisons between predictions of the analytic approach and numerical solutions of the time-dependent Schr\"odinger equation are presented. They allow the identification of the contribution of the Coulomb interaction to photoelectron spectra for different laser pulse forms. We show that the Coulomb effects appear more pronounced for bicircular fields, where they demonstrate considerable sensitivity to the photoelectron emission angle. Instead, for linear polarization, the Coulomb effect in the high-energy plateau is generally insignificant.