Strong-field ionization of Ar atoms with a 45∘ cross-linearly-polarized two-color laser field

Abstract

The two-colour light field has been extensively employed in strong field science. However, most of the published works were performed in the parallel polarised two-colour field scheme or the orthogonally polarised two-colour field scheme [1][2][3][4]. In this work, we measure the photoelectron momentum distributions of Ar atoms in cross linearly polarised two-colour (800 nm + 400 nm) laser field with an angle of 45 • . The photoelectron momentum distributions are controlled by tuning the phase of the synthesised two-colour fields. With semi-classical numerical simulation [5,6], we have analysed the subcycle dynamics of the tunnelling electron wave-packets and have studied the Coulomb effect on the evolution of the tunnelling electron wave-packets. Our investigation indicates that the Coulomb effects are strongly dependent on the history of the electric field after the tunnelling. The Coulomb focusing effect and the Coulomb defocusing effects can be controlled on the subcycle timescale at this interaction geometry. We also propose that, by tuning the phase delay of such a two-colour field in the generation of high harmonic, the ellipticity of the harmonics can be controlled without using any X-ray wave plate. We expect such new synthesised electric fields will be widely used in strong-field science.