Enabling elliptically polarized high harmonic generation with short cross polarized laser pulses

In this work we address the question of whether elliptically polarized harmonics can be generated using a two-color cross-polarized driving laser configuration and if so, how it can be controlled. Previous theoretical predictions disagreed with experimental observations which showed that even-order harmonics with large ellipticity could be generated. We present a theoretical analysis of this process using numerical simulations of high harmonic generation in atoms initially in a s- or p-state interacting with the two-color orthogonally polarized driving laser. The amount and sign of the ellipticity depends on the relative carrier-envelope phase of the pulses, their intensity ratio and the duration of the pulses.