Polarization control of attosecond pulses using bi-chromatic elliptically polarized laser

Abstract

We study the high harmonic generation (HHG) using elliptically polarized two-color driving fields. The HHG via bi-chromatic counter-rotating laser fields is a promising source of circularly polarized ultrashort XUV radiation at the attosecond time scale. The ellipticity or the polarization of the attosecond pulses (APs) can be tweaked by modifying the emitted harmonics’ ellipticity, which can be controlled by varying the driver fields. A simple setup is used to control the polarization of the driving fields, which eventually changes the ellipticity of the APs. A well-defined scaling for the ellipticity of the AP as a function of the rotation angle of the quarter-wave plate is also deduced by solving the time-dependent Schrödinger equation in two dimensions. The scaling can further be explored to obtain the APs of the desired degree of polarization, ranging from linear to elliptical to circular polarization.