Subpetahertz helicity modulation of attosecond pulse train using detuned two-color fields

Abstract

Abstract We theoretically demonstrate a scheme to obtain an attosecond pulse train with subpetahertz helicity modulation, based on high harmonic generation driven by detuned two-color fields. As the waveform of the detuned two-color field varies with time, the attosecond pulse train switches periodically between left and right elliptical polarization in the temporal domain. The frequency of the helicity modulation can reach subpetahertz. In addition, by adjusting the frequency detuning of the two-color field, the modulation frequency can be continuously controlled. The scheme is expected to provide a useful light source to explore and manipulate a wide range of ultrafast dynamics in magnetic materials and chiral molecules.