Controlling polarization of high-order harmonics generated in the mixed gases with orthogonal two-color laser fields

Abstract The generation of highly elliptically polarized high-order harmonics (EPHHs) is indispensable for investigating chirality-sensitive light-matter interactions. Recently, high-order harmonic generation (HHG) with controllable ellipticity and helicity has attracted considerable attention. In this work, we theoretically demonstrate the possibility of generating broadband EPHHs with the same helicity from mixed gases in orthogonal two-color fields. There is a specific relative phase between the HHG from different gas components of the mixture. In addition, manipulation of the phase difference can be achieved by controlling the alignment angle of the molecule in mixed gases. It enables us to selectively enhance one helicity component of the high-order harmonics in a wide spectral range. This scheme paves a way for possibly generating elliptically polarized attosecond pulses.