Polarization Control Of The High-Order Harmonics Generated From Molecules By The Carrier Envelope Phase Of Few-Cycle Laser Field

Polarization state of high-order harmonic generation from molecules with few-cycle circularly polarized laser field is investigated. It is found that by controlling the carrier envelope phase (CEP) of the few-cycle driving field, the high-order harmonics with arbitrary polarization state ranging from nearly left circular polarization through linear polarization to nearly right circular polarization can be generated. Moreover, the degree of circular polarization (DCP) of the harmonics changes periodically with the CEP of the driving field. The corresponding period depends on the molecular symmetry. Our results provide a method to control the harmonic polarization with the CEP of few-cycle circularly polarized laser field, which will benefit the generation of isolated attosecond pulses with tunable polarization.