Ultrafast control of polarization of terahertz generation from laser–gas interaction using orthogonal few-cycle double-pulse lasers

The effect of orthogonal few-cycle double-pulse laser parameters on the terahertz polarization states generated from laser-driven gas plasma is investigated. The results reveal that the terahertz polarization state can be continuously modulated from linear to circular polarization on the femtosecond time scale by varying the time delay between two laser pulses. In addition, terahertz with changing helicity and polarization direction can be produced by alternating the time delay, allowing for ultrafast full control of terahertz polarization states. The approach proposed in this study has the advantage of easy operation and providing a feasible option for generating ultrafast terahertz radiation sources with controllable polarization states.