Verification of the physical mechanism of THz generation by dual-color ultrashort laser pulses

We experimentally verified the physical mechanism of the dual-color ultrashort laser-driven THz wave generation in air by measuring its dependence on the dual-color field phase difference. Our results evidenced that the THz generation from the laser-induced plasma is dominated by the photo-current mechanism. A continuous rotation of THz polarization was observed by changing the dual-color phase difference, facilitating coherent control of the THz intensity and polarization.