Modulation of terahertz generation in dual-color filaments by an external electric field and preformed plasma

Li Min¹, Li An-Yuan¹, He Bo-Qu², Yuan Shuai¹, Zeng He-Ping^{1, 2, †,}

(a) Plots of measured THz peak-to-peak amplitude versus external electric field for s (hollow circle) and p (solid circle) polarization for the weak 800-nm energies of 0.37, 0.47, and 0.57 mJ, respectively. (b) The THz polarization rotations with the weak 800-nm pulse energies of 0.37, 0.47, and 0.57 mJ, respectively. Here the external electric field is at 5 kV.