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-Ping1, 2, †,
       

(a) and (b) Variations of THz electric fields in s and p directions as the external electric field increases from 1 kV to 5 kV. (c) Variation of the THz peak-to-peak amplitudes with an external electric field in s and p polarizations. (d) Plots of the THz polarization versus Ex at different external electric fields.