Evolution of terahertz waves in air plasma driven by orthogonally polarized two-color pulses

Abstract

We experimentally investigate the evolution of the terahertz (THz) waveform and polarization state inside the plasma filament produced by orthogonally polarized two-color pulses. We find that the variation of the THz polarization state along the plasma column is dominantly caused by the relative phase difference and spectra blue shift of the two-color field. Elliptically polarized THz radiation is generated by controlling the initial relative phase and the filament length. The result indicates the coherent control of the polarization state of the THz emission.