Generation of terahertz pulses with arbitrary elliptical polarization

We employ two different methods to generate controllable elliptical polarization of teraherz (THz) pulses. First, THz pulses are generated via optical rectification in nonlinear crystals using a pair of temporally separated and perpendicularly polarized optical pulses. The THz ellipticity is controlled by adjusting the relative time delay and polarization of the two optical pulses. We generate mixed polarization states of single-cycle THz pulses using ZnTe, and elliptically polarized multicycle THz pulses in periodically poled lithium niobate crystals. Second, we generate elliptically polarized THz pulses by making a THz “wave plate” using a combination of a wire-grid THz polarizer and a mirror to transform linearly polarized multicycle THz pulses into elliptical polarization.