Unipolar fields produced by ultrafast optical gating of terahertz pulses

Unipolar (sub-cycle) electromagnetic fields are a subject of current interest as a possible useful tool for light–matter interaction studies and applications. We propose, numerically simulate, and experimentally prove a method to produce unipolar terahertz fields by optical gating of conventional bipolar terahertz pulses in a GaAs wafer. In particular, picosecond long unipolar pulses with the electric field strength of ∼1 kV/cm were detected by electro-optic sampling at the output of the wafer.