Spatiotemporal transformations of ultrashort terahertz pulses

Abstract

We have experimentally studied the propagation in free space and through focusing optics of subpicosecond half- and single-cycle terahertz pulses emitted by large-aperture emitters. The spatial transformations of the beams are connected to phase changes and effective frequency filtering and lead to spectacular changes in the pulse time profile. The experimental results are in excellent agreement with the predictions of a simple analytical model based on a Gaussian-beam approximation.