Spatial chirp of the collimated single-cycle THz pulse

In this work the results of simulation of single- and multi-cycle pulse collimation are shown. Spatial and temporal field distribution of single-cycle pulse, which is typical for instance for THz radiation, were compared with the field distribution of multi-cycle pulse under the same conditions. Spatial chirp was observed for a single-cycle pulse - on-axis spectrum of the collimated single-cycle pulse is blue-shifted in comparison with the initial spectrum of the quasi-point source, whereas the off-axis spectrum is narrower and red-shifted.