THz pulse shape control via laser chirp and wavelength dispersion

The generation of Terahertz (THz) radiation using two-color plasma in gases has garnered significant interest within the scientific community for its ability to produce powerful waves with very broad and tunable spectra. Understanding how to modify the characteristics of the generated THz radiation paves the way for optimizing its performance for targeted applications. To achieve this, various approaches have been explored, however, the combined impact of chirp and wavelength dispersion has not yet been thoroughly investigated. Our study aims to understand how the laser chirp and the phase difference caused by air dispersion influence the shape of the THz pulse. The findings highlight that these factors significantly alter the shape of the THz pulse. Specifically, the nature of the chirp (positive or negative) in the pump laser distinctly affects the pulse shape. For instance, a pump laser with positive chirp results in a THz waveform with a negative monopolar configuration, while a laser with negative chirp generates a THz pulse with a positive configuration.