Ultrafast spatio-temporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases

TL;DR

This paper investigates how spatio-temporal effects influence terahertz generation in gases using two-color femtosecond pulses, combining experiments and simulations to clarify the underlying mechanisms.

Contribution

It provides a comprehensive analysis of spatio-temporal reshaping and plasma-induced blue-shift effects in THz generation, supported by both experimental data and advanced simulations.

Findings

Spectral broadening of THz with increased gas pressure

Spatio-temporal reshaping significantly affects THz emission

Simulations agree well with experimental results

Abstract

We present a combined theoretical and experimental study of spatio-temporal propagation effects in terahertz (THz) generation in gases using two-color ionizing laser pulses. The observed strong broadening of the THz spectra with increasing gas pressure reveals the prominent role of spatio-temporal reshaping and of a plasma-induced blue-shift of the pump pulses in the generation process. Results obtained from (3+1)-dimensional simulations are in good agreement with experimental findings and clarify the mechanisms responsible for THz emission.