Spectral tuning of broadband terahertz radiation from dc-biased laser plasma filaments

Abstract

Terahertz radiation from laser plasmas exhibits a broadband spectrum, making it a bright prospect for terahertz spectroscopy. In this work, we demonstrate that the continuous redshift of terahertz radiation from a dc-biased plasma filament can be achieved by increasing the length of the plasma filament. A theoretical model concerning a Lorentz distribution of the plasma density along a filament is proposed to interpret this spectral tuning effect. This finding provides not only an approach to spectral tuning but also a gentle way of diagnosing the distribution of the plasma density inside such plasmas.