Spectrum of Terahertz Emission from Single-Color Filament Plasma under Different Laser Beam Focusing

Abstract

The spectrum of terahertz radiation generated in plasma of a single-color laser filament is observed, using a new technique based on obtaining two-dimensional angular distributions at different frequencies. It is shown that the maximum of the spectrum occurs in the low-frequency region for different laser pump focusing conditions. It is demonstrated that with the initial beam numerical aperture growth the generation of terahertz radiation at high frequencies increases more intensely compared to low frequencies.