Scaling and saturation of high-power terahertz radiation generation in two-color laser filamentation

摘要

Broadband terahertz generation via two-color femtosecond laser filamentation is studied with laser input energies up to 60 mJ. In the small f-number focusing regime, the output THz energy strongly saturates, which is attributed to ionization-induced laser defocusing in filamentation. This saturation effect can be minimized by elongating the plasma filament with weak focusing. A conversion efficiency of ＞10~(-4) is achieved in elongated filamentation.