Terahertz and far infrared radiation generation in air plasma created by bichromatic subpicosecond laser pulses

Abstract

Here, we report on terahertz (THz) radiation generation in air driven by the fundamental and second harmonic of Yb:KGW laser pulses with durations of a few hundred femtoseconds. It was found that the spectrum of generated THz pulses surprisingly spans up to 50 THz, which is comparable to that usually obtained using much shorter Ti:sapphire laser pulses. The broad bandwidth is attributed to a strong spatiotemporal reshaping of the pump pulses in a filament. The achieved energy conversion efficiency is comparable to the one usually obtained from much shorter pump pulses and could be further improved by an optimized experimental setup. The obtained results indicate that compact Yb-based sources provide an attractive alternative to much larger and expensive laser systems.