Excitation-wavelength-dependent THz wave modulation via external bias electric field*

Abstract

A theoretical model was proposed to describe the effects of external bias electric field on terahertz (THz) generated in air plasma. The model predicted that for a plasma in a bias electric field, the amplification effect of the THz wave intensity increases with the increase of the excitation laser wavelength. We experimentally observed the relationship between the THz enhancement effect and the electric field strength at different wavelengths. Experimental results showed a good agreement with the model predictions. These results enhance our understanding of the physical mechanism by which femtosecond lasers excite air to generate THz and extend the practical applications of THz generation and modulation.

Terahertz Spectroscopy Applied to Diagnostics in Public Health: A Review

“…The usually THz radiation sources used comprise: a) harmonic multipliers of tunable microwave sources, b) vacuum electronics c) supercontinua generated by ultrafast lasers and photoconductive switches, and c) difference-frequency mixing of tunable continuous-wave lasers [8]. Recent studies have shown different sources to THz radiation, for example: a) air plasma [10]; b) spintronic next-generation ultra-wideband [11]; and c) Gas-phase molecular laser [8].…”