Terahertz Radiation Enhancement from Femtosecond Laser Ionized Air Micro-Plasma Under Static Electric Field

Femtosecond laser filamentation is one of the important approaches to obtain THz pulse with ultra-broad bandwidth and high electric field. With the rapid development of femtosecond laser technology, plasma based THz generation by femtosecond laser has been well studied.

Two theoretical models have reported for understanding the physical mechanism of THz pulse generation, namely the photocurrent model and the four wave mixing model, respectively. By applying an external static electric field to the laser-induced plasmas filament, the enhancement of THz radiation has been reported by several orders of magnitude. However, the physical mechanism of laser-induced THz emission under the external static electric field remains unclear because of the complex interaction of laser plasmas.