Full Current Model for Terahertz Wave Generation from Femtosecond Laser Filament Under External Electric Fields

In this work, we propose a full current model in order to interpret the mechanism of tcrahcrtz (THz) wave generation from single-color femtosecond laser filamentation under transverse and longitudinal direct current fields. The model consists of two processes, i.e., oscillation of the microscopic plasma current and radiation of the macro current transmission line. Both processes arc combined to describe the tcrahcrtz THz) radiation characteristics such as tcrahcrtz wave enhancement and spatial distribution evolution. Compared with the well-known transition-Cherenkov radiation theory, the proposed full current model can achieve phase matching under the condition of equal light speed, and has a clearer physical picture and simpler formulas. Moreover, it can reproduce the experimental results well.