Computational Investigation of Laser Polarization on Filament Properties

Ultrashort pulse laser filaments are a unique source of ultra-broadband radiation, from the visible spectrum to terahertz (THz) and radio frequencies (RF). Experimental investigation has found that there is a polarization dependence on the amount of RF radiation produced by an atmospheric laser filament. To explain the experimental results, the polarization properties of a filamenting 800nm ultra short laser pulse are examined computationally. Using a delayed rotational response model for the refractive index contribution of the atmospheric gases and a paraxial enveloped wave equation solver, a computational finite differences investigation is carried out. The intent is to develop an understanding of how the input laser polarization alters the laser interaction with the filament and by extension how properties such as RF/THz yield and laser energy conversion efficiency are affected.