Generation of terahertz radiation by nonlinear mixing of two laser beams in overdense plasma

Terahertz radiation generation by nonlinear mixing of two laser beams in an overdense plasma is investigated. The lasers penetrate into the plasma and impart oscillatory velocity to plasma electrons and exert a ponderomotive force on them at the beat frequency. The ponderomotive force has a transverse component that drives nonlinear current, producing terahertz radiation in the reflected component. The process is sensitive to the angle of incidence of the laser beams.