Abstract

A scheme is proposed to achieve a high power THz radiation based on the beating of two cross focused lasers in the spatially periodic density plasma. For the resonant excitation of THz radiation, the ripple wave number is suitably chosen to satisfy the phase matching condition. By considering ponderomotive nonlinearity, cross-focusing of two spatial-Gaussian lasers in the plasma has been investigated within the extended-paraxial regime. A nonlinear ponderomotive force at beat wave frequency also exerts to the electrons and the electrons experiences an oscillatory velocity at beat wave frequency. This nonlinear velocity couples with the density ripple and leads to the generation of transient transverse current density due to the spatial variation of the laser beams. This nonlinear current density drives the THz radiation. The emitted radiation power increases with the focusing of the laser beams.

© 2016 Optical Society of America