High Power Terahertz (THz) Radiation Generation through the Nonlinear Interaction of Cosh-Gaussian Laser Beams in Cluster Plasma

The nonlinear interaction of two co-propagating cosh-Gaussian laser beams in a cluster plasma is investigated and the electric field amplitude of emitted terahertz is evaluated. Due to spatial non-uniformity in the intensity of laser beam profiles, the cluster electron experience a nonlinear ponderomotive force at beat wave frequency in the perpendicular direction of the propagation wave. Due to this ponderomotive force, the cluster electrons acquire nonlinear oscillatory velocity. This oscillatory velocity couples with preformed density ripples to generate a strong transient nonlinear current which resonantly derives terahertz wave in the propagation direction of laser beams. The effects of laser beams and plasma parameters, including the decentered parameter, laser beam width, plasma density and amplitude of density ripples on the evaluation of THz electric field are examined, and it is found that the shape of generated THz radiation can be tuned by laser parameters. The THz filed amplitude strongly depends on the index of the decentered parameters of cosh-Gaussian beams and amplitude of density ripples.