Two color laser driven THz generation in clustered plasma

Abstract

A scheme of terahertz (THz) generation, using nonlinear mixing of two color laser (fundamental ω1 and slightly frequency shifted second harmonic ω2) in clustered plasma, is investigated. The lasers exert ponderomotive force on cluster electrons and drive density perturbations at 2ω1 and ω2−ω1. The density perturbations beat with the oscillatory velocities to produce nonlinear current at ω2−2ω1, generating THz radiation. The radiation is enhanced due to cluster plasmon resonance and by phase matching introduced through a density ripple. The generation involves third order nonlinearity and does not require a magnetic field or inhomogeneity to sustain it. We report THz power conversion efficiency ∼10−4 at 1μm and 0.5μm wavelengths with intensity ∼3×1014W/cm2.