Nearly degenerate four-wave mixing in a plasma by the resonance of an electron-plasma wave

Abstract

We investigate nearly degenerate four-wave mixing in a plasma that is caused by the density grating of a resonantly excited electron-plasma wave. The third-order nonlinear susceptibilities of the plasma are derived analytically, and the conditions necessary to permit phase matching are discussed. The coupled-wave equations are solved to yield the phase-conjugate reflectivity. The dependence of the reflectivity on the frequency difference between the pump beams and the probe beam, as well as on the interaction length, is investigated both analytically and numerically.