Two-Surface Wave Decay

The parametric excitation of pairs of electron surface waves (ESW) in the interaction of an ultrashort, intense laser pulse with an overdense plasma is discussed using an analytical model. The plasma has a simple step-like density profile. The ESWs can be excited either by the electric or by the magnetic part of the Lorentz force exerted by the laser and, correspondingly, have frequencies around omega/2 or omega, where omega is the laser frequency.