Nonlinear interaction among surface plasmon waves excited by finite-cross-section beams in a multilayer

Abstract

Nonlinear coupling processes involving surface plasmons are analyzed by the method of plane-wave expansion in the near-resonance approximation. Effects of the finite cross section of the interacting incident beams as well as of the linear and nonlinear growth of surface-plasmon waves are taken into account simultaneously. It is found that in the near-resonance approximation the nonlinear process is described by a set of nonlinearly coupled differential equations with driving terms representing the contribution of bulk beams. The theory is applied to a stack of nonlinear films, with particular attention to mixing of three surface waves and to second-harmonic generation in a prism film coupler with a nonlinear substrate.