Four-wave mixing with surface and guided-wave excitation in thin films

Abstract

A theory is presented which describes the excitation of a surface-polariton (surface electromagnetic wave) or a guided wave through the interaction of three bulk electromagnetic waves that are incident on the surface of a thin-film coating on a metal substrate. The film is modeled as a lossy dielectric (complex linear dielectric constant) with a third-order optical nonlinearity. The metal substrate is also described by a complex dielectric constant. A three-layer Green’s function method is used to calculate the Poynting vector parallel to the surface. The resonant excitation of surface waves or guided waves is calculated to occur at the sum or difference frequencies of the incident waves for certain incidence angles determined by the kinematics. One of the three incident waves may be taken as a static field to explore the effects of an applied voltage. Various wavelengths of the incident beams and of the surface or guided waves are considered.