Nonlinear optical effects in holey metal films

Abstract

Interaction of intense light with matter gives rise to great variety of nonlinear optical phenomena: Raman scattering, photo-luminescence in metals, Second Harmonic Generation (SHG), Four Wave Mixing (FWM), Third Harmonic Generation (THG) and Optical Kerr Effect (OKE) are among them. The possibility of taking advantage from those or other nonlinear effects has attracted the attention of the scientific community, looking forward to getting active components at the nano-scale. Steps towards the non-linear regime require better understanding on the behavior of nonlinear materials at the nano-scale and, in particular when combined with nano-structured metals. In following that, we theoretically study OKE and THG in metal films pierced by periodically arranged slits. We show the important role played by the metal properties and the particular geometry of the system in non-linear efficiency. Finally we envisage the possibility of building an optical limiter of the transmitted intensity, in which the output intensity decreases when the incident one increases, and an optical switch, where the output intensity increases abruptly under a small change of the incident power. These two operating modes are found in an array of metallic slits placed on a nonlinear Kerrtype dielectric layer, at the telecom regime. This approach relays on the abrupt changes of the output light intensity usually observed near linear transmission minima.