Fabrication and SNOM characterization of plasmon-optical elements

Abstract

Refractive elements like lenses and prisms for surface plasmons with predefined effective refractive index were realized by thin-film elements. We demonstrate that the straightforward approach of using topographically structured dielectric coatings like polymethylmetacrylate can be successfully applied. The preparation process can thus be greatly simplified with respect to conventional approaches. The effective refractive index for plasmons is deduced in dependence on the film thickness. The value obtained is verified by SNOM imaging of refraction on prisms. Apart from common refraction, some plasmon-specific effects were observed and explained by finite element simulations. © 2007 IOP Publishing Ltd.