%0 Journal Article
%T Design of Matched Absorbing Layers for Surface Plasmon-Polaritons
%A Sergio de la Cruz
%A Eugenio R. M¨Śndez
%A Alexei A. Maradudin
%J Advances in OptoElectronics
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/598213
%X We describe a procedure for designing metal-metal boundaries for the strong attenuation of surface plasmon-polaritons without the introduction of reflections or scattering effects. Solutions associated with different sets of matching materials are found. To illustrate the results and the consequences of adopting different solutions, we present calculations based on an integral equation formulation for the scattering problem and the use of a nonlocal impedance boundary condition. 1. Introduction In the numerical solution of spatially unbounded electromagnetic problems it is often necessary to truncate the computational domain. The use of a region of finite spatial size can introduce reflections and other spurious effects in the calculations. Several techniques have been proposed to overcome this problem. An established one, used commonly in finite-difference time-domain (FDTD) calculations [1], is the perfectly matched layer (PML) technique proposed by Berenger [2]. Such a layer can absorb electromagnetic waves without reflections at the vacuum-PML interfaces. Methods of calculation based on GreenĄŻs theorem (see, e.g., [3]) do not present such complications with volume waves, but the truncation of the interfaces can produce spurious effects in the presence of surface waves, like surface plasmon-polaritons (SPPs). The basic properties of SPPs have been known for some time, but their importance for nanophotonic applications has produced a renewed interest on the subject [4, 5]. In studies of the interactions of SPPs with objects or surface structures, the computational problem grows as a function of the physical size of the sample and, thus, it is desirable to reduce the computational domain as much as possible. The PML techniques known to us were not designed to handle truncation effects involving SPPs, and are not well-adapted for situations involving metallic structures and evanescent waves [6]. In this paper, we present a procedure for determining the optical constants of absorbing materials for the attenuation of SPPs without introducing, or minimizing at least, spurious reflections and/or radiative scattering effects. Although SPPs are already lossy traveling waves, a reduction of their propagation length in the matched medium permits an important reduction in the dimensions of the region over which the computational domain extends. Although our approach is related in spirit to the usual PML techniques, we point out that it addresses a different problem, namely, the termination of surfaces over which surface waves propagate without the introduction
%U http://www.hindawi.com/journals/aoe/2012/598213/