Characterization of Surface-Plasmon Polaritons at Lossy Interfaces

TL;DR

This paper derives strict bounds on permittivity and permeability for the successful propagation of surface-plasmon polaritons at lossy interfaces, providing a tool to evaluate the viability of related applications and correcting previous misconceptions.

Contribution

It introduces a method to determine the conditions under which surface-plasmon polaritons can propagate at lossy interfaces, correcting prior assumptions about double-negative media.

Findings

Propagation occurs only within specific permittivity and permeability bounds.

The method falsifies the claim that surface-plasmon propagation is universal in double-negative media.

Provides a practical check for the viability of plasmonic applications.

Abstract

We characterize surface-plasmon polaritons at lossy planar interfaces between one dispersive and one nondispersive linear isotropic homogeneous media, i.e., materials or metamaterials. Specifically we solve Maxwell's equations to obtain strict bounds for the permittivity and permeability of these media such that satisfying these bounds implies surface-plasmon polaritons successfully propagate at the interface, and violation of the bounds impedes propagation, i.e., the field delocalizes from the surface into the bulk. Our characterization of surface-plasmon polaritons is valuable for checking viability of a proposed application, and, as an example, we employ our method to falsify a previous prediction that surface-plasmon propagation through a surface of a double-negative refractive index medium occurs for any permittivity and permeability; instead we show that propagation can occur only for certain medium parameters.