Excitation of surface waves on the interfaces of general bi-isotropic media

TL;DR

This paper provides a theoretical analysis of surface waves at the interface between metals and bi-isotropic media, deriving dispersion relations and analyzing how parameters like chirality and Tellegen affect wave properties.

Contribution

It introduces an analytical dispersion relation for surface waves on bi-isotropic media and explores their behavior using the invariant imbedding method, including quasi surface wave excitation.

Findings

Effective index increases with chirality in chiral media.

Propagation length increases with both chirality and Tellegen parameters.

Surface wave properties depend critically on the medium parameters.

Abstract

We study theoretically the characteristics of surface waves excited at the interface between a metal and a general bi-isotropic medium, which includes isotropic chiral media and Tellegen media as special cases. We derive an analytical dispersion relation for surface waves, using which we calculate the effective index and the propagation length numerically. We also calculate the absorptance, the cross-polarized reflectance and the spatial distribution of the electromagnetic fields for plane waves incident on a bilayer system consisting of a metal layer and a bi-isotropic layer in the Kretschmann configuration, using the invariant imbedding method. The results obtained using the invariant imbedding method agree with those obtained from the dispersion relation perfectly. In the case of chiral media, the effective index is an increasing function of the chirality index, whereas in Tellegen media, it is a decreasing function of the Tellegen parameter. The propagation length for surface waves in both cases increase substantially as either the chirality index or the Tellegen parameter increases. In Tellegen media, it diverges to infinity when the effective index goes to zero, whereas in chiral media, it does when the parameters approach the cutoff values where quasi surface waves are excited. We investigate the characteristics of quasi surface waves excited when the chirality index is sufficiently large.