Surface polaritons on left-handed cylinders: A complex angular momentum analysis

TL;DR

This paper analyzes electromagnetic scattering by left-handed cylinders using complex angular momentum methods, revealing families of surface polaritons, including unique whispering-gallery modes, and describing their dispersion and damping.

Contribution

It introduces a detailed classification of surface polaritons on left-handed cylinders via Regge poles, highlighting new whispering-gallery modes unique to left-handed materials.

Findings

Long-lived resonant modes are classified into families generated by surface polaritons.

Each surface polariton is characterized by its dispersion relation and damping.

Existence of unique whispering-gallery surface polaritons specific to left-handed materials.

Abstract

We consider the scattering of electromagnetic waves by a left-handed cylinder -- i.e., by a cylinder fabricated from a left-handed material -- in the framework of complex angular momentum techniques. We discuss both the TE and TM theories. We emphasize more particularly the resonant aspects of the problem linked to the existence of surface polaritons. We prove that the long-lived resonant modes can be classified into distinct families, each family being generated by one surface polariton propagating close to the cylinder surface and we physically describe all the surface polaritons by providing, for each one, its dispersion relation and its damping. This can be realized by noting that each surface polariton corresponds to a particular Regge pole of the $S$ matrix of the cylinder. Moreover, for both polarizations, we find that there exists a particular surface polariton which corresponds, in the large-radius limit, to the surface polariton which is supported by the plane interface. There exists also an infinite family of surface polaritons of whispering-gallery type which have no analogs in the plane interface case and which are specific to left-handed materials.