Low-Q whispering gallery modes in anisotropic metamaterial shells

TL;DR

This paper explores low-Q whispering gallery modes in anisotropic metamaterial shells, demonstrating their controllable quality factors and potential for electromagnetic energy harvesting through multilayer design.

Contribution

It introduces a novel analysis of low-Q whispering gallery modes in multilayer anisotropic shells with radially dependent parameters, highlighting their energy localization and tunable Q-factors.

Findings

Whispering gallery modes are created at shell boundaries with high radiative energy localization.

Q-factors can be controlled by the number of layers in the shell.

Resonant frequencies are independent of shell thickness.

Abstract

Anisotropic and inhomogeneous metamaterial shells are studied in order to exploit all their resonant mode richness. These multilayer structures are based on a cylindrical distribution of radially dependent constitutive parameters including an inner void cavity. Shell, cavity and whispering gallery modes are characterized, and special attention is paid to the latter ones. The whispering gallery modes are created at the boundary layers of the shell with the background and energy localization is produced with highly radiative characteristics. These low-Q resonant states have frequencies that are independent of the shell thickness. However, their quality factors can be controlled by the number of layers forming the shell, which allows confining electromagnetic waves at the interface layers (internal or external), and make them suitable for the harvesting of electromagnetic energy.