Tunable Double Negative Band Structure from Non-Magnetic Coated Rods

TL;DR

This paper demonstrates a tunable negative index band structure in a non-magnetic nano-rod system by exploiting Mie resonances and coating properties, enabling control over negative permittivity and permeability.

Contribution

It introduces a novel non-magnetic coated nano-rod system with tunable negative index properties based on explicit band structure calculations.

Findings

Negative effective magnetic permeability near Mie resonances.

Tunable pass bands with negative group velocity.

Control of negative index via geometric parameters.

Abstract

A system of periodic poly-disperse coated nano-rods is considered. Both the coated nano-rods and host material are non-magnetic. The exterior nano-coating has a frequency dependent dielectric constant and the rod has a high dielectric constant. A negative effective magnetic permeability is generated near the Mie resonances of the rods while the coating generates a negative permittivity through a field resonance controlled by the plasma frequency of the coating and the geometry of the crystal. The explicit band structure for the system is calculated in the sub-wavelength limit. Tunable pass bands exhibiting negative group velocity are generated and correspond to simultaneously negative effective dielectric permittivity and magnetic permeability. These can be explicitly controlled by adjusting the distance between rods, the coating thickness, and rod diameters.