Negative refractive index induced by percolation in disordered metamaterials

TL;DR

This paper develops an effective medium model for disordered metamaterials with dielectric spheres, predicting negative refractive index emergence due to percolation-induced resonance overlap.

Contribution

It introduces a novel effective medium model that accounts for percolation effects in disordered metamaterials, predicting negative refractive index.

Findings

Resonances in permeability and permittivity are predicted.

Electric resonance redshifts with increased particle loading.

Negative refractive index occurs when particle loading exceeds 33%.

Abstract

An effective medium model is developed for disordered metamaterials containing a spatially random distribution of dielectric spheres. Similar to effective medium models for ordered metamaterials, this model predicts resonances in the effective permeability and permittivity arising from electric- and magnetic-dipole Mie resonances in the spheres. In addition, the model predicts a redshift of the electric resonance with increasing particle loading. Interestingly, when the particle loading exceeds the percolation threshold of 33\%, the model predicts that the electric resonance overlaps with the magnetic resonance, resulting in a negative refractive index.