Voigt waves in homogenized particulate composites based on isotropic dielectric components

TL;DR

This study investigates how the orientation, shape, size, and volume fraction of isotropic dielectric particles in homogenized composites influence the support and propagation of Voigt waves, a unique optical phenomenon.

Contribution

It extends the Bruggeman homogenization formalism to analyze the effects of particle characteristics on Voigt wave support in biaxial HCMs.

Findings

Voigt wave propagation directions are highly sensitive to particle orientation and volume fraction.

Support for Voigt waves depends critically on particle size and volume fraction.

Shape and size of particles have less influence on Voigt wave propagation.

Abstract

Homogenized composite materials (HCMs) can support a singular form of optical propagation, known as Voigt wave propagation, while their component materials do not. This phenomenon was investigated for biaxial HCMs arising from nondissipative isotropic dielectric component materials. The biaxiality of these HCMs stems from the oriented spheroidal shapes of the particles which make up the component materials. An extended version of the Bruggeman homogenization formalism was used to investigate the influence of component particle orientation, shape and size, as well as volume fraction of the component materials, upon Voigt wave propagation. Our numerical studies revealed that the directions in which Voigt waves propagate is highly sensitive to the orientation of the component particles and to the volume fraction of the component materials, but less sensitive to the shape of the component particles and less sensitive still to the size of the component particles. Furthermore, whether or not such an HCM supports Voigt wave propagation at all is critically dependent upon the size of the component particles and, in certain cases, upon the volume fraction of the component materials.