Bloch Waves in Crystals and Periodic High Contrast Media

TL;DR

This paper develops analytic formulas and power series to describe the band structure of electromagnetic and acoustic waves in high contrast periodic media, using resonance spectra of quasi-periodic modes.

Contribution

It introduces a novel approach utilizing resonance spectra to represent solution operators and derive convergent power series for Bloch wave spectra in high contrast media.

Findings

Derived explicit conditions on contrast for convergence

Provided lower bounds on the convergence radius

Achieved separation of spectral branches in dispersion relations

Abstract

Analytic representation formulas and power series are developed describing the band structure inside periodic photonic and acoustic crystals made from high contrast inclusions. Central to this approach is the identification and utilization of a resonance spectrum for quasi-periodic source free modes. These modes are used to represent solution operators associated with electromagnetic and acoustic waves inside periodic high contrast media. Convergent power series for the Bloch wave spectrum is recovered from the representation formulas. Explicit conditions on the contrast are found that provide lower bounds on the convergence radius. These conditions are sufficient for the separation of spectral branches of the dispersion relation.