Beam oscillations and curling in chirped periodic structures with metamaterials

TL;DR

This paper investigates electromagnetic wave propagation in linearly chirped layered metamaterials, revealing unique beam steering capabilities due to opposite energy flow directions at band edges, contrasting with traditional dielectric structures.

Contribution

It introduces an asymptotic analytical approach to study Bloch oscillations in chirped metamaterial structures, highlighting novel energy flow behaviors at band edges.

Findings

Energy flow can reverse direction at band edges in metamaterials.

Chirped structures enable beam steering within transmission bands.

Contrasts with behavior in ordinary dielectric periodic structures.

Abstract

We study the propagation of electromagnetic waves in one-dimensional chirped periodic structures composed of alternating layers of negative-index (or left-handed) metamaterial and conventional dielectric, under the condition of the zero average refractive index. We consider the case when the periodic structure has a linear chirp, and the chirp is introduced by varying linearly the thickness of the layers across the structure. We apply an asymptotic analytical method for the analysis of the Bloch oscillations and find that, in a sharp contrast to ordinary periodic dielectric structures, the energy flow in multi-layered stacks with metamaterials may have the opposite direction at the band edges, thus providing novel possibilities for the beam steering in the transmission band.