The Photonic Band theory and the negative refraction experiment of metallic helix metamaterials

TL;DR

This paper develops a novel theory to analyze the photonic band structure of metallic helix metamaterials and experimentally demonstrates negative refraction through direct measurement of Goos-Hänchen shift.

Contribution

It introduces the first comprehensive theory for the photonic band structure of metallic helix arrays and provides experimental evidence of negative refraction in such chiral metamaterials.

Findings

Identification of unique polarization modes and wide polarization gap

Existence of negative group velocity bands at specific frequencies

Experimental confirmation of negative refraction via Goos-Hänchen shift

Abstract

We develop a theory to compute and interpret the photonic band structure of a periodic array of metallic helices for the first time. Interesting features of band structure include the ingenuous longitudinal and circularly polarized eigenmodes, the wide polarization gap [Science 325, 1513 (2009)], and the helical symmetry guarantees the existence of negative group velocity bands at both sides of the polarization gap and band crossings pinned at the zone boundary with fixed frequencies. A direct proof of negative refraction via a chiral route [Science 306, 1353 (2004)] is achieved for the first time by measuring Gooshanchen shift through a slab of three dimensional bona fide helix metamaterial.