Metallic helix array as a broadband wave plate

TL;DR

This paper introduces a metallic helix array that functions as a broadband wave plate, capable of transforming polarized states over a wide frequency range, with both theoretical and experimental validation.

Contribution

It presents a novel metallic helix array design that achieves broadband wave plate functionality through unique polarization eigenstate modulation.

Findings

Demonstrates broadband wave plate operation in experiments

Shows polarization transformation over a wide frequency range

Identifies separate modulation of eigenstates via Bragg scattering and resonance

Abstract

This study proposes that a metallic helix array can operate as a highly-transparent broadband wave plate in propagation directions perpendicular to the axis of helices. The functionality arises from a special property of the helix array, namely that the eigenstates of elliptically right-handed and left-handed polarization are dominated by Bragg scattering and local resonance respectively, and can be modulated separately with nearly fixed difference between their wavevectors in a wide frequency range. The wave plate functionality is theoretically and experimentally demonstrated by the transformation of polarized states in a wide frequency range.