Dual-polarity metamaterial circular polarizer based on giant extrinsic chirality.

J H Shi,G Y Nie,T J Cui,C Y Guan,Q C Shi,Y X Li

doi:10.1038/srep16666

Abstract

Chirality is ubiquitous in nature. The associated optical activity has received much attention due to important applications in spectroscopy, analytical chemistry, crystallography and optics, however, artificial chiral optical materials are complex and difficult to fabricate, especially in the optical range. Here, we propose an ultrathin dual-polarity metamaterial circular polarizer by exploiting the mechanism of giant extrinsic chirality. The polarity of the circular polarizer with large suppression of linear anisotropy can be switched by changing the sign of incident angle. The microwave experiments and optical simulations demonstrate that the large angle of incidence facilitates the high-efficiency circular polarizer, which can be realized in the whole spectra from microwave to visible frequencies. The ultrathin single-layer metamaterials with extrinsic chirality will be a promising candidate for circular polarization devices.

Highlights

According to Babinet’s principle, the magnetic dipole (m) in the plane of the asymmetrically split ring apertures (ASRAs) metamaterial and the electric dipole (d) perpendicular to the plane of the ASRA metamaterial are alternatively induced when a wave polarized along the mirror line of the ASRA is incident
It is anticipated that the ASRA metamaterial can work as a dual-polarity circular polarizer
We have demonstrated a high-efficiency dual-polarity circular polarizer exploiting extrinsic chirality in the single-layer ASRA metamaterial

Summary

Introduction

Following the previous work by Plum et al.[15], the linear polarization conversion in the extrinsic chiral metasurface was numerically studied to experience a change from a single ripple-free peak to a spectrum splitting with two separated peaks at a grazing incidence[37]. Such a metasurface can be expected as a circular polarizer to distinguish between RCP and LCP waves[15,37]. Microwave experiments and optical simulations demonstrate that the strong circular dichroism and birefringence can be tailored to be anywhere from microwave to optical frequencies Such the single-layer metamaterial with extrinsic chirality will be a promising candidate for diverse circular polarization functionalities

Methods

Results

Conclusion