Tunable Linear-to-Circular Polarization Converter Using the Graphene Transmissive Metasurface

Hai-Feng Zhang,Guo-Biao Liu,Tong Huang,Li Zeng

doi:10.1109/access.2019.2950847

Abstract

In this article, a tunable linear-to-circular polarization converter (LTCPC) in terahertz (THz) regime using the graphene transmissive metasurface is proposed, which is composed of two resonant layers containing the metal and graphene resonators separated by a dielectric spacer. The linearly-polarized wave with normal incidence can be transformed to the circularly-polarized wave. The operating band can be dynamically regulated in THz band by electrically controlling the Fermi energy ( $E_{\mathrm {f}}$ ) of the graphene sheets rather than reforming the structures. The optimized result of axial ratio (AR) band which is less than 3 dB is located at 2.64-3.29 THz (the relative bandwidth is 21.92%) in the case of $E_{\mathrm {f}}=0.1$ eV. The physical characteristics of graphene are explored and the relevant operational results of the presented LTCPC are elucidated in this article. Compared with the conventional LTCPC, our design provides a more effective implementation method for wide applications, and it offers a further step in graphene controllable devices.

Highlights

Terahertz (THz) waves [1], generally referred to the electromagnetic radiation in the frequency range of 0.1-10 THz, are located between microwave and infrared radiation in the spectrum
The front view and the back view of the proposed linear-to-circular polarization converter (LTCPC) unit cell are displayed in Fig.1(a), and the side view and the stereoscopic perspective are given in Figs.1(b) and (c), respectively
From the Stoke parameters, the ellipse angle β and axial ratio (AR) are deduced by Eqs.(10) and (11) with Ef = 0.4 eV, which are calculated in Figs.5(a) and (b)

Summary

Introduction

Terahertz (THz) waves [1], generally referred to the electromagnetic radiation in the frequency range of 0.1-10 THz, are located between microwave and infrared radiation in the spectrum. The unique position between electronics and photonics makes THz wave possess a series of unique properties [2], [3], such as transient, broadband, coherence, low energy and strong penetration. Thanks to these particularities, THz wave shows great potential applications [4]–[6] in communication technology, electronic weapon countermeasure, radar monitoring, medical imaging, biochemical inspection and

Methods

Results

Conclusion