Open AccessDielectric-resonator metasurfaces for broadband terahertz quarter- and half-wave mirrors
Author(s) -
Wendy S. L. Lee,
Rajour Tanyi Ako,
Mei Xian Low,
Madhu Bhaskaran,
Sharath Sriram,
Christophe Fumeaux,
Withawat Withayachumnankul
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.014392
Subject(s) - optics , terahertz radiation , resonator , broadband , polarization (electrochemistry) , circular polarization , bandwidth (computing) , physics , metamaterial , waveplate , wavelength , optoelectronics , telecommunications , laser , computer science , microstrip , chemistry
Polarization conversion of terahertz waves is important for applications in imaging and communications. Conventional wave plates used for polarization conversion are inherently bulky and operate at discrete wavelengths. As a substitute, we employ reflective metasurfaces composed of subwavelength resonators to obtain similar functionality but with enhanced performance. More specifically, we demonstrate low-order dielectric resonators in place of commonly used planar metallic resonators to achieve high radiation efficiencies. As a demonstration of the concept, we present firstly, a quarter-wave mirror that converts 45° incident linearly polarized waves into circularly polarized waves. Next, we present a half-wave mirror that preserves the handedness of circularly polarized waves upon reflection, and in addition, rotates linearly polarized waves by 90° upon reflection. Both metasurfaces operate with high efficiency over a measurable relative bandwidth of 49% for the quarter-wave mirror and 53% for the half-wave mirror. This broadband and high efficiency capabilities of our metasurfaces will allow to leverage maximum benefits from a vast terahertz bandwidth.