Wideband and Tunable Reflective Cross-Polarization Conversion Metasurface for TeraHertz Applications

Abstract

An ultrathin and wideband reflective cross-polarization converter is presented in this paper. The design consists of a pair of modified dumbbell shaped resonators which are connected together with a conductive strip. The proposed single-layer THz metasurface achieved a high polarization conversion ratio (PCR) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ge$</tex-math></inline-formula> 95% in the operating frequency ranging from 1.76–4.26 THz. This wide-bandwidth cross-polarization conversion is obtained by exciting multiple closely spaced resonant frequencies at 1.98 THz, 2.61 THz, 2.95 THz, and 3.93 THz. The working mechanism of the proposed structure is analyzed and the polarizer exhibits an excellent angular stability upto 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{0}$</tex-math></inline-formula> of incidence. Further, the proposed cross-polarizer exhibits continuous tunability of PCR over the operating frequencies when photoconductive silicon (Si) is filled in the gap between pair of dumbbell-resonators. The wideband characteristics and the switchable property show that the proposed reflective cross polarizer is an excellent candidate for manipulation and control of polarization in THz communication systems.