Tunable broadband cross polarization converter based on a graphene sheet with a T-shaped carved-hollow array

Abstract

We propose a tunable broadband reflective cross polarization converter (CPC) composed of a graphene sheet with a T-shaped carved-hollow array. In the mid-infrared region, cross polarization conversion with 5.17 THz bandwidth is achieved due to the superimposition of the two reflection components with a phase difference of nearly 180°. The polarization conversion ratio is larger than 80% in this broadband range, and the fractional bandwidth is 40%. The physical mechanism of CPC is attributed to the excitation of symmetric and antisymmetric graphene surface plasmons. The CPC broadband can always be retained when the incident angle increases from 0° to 20°, and the polarization angle increases from 40° to 50°. Also, the tunable responses of the reflective polarizer with Fermi energy and electron scattering time are discussed. Our design can be widely applied to adjustable broadband polarization conversion.