A flexible U-shaped metamaterial terahertz quarter-wave plate with corner design

Abstract

To overcome the bottleneck problem that the right-angle of metamaterial metal unit cell can’t be perfectly machined in the existing photolithography process, the tangent treatment of U-shaped corners is carried out in this paper. Using two layers of U-shaped metamaterial gold unit cell with corner design sandwiched with three polyimide layers, a flexible terahertz quarter-wave plate (QWP) with polarization conversion efficiency of 0.8 and operating bandwidth of 0.2 THz is obtained. The equivalent dielectric parameter of substrate is proposed to provide the correct dielectric parameter input of polyimide for the precise simulation. The influences of the equivalent dielectric parameter, the corner tangent length and the geometric parameters of the metamaterial metal unit cell on the QWP performance are analyzed. To better understand the effects of these parameters on the QWP performance, an empirical formula for multilayer U-shaped metamaterial is given in this paper. This work has good application potential in terahertz wireless communications, terahertz imaging, and terahertz medical diagnostic systems and other fields.