Comparing the Absorption Characteristics of Different Fractal Shapes as Unit Cells for THz Metasurface

In this paper, a comparison of the absorption characteristics of three fractal shaped unit cells augmented with graphene in THz frequency range is presented. The unit cells chosen for this study are the Haferman carpet, Sierpinski carpet, and a variant of the Sierpinski gasket. The proposed metasurface unit cell consists of monolayer graphene and bottom layer gold insulated by Alumina (Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>). Among the 3 different fractal shapes, the Sierpinski gasket gives the widest absorption bandwidth of 1.32 THz above 80% absorption rate for a graphene chemical potential 1.0 eV. The proposed absorber is characterized by invoking parametric studies of incident angles. The suggested absorber can be utilized for THz imaging as well as signal absorption to prevent scattering in undesired directions.