Design and Simulation Investigations of Ultrawideband Metamaterial-Based Terahertz Absorber

A simple, ultrawideband metamaterial-based perfect absorber is proposed, featuring a novel unit cell composed of three vanadium dioxide (VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>) rings strategically interrupted by rectangular cut outs. The multilayer structure consists of tetrafluoroethylene (Teflon) positioned between VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and is backed by a gold (Au) ground plane, which acts as a reflective layer. The simulation results of the proposed unit cell predict that the absorption bandwidth of the proposed absorber is 4.93 terahertz (THz), spanning from 3.44 to 8.37 THz when VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is in the conducting (metallic) state. Within this band, the structure also demonstrates angular stability and near unity (perfect) absorption at 4 and 6 THz, making it highly suitable for applications such as THz sensing, imaging, and stealth applications. The fractional bandwidth (FBW) of the absorber is found to be 83.4%. The electric field distribution and surface current density result at frequencies, namely, 2.5, 4, 6, and 8.24 THz are presented. Moreover, the sensitivity studies of the proposed design are explored for several geometric parameter variations and conductivities of the VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>, and the potential reasons behind the respective performance are presented.