Adaptive Terahertz Absorber Based On Tunable Graphene Multilayer

A new adaptive terahertz absorbing screen providing a reflection coefficient lower than 10 dB in the frequency range 0.6-2.2 THz and with total thickness around 70 mu m is proposed. The designed Salisbury screen, backed by a perfect electric conducting plate, consists of a first graphene layer as lossy sheet and two spacers made of polyethylene terephthalate (PET), separated by a tunable graphene/SiO2 laminate (GL). An electrostatic field up to 0.06 V/nm is applied across the GL in order to tune the electrical conductivity of the graphene layers, with the aim of minimizing the screen total reflection coefficient. A design procedure based on the transmission line method is proposed and a parameter sensitivity analysis of the reflection coefficient is carried out. The influence of the carrier charge mobility and of the number of graphene sheets composing the GL is investigated, considering different values of the electrostatic field in the frequency range 0.1-5 THz.