Multi-functional graphene periodic patterns

Abstract

By describing an idea based on binary matrices, a meta-surface design methodology has been introduced in the THz spectrum window. Independence of the numerical values of the geometrical parameters, the shape of graphene patterns, as well as the mode of the bias network for the patterns, have been investigated. The possibility of describing meta-surfaces by circuit equivalents has made it possible to predict the behavior of meta-surfaces at least in the THz band with acceptable accuracy by exploiting the idea of impedance matching. Considering the significant effect of changing graphene patterns and applying multiple biases, this work tries to optimize the pattern's shapes and external bias application. In this regard, two simple binary matrices are introduced which present pattern types and corresponding biasing schemes. Leveraging developed equivalent circuit models for known periodic graphene patterns, a systematic procedure is suggested to consider pattern diversity and simultaneous multiple biases for single layers. Exploiting patterns of graphene disks, rings, and ribbons besides a back reflector and polymer substrate, a reconfigurable and adjustable wave absorber is suggested. Two sets of external stimulations via chemical potentials force the device to show wide-band and multi-band absorption while appealing tuning capability is achieved for multi-band mode. Considering both operational modes, it seems that the proposed absorber can cover almost all of the THz spectrum with excellent shifting possibilities. The validity of impedance matching description is verified by full-wave simulations while ample analysis is shown to investigate reliability against oblique radiation.