Dual-band, Dynamically Tunable Plasmonic Metamaterial Absorbers Based on Graphene for Terahertz Frequencies

In this paper, a compact plasmonic metamaterial absorber for terahertz frequencies is proposed and simulated. The absorber is based on metamaterial graphene structures, and benefits from dynamically controllable properties of graphene. Through patterning graphene layers, plasmonic resonances are tailoredto provide a dual bandas well as an improvedbandwidth absorption. Unit cell of the designed structure is made of four complementarysquare rings, ona thingroundedSiO2 layerof 5 µm thickness. Four splits are includedin the square rings to provide continuityofgraphene layer. Dual bandabsorption of 90% is provided, which frequencyofpeakabsorptionincreases with increasingchemical potential of graphene layer. It is shown that with varying dimensions of the split rings an improved bandwidth absorber is also achieved, whereabsorptionbandincreases with increasinggraphene's chemical potential either. To better understandexcitationof plasmonic resonances on the proposedstructure, electric field distribution onthegraphene layeras well as at theunit cell’s cross sectionis investigatedandgraphically demonstrated. Dependence of absorption onincidence andpolarizationangles of theincomingwave is studied and also graphically presented. © 2019 Materials and Energy Research Center. All rights reserved.