Design of novel sensitive terahertz metamaterial absorbers based on graphene-plasmonic nanostructures

Abstract

In this paper, four different configurations of sensitive metamaterial absorbers based on graphene-plasmonic combinations are designed and proposed. The nanostructures are made of graphene, SiO₂, aluminum and gold layers on a silicon substrate. Graphene-ring shaped structures with diagonal strips in vertical and horizontal directions are considered in the structures which greatly affect the absorption characteristics (absorption peak value and wavelength). Aluminum layer is used in the structure to prevent the transmission of light throughout some layers and improve the absorption factor. To promote the functionality of the structures, effects of the structural parameters (R₁ and R₂) and chemical potentials (E_f1, E_f2, E_f3 and E_f4) on the absorption peak are also studied. The four individual configurations with different layers and strip directions demonstrate distinct and different wavelength ranges; structure-1: 45–60 µm, structure-2: 50–70 µm, structure-3: 70–85 µm, and structure-4: 80–100 µm. Thus, they can be utilized for wide categories of applications. Sensitivities of 1500 nm/RIU, 2250/RIU, 3750 nm/RIU and 4850 nm/RIU are obtained for four types, respectively. The proposed structures can be categorized as refractive index biosensors, which indicate acceptable sensitivities and can be used for detection of different elements like hemoglobin and glucose in blood samples.