A relatively broadband, polarization-insensitive, and tunable graphene-based metamaterial absorber in the THz ranges

Abstract To address the limitations of traditional electromagnetic wave absorbers, such as their very narrow absorption bandwidth and untunable features, this paper introduces a graphene-based metamaterial absorber. A terahertz metamaterial absorber with nearly complete absorption across a broad terahertz spectral range is demonstrated using a patterned monolayer graphene, which offers a simpler structural design, higher absorption efficiency, and wider bandwidth compared to existing absorbers. The proposed structure features a graphene layer embedded within a 60 μm-thick SiO 2 layer, positioned on an Au layer, which results in light reflection from the rear side and enhanced absorption efficiency. A figure of merit is introduced to identify the optimal structure with the broadest absorption bandwidth in the 0.1 THz to 10 THz range, considering the placement and pattern of the graphene layer. The optimized design achieves power absorption exceeding 90% within the 0.81 THz to 1.75 THz range, with the highest figure of merit of 0.89. The insensitivity of the proposed structure to incident angle (from 0° to 75°) and polarization has been analyzed using the finite element method.