Polarization-insensitive, ultrathin, miniaturized, broadband graphene-based terahertz metamaterial absorber

Abstract This paper presents the design and analysis of a novel, ultrathin, polarization-insensitive, broadband, and miniaturized terahertz metamaterial absorber based on graphene material. The suggested design exhibits a compact volumetric profile with normalized dimensions of 0.068λ₀ × 0.068 λ₀ × 0.068 λ₀, demonstrating a high level of miniaturization through its small wavelength-normalized dimensions referenced to the minimum operating frequency compared with previously reported THz absorbers. The broadband absorption mechanism is enabled by the controlled merging of multiple resonance modes, arising from edge-induced capacitive coupling and geometrically distributed current paths within the symmetric unit cell. As a result, the structure maintains an absorption level exceeding 90% over the 2.05–3 THz frequency range, corresponding to an effective bandwidth of approximately 1 THz, while achieving absorption above 96% within 2.1–2.9 THz. Electric-field localization, impedance matching characteristics, and design evolution were investigated to clarify the absorption mechanism and electromagnetic behavior of the proposed absorber. In addition to its compactness and broadband performance, the proposed absorber demonstrates strong polarization insensitivity and angular stability due to its symmetric configuration, maintaining high absorption for both TE and TM modes under oblique incidence up to 70°. The findings confirm that the system maintains stable performance under different incidence angles and wave orientations, confirming its strong angular stability.