Graphene-based terahertz tunable double-broadband perfect absorber

The rapid advancement of terahertz(THz) technology has sparked significant interest in exploring tunable broadband functional devices. In this study, we propose an antisymmetric graphene skeletonized structure to achieve a terahertz double-broadband perfect absorber. This absorber consists of a gold (Au) substrate, a TOPAS dielectric layer and C4 regular antisymmetric-patterned graphene embedded in the polymer. It exhibits two unpolarized perfect absorbing broadbands through the resonance mechanisms of localized surface-isolated exciton resonance and electromagnetic dipole resonance. The results indicate high absorbance exceeding 90% across two distinct frequency ranges of 0.93–2.03 THz and 4.16–5.3 THz. The dual-broadband absorption feature stems from the pronounced aggregation effect of the "Hollow-out corner" on the electric field, enabling modulation of the second Harmonic while leaving the first Harmonic largely unaffected. The absorber's response can be dynamically tuned through adjusting the Fermi energy level and structural parameters of graphene. Our design opens up possibilities for diverse applications in photodetectors, THz modulation, and stealth technologies.