Thin Metal-Free THz Absorbers: Broadband Sensing Solutions

This paper introduces an innovative technique for achieving broadband and near-unity absorption in a Metal-Free Absorber (MFA) using graphite within the THz range. The MFA design consists of graphite slots and notches at the top that function as resonators, a dielectric SiO2 substrate positioned in the middle, and a graphite sheet placed at the bottom. Graphite is chosen for thermal stability and its excellent electrical properties in the THz region, which contribute to the absorber's high performance. Results demonstrate that the single-layer MFA achieves an absorption rate of ≥90%, spanning a bandwidth of 6.58 THz (from 7.85 THz to 14.44 THz), peak absorption at 11 THz of 95.5%. The double-layer MFA extends the absorption bandwidth to 12.78 THz (from 4.92 THz to 17.70 THz) and achieves a peak absorption of 100% at both 7.4 THz and 14.9 THz. These findings underscore the potential of the proposed MFA structure for effective broadband absorption in the THz frequency range, constructing it a promising candidate for various advanced THz applications.