Highly Sensitive and Tunable Graphene Metamaterial Perfect Absorber in the Near-Terahertz Band

This paper presents a highly sensitive and tunable graphene-based metamaterial perfect absorber (MPA) operating in the near-terahertz band. The structure features a unique flower-like graphene pattern, consisting of a Au substrate, a SiO2 dielectric layer, and the patterned graphene. Multiple reflections of incident light between the gold and graphene layers increase the duration and intensity of the interaction, resulting in efficient absorption at specific frequencies. The design utilizes surface plasmon resonance (SPR) to achieve near-perfect absorption of 99.9947% and 99.6079% at 11.7475 THz and 15.8196 THz, respectively. By tuning the Fermi level and relaxation time of graphene, it is possible to precisely control the frequency and absorptivity of the absorption peak, thereby demonstrating the dynamic tunability of the absorber. The high symmetry and periodic arrangement of the structure ensures insensitivity to the polarization angle of the incident light in the range of 0° to 90°, making it extremely valuable in practical applications. In addition, the absorber exhibits very high sensitivity to changes in ambient refractive index with a maximum sensitivity of 3.205 THz/RIU, a quality factor (FOM) of 11.3011 RIU−1, and a Q-Factor of 48.61. It has broad application prospects in the fields of sensors, optoelectronic devices, and terahertz imaging.