Numerical Investigation of an Electrically Tunable Graphene–Based Perfect Metamaterial Absorber in the Terahertz Regime

The development of highly tunable terahertz metamaterial absorbers is critical for assuring enhanced sensing and optoelectronic technologies. This study proposes a compact, electrically tunable graphene–based metamaterial absorber featuring a triangular graphene pattern on a 3 μm ultrathin SiO₂ substrate with integrated gold layers. The proffered graphene metamaterial absorber (GMMA) operates well within the 5–10 THz range, demonstrating high absorption efficiency at multiple resonant frequencies. The absorption characteristics of the proposed GMMA can be precisely tuned through the alteration of fermi energy of graphene through an externally applied gate voltage, making the device highly adaptable for a multitude of applications. Numerical simulations using Lumerical FDTD reveal four notable absorption peaks at 5.98 THz, 7.12 THz, 8.257 THz, and 9.32 THz, achieving near-perfect absorption with efficiencies of 99.7%, 99.4%, 97.97%, and 92.41%, respectively. The structure demonstrates exceptional sensitivity to variations in refractive index (RI), covering a broad RI range from 1.1 to 1.8 with a spectral sensitivity of 2 THz/RIU. A comparative analysis utilizing particle swarm optimization depicts the superiority of the triangle structure over alternative shapes, including rectangles, rings, and nanostrips, providing optimal performance with fabrication simplicity. The proposed metamaterial absorber, characterized by enhanced absorption efficiency, exquisite tunability, and ease of fabrication, possesses considerable potential for applications in nanoscale sensing, gas detection, high-speed communication, and stealth technology, thereby propelling the development of next-generation terahertz devices.