High sensitivity and high figure of merit graphene mid-infrared multi-band tunable metamaterial perfect absorber

In the research of this paper, we have devised a mid-infrared band metamaterial perfect absorber made of graphene material. The absorber is composed of a traditional three-layer structure of MPA. The top layer is a graphene layer with a specific structure, with SiO₂ as the dielectric layer and the gold film as the substrate. In the wavelength range of 5500 – 13,000 nm, the graphene layer generates seven absorption peaks and shows ultra-high absorption efficiency. The respective absorption rates are 91.17 %, 99.41 %, 99.01 %, 95.69 %, 94.16 %, 96.89 %, and 95.01 %. By verifying the absorption spectra and the principle of effective impedance matching, analyze the electric field distribution image of the xoy plane based on the principle of surface plasmon resonance, we have proved that it conforms to the classical physical theory and expounded the reason why the absorption peaks were formed. The comparison of different graphene patterns has confirmed the superiority of this structure. By changing the relaxation time and Fermi level of graphene, the tunability of the absorber structure has been verified. Changing the incident angle has proved its insensitivity to the polarization angle (0° - 50°). Finally, by calculating and comparing the figure of merit (FOM) and the sensitivity (S), it is shown that this structure has significant sensitivity and excellent application ability and value. We firmly believe that our absorber can be well applied in high-sensitivity sensors, filters and detectors, and can contribute to fields such as photoelectric detection, optical communication and photoelectric sensing.