Ultrasensitive and tunable multi-narrowband metamaterial absorber

In recent years, metamaterials have been widely used as a new type of optoelectronic device materials, such as optical stealth, holographic imaging, and metamaterial absorbers. In particular, the research of metamaterial absorbers with multi-narrowband, high absorption and tunability has attracted much attention. However, it is a great challenge to integrate multi-narrowband, high absorption, polarization independence, high sensitivity and tunability into a simple absorption structure. In this paper, we use FDTD to design a multi-narrow band, polarimetric independent, high sensitivity and tunability of metamaterial perfect absorber, which is a metal-dielectric-metal three-layer structure. From the bottom to the top of the structure, they are Au layer, SiO2 layer and Au pattern layer. The simulation results show that three resonance absorption peaks are obtained under the coaction of local surface plasmon resonance, magnetic resonance and cavity resonance. The absorption peaks are located at 878 nm, 1020 nm and 1276 nm, and the absorption rates are 98.7%, 99.3% and 99.5%, respectively. In addition, it is found that the number of absorption peaks can be changed by adjusting the top pattern layer structure. Further, the position of the absorption peak and the absorption rate can be altered by adjusting the geometric parameters of the structure. Besides its simple structure, the analysis also show that the structure has high sensitivity under different refractive index environment. Finally, it can also be used for optical conversion devices, such as optical absorption switches, splitters, optical modulators.