Effects of Silicon Dioxide as the Polar Dielectric on the Infrared Absorption Spectrum of the Metal-Insulator-Metal Metasurface


 Metal-insulator-metal metasurfaces have been widely used as high-performance absorbers in almost all electromagnetic spectral range. Their absorption spectra can be engineered by making variations in the geometry of the unit cells and/or by embedding materials with specific optical constants. Including a polar dielectric in their structure is another approach for manipulating their absorption spectra. In this research, we have numerically and experimentally investigated the effect of using silicon dioxide (SiO2) as a polar dielectric on the absorption spectrum of a metal-insulator-metal metasurface composed of a tri-layer of Ni-SiO2-Ni. Our results have shown the presence of absorption peaks in the mid-infrared which are attributed to the excitation of the optical phonons in the SiO2 spacer layer. Particularly, the excitation of the Berreman mode in the SiO2 spacer layer was observed and its effect on the total absorption spectrum is studied. The parametric effects of the top patterned Ni layer, the incident angle, and the polarization are also investigated. This study can provide engineering capabilities for the mid-infrared absorbers and reflection filters.