The Study of Midinfrared Extremely Narrow Dual-Band Absorber Based on a Novel Metamaterial Structure

Due to the problems that the metal pattern layer on the top of the traditional metamaterial structure is easy to be oxidized and easy to fall off, in this paper, a novel semiconductor metamaterial nanostructure composed of a periodic array of GaAs-SiO2 cubes and a gold (Au) film has been proposed. Using FDTD solutions software to prove this metamaterial structure can achieve ultranarrow dual-band, nearly perfect absorption with a maximum absorbance of 99% and a full-width at half-maximum (FWHM) value that is less than 20 nm in the midinfrared region. The refractive index sensitivity is demonstrated by changing the background index and analyzing the absorption performance. It had been proved that this absorber has high sensitivity (2000/RIU and 1300/RIU). Using semiconductor material instead of the metal material of the top pattern layer can effectively inhibit the performance failure of the metamaterial structure caused by metal oxidation. The proposed narrow, dual-band metamaterial absorber shows promising prospects in applications such as infrared detection and imaging.