Broadband Absorber Using Ultra-thin Plasmonic Metamaterials Nanostructure in the Visible and Near-Infrared Regions

In this work, an ultra-thin plasmonic metamaterial nanostructure absorber is simulated using finite difference time domain method in the visible and near infrared regions. A metamaterial, metal-insulator-metal, of a periodic structure of titanium-silica cap mounted on a top of a silver substrate covered by glass substrate is introduced in this paper. The glass substrate is used to enhance the absorption bandwidth by 276%, from 510 nm to 1410 nm. An almost perfect absorber, over 90% of the incident light, has been obtained for wavelengths from 440 nm to 1850 nm which produces an absorption bandwidth of 1410 nm. The square base unit cell dimensions of the silver substrate and of the cap are simulated and found as 250 nm and 200 nm consequently. The effect of using different materials for the top of the cap and for the insulator are also tested. The considered materials are titanium, nickel, silver, aluminum, and gold; however, the insulators are silica, quartz, vanadium dioxide, methyl methacrylate, and aluminium dioxide. In addition, aluminium, silver, copper, and gold are then simulated as a substrate metal. The optimum structure, which produce the maximum absorber bandwidth, 1410 nm, with a higher absorption, over 90%, is Glass-Ti-SiO2-Ag. Finally, the absorption bandwidth is calculated using different polarization angle, from 100 to 700 with a step100.