Hydrogen absorbing multilayers as switchable metamaterials

Abstract

Multilayered metamaterials with switchable optical properties are desirable for application purposes such as sensors and imaging systems. Some rare-earth metals (RE) could be used for this purpose as they undergo a metal-dielectric phase transition upon hydrogen absorption. Alternating layers of palladium and REs exposed to a hydrogen atmosphere are shown to exhibit a switchable and reversible reflectance band. The reflectance band is tunable across the visible spectrum by changing the thickness of the RE layers, while increasing the number of layers enhances the reflectance band amplitude. The result is a switchable multilayer metamaterial whose optical properties are tunable by changing the surrounding hydrogen pressure.