Broadband absorption in layered TiO2/AgOx/Ag pattern-free hyperbolic metamaterials

Hyperbolic metamaterials (HMMs) composed of metal-dielectric layered structures with subwavelength thickness are promising for broadband absorption due to their intensive photonic density of states. In this paper, we demonstrated a broadband absorber composed of TiO 2 /AgO x /Ag layered structure which exhibits hyperbolic dispersion properties from visible light to near-infrared regions. Specifically, the AgO x layer forms naturally at the interface between TiO 2 and Ag. The proposed structure achieves over 90% absorption in the visible range, and the naturally formed interfacial AgO x provides a promising route toward broadband absorbers.