Observation of Enhanced Thermal Emission from Patterned Hyperbolic Metamaterials

Hyperbolic metamaterials (HMMs) are known to theoretically possess an unbounded range of wave vectors to which radiation can couple due to the hyperbolic shape of the HMM isofrequency surface. Thus, in practice, there exists a large range of modes that can be excited by thermal fluctuations that can then reradiate by coupling to high spatial frequency features. Herein, we show direct observation of enhanced thermal emission in an alternating gallium-doped zinc oxide (GZO) and zinc oxide (GZO/ZnO) multilayer HMM by utilizing a FLIR IR camera. This observation is supported by numerical simulations performed in CST MWS using index of refraction and extinction coefficient parameters obtained from an IR VASE.