Nanostructured Metamaterials for Thermal Applications

Abstract

Metamaterials are artificially engineered materials with tailored properties for applications in imaging, sensing, waveguiding and quantum optics. Even though they hold the potential for transformative impact, industrial applications have been impeded by large absorption losses in material properties. This thesis puts forth thermal applications of metamaterials where optical losses are a necessary design component and can be fruitfully utilized for applications. A wide range of metamaterial designs have been numerically studied and optimized for applications as narrowband perfect absorbers/emitters in the near-infrared wavelength region compatible with low bandgap thermophotovoltaic cells. We study the collective polaritons of nanowire and thin film metamaterials to show that their selective absorption and thermal emission properties could be used for thermophotovoltaic applications. The design and simulation results are in excellent agreement with initial the results of experiments on metallic nanowire arrays in a dielectric host matrix. We also evaluate the contribution of phonon-polaritons to thermal conductivity of silicon carbide nanowire arrays. The comprehensive analysis of collective metamaterial modes and analytical tools developed in the thesis can aid future design and optimization of thermal metamaterials.