Thermal Transport and Conversion Using Photonic Nanostructures

Photonics can be harnessed to engineer and in certain cases enhance thermal energy transport and conversion processes due to favorable characteristics of thermal photons relative to phonons under certain conditions, such as long wavelength, long propagation length, high speed, and spectral tunability. Here we present our work on thermal transport and conversion in nanostructures over the past few years. First, we showed that the coupling between photons and traditional heat carriers such as phonons and electrons can be utilized to manipulate radiation and conduction heat transfer in polar dielectric and metallic nanostructures. In particular, we observe enhanced effective emissivity and thermal conductivity in rationally designed nanostructures of polar dielectrics and metals. Second, we developed high-temperature selective emitters based on photonic metamaterials. While selective emitters have been extensively studied previously, they are often not stable at high temperature due to the presence of nanoscale interfaces. We use novel material and structural designs to achieve high temperature stability. These selective emitters could be utilized for converting optical and electrical energy more efficiently into thermal energy within a desirable spectrum that are useful for systems such as thermophotovoltaic and infrared heating.