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ABSTRACT The vast majority of power generation in the United States today is produced through the same processes as it was in the late-1800s: heat is applied to water to generate steam, which turns a turbine, which turns a generator, generating electrical power. Researchers today are developing solid-state power generation processes that are more befitting the 21 st -century. Thermophotovoltaic (TPV) cells directly convert radiated thermal energy into electrical power, through a process similar to how traditional photovoltaics work. These TPV generators, however, include additional system components that solar cells do not incorporate. These components, selective-emitters and filters, shape the way the radiated heat is transferred into the TPV cell for conversion and are critical for its efficiency. Here, we present a review of work performed to improve the components in these systems. These improvements will help enable TPV generators to be used with nearly any thermal source for both primary power generation and waste heat harvesting. 

ABSTRACT Interest in active metamaterial (MM) devices has recently increased due to their potential for tunable, switchable, and scalable optical responses. More specifically, a dynamic, on-chip MM polarizer has applications ranging from material characterization to sensing without the need for cumbersome external filters. This work demonstrates efforts to optimize MM devices for dynamic polarization filtering by combining elements from split-ring resonators, wire-pairs, and fishnet patterns. The polarization grid has been designed to operate under an applied voltage with simulated on/off ratios of 75% and dynamic polarization selectivity of 70%. Samples have been fabricated using epitaxial GaAs on sapphire with various n-type doping concentrations to approximate electrical tuning.