(401c) Tailoring Thermal Emission Using Photonic and Plasmonic Metal Nanostructures

Radiative thermal emission from hot bodies is broad in energy and is non-directional.  This poses problems for efficient energy conversion of this emitted radiation from hot body sources (eg. from sun) into electricity using an infrared photocell. Metal nanostructures, patterned as three-dimensional photonic crystals, selectively tailor the light-matter interaction near the photonic bandgap and the increased photonic density of states is used to selectively emit light of particular frequency from a hot metallic nanostructure. Here I will present results from selective tailoring of thermal emission at low temperatures for development of efficient thermophotovolatic emitters. This can possibly serve as an efficient route for harnessing solar-thermal energy and waste heat, and converting it into electricity with an upper conversion limit of over 60 percent.  

Another possible route towards tailoring thermal emission is utilizing surface plasmons. While these hybrid photon-electron waves on metal surfaces are typically excited using light or fast electrons, recently we have explored excitation of surface plasmon polaritons using heat. I will discuss recent results on fabricating ultrasmooth patterned surface with nanometer scale precision for low loss propagation of surface plasmons. These patterned surfaces will then be combined with designed nanostructures for modulating the frequency of emitted radiation, and also the directionality of the emitted glow. Such unprecedented control over hot body radiation opens up new opportunities and challenges for utilizing plasmonics, while also opening up alternate route towards efficient photovoltaic conversion.