Near-Field Thermal Radiation by Transdimensional Plasmonics and Subwavelength Structures

Near-field radiative heat transfer has attracted enormous interest for energy conversion, solid-state cooling, and thermal management owing to the substantial radiation enhancement beyond Planck’s law at nanoscale gaps. So far, effects of nonlocality to near-field thermal radiation have been examined only in the extreme near-field with gap sizes of a few nanometers. Also, our fundamental understanding of near-field heat transfer between subwavelength surfaces is still quite limited. In this talk, using transdimensional plasmonic materials, we experimentally demonstrate nonlocality in dielectric response alters near-field heat transfer at gap sizes on the order of hundreds of nanometers. We also report the first measurements of near field thermal radiation between coplanar subwavelength membranes over a broad range of temperature differences up to 190 K. Our measurement with membrane dimensions comparable to near-field separations shows maximum 20-times enhancement in heat transfer compared to blackbody radiation.