Optical antenna thermal emitters

Optical antennas are a critical component in nanophotonics research(1) and have been used to enhance nonlinear(2,3) and Raman(4) cross-sections and to make nanoscale optical probes(5). In addition to their 'receiving' properties, optical antennas can operate in 'broadcasting' mode, and have been used to modify the emission rate(6) and direction(7) of individual molecules. In these applications the antenna must operate at frequencies given by existing light emitters. Using thermal excitation of optical antennas, we bypass this limitation and realize emitters at infrared frequencies where sources are less readily available. Specifically, we show that the thermal emission from a single SiC whisker antenna is attributable to well-defined, size-tunable Mie resonances(8). Furthermore, we derive a fundamental limit on the antenna emittance and argue theoretically that these structures are nearly ideal black-body antennas. Combined with advancing progress in antenna design, these results could lead to optical antenna emitters operating throughout the infrared frequency range.