Thermal radiation spectra of individual subwavelength microheaters

Polarization resolved spectra of infrared radiation from individual electrically driven platinum microheaters have been measured by Fourier-transform infrared spectrometry as a function of heaters' width. When the heater width approaches zero, the signal with polarization parallel to the heater long axis converges to a finite value, while its perpendicularly polarized counterpart drops below our detection limit. As a result this leads to strongly polarized radiation for very narrow heaters. Further, while the parallel polarized radiation spectra appear to be insensitive to heater width variation (at least within the sensitive range of our light detector), the perpendicular polarized spectra were heavily affected. We observed a lambda/2-like resonance that we attribute to correlation of charge oscillations across the heater's width, which are possibly mediated by surface plasmons. These findings provide implications for fabrication of nanoscale electrically driven thermal antennas.