Experimental Verification of the Shift between Near-Field and Far-field Peak Intensities in Plasmonic Nanoantennas

P. ALONSO; P. ALBELLA; F. NEUBRECH; J. CHEN; F. GOLMAR; F. CASANOVA; L. HUESO; A. PUCCI; J. AIZPURUA; R. HILLENBRAND

San Sebastián

Conferencia; International Near-Field Optics NFO12; 2012

Donostia International Physics Center and CIC nanoGUNE

Plasmonic nanoantennas show a large potential for application in optical microscopy, sensing and communication on the nanometer scale, owing to the strongly enhanced near-fields in the antenna vicinity and their strong far-field extinction. Recently, a distinct spectral shift between the near- and far-field optical responses of plasmonic antennas has been predicted and indicated by a few experimental studies. Here, we will present a combined study of near-field optical microscopy and far-field spectroscopy of individual infrared-resonant nanoantennas that provides an experimental verification of this spectral shift. Numerical calculations corroborate our experimental results. We will also discuss the implications of this effect in surface-enhanced infrared spectroscopy (SEIRS).