Plasmonic-Enhanced Radiative Transfer Through Nanoscale Aperture Antennas

Nanoscale ridge aperture antenna as a nanoscale high transmission optical device is demonstrated. High transfer efficiency and confined radiation are achieved simultaneously in the near field compared with regularly-shaped apertures. The radiation enhancement is attributed to the fundamental electromagnetic field propagating in the TE₁₀ mode concentrated in the gap between the ridges. The transfer efficiency is further enhanced through plasmon excitation and resonance. This paper reports spectroscopic measurements of radiative transfer through bowtie shape ridge aperture antennas. Resonance in these aperture antennas and its relation with the aperture geometry are investigated. The near-field radiation through the bowtie aperture and the regular nanoaperture is also mapped with near-field scanning optical microscopy. It is revealed that plasmon excitation and resonance contribute to the radiation enhancement through the ridge aperture antennas.