Surface-enhanced fluorescence with corrugated nanoapertures
Subwavelength apertures milled in metallic films are receiving a growing interest to tailor light at the nanoscale, and improve the detection methods of single molecules.
In an article published in the July 04th issue of Optics Express, we quantify the influence of the number of circular corrugations surrounding a central nanoaperture to further enhance the fluorescence emission per molecule. This work has three aspects of general interest:
1) We quantify both the excitation and emission gains contributing to the fluorescence enhancement, providing the first complete characterization of corrugated apertures as the number of corrugations is increased.
2) We demonstrate efficient single molecule detection with fluorescence rates clearly above 10,000 counts/second with a simple low NA lens.
3) We show that a single groove milled around a nanoaperture already provides a supplementary 3.5 fold increase in the fluorescence enhancement as compared to a bare nanoaperture. This constitutes the first experimental observation of the effect numerically predicted in Bonod et al, Optics Express 16, 2276-2287 (2008).