Stand-Alone Three-Dimensional Optical Tweezers Based on Fibred Bowtie Nanoaperture

We study optical trapping of small particles based on the use of a bowtie nanoaperture antenna (BNA) engraved at the end of a metal-coated near-field optical microscope tip. Within the obtained light confinement, a 3-D trapping of latex nanoparticles is studied and quantified as a function of the incident light power. Good agreement between experimental and numerical results is obtained for a BNA operating in water at (lambda = 1064 nm) that faithfully traps 250-nm-radius latex particles. Further numerical investigations are performed to study the dynamic of the trapping process in comparison with experimental results. In addition, numerical results for R = 100 nm and R = 30 nm-radii latex particles are presented and show that such a configuration has the potential to trap latex particles as small as 30 nm in radius.