Plasmonic annular aperture arrays for nanoparticle manipulation

In this work, we present experimental results on the optical trapping and manipulation of micro- and nanoparticles using plasmonic tweezers based on arrays of annular nanoapertures. By increasing the inner disk size of the nanoaperture, a redshift of the resonant wavelength is observed. We demonstrate both trapping and transportation of particles across the plasmonic device using a drag force method with incident laser intensities less than 1.5 mWμm^-2. We calculate trap stiffnesses equal to 0.25 pN/μm·mW and 1.07 pN μm^-1mW^-1 for 0.5 μm and 1 μm diameter particles, respectively. A high trap stiffness of 0.85 fN/nm· mW at a low incident laser intensity of ∼0.51 mW/μm² at 980 nm was obtained for 30 nm diameter polystyrene particles. We perform sequential single-nanoparticle trapping within specific trapping sites. The demonstrated plasmonic nanotweezers could be used for lab-on-a-chip devices where efficient particle trapping with high tunability of the applied laser wavelength is required.

Duke Scholars

Author Domna Kotsifaki DKU Faculty