Plasmonic annular aperture arrays for nanoparticle manipulations

摘要

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