Ultra-efficient nanoparticle trapping by integrated plasmonic dimers

We numerically demonstrate that gold dimers coupled with a silicon-on-insulator waveguide enable an efficient plasmonic tweezing of dielectric nanobeads, having radii down to 50 nm. By means of a rigorous 3D finite difference time domain and simplified gradient force-based calculations, we investigate the effect of the gap size involved on the tweezing action. We also demonstrate that the scattering force helps the trapping in the proximity of the dimer, thanks to the establishment of light vortices.