Efficient optical trapping using semi-conical plasmonic nanoantennas

Abstract In this paper, the design of a semi-conical gold nanoantenna for optical trapping of dielectric nanoparticles has been proposed. The design exploits the strong plasmonic resonance and field localization properties of gold to generate high gradient optical forces within a nanoscale gap under near-infrared excitation of 905 nm. The nanoantenna structure has been optimized using the finite element method to evaluate electric field confinement, photothermal behavior, and optical force distributions through Maxwell stress tensor analysis. The proposed nanoantenna achieves efficient trapping of 20 nm dielectric nanoparticles with a maximum trapping stiffness of approximately 2.1fN nm. μ W −1 , outperforming existing plasmonic designs such as bowtie antennas, nanohole arrays, and slot waveguides.