Far Field, Suspended Trapping of a Single Dielectric Nanoparticle using Annular Slit-ring Plasmonic Zone-plate Lens

This paper demonstrates far field, trapping of a single dielectric nanoparticle using a Plasmonic Zone Plate Lens. This is achieved by beaming a linearly polarized light through series of concentric annular slit-rings formed in Gold, leading to creation of a sub-diffraction focal spot in the far field which can be used as a hotspot to trap the nanoparticle in it, suspended. A stable trap is formed in the far field using this structure and a 100-nm Polystyrene particle is successfully trapped using this technique. Forces are calculated in both x and z directions and the stability of the trap is further proved by calculating the potential well for x and z directions at location of the focal spot.