Plasmonic optical trap having very large active volume realized with nano-ring structure.

The feasibility of using gold nano-rings as plasmonic nano-optical tweezers is investigated. We found that at a resonant wavelength of λ=785 nm, the nano-ring produces a maximum trapping potential of ~32k(B)T on gold nanoparticles. The existence of multiple potential wells results in a very large active volume of ~10(6) nm(3) for trapping the target particles. The report nano-ring design provides an effective approach for manipulating nano-objects in very low concentration into the high-field region and is well suited for integration with microfluidics for lab-on-a-chip applications.