Optical Manipulation of Dielectric Nanoparticles with Au Micro-racetrack Resonator by Constructive Interference of Surface Plasmon Waves

We design a gold micro-racetrack resonator (Au-MRR) which can tightly trap and drive the dielectric nanoparticle to rotate around the circuit of racetrack with an adjustable velocity. Since the surface plasmon waves can be excited and obey the resonance condition of the Au-MRR, the optics force can be strengthened observably due to the resonance. The optical forces applied on dielectric nanoparticle are discussed by utilizing the Maxwell’s stress tensor integration with a numerical finite element method. The depth of longitudinal trapping potential well in the Au-MRR is four times as large as that of a straight waveguide. At the same level of input power, the velocity of particle with radius of 50 nm driven by optical forces on Au-MRR is 200 times larger than that on a straight waveguide. Further, we explore the motion behavior of single nanoparticle lies on different position of Au-MRR, which can provide the details to trap and manipulate multiple nanoparticles and predict their trace of movement. This optimum geometry of Au-MRR allows further enhancement of the optical forces which is expected to realize all-optical on-chip manipulation of nanoparticles, biomolecules, and many other nanomanipulation applications.