Capturing range of a near-field optical trap
Phys. Rev. A 96, 043825 – Published 11 October, 2017
DOI: https://doi.org/10.1103/PhysRevA.96.043825
Abstract
A study on the spatial characteristics of a near-field optical trap is presented. For analysis, a plasmonic near-field trap consisting of a C-shaped engraving is considered. Numerical simulations are performed to calculate the optical force exerted on a spherical nanoparticle by the trap. A Brownian dynamics model is used to simulate a large number of independent trajectories of a nanoparticle submerged in the optical force field. Statistical analysis is performed on the trajectory data to calculate the trapping probability at different points in space. The points with equal trapping probabilities are enclosed in a surface to visualize the influence domain of the trap. The metric capturing range is defined and calculated from the spatial extent of such surfaces. The possible applications of the defined metric are discussed. Some design examples from the literature are also analyzed and are found to be consistent with the proposed analysis.