Control of diffusion of nano-particles in an optical vortex lattice

TL;DR

This paper proposes a two-dimensional optical force field combining conservative and vortical forces to control nano-particle diffusion, analyzing flow patterns and diffusion coefficients through analytical and numerical methods.

Contribution

It introduces a novel optical force field design that influences nano-particle diffusion and provides analytical and numerical analysis of diffusion behavior in this system.

Findings

Identified deterministic flow patterns in the optical force field.

Computed diffusion coefficients using Mean First Passage Time.

Numerical simulations agree with analytical predictions.

Abstract

A two-dimensional periodic optical force field, which combines conservative dipolar forces with vortices from radiation pressure, is proposed in order to influence the diffusion properties of optically susceptible nano-particles. The different deterministic flow patterns are identified. In the low noise limit, the diffusion coefficient is computed from a Mean First Passage Time (MFPT) and the Most Probable Escape Paths (MPEP) are identified for those flow patterns which possess an stable stationary point. Numerical simulations of the associated Langevin equations show remarkable agreement with the analytically deduced expressions. Modifications of the force field are proposed so that a wider range of phenomena could be tested.