Transverse optical binding for a dual dipolar dielectric nanoparticle dimer

Abstract

The physical origins of transverse optical binding force and torque beyond Rayleigh approximation have not been clearly expressed to date. Here, we present analytical expressions of the force and torque for a dual dipolar dielectric dimer illuminated by a plane wave propagating perpendicularly to the dimer axis. Using this analytical model, we explore the role of the hybridized electric dipolar, magnetic dipolar, and electric-magnetic dipolar coupling interactions in the total force and torque on the particles. We find significant departures from the predictions of the Rayleigh approximation, especially for high-refractive index particles, where the force is dominated by the magnetic interaction. This results in the enhancement of the dimer stability by 1 to 4 orders of magnitude compared to the predictions of the Rayleigh approximation. For the torque, this is dominated by the coupling interaction and increases by an order of magnitude. Our results will help to guide future experimental work in the light-controlled self-assembly of high-refractive-index dielectric particles.