Can a single gradientless light beam drag particles?

TL;DR

This paper explores how strongly non-paraxial gradientless light beams can exert attractive forces on particles, enabling potential new methods for nanoparticle manipulation beyond traditional pushing effects.

Contribution

It demonstrates that non-paraxial gradientless beams can produce dragging forces on particles, a novel finding in optical manipulation.

Findings

Strong non-paraxiality induces attractive forces on particles.

The cone angle is critical for achieving dragging forces.

Potential applications in nanoparticle manipulation.

Abstract

Usually a light beam pushes a particle when the photons act upon it. This is due to that the electric-dipole particle in the paraxial beam is considered. We investigate the scattering forces in non-paraxial gradientless beams and find that the forces can drag certain particles towards the beam source. The major criterion to be carried out to get the attractive force is the strong non-paraxiality of the light beam. The cone angle denoting the non-paraxiality has been investigated to unveil its importance on achieving dragging force. We hope the attractive forces will be very useful in nanoparticle manipulation.