# Light-induced rotation of dielectric microparticles around an optical nanofiber

## TL;DR

This paper experimentally demonstrates that dielectric microparticles can be made to orbit around an optical nanofiber due to transverse radiation forces from evanescent fields, confirming theoretical predictions of negative optical torque.

## Contribution

First experimental verification of negative optical torque causing microparticle orbiting around an optical nanofiber due to evanescent field interactions.

## Key findings

- Microparticles orbit around nanofibers driven by evanescent field forces.
- The direction of the force is opposite to the energy flow circulation.
- Results confirm theoretical predictions of negative optical torque.

## Abstract

We experimentally demonstrate orbiting of isotropic, dielectric microparticles around an optical nanofiber that guides elliptically polarized fundamental modes. The driving transverse radiation force appears in the evanescent electromagnetic fields due to orbital angular momentum. The force direction is opposite to that of the energy flow circulation around the nanofiber. Our results verify the theoretically predicted negative optical torque on a sufficiently large particle in the vicinity of a nanofiber.