Juggling with light

TL;DR

This paper reveals how optically levitated particles perform a juggler-like dance due to alternating forces and anisotropic scattering, providing insights into light-particle interactions.

Contribution

It introduces a novel observation of particle juggling behavior and explains the underlying mechanisms involving radiation pressure, gravity, and anisotropic scattering.

Findings

Particles execute a planar juggling motion.

The motion results from alternating radiation pressure and gravity.

The plane of motion is explained by anisotropic scattering at curved interfaces.

Abstract

We discovered that when a pair of small particles is optically levitated, the particles execute a dance whose motion resembles the orbits of balls being juggled. This motion lies in a plane perpendicular to the polarization of the incident light. We ascribe the dance to a mechanism by which the dominant force on each particle cyclically alternates between radiation pressure and gravity as each particle takes turns eclipsing the other. We explain the plane of motion by considering the anisotropic scattering of polarized light at a curved interface.