A chiral route to pulling optical forces and left-handed optical torques

TL;DR

This paper explores how chirality in objects can produce unconventional optical forces and torques, including pulling forces and left-handed torques, through the interaction of light's linear and angular momentum.

Contribution

It introduces a detailed analysis of chiral effects on optical forces and torques, revealing mechanisms for pulling forces and sign reversals in large chiral spheres.

Findings

Chirality can induce pulling optical forces.

Chirality can cause left-handed optical torques.

Sign reversal of forces and torques in large chiral spheres.

Abstract

We analyze how chirality can generate pulling optical forces and left-handed torques by cross-coupling linear-to-angular momenta between the light field and the chiral object. In the dipolar regime, we reveal that such effects can emerge from a competition between non-chiral and chiral contributions to dissipative optical forces and torques, a competition balanced by the strength of chirality of the object. We extend the analysis to large chiral spheres where the interplay between chirality and multipolar resonances can give rise to a break of symmetry that flips the signs of both optical forces and torques.