Dominant chiral optical forces in vicinity of optical nanofibers

TL;DR

This paper demonstrates that optical nanofibers can generate dominant chiral optical forces by spatially separating transverse spin density from field intensity, potentially improving chiral biomolecule separation techniques.

Contribution

It introduces a method to enhance chiral forces over non-chiral forces near nanofibers by spatially separating spin density maxima from field intensity gradients.

Findings

Chiral optical forces can surpass gradient and scattering forces near nanofibers.

Spatial separation of spin density and field intensity enhances chiral force dominance.

Potential application in improved optical separation of chiral biomolecules.

Abstract

Transverse spin angular momentum (SAM) of light and associated transverse chiral optical forces have received tremendous attention recently as the latter may lead to an optical separation of chiral biomolecules. In this context, the relative magnitude of chiral and non-chiral forces represents a challenge for the implementation of chiral separation schemes. In this work we demonstrate that, by spatially separating the maxima of transverse spin density from the gradient of field intensity, it is possible to dominate chiral-specific components of the force over non-chiral ones. To that end, we study optical nanofibers and nanowires as a candidate for such scheme and demonstrate that in their vicinity, chiral optical forces can emerge that are stronger than gradient and scattering forces. This finding may be of significance in the design of improved optical separation schemes for chiral biomolecules.