Dominant chiral optical forces in the vicinity of optical nanofibers

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 is a challenge when implementing chiral separation schemes. In this work we have demonstrated 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 studied optical nanofibers and nanowires as candidates for such a scheme and demonstrated 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.