Optical tweezing chiral particles with 3D structured light

In this work we highlight enantioselective optical gradient forces acting on Rayleigh-seized chiral particles present in 3D structured (non-paraxial) optical vortex tweezing systems. One discriminatory force originates from the circular polarization of the light and is similar to previous chiral optical gradient trapping forces. Much more remarkable is the other which is independent of the input beam’s polarization state - even occurring for unpolarized light – and is not present in 2D structured light nor propagating plane waves. This latter chiral sorting mechanism allows for the enantioselective trapping of chiral particles into distinct rings in the transverse plane through conservative radial forces.