Chirality sorting using a structured caustic vector vortex field

Abstract

In this work, we theoretically demonstrate that the simultaneous manipulation of both the orbital angular momentum and the polarization conversion can be realized in a structured caustic vector vortex field. Under a slight focusing condition, the structured caustic vector vortex field would be auto-focused into dual foci with specific topological charge and orthogonal polarizations, which can be manipulated through adjusting the initial state of polarization distribution and a caustic phase applied on the illumination. Furthermore, we demonstrate that the structured focal field carrying opposite spin angular momentum is suitable to sort chiral nanoparticles, in which the different energy flow directions would bring distinct dynamic behaviors to enantiomers. This finding may have potential applications in all-optical enantiopure chemical syntheses and enantiomer separations in pharmaceuticals.