Selective transport of chiral particles by optical pulling forces

Abstract

We propose a simple approach for chirality sorting based on the optical pulling forces. The scenario is to employ three simple plane waves with the same circular polarization. The three wave vectors have the same longitudinal positive z component while their corresponding transverse projections in the x-o-y plane form a regular triangle. In such an optical lattice, particles with certain chirality will be drawn by the transverse optical force to the periodic intensity maxima, where they are stably trapped and exerted by an optical pulling force along the negative z direction. On the contrary, particles with the opposite chirality are de-trapped transversely away from the intensity maxima and then dispersed in regions where they subject to a positive (pushing) force along the z direction. The phenomena therefore give rise to an alternative all-optical method for selective transport of chiral particles with a wide range of chirality parameters.