Optical Enantioseparation of Chiral Nanoparticles in Macroscopic Scale Within a Microfluidic Channel

In this Letter, we have proposed an all-optical scheme for chiral particle separation with a microcylinder-pair system (MCPS) with a micrometer scale channel, applicable in microfluidic environments. By illuminating the MCPS with two counter-incident plane waves of orthogonal polarization, the electromagnetic chirality gradient can be generated. The MCPS can also enhance chirality-dependent lateral optical forces of the coupled fields so that the setup can shift trapping equilibrium positions for opposite-handedness nanoparticles and make the sideways motion observable. Our thorough numerical calculations demonstrate that the chiral-separation MCPS here can offer high efficiency in selectively trapping and transporting enantiomers in an optofluidic system. Furthermore, the MCPS can realize the sorting and collecting of enantiomers with a directional flow in a larger spatial distance from the macroscopic perspective. We believe that our research provides a new, to the best of our knowledge, and promising method for chiral optical tweezers and optofluidic transporting applications.