Circularly-polarized Airy light-sheet spinner tweezers and particle transport

Abstract

Circularly-polarized Airy light-sheet spinner tweezers are introduced, and their interaction with a subwavelength absorptive dielectric sphere is considered. The mathematical representation of the Cartesian components of the radiated fields is made using the vector angular spectrum method, the Lorenz gauge, and Maxwell's equations for an Airy light-sheet with circular polarization. The results demonstrate the existence of an attractive (pulling) longitudinal force. Furthermore, in contrast with linearly (TM or TE) polarized Airy light-sheets for which the longitudinal spin torque vanishes, the circularly polarized Airy light sheet induces both longitudinal and lateral spin torques causing counter-clockwise or clockwise rotation contingent upon the location of the sphere in the transverse plane. The study is extended to calculate the trajectories of the sphere in the transverse illuminating plane (xy), stemming from a particle dynamics analysis based on Newton's second law of motion. The results are of particular importance in the development of light-sheet spinner tweezers, optical polarization switching for the development and optimization of sorting miniature devices, novel polarization reconfigurable methods and techniques, and related applications in particle manipulation, transport and rotation.