Generation of three-dimensional polarization-controlled tunable multiplex focused optical vortex and vector vortex beams via liquid crystal geometric phase

Abstract

Optical vortex beams carrying the orbital angular momentum (OAM), especially vector vortex beams, play essential roles in many fields such as optical communication and optical manipulation. In recent years, focusing and multiplexing optical vortex beams have attracted significant interest and become important research topics. In this study, a new type of liquid crystal geometric phase optical element is demonstrated to achieve multiplex focused optical vortex (FOV) beams. The 3D coordinates and the topological charges of each FOV in arrays can be customized on demand. Meanwhile, the distribution of arrays can be switched by the polarization of the incident light. Furthermore, the liquid crystal element is modified to generate multiplex focused vector vortex beams (FVVBs) based on the superposition of multiple OAM states. Similarly, the positions, the Pancharatnam topological charges, and the polarization orders of FVVBs can be preset as required. Besides, the polarization direction of incidence controls the polarization states of the generated FVVBs. This research achieves customized polarization-controlled multiplex FOVs and FVVBs with both multichannel and focusing properties, providing more flexibility for applications.