Generating Electrically-Tunable, Polarization-Dependent, Highly-Efficient Optical Vortices Based on Phase-Separated Liquid Crystal-Polymer Blazed Fork Gratings

Abstract

Conventionally, the fabrication processes for optical vortex (OV) modulators are cumbersome and costly. In this work, we propose a simple method to generate high-efficiency vortex beams using the phase-separated liquid crystal (LC)-polymer blazed fork gratings, which are prepared by single-step photopolymerization-induced phase separation (PIPS). By designing the photomask patterns to create specific light fields, which further induce the photopolymerization of monomers in specific regions within a LC cell infiltrated with a mixture of LCs and prepolymer, the designed phase-separated LC-polymer blazed fork gratings within the LC cell will be finally formed. Based on the electrically-tunable and polarization-dependent phase compensation of LCs, the prepared fork gratings can have a high single-order diffraction efficiency of 60% (i.e., conversion efficiency for OVs). Compared with previous methods, the proposed approach for OV beam generation offers several advantages, including high efficiency, simple fabrication, and low cost.