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.