Electrically Switchable Transmissive and Reflective Liquid Crystal Polarization Gratings Based on Cholesteric Liquid Crystals

Liquid crystal polarization gratings (LCPGs) are a superior alternative to traditional diffraction gratings due to their high diffraction efficiency, strong polarization sensitivity, and versatile tunability. This paper introduces an electrically switchable LCPG based on cholesteric liquid crystals (CLCs). The LCPG is designed to operate in reflective (R-mode) and transmissive (T-mode) states. It utilizes the standing helical (SH) configuration of CLCs for reflective functionality and transitions to a lying helical (LH) configuration for transmissive operations. This dual-mode capability is achieved through a unique application of electric fields, which reorient the liquid crystal helix axis according to the desired optical function. The performance of the LCPG in both R-mode and T-mode is evaluated by applying different frequencies and voltages to dynamically switch between the helical states. The manufacturing process is simple, and the device performs robustly. This suggests that the technology could be useful for developing optical systems that require dynamic control over light modulation.