Advanced electrode designs for High-Performance tunable diffraction grating

Abstract

Traditional binary gratings provide high diffraction efficiency but lack dynamic tunability, while liquid crystal (LC)-based gratings often suffer from low efficiency and limited spatial control. To address this limitation, we proposed an LC diffraction grating featuring a novel electrode configuration that enables both high diffraction efficiency (DE) and tunable spatial modulation. Our design includes spatially adjusted patterned electrodes arranged in parallel and orthogonal configurations, generating a complex electric field distribution combination of parabolic and vertical fields that effectively reorient the nano-confined LC molecules. Despite their strong nanoscale confinement, these droplets exhibit significant orientational freedom to show Debye-type dielectric relaxation. Under applied voltage, the opposite polarity electrodes overlapping configuration induces up to 45% dielectric and 55% birefringence modulation of pristine nematic LC. Further, this electrode configuration creates a parabolic field between electrodes and a vertical field on top of the electrodes, resulting in increased refractive index contrast and a 4% improvement in DE. Additionally, the orthogonal arrangement of electrodes enables precise and tunable 2D diffraction control. This multi-functional LC grating design offers a promising platform for reconfigurable and highly efficient beam shaping in advanced photonic applications.