Reconfigurable Geometrical Phase Spatial Light Modulator Using Short-Pitch Ferroelectric Liquid Crystals

This article presents an approach to achieve a fast and analog geometrical phase modulation based on the optical axis rotation of the defect-free Deformed Helix Ferroelectric Liquid Crystal (DHFLC) with a short pitch. This study demonstrates a Spatial Light Modulator (SLM) prototype with a feature size of 3 mu m without Fringe Field Effect (FFE), having a phase depth of 1.9 pi, fast switching time (<250 mu s) at a low operating voltage (<7 V), and high diffraction efficiency (>77%). The high phase modulation depth is achieved by developing DHFLC with a cone angle of up to 85 degrees, which is inherently immune to FFE. The ellipticity is minimized by using a compensation film that can suppress the changes in birefringence under the applied electric field. The proposed SLM is promising in applications such as a real-time hologram and dynamic beam steering in Light Ranging and Detector (LiDAR).