An All-Liquid-Crystal Strategy for Fast Orbital Angular Momentum Encoding and Optical Vortex Steering

An all-liquid-crystal device for fast orbital angular momentum encoding and optical vortex beam steering is proposed and demonstrated. It is a combination of a cascaded spin-determined beam deflector and an optical vortex generator. The fast switching derives from the rapid in-plane optical axis rotation of ferroelectric liquid crystal half-wave plates, while the
q
-plate and meta-
q
-plate made by photopatterned liquid crystal polymer ensure high-quality and efficient orbital angular momentum encoding. By programing the binary signals applied to the half-wave plates, electrical optical vortex deflection and 32 different orbital angular momentum encoding are achieved faster than 70 µs with a total efficiency over 85%. It supplies a practical strategy for fast optical vortex steering and orbital angular momentum encoding and may be broadly used in vortex LiDAR, multitarget communications and orbital angular momentum multiplexed optical telecoms.