Ferroelectric liquid crystal mediated fast switchable orbital angular momentum of light.

Abstract

Orbital angular momentum (OAM) of light has been extensively studied during the past two decades. Till now, it is a formidable challenge to dynamically manipulate OAM in fast switching speed, good beam quality and low power consumption. Here, an alternative strategy is proposed through the combination of the uniformly-aligned ferroelectric liquid crystal (FLC) and the space-variant photo-patterned nematic liquid crystal. Owing to the excellent electro-optical properties of the adopted FLC, the high-performance electrical switching of OAM, especially, its helicity and the superposed state (i.e., the cylindrical vector beam), can be realized in good quality and high efficiency. The symmetric switching time is down to 120 µs even at a very low driving voltage of 1.7 V/µm. This supplies a practical and universal method towards high-frequency manipulation of OAM and other structured beams.