Dynamic polarization rotation and vector field steering based on phase change metasurface

Polarization rotation and vector field steering of electromagnetic wave are of great significance in modern optical applications. However, conventional polarization devices are bulky, monofunctional and lack of tunability, which pose great challenges to the miniaturized and multifunctional applications. Herein, we propose a meta-device that is capable of multi-state polarization rotation and vector field steering based on phase change metasurface. The supercell of the meta-device consists of four Ge2Sb2Te5 (GST) elliptic cylinders located on a SiO2 substrate. By independently controlling the phase state (amorphous or crystalline) of each GST elliptic cylinder, the meta-device can rotate the polarization plane of the linearly polarized incident light to different angles that cover from 19.8° to 154.9° at a wavelength of 1550 nm. Furthermore, by merely altering the phase transition state of GST elliptic cylinders, we successfully demonstrated a vector field steering by generating optical vortices carrying orbital angular momentums (OAMs) with topological charges of 0, 1 and −1, respectively. The proposed method provides a new platform for investigating dynamically tunable optical devices and has potential applications in many fields such as optical communications and information processing.