Active Phase-Change Metasurfaces for Optical Mode Conversion and Orbital Angular Momentum Control

In this work we demonstrate two phase-change material based actively controllable metasurfaces for optical mode conversion and control of optical orbital angular momentum. Such control finds a variety of important applications across technologically relevant fields including information processing, communication and quantum optics, and the need for versatile control devices in a compact and lower power form-factor is ever increasing [1]. The metasurface architecture used here exploits high contrast phase-change materials (PCMs) as the active component, allowing for very different metasurface functionalities upon switching of the PCM meta-atoms and offering the advantages of non-volatile, low-power and fast switching [2].