Conventional metasurfaces incorporating phase-change materials (PCMs) are typically limited to small-range adjustments of the orbital angular momentum (OAM) carried by optical vortex beams. This study presents a metasurface design paradigm for the reconfigurable, broad range generation of vortex beams across a broad range of topological charges. The design utilizes low-loss, non-volatile antimony trisulfide (SbS) as the active PCM at an operational wavelength of 800 nm. We identified eight distinct crystallinity levels of SbS that collectively provide a full phase coverage under a fixed geometry, with a phase step of between adjacent levels.
Pour en savoir plus : Phase-change material-based metasurface for orbital angular momentum switching of vortex beams
