Analysis and Design of a Reconfigurable Metasurface based on Chalcogenide Phase-Change Material for Operation in the Near and Mid Infrared

We analyze, design and assess the performance of a reflective reconfigurable metasurface (MS) architecture for optical wireless communications. The device is based on the Ge-Sb-Te (GST225) phase-change material (PCM) alloy, thermally toggled between highly distinct amorphous and crystalline phase-states. We employ simple conductive MS patterns to tune its resonance frequency, while allowing the unit cell response to be analytically predicted using transmission line theory and equivalent circuits. The GST material dispersion is computed in its two extreme phase-states using a Drude/Tauc-Lorentz model (DTLM), whose parameters are fitted to state-of-the-art experimental data; the dispersion in intermediate partially crystallized phase-states is computed using the Lorentz-Lorenz formula. Our results, corroborated by full-wave simulations, demonstrate the potential of PCM materials for the implementation of continuously reconfigurable holographic metasurfaces operating in the infrared bands.