Reconfigurable image processing metasurfaces with phase-change materials.

Optical metasurfaces have enabled analog computing and image processing within sub-wavelength footprints, and with reduced power consumption and faster speeds. While various image processing metasurfaces have been demonstrated, most of the considered devices are static and lack reconfigurability. Yet, the ability to dynamically reconfigure processing operations is key for metasurfaces to be used within practical computing systems. Here, we demonstrate a passive edge-detection metasurface operating in the near-infrared regime whose response can be drastically modified by temperature variations smaller than 10 °C around a CMOS-compatible temperature of 65 °C. Such reconfigurability is achieved by leveraging the insulator-to-metal phase transition of a thin layer of vanadium dioxide, which strongly alters the metasurface nonlocal response. Importantly, this reconfigurability is accompanied by performance metrics-such as numerical aperture, efficiency, isotropy, and polarization-independence - close to optimal, and it is combined with a simple geometry compatible with large-scale manufacturing. Our work paves the way to a new generation of ultra-compact, tunable and passive devices for all-optical computation, with potential applications in augmented reality, remote sensing and bio-medical imaging.