The emerging, interdisciplinary science of metasurfaces has fascinated optical and photonic scientists and engineers, who see these high-tech materials as a route toward a new generation of ultra-compact flat optics such as photographic lenses. But most metasurfaces demonstrated thus far have been predesigned for a single functionality; only recently have researchers begun to explore the possibilities for “active” metasurfaces that can be reconfigured on the fly.
A research team recently demonstrated one such active metasurface: a hybrid of silicon and so-called phase-change materials whose transparency and optical properties can be changed with a quick pulse of laser light. The researchers believe that the material could create new opportunities in LiDAR, ultrathin photographic lenses, tunable lenses, and other application areas.
In most cases, metasurfaces are designed and created as passive objects, with the changes the surface imparts to the light field frozen-in when the surface is fabricated. It’s becoming increasingly clear, however, that the development of active metasurfaces—in which the optical effect of the metasurface can be dynamically controlled—holds one key to realizing their full potential in real-world devices in wearable technology, augmented and virtual reality, imaging and a host of other areas.