Uniform Thermo-Optic Tunability of Dielectric Metalenses

The advent of low-loss dielectric metasurfaces offers a paradigm of miniaturization for free-space optical elements like lenses and deflectors, but these are limited to static functionality. This study illustrates the possibility to tune the focal length of a metalens through spatially uniform modulation of refractive index. Using traditional thermo-optic effects, the authors demonstrate large refractive index changes (Δ00exn = 0.15) in InSb Mie resonators. They furthermore show how to form a metasurface from a single material, enabling easier wafer-scale production.