Dielectric metasurfaces have become efficient tools for creating ultrathin optical components with various functionalities for imaging, holography, quantum optics, and topological photonics. While static all-dielectric resonant metaphotonics is reaching maturity, challenges remain in the design and fabrication of efficient reconfigurable and tunable metasurface structures. A promising pathway towards tunable metasurfaces is by incorporating phase-transition materials into the photonic structure design. Here we demonstrate Mie-resonant silicon-based metasurfaces tunable via the insulator-to-metal transition of a thin VO2 layer with reversible properties at telecom wavelengths. We experimentally demonstrate two regimes of functional tunability driven by the VO2 transition: (i) two orders of magnitude modulation of the metasurface transmission, (ii) spectral tuning of near-perfect absorption. Both functionalities are accompanied by a hysteresislike behavior that can be exploited for versatile memory effects. Beyond this demonstration of multifunctional properties, this work provides a general framework to efficiently use the full complex refractive index tuning of VO2, both for its refractive index modulation and optical absorption tuning. Tunable dielectric metasurfaces may find their applications in various photonics technologies including optical communications, information storage, imaging, detectors, and sensors.

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