  Nonlocal metasurfaces are currently emerging as advanced tools for the
manipulation of electromagnetic radiation, going beyond the widely explored
Huygens metasurface concept. Nonetheless, the lack of an unified approach for
their fast and efficient tunability still represents a serious challenge to
overcome. In this article we report on gigahertz modulation of a dielectric
slab-based, nonlocal (i.e. angle-dispersive) metasurface, whose operation
relies on the optomechanical coupling with a mechanical wave excited
piezoelectrically by a transducer integrated on the same chip. Importantly, the
metasurface region is free from any conductive material, thus eliminating
optical losses, and making our device of potential interest for delicate
environments such as high-power apparatuses or quantum optical systems.
