  We present a graphene-based metasurface that can be actively tuned between
different regimes of operation, such as anomalous beam steering and focusing,
cloaking and illusion optics, by applying electrostatic gating without
modifying the geometry of the metasurface. The metasurface is designed by
placing graphene nano-ribbons (GNRs) on a dielectric cavity resonator, where
interplay between geometric plasmon resonances in the ribbons and Fabry-Perot
resonances in the cavity is used to achieve 2$\pi$ phase shift. As a proof of
the concept, we demonstrate that wavefront of the field reflected from a
triangular bump covered by the metasurface can be tuned by applying electric
bias so as to resemble that of bare plane and of a spherical object. Moreover,
reflective focusing and change of the reflection direction for the
above-mentioned cases are also shown.
