  We report a THz reflectarray metasurface which uses graphene as active
element to achieve beam steering, shaping and broadband phase modulation. This
is based on the creation of a voltage controlled reconfigurable phase hologram,
which can impart different reflection angles and phases to an incident beam,
replacing bulky and fragile rotating mirrors used for terahertz imaging. This
can also find applications in other regions of the electromagnetic spectrum,
paving the way to versatile optical devices including light radars, adaptive
optics, electro-optical modulators and screens.
