▎ 摘　　要

A reconfigurable graphene based metasurface is presented to controllably focus a circularly polarized incident plane wave. The unit cell of the proposed metasurface consists of split ring resonators on both sides of a dielectric layer. The required phase shift for focusing purpose is achieved by concurrent rotation of the elements to obey to the Pancharatnam-Berry concept. Convergence/Divergence of the transmitted wave can be controlled by handedness of the impinging plane wave and direction of the elements' rotation. The operating frequency of the designed lens and its focal length can be adjusted by properly exploiting to the unique property of graphene, i.e. by tuning its chemical potential.