Tunable Lens Based on Graphene Metasurface for Circular Polarization

A graphene based metasurface is considered to operate as a tunable lens for a circularly polarized incident electromagnetic field. The unit cell of the proposed metasurface consists of a graphene split-ring resonator on a dielectric layer. It has been designed to have large linear phase shift for the transmitted cross-polarized wave. The required phase shift has been obtained by changing the orientation of the element pair within unit cells. The lens consists of a sequence of elements with proper orientation angles providing the required phase shift for focusing purpose. Thanks to unique property of graphene, operating frequency of the metasurface can be tuned by changing the bias voltage applied to it. By adjusting the chemical potential of graphene, the operating frequency of the lens is changed.