Focused regulation of metalens based on multilayer graphene in terahertz bands

We propose a metalens structure based on graphene ribbons that can achieve the regulation function in terahertz bands. The metalens structure based on multilayer graphene we proposed in this paper can achieve focus at the different locations through the regulation of the Fermi level of graphene. The structure can be focused separately at 300μm(state1) or at 100μm(state2) or at 200μm(state3). And we can accurately regulate the focusing position of the reflected light by regulating the switch of states 1,2 and 3. This function can not only realize the switch control of metalens, but also realize the precise positioning function of subwavelength. We believe that our findings can provides a new method for wavefront manipulation of metalens and are beneficial in designing new function controlling devices.