Electrically Tunable Goos-Hanchen Effect with Graphene in the Terahertz Regime

Goos-Hanchen (G-H) effect is of great interest in the manipulation of optical beams. However, it is still fairly challenging to attain efficient controls of the G-H shift for diverse applications. Here, a mechanism to realize tunable G-H shift in the terahertz regime with electrically controllable graphene is proposed. Taking monolayer graphene covered epsilon-near-zero metamaterial as a planar model system, it is found that the G-H shifts for the orthogonal s-polarized and p-polarized terahertz beams at oblique incidence are positive and negative, respectively. The G-H shift can be modified substantially by electrically controlling the Fermi energy of the monolayer graphene. Reversely, the Fermi energy dependent G-H effect can also be used as a strategy for measuring the doping level of graphene. In addition, the G-H shifts of the system are of strong frequency-dependence at oblique angles of incidence, therefore the proposed graphene hybrid system can potentially be used for the generation of terahertz rainbow, a flat analog of the dispersive prism in optics. The proposed scheme of hybrid system involving graphene for dynamic control of G-H shift will have potential applications in the manipulation of terahertz waves.