Electrically Tunable Goos–Hänchen Effect with Graphene in the Terahertz Regime

TLDR

The Goos–Hänchen effect is widely studied for optical beam manipulation, yet efficient control of the shift remains challenging for diverse applications. The study proposes a tunable G–H shift mechanism in the terahertz regime using electrically controllable graphene. The mechanism employs monolayer graphene on an epsilon‑near‑zero metamaterial to achieve electrically tunable G–H shifts. The monolayer graphene–epsilon‑near‑zero metamaterial system produces orthogonal s‑ and p‑polarized terahertz G–H shifts that are positive and negative, respectively, and can be substantially tuned by the graphene Fermi energy, enabling doping measurement, strong frequency‑dependent shifts for terahertz rainbow generation, and potential terahertz wave manipulation applications.

Abstract

Goos–Hänchen (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.