The transition from non-convex region to hyperbolic region and vice versa in the Beryllium-Graphene-Beryllium three-layer structure: Plasmonics
Meta-materials are one of the important discussions of condensed matters which have unusual optical properties. They can be used to regulate light and wave propagation. Natural hyperbolic and non-convex plasmons are the characteristics of meta-materials that are observed in these materials. In this paper, we have studied Beryllium-Graphene-Beryllium (BeCBe) three-layer optical properties and have shown this material has hyperbolic plasmon in the THz frequency region and non-convex plasmons. We have shown most of the plasmon energy propagation along the $q_y$ axis for the hyperbolic region. Also, it can be seen that there is an elliptic case only in 1029.71 THz frequency. The starting point of the hyperbolic region occurs at the frequency of 289.31 THz, which is the first and the narrowest hyperbolic window. Due to the existence of far more free electrons in the BeCBe plasmonic material, the presence of the visible region in the third hyperbolic window causes a high plasma frequency.