Hyperbolic Phonon-Plasmon Modes in Grounded Graphene-hBN Heterostructures for Mid-Infrared Applications

In recent years, the hybridization of hyperbolic van der Waals heterostructures with plasmonic two-dimensional nano-materials is one of the interesting research areas at THz frequencies due to the coupled features of the hybrid structure. This article investigates the propagation of tunable surface phonon-plasmon polaritons in grounded hybrid graphene-hexagonal Boron Nitride (hBN) heterostructures. An analytical model is presented for the proposed structure, by applying the boundary conditions for the electromagnetic components in the various regions, to derive an exact dispersion relation. The structure is simulated and the results are reported in the upper Reststrahlen band. A good agreement is seen between simulation and analytical results, which shows the high accuracy of our mathematical relations. The tunability of the heterostructures is shown by studying the effect of chemical potential on the performance of the structure. A high value of the figure of merit, i.e. FOM=190, is reported at the frequency of 48.3 THz. The presented study can open the way for the design of novel THz devices for future nano-plasmonic applications.