In this manuscript, numerical analysis in graphene-wrapped cylindrical waveguide filled with lithium fluoride (LiF) in terahertz (THz) frequency regime. Transfer matrix technique is used to derive the characteristics curve. The analysis of surface plasmon polaritons (SPPs) at the graphene-LiF interface is examined under various parameters, including chemical potential \({\mu }_{c}\) , relaxation time ( \(\tau\) ), and radius (R) of the waveguide, as well as the incident wave frequency. Numerical results reveal the dependence of the real part of the propagation constant (Re ( \({k}_{z}/{k}_{0}\) )), lithium fluoride permittivity ( \({\varepsilon }_{LiF}\) ), and radius of waveguide on these parameters, highlighting the tunability of the waveguide’s dispersion characteristics through external controls such as graphene parameters, i.e., chemical potential, relaxation time, and number of graphene layers. The results demonstrate that decreasing \({\mu }_{c}\) and τ enhances the plasmonic confinement, improving the propagation constant \(Re({k}_{z}/{k}_{0}\) ) and improved mode efficiency. Furthermore, frequency-based analysis indicates that the waveguide supports the tunable plasmonic mode, particularly in the THz regime. The coupling efficiency and dynamic tunability provided by the graphene-LiF interface open new avenues for applications in terahertz sensing, communication, and integrated photonics.
