One-Step Leapfrog HIE-FDTD Modeling of Plasmonic Structures Using Partial-Fraction Dispersion Models

An improved one-step Leapfrog hybrid implicit-explicit finite-Difference Time-Domain (HIE-FDTD) method is developed for simulating complex plasmonic structures that comprise dispersive materials over an ultra-wide optical frequency range. The dispersive media is described by a partial fraction (PF) dispersion model by using the vector fitting technique and further implemented into the Leapfrog HIE-FDTD scheme via an auxiliary difference equation (ADE) formulation. The performance of the proposed method is evaluated in optical response of a multi-functional plasmonic structure which can act as a dynamically tunable band-stop filter and refractive index sensor. Simulation results demonstrate good numerical accuracy and high computational efficiency and may find some potential applications in sensing, detecting and optical communications.