Analysis of Nonlinear Metallic Metasurface Elements Using Maxwell-Hydrodynamic Model With Time-Domain Perturbation Method

A time-domain perturbation method (TDPM) for simulating nonlinear metallic metasurface elements with Maxwell-hydrodynamic model is presented. Finite-difference time-domain (FDTD) method is implemented to the model with peculiar boundary conditions on metallic surfaces. A complete numerical algorithm is developed accordingly. The stability of the algorithm is analyzed, and corresponding stable conditions are derived. Several nonlinear metallic metasurface elements are computed by the proposed algorithm with the numerical results agreeing with references. The proposed algorithm could achieve wideband full-wave nonlinear simulations for nonlinear metallic metasurfaces and is able to analyze linear and nonlinear responses separately, not only helping the detailed study of nonlinear mechanisms but also guaranteeing the iteration stability of the whole algorithm. Both the bulky and surface nonlinear effects could be computed simultaneously in the proposed algorithm, which improves its accuracy on calculating nonlinear responses.