Fast Nonuniform Metasurface Analysis in FDTD Using Surface Susceptibility Model

Analysis of nonuniform metasurfaces requires enormous computational resources and even cannot be achieved in some cases, due to their multiscale property. To address this, we propose a fast analysis method in finite difference time domain (FDTD) scheme in this article. Two steps are required: first, nonuniform metasurfaces are modeled as a distribution of surface susceptibilities. Secondly, the surface susceptibility model (SSM) is inserted into FDTD equations in a form of surface polarization currents based on generalized sheet transition conditions (GSTCs). A detailed comparison is made between brute force simulation and our proposed method. Compared with the hours consumed for physical model simulation, surface susceptibility model simulation's time consumption is in seconds while simultaneously maintaining similar field responses independent of the incident wave's angle and polarization.