Conformal Anisotropic Periodic Boundary Condition for FDTD Method

A novel conformal periodic boundary condition (CPBC) is proposed for the finite-difference time-domain (FDTD) method to accurately model anisotropic periodic structures. The conformal FDTD algorithms based on the effective material parameters are attractive due to their simplicity of implementation, but they require a reduced time step to maintain the Courant-Friedrichs-Lewy condition. In this letter, we introduce a novel conformal FDTD scheme for anisotropic materials. This scheme integrates the simplified conformal (SC) finite integration technique with the effective material parameters, which is not only simple to implement, but also avoids the time step reduction due to the effectively small cells. Additionally, we extend this conformal algorithm to periodic boundary condition (PBC) to accurately simulate anisotropic periodic structures. Finally, to validate the proposed method's accuracy and efficiency, we present two illustrative examples.