Unconditionally Stable Leapfrog Algorithm of the Split-Field FDTD for Periodic Structures

An unconditionally stable one-step leapfrog algorithm is presented to analyze the oblique incident plane wave on periodic structures. The algorithm is originated from the improved split-field method, but no sub-step computations are required. It is more computationally efficient while preserving the properties of the improved split-field method. The complex frequency shifted perfectly matched layer (CFS-PML) for the new algorithm is also developed to truncate the computational domain. To verify the accuracy and the efficiency of the proposed method, we compare its results with that of the improve split-field method.