The WLP-FDTD Method for Periodic Structures With Oblique Incident Wave

A new unconditionally stable finite-difference time-domain (FDTD) method for periodic structures is presented, which is based on the field transformation method and the weighted Laguerre polynomials FDTD (WLP-FDTD). The proposed method uses a field transformation to remove the time gradient across the grid, and then uses the concept of the WLP-FDTD to get the implicit relationship between the transformed field variables. It holds the advantages of the WLP-FDTD, can eliminate the restriction of the Courant-Friedrich-Levy (CFL) stability condition. Compared with other field transform methods, the new method needn´t to do special treatment for the additional terms. It appears to be much more efficient than the other field transformation FDTD method for solving periodic structures with fine structures and large incident angle. To verify the accuracy and the efficiency of the proposed method, we compare the results of the Split-Field FDTD method with the proposed method.