Relaxing CFL limit of FDTD by DWT

To extend the Courant-Friedrichs-Lewy (CFL) limit, a discrete wavelet transform (DWT) is incorporated into the finite difference time domain (FDTD) scheme. With the Mallat algorithm for the decomposition and reconstruction of the electromagnetic components, the unstable spatial modes can be efficiently filtered out. Consequently, the original strict CFL limit of the FDTD can be significantly relaxed, and much execution time can be saved. The performance and versatility of the proposed method is demonstrated by the numerical examples.