A compact fourth-order unconditionally-stable four-stages split-step FDTD method

A compact fourth-order four-stages split-step finite-difference time-domain (SS4-FDTD) method is developed, that achieves higher computation efficiency than the previous original fourth-order SS4-FDTD by reducing the band-width of the system involved. From the stability and dispersion analysis, it can be concluded that the compact fourth-order SS4-FDTD method is also unconditionally-stable and has the same level of accuracy as the original fourth-order method.