Improved shift operator FDTD method for high order dispersive media

An improved shift operator finite-difference time-domain (SO-FDTD) method for the high order Debye, Drude, Lorentz and hybrid model dispersive media is presented. The susceptibility function of dispersive media is firstly represented as the sum of rational fractions. The computational complexity and large storage requirement in the conventional SO-FDTD method for the high order dispersive model is solved by introducing an intermediate variable and setting a temporary variable. Meanwhile, the generality of updated formulation in the improved SO-FDTD method is superior to that of the conventional recursive convolution FDTD(RC-FDTD) method, in which different formulations are required for different dispersive models. Finally, the generality and feasibility of the presented scheme are validate