Newmark method for finite-difference time-domain modeling of wave propagation in frequency-dispersive medium

Abstract

The complex polarizations of three kinds of general dispersive medium models, i.e. Debye model, Lorentz model, Drude model, are described by rational polynomial fraction in jω. The relationship between the polarization vector P and the intensity of electric field E in time domain is obtained by utilizing the transformation relationship from frequency domain to time domain jω→∂/∂t. Then, the time domain second order equation is solved by using the Newmark β and γ method, which has higher accuracy than the traditional center difference method. Once the recursive formulations for E and P are obtained, the recursive formulations for D and E in time domain can be also obtained based on the constitutive relation. Therefore for a dispersive medium the iterative electromagnetic field calculation is conducted by finite-difference time-domain (FDTD) method. The present numerical results demonstrate that the proposed method is a general algorithm for three kinds of general dispersive medium models, and has higher accuracy than the shift operator-FDTD, which is based on the central difference discrete scheme.