ADI-FDTD Modeling of Tellegen Media

The magnetoelectric coupling that appears in the constitutive relations of Tellegen media makes formulating unconditionally stable finite-difference time-domain (FDTD) extensions a challenging problem. In this letter, we present an alternating-direction implicit (ADI)-FDTD approach for modeling transient wave propagation in Tellegen media. In the proposed formulation, the discretization of the governing equations is performed introducing weighted average parameters. The numerical features are then carefully examined and the weighted discretization parameters conveniently chosen to yield an unconditionally stable scheme. Moreover, the resulting approach presents second-order accuracy and preserves the tridiagonal structure of the data matrices. Finally, the numerical dispersion relation is given in a closed form. The new method has been validated by means of numerical experiments and has shown good agreement.