A simple finite difference time domain (FDTD) scheme is proposed for modeling three-dimensional (3D) nondispersive chiral media. Based on the recently reported new BI-FDTD mesh method and rearranged curl equations, this scheme implements a simple leapfrog algorithm. By adding the mirror layer, the perfect electric conductor (PEC) condition is implemented in the BI-FDTD mesh method of 3D problem. Results of this scheme are presented for the scattering coefficients of discontinuity in waveguides, which are partially filled with chiral or achiral media. The validation is performed by comparing the results with those obtained from the literature and software simulation.

An unconditionally stable scheme, which employs a similar technique to the locally one-dimensional (LOD) method, is proposed to study the one-dimensional (1D) nondispersive chiral media. In the proposed scheme, the recent new mesh-dividing method for bi-isotropic media is used. The method regards the two terms on the right-hand side of the rearranged curl equations as two directions and uses the LOD algorithm to deal with the equivalent two-dimensional (2D) problem. Through Fourier stability analysis and numerical simulation, it is found that the time-step size is not restricted by the Courant-Friedrich-Levy (CFL) stability condition, hence the proposed scheme is unconditionally stable. Compared with the similar Alternating Direction Implicit (ADI) method, the proposed scheme has lighter calculation burden and higher accuracy.Index Terms-Chiral media, finite-difference time-domain method (FDTD), locally one-dimensional (LOD), unconditionally stable.

Abstract-A LOD-like method that characterizes the analytical solution is proposed to study the one-dimensional (1-D) chiral media. Through theoretical analysis and numerical simulation, it is found that the proposed scheme is unconditionally stable. This scheme employs the new mesh-dividing method for bi-isotropic media, in which the two sections on the right side of the rearranged curl equations are regarded as two directions and the LOD-like algorithm is used to deal with the equivalent two-dimensional (2-D) problem. In the first substep, the conventional LOD method is used in computation, while for the second substep, the analytical solution is employed instead. By simulating the polarization rotation of a mono-frequency linear polarized wave both in a 1-D homogeneous chiral media and through a chiral slab, the scheme is testified to be unconditionally stable.