Animations obtained by the finite-difference time-domain method showing   the backward wave propagation in double-negative single-layer waveguides
  The materials having negative permittivity and negative permeability, which are labeled as double-negative (DNG) materials, have attracted much attention because of their unusual physical properties, which are different from those of conventional double-positive (DPS) materials. Animations obtained by the finite-difference time-domain method (FDTD) are provided showing how a transient sinusoidal signal that starts at t=0 propagates in the DPS and DNG waveguides. Three types of waveguides are considered: a slab or grounded slab inside the cladding medium and a parallel-plate waveguide filled with the slab. Dispersion curves in terms of normalized parameters are also provided. 
E. Cojocaru
physics.optics