FDTD analysis of slow light propagation in negative-refractive-index metamaterial waveguides

Using finite-difference time-domain (FDTD) simulations we investigate the propagation of light pulses in waveguides having a core made of a negative-refractive-index metamaterial. In order to validate our model we carry out separate simulations for a variety of waveguide core thickness. The numerical results not only qualitatively confirm that light pulses travel slower in waveguides with thinner cores, but further they reveal that the effective refractive indices experienced by the propagating pulses compare favourably with exact theoretical predictions. We also examine the propagation of light pulses in waveguides with adiabatically, longitudinally varying core refractive index. The effective refractive indices extracted from these simulations confirm previous theoretical predictions while, both a slowing and an increase in the amplitude of the pulses are observed.