Slow microwaves in left-handed materials

Remarkably slow propagation of microwaves in two different classes of left-handed materials (LHM's) is reported from microwave-pulse and continuous-wave transmission measurements. Microwave dispersion in a composite LHM made of split-ring resonators and wire strips reveals group velocity v(g)similar to c/50, where c is the free-space light velocity. Photonic crystals (PhC's) made of dielectric Al2O3 rods reveal v(g)similar to c/10. Group delay dispersion of both the composite LHM and PhC's determined from the experiment is in complete agreement with that obtained from theory. The slow group velocities are quantitatively described by the strong dispersion observed in these materials.