Slow and stopped light in metamaterials

We demonstrate the deceleration of guided electromagnetic waves propagating along an adiabatically tapered negative-refractive-index metamaterial heterostructure and show that light can ideally be brought to a complete halt. It is analytically shown that, in principle, this method simultaneously allows for broad bandwidth operation (since it does not rely on group index resonances), large delay-bandwidth products (since a wave packet can be completely stopped and buffered indefinitely) and high, almost 100 % in/out-coupling efficiencies. The halting of a monochromatic field component travelling along the heterostructure is demonstrated on the basis of a wave analysis and confirmed in a pertinent ray analysis, which unmistakably illustrates the trapping of the associated light-ray and the formation of a double light-ray cone (optical clepsydra) at the point where the ray is trapped. This method for trapping photons conceivably opens the way to a multitude of hybrid optoelectronic devices to be used in quantum information processing, communication networks and signal processors and may herald a new realm of combined metamaterials and slow light research.