The Trapped Rainbow effect for broadband slow light and light storage

The effect on the propagation of the pulse on varying the thickness of the core of an adiabatically tapered negative refractive-index metamaterial (MM) heterostructure is investigated. In addition to the ´trapped rainbow´ effect, a corresponding arrangement in which the refractive index of a uniform core layer, rather than its thickness is adiabatically varied, is numerically studied. This avoids numerical issues related to the boundary conditions between negative and positive index layers, which normally require averaging the tangential and normal field components at the core/cladding interfaces.