Gain in negative-refractive-index slow-light waveguides

摘要

We outline the theory of slow-light propagation in waveguides featuring negative electromagnetic parameters (permittivity, permeability and/or refractive index). We explain the mechanism by which these heterostructures can enable stopping of light even in the presence of disorder and, simultaneously, dissipative losses. Using full-wave numerical simulations and analytical transfer-matrix calculations we show that the incorporation of thin layers made of an active medium adjacently to the core layer of a negative-refractive-index waveguide can completely remove dissipative losses - in a slow- or stopped-light regime where the effective index of the guided lightwave remains negative. We also review and compare several 'trapped rainbow' schemes that have recently been proposed for slowing and stopping waves.