Ultra-slow and superluminal light propagation in solids at room temperature

Abstract

Slow and superluminal group velocities can be observed in any material that has largenormal or anomalous dispersion. While this fact has been known for more than a century,recent experiments have shown that the dispersion can be very large without dramaticallydeforming a pulse. As a result, the significance and nature of pulse velocity is beingreevaluated. In this review, we discuss some of the current techniques used forgenerating ultra-slow, superluminal, and even stopped light. While ultra-slow andsuperluminal group velocities have been observed in complicated systems, from anapplications point of view it is highly desirable to do have this done in a solidthat can operate at room temperature. We describe how coherent populationoscillations can produce ultra-slow and superluminal light under these conditions.