Causality-induced pulse steepening and shock-like waves in superluminal media
Optics and Materials Group - OPTMA, Universidade Federal de Alagoas - Caixa Postal 2051, 57061-970, Maceió, AL, Brazil
Accepted: 18 January 2012
Using pulses based on functions with compact support and perfectly smooth infinitely differentiable zero-intensity nonanalytical points, a new approach to model information propagating through an anomalous dispersive medium is demonstrated. Information can be unambiguously associated to the nonanalytical point in the pulse's leading edge, and its velocity investigated numerically and experimentally in fast-light media. We have clearly observed that the velocity of this nonanalytical point is bounded by Einstein causality and it is exactly equal to the light speed in vacuum c when the pulse's group velocity is superluminal. Moreover, we observed that causality can also cause steepening and a pulse shock-like effect.
PACS: 42.25.Bs – Wave propagation, transmission and absorption / 42.50.Gy – Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption / 89.70.-a – Information and communication theory
© EPLA, 2012