Transparent anomalous dispersion and superluminal light-pulse propagation at a negative group velocity

A. Dogariu, A. Kuzmich, L. J. Wang

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Anomalous dispersion cannot occur in a transparent passive medium where electromagnetic radiation is being absorbed at all frequencies, as pointed out by Landau and Lifshitz. Here we show, both theoretically and experimentally, that transparent linear anomalous dispersion can occur when a gain doublet is present. Therefore, a superluminal light-pulse propagation can be observed even at a negative 7group velocity through a transparent medium with almost no pulse distortion. Consequently, a negative transit time is experimentally observed resulting in the peak of the incident light pulse to exit the medium even before entering it. This counterintuitive effect is a direct result of the rephasing process owing to the wave nature of light and is not at odds with either causality or Einstein’s theory of special relativity.

Original languageAmerican English
Pages (from-to)12
Number of pages1
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number5
StatePublished - 2001
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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