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arXiv · 1208.4309

Maximal refraction and superluminal propagation in a gaseous nanolayer

J. Keaveney·I. G. Hughes·A. Sargsyan·D. Sarkisyan·C. S. Adams
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Abstract

We present an experimental measurement of the refractive index of high density Rb vapor in a gaseous atomic nanolayer. We use heterodyne interferometry to measure the relative phase shift between two copropagating laser beams as a function of the laser detuning and infer a peak index n = 1.26 \pm 0.02, close to the theoretical maximum of 1.31. The large index has a concomitant large index gradient creating a region with steep anomalous dispersion where a sub-nanosecond optical pulse is advanced by >100 ps over a propagation distance of 390 nm, corresponding to a group index of -1x10^5, the largest negative group index measured to date.

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J. Keaveney, I. G. Hughes, A. Sargsyan, D. Sarkisyan, C. S. Adams. 2012-08-21. Maximal refraction and superluminal propagation in a gaseous nanolayer. https://doi.org/10.1103/physrevlett.109.233001

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