Anomalous dispersion of transparent atomic two-, three-, and four-level ensembles

Amitabh Joshi, Min Xiao

Alessandra S. Rocco, Andreas Wicht, R.-H. Rinkleff +1 more

The absorption and dispersion properties of a driven two-level atomic system probed by a weak field have been measured simultaneously with a phase modulated Mach-Zehnder interferometer. We find that the resonant absorption and the negative dispersion are reduced with respect to the nondriving case by a factor of 490 and 47, respectively, which is in good agreement with the theory. This means a $\ensuremath{\sim}10$-fold enhancement of the amount of dispersion provided per amount of residual absorption. The experimental values are compared to the requirements that have to be fulfilled for the realization of a broadband, high finesse optical cavity. Finally, we propose a specific degenerate three-level system that overcomes some of the shortcomings of the driven two-level atom.

B. Hönerlage, J.‐Y. Bigot

Z. Ficek, JOSIP SEKE, Andrey Vladimirovich Soldatov +2 more

Zhi‐Hui Kang, Fan Meng, Yan-Ji Qu +4 more

Abstract The manipulation of the group velocity of light is very important in further information processing and quantum network. It is well known that subluminal and superluminal light propagation can be obtained by controlling the dispersion property of the experimental medium. In order to realize the switching from normal dispersion to anomalous dispersion at the same frequency, we investigate the dispersion and absorption properties of a four-level atomic system. By adjusting the intensity of an incoherent pump, we get transparent normal dispersion and lossless anomalous dispersion, which lead to subluminal and superluminal light propagation respectively. For a strong incoherent pump, the intensity of the coherent coupling field also can be used to realize a similar switching effect.

А. Ч. Свистун, Л. С. Гайда, Anatoly A. Afanas'ev