Parametric dispersion in electromagnetically induced transparency - art. no. 060501

We analyze both experimentally and theoretically the phase shift of a fixed coupling laser field in a Lambda -type system induced by a tunable probe l aser field. The measurements are performed with a heterodyne interferometer on a beam of cesium atoms in the D-2 line. This system exhibits electromag netically induced transparency with a rapidly varying refractive index. The parametric dispersion of the coupling field over a range of six decades of coupling laser intensities is investigated and found to be in accord with the predictions from the semiclassical model.