M. Muller et al., Heterodyne measurement of parametric dispersion in electromagnetically induced transparency - art. no. 013803, PHYS REV A, 6401(1), 2001, pp. 3803
Using three phase-locked lasers, we have observed in a three-level system t
he phase shift of the frequency fixed coupling laser in dependence of the p
robe laser frequency relative to an off-resonant reference laser. In the vi
cinity of the two-photon resonance, the system exhibits electromagnetically
induced transparency and we show that the dispersion of coupling and probe
field shows different spectra if the probe field frequency is tuned. The p
arametric dispersion of the coupling field is measured on a cesium atomic b
eam with a heterodyne interferometer over several decades of coupling and p
robe laser power. Even with coupling powers in the nW range, the interferom
eter gives a good signal-to-noise ratio. The results are in good agreement
with a numerical simulation of a semiclassical model. Analytical expression
s for the dispersion are given.