S. Briaudeau et al., COHERENT DOPPLER NARROWING IN A THIN VAPOR CELL - OBSERVATION OF THE DICKE REGIME IN THE OPTICAL DOMAIN, Physical review. A, 57(5), 1998, pp. 3169-3172
Single light beam transmission spectroscopy in an ultrathin dilute vap
or cell (10-100 mu m) reveals sub-Doppler features. Indeed, atoms with
fast (normal) velocity undergo a short interaction between the cell w
alls, and are shown to be less absorbing because they have not reached
their steady state of interaction with light. The effect is observed
in the linear-response regime with a simple two-level system, as ensur
ed from the ultralow level of light irradiation (less than or equal to
1 mu W/cm(2) for the Cs D-2 line). The effect, known for a long time
in the microwave domain, is demonstrated here in the optical domain, a
nd is extended to cell thicknesses large relative to the optical wavel
ength.