Laser-induced structure in the continuum of sodium: A weak dressing field measurement

We report an experimental study of a laser-induced resonance in the continuum of sodium, performed by measuring the modified atomic susceptibility. The sensitivity of the set-up has allowed the observation of the induced structure in conditions of relatively weak intensity of the dressing laser field, where the line shape is independent of the field amplitude and the comparison with theory is strict and direct. We have found a good agreement with theoretical predictions and measured the Fano parameter of the resonance. © 1995 IOP Publishing Ltd.