Coupling between cw lasers and a frequency comb in dense atomic samples

We report on a detailed investigation of the coupling between a femtosecond-laser frequency comb and a cw diode laser interacting with an atomic medium of variable density. The comb is printed on a Doppler-broadened atomic transition and the frequency-dependent transmission of the cw laser is monitored as it is scanned over the inhomogenously broadened absorption profile. The printing process and its probing are analysed, experimentally and theoretically, as a function of both laser intensities and the atomic density. The results reveal the importance of optical pumping and power broadening by both lasers, allowing us to determine various regimes of competition between them.