Asymmetric optical pulse propagation through a resonant absorber

We experimentally measure the propagation delays for chirped optical pulses with asymmetric temporal envelope functions, through a resonantly absorbing dye solution. The transmitted pulses suffer a strong deformation and the arrival times are dramatically modified by the interaction between the chirp and the absorption effect of the sample. It is shown that the arrival time, represented by the centroid of energy of the transmitted pulse, can be well described by the reshaping delay and has a greater significance than the peak of the pulse.