0π pulse shape in the sharp line limit case

We observe the propagation and the reshaping of low intensity (zero area) 60 fs pulses through high density atomic Cs vapor. The breakup of the pulses is measured for both resonant excitation of the Cs atoms and for laser detunings such that the atomic resonance frequency is in the wings of the pulse spectrum. The theory of 0π pulse propagation, in the extreme sharp-line limit, is extended to include both resonant and off resonant excitation. Good agreement is demonstrated between the observations and the theoretical predictions.