0π pulse propagation in the extreme sharp-line limit

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 both for 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.