Pulse breakup in the extreme sharp-line limit

The propagation and reshaping of low intensity, 0_π pulses, is observed and compared with theory in experiments using 60 fs pulses. The bandwidth of such pulses is much greater than the width of the atomic absorption lines and we can therefore use the extreme sharp line limit in the theoretical interpretation of the experiments. The experiments were performed for both resonant excitation and for detunings of the pulse central frequency from the 852 nm Cs atomic resonance frequency. The theory of short pulse propagation is extended to include the off-resonant case.