Peculiarities of the evolution of a precursor pulse in the shaping of quasi-resonance self-induced transparency pulses

The results of a numerical simulation of the evolution of a precursor pulse are presented. This pulse exists at the stage of the conversion of a quasi-resonance input pulse into a 2π pulse considered in the theory of self-induced transparency. Calculations have shown that the efficiency of precursor-pulse formation increases as the input laser pulse shortens and its area approaches π. The results of a numerical analysis of the known experiments on the observation of a precursor pulse in ruby crystals are also presented. In one of the cases considered, the calculation results cast some doubt on the interpretation of the experiment adopted earlier.