Luminescence tracks in a semiconductor subjected to two-photon excitation with ultrashort light pulses

An investigation was made of luminescence tracks in a CdS_0.7Se_0.3 crystal subjected to two-photon excitation with ultrashort light pulses. The characteristics of these tracks (dependence of the luminescence intensity of the distance between the point of observation and the entry face of a sample), observed in a crystal cooled to liquid-nitrogen temperature, were explained by the self-induced transparency. The problem of the propagation of an ultrashort light pulse in a resonantly absorbing medium is solved using a two-level model and allowing for the finite polarization relaxation time. This solution explains qualitatively the experimental results.