Resonant excitation of excitons in a semiconductor by a laser with a variable pulse duration

Resonant excitation with variable-duration ($10^{-11}$–$10^{-9}$ sec) pulses of the second harmonic of neodymium laser radiation produced self-induced transparency and exciton saturation in a single crystal of CdS$_{0,75}$ Se$_{0,25}$ ($T$ = 80°K). Changes in the pulse shape typical of these two effects were observed after passage through this crystal and the velocity of pulses of $\tau\lesssim T_2$ duration decreased ($T_2$ is the transverse relaxation time of excitons).