General theory of laser-induced quantum beats. I. Saturation effects of single laser excitation

A general theory of quantum beats induced by pulsed-laser excitation is presented. The theory accounts for laser saturation effects such as stimulated emission from the excited atomic state during passage of the light pulse and light-induced atomic-level displacements. Under certain experimental conditions saturation may result in a modification, sometimes even in a regeneration, of the beat amplitudes.