  We report on a detailed investigation of the dynamics and the saturation of a
light grating stored in a sample of cold cesium atoms. We employ Bragg
diffraction to retrieve the stored optical information impressed into the
atomic coherence by the incident light fields. The diffracted efficiency is
studied as a function of the intensities of both writing and reading laser
beams. A theoretical model is developed to predict the temporal pulse shape of
the retrieved signal and compares reasonably well with the observed results.
