DEGENERATE 4-WAVE-MIXING IN PICOSECOND PULSES - STUDY OF THE TEMPORALSHAPE OF THE DIFFRACTED SIGNAL AS A FUNCTION OF THE MATERIAL RESPONSE-TIME

We present a time-resolved study of the diffracted pulse in degenerate four-wave mixing experiments with short-response-time materials. The first step is the validation of a theoretical model that takes into ac count the temporal characteristics of the energy level (relaxation tim e T1 and dephasing time T2) and of the incident pulse (duration and sp ectral phase) in a simple particular case. Two methods are used for ch aracterizing the diffracted beam: the amplitude correlation with the r eference pulse and the spectrum intensity measurements. We discuss the experimental results, which show good agreement with the theoretical model and evidence the strong influence of the incident pulse characte ristics.