PERTURBATION ANALYSIS OF RAMAN ECHO

A time-dependent perturbational approach is used to study the Raman ec ho generated by an inhomogeneous ensemble of three-level atomic system s in the A configuration. The sixth-order perturbative solution for co herence between the two lower states contains eight echo terms that ar e visualized with double Feynman diagrams. The echo is interpreted as a response of the ensemble to six short single-frequency optical pulse s whose timing satisfies a special condition. Nonperturbative numerica l simulation confirms the predictions of the perturbation analysis abo ut the main characteristics of the echo. When the excitation pulses va ry adiabatically with respect to fast optical coherence decay the echo amplitude depends on interference of the eight terms. A computational scheme developed for the higher-order perturbative analysis is also d iscussed. (C) 1998 Optical Society of America.