Comparison of the propagation of single and double 4π pulses in two-level and three-level systems

We report on the spatial and temporal dynamics of a pair of optical pulses propagating through a three-level, nonabsorbing lambda system, Where one pulse is tuned to the pump transition and the other to the Stokes transition. Assuming a sech profile for the pump pulse, and an area of 4 pi, we compare two different situations, one where the pump pulse is a single pulse and the other where it is a double pulse. The results of our computer experiments focus on certain transient dynamics, which reveal how the pulse pairs evolve before reaching a steady state behavior. The results are compared to the well-known results that arise when a 4 pi pulse propagates in a two-level medium. (C) 2001 Elsevier Science B.V. All rights reserved.