Analysis of adiabatic passage by light-induced potentials with chirped laser pulses in three- and four-level diatomic systems.

This paper describes an investigation into the process of adiabatic passage by light-induced potentials (APLIP), which was previously suggested as a method for employing two strong picosecond laser pulses to transfer the population between two electronic states. We have extended earlier numerical studies in order to assess the feasibility of an experimental implementation of the APLIP concept. APLIP has been modeled in a three-level model system based on Na2 with chirped pulses, using laser parameters available from a typical chirped pulse amplified Ti:sapphire laser. The model showed that the APLIP process remains essentially unchanged for chirped pulses of equal magnitude and the opposite, or equal and positive sign of chirp as compared to the transform-limited case. We also examined the case of additional electronic states by introduction of a fourth state that lies close to the "target," i.e., final, state. The investigation showed that there are circumstances in which a significant fraction of the population gets transferred to this state which will disrupt the APLIP process. However, by switching to this fourth state as the target state in an experiment, good transfer efficiency is recovered. The results of the extension of the original APLIP modeling to chirped pulses and additional electronic states indicate that an APLIP experimental realization should be feasible in Na2.