Radiative and collisional damping effects on efficient population transfer in a three-level system driven by two delayed laser pulses.

Abstract

The effect of radiative decay and collisional damping on the delayed-field population transfer in the three-level system is investigated. The simple analytical steady-state solution of the three-level system, interacting with two intense delayed laser pulses in the dressed-state frame, is obtained and analyzed. The radiative relaxation transfers the system to the ``trapped state,'' which is shown to be stable relative to both radiative decay and collisional damping. The effect of an additional level \ensuremath{\Vert}m〉, situated close to the final level \ensuremath{\Vert}3〉, on the population-transfer process is considered. The field-induced relaxation rate from intermediate level \ensuremath{\Vert}2〉 to level \ensuremath{\Vert}3〉 is shown to be a very easily controllable parameter of the field intensities and their relative delay. This result leads to selective population transfer to the desired level and may prevent leaking out of the three-level system. Theoretical analysis corresponds entirely to recent experimental data [U. Gaubatz et al., J. Chem. Phys. 92, 1 (1990); 92, 5363 (1990)].