Stimulated Raman adiabatic passage with trains of weak pulses* * This work is dedicated to Bruce Shore, a brilliant and inspiring physicist, a pioneer in coherent light-matter interaction theory, a mentor and a friend.

We consider coherent population transfer in multilevel quantum systems driven by time-delayed pulse trains. We show how to choose the parameters of the trains so that the population dynamics tracks the behavior of a Λ-type three-level system under stimulated Raman adiabatic passage (STIRAP). Efficient population transfer can be achieved regardless of the order and with or without overlap of the pump and the Stokes sub-pulses of the trains. Generalized STIRAP schemes of population transfer in N-level system with sequential couplings are also examined. The mechanism of the population transfer and the robustness of the proposed schemes are discussed.