Multiphoton processes in lambda three-level systems

We study population transfer and multiphoton processes occuring in lambda three-level systems driven by two pulse-shaped laser fields. We choose parameters that are known from numerical solutions of the the semiclassical time dependent Schrodinger equation to induce complete population transfer. We construct in the frame of the adiabatic Floquet theory the associated dressed Schrodinger equation and show that it reveals additionnal information not contained in the semiclassical Schrodinger equation: the population transfer is accompanied by multiphoton absorption from and emission into the laser fields, where time dependence can be explicitely calculated in the Floquet representation.