Pulse propagation in three-level medium
  We investigate propagation of a pulse pair in a three-level medium under the adiabatic following condition for the general case of unequal oscillator strengths. Exact analytical solutions to the propagation equations have been obtained. It is shown that propagation dynamics strongly depends on the relationship between oscillator strengths. The adiabaticity criterion for the interaction of pulses with three-level media has been derived and analyzed in detail. 
Y.T. Pashayan and G.G. Grigoryan