NONLINEAR WAVE-FRONT SHARPENING IN THE ADIABATIC POPULATION TRANSFER REGIME

We examine the propagation of a pair of electromagnetic pulses through a medium in the adiabatic passage regime in the case of unequal oscil lator strengths of two optical transitions in an atom. It is shown tha t light waves propagating in a nonlinear medium under such conditions are not shape-preserving. We demonstrate that a front sharpening occur s in this case.