A sequence of two femtosecond coherent pulses—a strong pi-polarized pulse and a weak sigma-polarized pulse—excite the S1/2-P1/2 transition of atomic rubidium in an optically dense vapor. The sigma pulse induces transitions between the adiabatic states with a coupling strength that is different for identically and oppositely light-shifted coupled states, and that can be modified by tuning the relative phase between the pulses. An efficient control of the medium gain for the sigma pulse is experimentally demonstrated. It is shown to be the result of interference between the absorption and the stimulated emission paths for sigma photons.
doi:10.1103/PhysRevLett.98.053602
Voir en ligne : Phys. Rev. Lett. 98, 053602 (2007)