Influence of relaxation on propagation, storage and retrieving of light   pulses in electromagnetically induced transparency medium
  By solving the self-consistent system of Maxwell and density matrix equations to the first order with respect to nonadiabaticity, we obtain an analytical solution for the probe pulse propagation. The conditions for efficient storage of light are analyzed. The necessary conditions for optical propagation distance has been obtained. 
Gor Nikoghosyan, and Gayane Grigoryan