Stationary and quasi-stationary light pulse in three-level cold atomic   system
  We have studied stationary and quasi-stationary signal light pulses in cold lambda-type atomic media driven by counterpropagating control laser fields at the condition of electromagnetically induced transparency. By deriving a dispersion relation we present spectral and temporal properties of the signal light pulse and a significant influence of atomic decoherence on the coupled stationary light pulses for spatial splitting. Finally we discuss quasi-stationary light pulse evolution characterized by frozen spatial spreading for a robust coherent control of slow light pulses. 
S. A. Moiseev, A. I. Sidorova, and B. S. Ham
physics.optics physics.atom-ph quant-ph