Electromagnetically induced transparency and storing of a pair of pulses of light

Electromagnetically induced transparency and light storing are discussed in the case of an atomic medium in a double Lambda configuration. A polariton description of both phenomena is systematically introduced. Analytic expressions are given which allow one to predict the shapes and phases of both the transmitted pulses and the stored and released ones as well as the atomic coherence in the storage stage. A comparison of the numerical solutions of the Maxwell-Bloch equations with the results due to the polariton model proves a strong predictive power of the latter.