Cooperative Emission of a Coherent Superflash of Light
  We investigate the transient coherent transmission of light through an optically thick cold stron-tium gas. We observe a coherent superflash just after an abrupt probe extinction, with peak intensity more than three times the incident one. We show that this coherent superflash is a direct signature of the cooperative forward emission of the atoms. By engineering fast transient phenomena on the incident field, we give a clear and simple picture of the physical mechanisms at play. 
C.C. Kwong (PAP), T. Yang (CQT), M.S. Pramod (CQT), K. Pandey (CQT),   D. Delande (LKB (Jussieu)), R. Pierrat, D. Wilkowski ...
physics.atom-ph physics.optics