Electromagnetic field induced switching off of radiation trapping

We report on the observation of radiation trapping removal by the application of a strong laser pulse which couples the upper level of the involved atomic transition to a third higher level. The process was studied using the fluorescent pulse detected in concomitance with the laser application. A spectroscopic analysis was performed in a time gate comparable to the pulse duration in correspondence to three different atomic densities. The spectra were compared to theoretical curves obtained using the density matrix formalism.