Coherent and incoherent solitons of self-induced transparency in dense, resonant media

The spatiotemporal dynamics of a light pulse injected into a dense, resonant medium under near-dipole-dipole interaction conditions is considered. Two regimes for soliton formation are investigated numerically and analytically. The first one occurs if the pulses are much shorter than both relaxation times. In the second, the pulse duration falls between those of the relaxation times and may be regarded as an incoherent one. In the latter case there are conditions in which the dephasing process is suppressed by dipole-dipole interatomic interaction. Not only are one-soliton solutions found but also a powerful pulse splitting into separate solitons is revealed. The regions in which solitons are found have been estimated. The possibility of finding incoherent solitons has been analyzed, with group-velocity dispersion and diffraction of tilted pulses, which are shown to make soliton formation easier, taken into account. (C) 2002 Optical Society of America.