On-resonance self-focusing of coherent optical pulses in absorbers

Analytic and numerical solutions of the Maxwell-Blcch equaticns including transverse and time-dependent phase variations predict on-resonance self-focusing (SF) and elucidate its formation due to the combined effect of diffraction and inertial response of the medium. This new SF can be characterized by a simple parameter in terms of the beam and medium parameters. Recently, two independent experiments in Na and Ne demonstrated convincingly this new SF effect of spatially non-uniform self-induced transparency pulses propagating in thick resonant absorbers.