Soliton model for propagation of subpicosecond light pulses interacting with Wannier excitons

Light pulse propagation with excitonic nonlinearities was investigated, analytically and numerically and compared with two related phenomena: self-induced transparency in atomic systems and femtosecond soliton propagation in Kerr media. For resonant excitation at the s-exciton resonance, the light-matter interaction can be described by reduced semiconductor Maxwell-Bloch equations for the electric field of light and induced excitonic polarization. The model assumes a large exciton binding energy thus allowing higher exciton and continuum states to be neglected. For femtosecond light pulses with moderate intensities, the observed effect justifies the neglect of the screening.