QUASI-ADIABATIC FOLLOWING OF FEMTOSECOND OPTICAL PULSES IN A WEAKLY EXCITED SEMICONDUCTOR

Using semiconductor Maxwell-Bloch equations, we analyze the response o f an ensemble of is excitons driven by a femtosecond optical pulse bey ond the traditional approach of slowly varying amplitudes and phases. For optical pulses of a given duration, we show that the off-resonance optical field can evolve into a stable soliton. Besides hyperbolic-se cant solitons, we find a single soliton with nonzero asymptotics that is stable against low-amplitude perturbations and whose form is not af fected by collisions.