Propagation-Induced Escape From Adiabatic Following In A Semiconductor

Breakup of a below-resonance femtosecond pulse is observed in a room-temperature GaAs/AlGaAs multiple-quantum-well waveguide using cross-correlation techniques. The breakup is due to neither self-induced transparency nor temporal solitons. Instead, calculations based on the coupled semiconductor Maxwell-Bloch equations show that coherent self-phase-modulation during propagation drives the system out of the initial adiabatic following regime into excitation density oscillations and eventually pulse-shape modulations.