Effects of hole burning on pulse propagation in GaAs quantum wells

Pulse time-of-flight measurements at the heavy exciton resonance in GaAs quantum wells reveal large pulse delays which are dependent on intensity and pulse spectral width. The measured pulse velocities are comparable to those seen in bulk GaAs and are as low as 6.7×${10}^6$cm${\mathrm{s}}^{-1\mathrm{}}$. We obtain quantitative agreement with a simple theory based on hole burning observed in the inhomogeneous exciton line, and we show that the measurements are useful in estimating exciton damping, under certain conditions.