  We experimentally study the optical emission of a thin quantum well and its
dynamic modulation by a surface acoustic wave (SAW). We observe a
characteristic transition of the modulation from one maximum to two maxima per
SAW cycle as the acoustic power is increased which we find in good agreement
with numer- ical calculations of the SAW controlled carrier dynamics. At low
acoustic powers the carrier mobilites limit electron-hole pair dissociation,
whereas at high power levels the induced electric fields give rise to efficient
acousto-electric carrier transport. The direct comparison between the
experimental data and the numerical simulations provide an absolute calibration
of the local SAW phase.
