Ds. Chemla et Jy. Bigot, ULTRAFAST PHASE AND AMPLITUDE DYNAMICS OF COHERENT TRANSIENTS IN SEMICONDUCTOR QUANTUM-WELLS, Chemical physics, 210(1-2), 1996, pp. 135-154
We present investigations of the temporal evolution of phase and ampli
tude of coherent emission of GaAs/GaAlAs quantum well structures, exci
ted by ultrashort laser pulses. We find that the coherent light emitte
d by excitons or by electron-hole pairs exhibits a complex phase behav
ior, which depends critically on the intensity and the central frequen
cy of the exciting pulses. We observe nonlinear shifts of the instanta
neous frequency within one ultrashort pulsed emission. We also discuss
the theoretical interpretation the experiments. Although it is clear
that non-local Coulomb correlation and non-Markovian dephasing process
es are responsible for the observations, quantitative theories are not
available presently. Therefore our experiments, point the need for th
eoretical refinements of nonlinear optical processes in semiconductors
.