POLARIZATION CHOICES IN EXCITON-BIEXCITON SYSTEM OF GAAS QUANTUM-WELLS

We study the induced absorption due to biexciton formation in absorpti on bleaching pump-probe signals and the quantum beats between exciton and biexciton in the four-wave-mixing signals. The origin is confirmed by the polarization dependence of the signals in both experiments. Th e definite discrimination between exciton-biexciton quantum beats and the others by the polarization choices is demonstrated clearly. We als o show the well-width dependence of the biexciton binding energy that is determined by the period of the quantum beats in the range of well width 45-150 Angstrom of GaAs/AlxGa1-xAs (x=0.3-1.0) multiple quantum wells.