Scaling of the nonlinear optical cross sections of GaAs-AlGaAs multiple quantum-well hetero n-i-p-i's

We study the dependence of the Stark shift optical nonlinearity of GaAs-AlGaAs multiple quantum-well hetero n-i-p-i's on the number of quantum wells per intrinsic region in otherwise identical hetero n-i-p-i's. We determine that /spl sigma//sub eh/, the nonlinear absorption cross section, is proportional to the number of quantum wells per intrinsic region. A study of the fluence dependence of /spl sigma//sub eh/ shows that the saturation carrier density is inversely proportional to the number of wells per intrinsic region. We find that the turn-on time of the nonlinear absorption change in our samples is independent of the number of quantum wells per intrinsic region. All of these results are consistent with the absence of retrapping of photogenerated carriers.<
>