SCALING OF THE NONLINEAR-OPTICAL CROSS-SECTIONS OF GAAS-ALGAAS MULTIPLE-QUANTUM-WELL HETERO N-I-P-IS

We study the dependence of the Stark shift optical nonlinearity of GaA s-AlGaAs multiple quantum-well hetero n-i-p-i's on the number of quant um wells per intrinsic region in otherwise identical hetero n-i-p-i's, We determine that sigma(eh), the nonlinear absorption cross section, is proportional to the number of quantum wells per intrinsic region, A study of the fluence dependence of sigma(eh), shows that the saturati on carrier density is inversely proportional to the number of wells pe r intrinsic region, We find that the turn-on time of the nonlinear abs orption change in our samples is independent of the number of quantum wells per intrinsic region, All of these results are consistent with t he absence of retrapping of photogenerated carriers,