In-well screening nonlinearities in piezoelectric multiple quantum wells

The contribution of the in-well screening of the piezoelectric field to the nonlinear optical response of a [111]-oriented strained InGaAs/GaAs multiple quantum well is separated from, and compared to, that associated with the out-of-well screening and with bleaching by using picosecond nondegenerate differential transmission techniques. These measurements demonstrate that the per-carrier nonlinearity associated with the in-well screening is smaller than that associated with the out-of-well screening by a factor roughly equal to the number of wells.