Abstract

Strained multiple quantum wells (MQWs) that are grown on [111]-oriented substrates have huge intrinsic piezoelectric fields along the growth direction.¹ The presence of this piezoelectric field shifts the exciton to the red through the quantum-confined Stark effect (QCSE). The nonlinearity in these materials then arises as the photogenerated charge screens the piezoelectric field, causing the exciton to shift to the blue as the QCSE is reduced. Early theoretical work² (based on mechanically free lattices) predicted a large nonlinear response of such materials because of the screening of these piezoelectric fields by the photoexcited carriers that remained in the quantum wells (in-well screening). Clearly, any mechanism or material that purports to have a large per-carrier nonlinearity is of interest for any number of electro-optical switching applications.

© 1995 Optical Society of America