Abstract

Extremely large optical nonlinearities have been predicted¹ in strained quantum wells and superlattices composed of zincblende materials grown on substrates oriented in directions other than (100). In such materials, the strain produces a piezo-electric field along the growth direction, which Stark shifts the excitonic resonances to lower energies. The nonlinearity then arises from a blue shift of the exciton as this strain-induced field is screened by the redistribution of photogenerated charge within the quantum wells. Recently, the existence and screening of these fields has been demonstrated²,³ and the first measurements of the optical nonlinearity reported⁴. Specifically, in the latter studies⁴, optical nonlinearities were measured in In_0.15Ga_0.85As/GaAs multiple quantum wells oriented in the (211) direction that were approximately one order of magnitude larger than those of a similar structure grown in the (100) direction and roughly an order of magnitude larger than those previously reported in multiple quantum well structures.

© 1992 Optical Society of America