Optical properties of strained-layer superlattices with growth axis along

Abstract

We show that large piezoelectrically induced electric fields strongly modify the optical properties of [111] growth axis strained-layer superlattices with growth axis along [111]. These internal fields reduce the superlattice band gap, change optical matrix elements, and cause a spatial separation of photoexcited electrons and holes so as to screen the fields. Very large (${\mathrm{\ensuremath{\chi}}}^{3}$\ensuremath{\sim}${10}^{\mathrm{\ensuremath{-}}1}$ esu) optical nonlinearities occur because of the free-carrier screening of the strain-generated internal electric fields.