Abstract

It was pointed out by Smith and Mailhot^1,2 that lattice-mismatch strain in [111] grown strained layer superlattices (SLSs) gives rise to piezoelectric fields of the order of 10⁴-10⁵ V/cm. These fields lead to large Stark shifts in the optical spectra and interesting nonlinear optical effects, which can depend on the density of free carriers.² Even at low carrier density, there is an effect of the piezoelectric fields on the nonlinear susceptibilities due to parity mixing of the levels [χ⁽²⁾] and changes in the carrier dispersion relations caused by the piezoelectric fields [χ⁽³⁾]. In a freestanding SLS, we use a transfer matrix technique and Floquet's theorem to obtain exact dispersion relations for the superlattice miniband together with an exact superlattice wave function. This is done within a Kronig-Penney-type model with tilted bands due to piezoelectric fields.

© 1990 Optical Society of America