ELECTROOPTIC AND PHOTOREFRACTIVE PROPERTIES OF LONG-PERIOD FIBONACCI SUPERLATTICES

We have investigated the transverse-field electroabsorption of long-pe riod GaAs/AlGaAs Fibonacci superlattices for three different realizati ons of the Fibonacci sequence and assessed their bandwidth in photoref ractive four-wave mixing experiments, The one-electron density of stat es exhibits a wide fractal distribution of quasibands, suggesting the ability to tailor bandwidths for optical applications. Many-electron e ffects and the inter-well coupling shift the excitonic oscillator stre ngth to the low-energy edge of the spectrum in all cases, producing a diffraction bandwidth that is relatively independent of coupling in bo th weak- and strong-coupling Fibonacci superlattices. (C) 1996 America n Institute of Physics.