Abstract

We have examined the nonlinear optical properties of InAs/GaAs superlattice quantum wells imbedded in a n-i-p-i structure. Measurements were made over a wide range of optical intensities from ≈100 mW/cm² to 1 kW/cm². At the smallest intensities, optical nonlinearities are observed which arise from the screening of the built-in electric fields and the corresponding electroabsorption. These nonlinearities are very energy efficient; however, they saturate at a relatively small value (ΔT/T = 10%). At higher intensities, changes ΔT/T ≈ 50% or larger are observed due to state filling and saturation of the excitonic absorption resonance. These effects are similar to those observed in conventional quantum wells; however, the presence of the doped material causes a separation of electron and hole populations which lengthens photocarrier lifetimes and reduces the required intensities. All material in the structures, grown by molecular beam epitaxy, is GaAs (transparent at the wavelengths of interest) except for the quantum wells which are short period InAs/GaAs superlattices. The use of alternating InAs and GaAs layers to produce a region of smaller band-gap avoids the problem of alloy disordering arising from the use of an InGaAs ternary.

© 1990 Optical Society of America