OPTICAL NONLINEARITIES IN HIGHLY EXCITED SI-SIGE QUANTUM-WELL STRUCTURES

In this study we present the first theoretical predictions concerning the intensity-dependent (nonlinear) optical properties of certain high ly excited Si-SiGe semiconductor microstructures. We use a simplified model that can only be applied to a limited range of effects. However, we show that this model correctly accounts for the relevant experimen tal results available for bulk GaAs and some GaAs-GaAlAs microstructur es. We find that in the range of applicability of our theory the nonli near refractive index in certain Si-SiGe quantum well structures is co mparable to that in analogous GaAs-based microstructures.