Effect of carriers on the optical properties of AlGaAs/GaAs interdiffused quantum well lasers

Abstract

The carrier-induced effects in the change of refractive index on the GaAs/AlWGa1-W as square quantum well (SqQw) and diffused quantum well (DFQW) was investigated. Band-filling, bandgap shrinkage, and free- carrier absorption were included. Carrier concentrations from 1016 to 1018 cm-3 were considered. The energy levels and their associated wavefunctions in the SqQW or DFQW structures are calculated by solving both the Schroedinger and the Poisson equations self-consistently. It is followed by the absorption change, which is defined as the difference between the absorption coefficient with carrier injection in QW and that without carrier injection. The refractive index change can be obtained by applying Kramers-Kronig Transformation. These results obtained are useful in the design of devices, such as lasers, optical phase, modulators and switches. Thus, it is important to know the carrier-induced energy shift in GaAs/AlWGa$_1-W) as quantum well structures.