Enhanced Stark Shift in GaAs/AlGaAs Step Quantum Well Under an Applied Electric Field

Theoretical calculations of the quantum confined Stark shift for the first heavy hole exciton (hhl--el) in step quantum well are given. A significant change in Stark shift is achieved in specially stepped potential shape, which is more than two times larger than the conventional rectangular quantum well. The structure has the advantage of a large change in absorption, which is one of the best candidates for the optical modulators utilizing the quantum confined Stark effect (QCSE) in GaAs/AlGaAs. Relations between QCSE and stepped structure are discussed in the optimization for large Stark shift.