Optically induced blueshift of photoluminescence excitation spectrum in n–i–p–i multiple quantum well structures

Abstract

In this paper, the nonlinear optical properties of hetero n–i–p–i multiple quantum well (MQW) structures are investigated through a two-beam photoluminescence excitation (PLE) measurement. A large blue shift of the PLE spectra of n–i–p–i MQW structures has been observed when the optical excitation power intensity is varied from as low as ∼1 mW cm −2 to ∼10 W cm −2. This nonlinear optical modulation has been enhanced greatly by using multiple step-quantum wells to replace normal rectangular quantum wells in the n–i–p–i MQW structure. The experimental results agree well with our theoretical model.