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.