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

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 similar to1 mW cm(-2) to similar to10 W cm(-2). This nonlinear optical modulation has been enhanced much 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. (C) 2003 Elsevier Science Ltd. All rights reserved.