Two-photon transitions between bound-to-continuum states in AlGaAs/GaAs multiple quantum well

Summary form only given.Quantum-confined structures such as multiple quantum wells (MQWs) exhibit room temperature exciton resonances, and it is well known that these resonances may enhance the nonlinear optical properties of an MQW compared with that of a bulk material. Although there have been some studies on the nonlinear optical properties of MQWs near half the bandgap, they an failed to show clearly both the magnitude and the position of the two photon excitonic resonance. In this work, we show detailed two-photon absorption (TPA) studies of an MQW near half the bandgap where we have observed the excitons with reduced binding energy due to the two-photon transitions between the bound and continuum states. For the experiments, we used a l-cm-long MQW channel waveguide with 7-nm-thick GaAs wells.