Nonlinear optical absorption and dynamics in quantum wells

We present measurements of differential transmission and four‐wave mixing in GaAs quantum well structures at 1.8 K near the inhomogeneously broadened lowest heavy‐hole (hh1) exciton resonance using narrow band cw excitation. The data show an increase in absorption and an excitation lifetime of order 1–10 μs outside the spectral hole produced by the pump. The long lifetime and the experimentally determined absence of excitation spatial diffusion in this region suggests that optical absorption produces electron‐hole pairs that are correlated but separately localized due to disorder. A phenomenological model is proposed to explain the nonlinear response based on two‐photon absorption.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69941/2/APPLAB-61-11-1301-1.pd