Nonlinearity and recovery time of 1.55 µmintersubbandabsorption in InGaAs/AlAs/AlAsSb coupled quantum wells

Abstract
Values for the nonlinearity and recovery time of 1.55 µm intersubband absorption have been experimentally obtained for the first time by using InGaAs/AlAs/AlAsSb coupled quantum wells. The third-order susceptibility (χ(3)) has been evaluated to be 5.8×10-17 m2/V2. An ultrafast recovery time (τ) of ~685 fs has been obtained while keeping the figure of merit (χ(3)/ατ) as large as those of interband transitions.