Intersubband absorption saturation in multiple-quantum-well structures: The sheet model approach

We present a theoretical formalism, based on the transfer-matrix method and the so-called sheet model, describing light propagation in multiple-quantum-well (MQW) structures in the range of the saturated intersubband absorption. A commonly used total internal reflection geometry is considered. Intensity of the reflected light as a function of the input intensity is calculated for two-level GaAs/AlxGa1-xAs MQW. Numerical simulations show that the optical nonlinearity of the structures can be greatly modified by optical interference effects. In the case of sufficiently thick structures and grazing angle of incidence the multiple reflections inside the MQW can lead even to bistability.