Nonlinear gain and output power characteristics of quantum-well sources

The gain saturation in quantum-well heterostructures under the change in the populations of the subband levels is described in detail. The nonlinearity parameters are introduced and their change with the pump, radiation frequency, temperature, polarization, and the quantum-well level distribution is examined. The main attention is given to quantum-well heterostructure sources based on III-V compounds, including GaInAsSb, GaInAs, GaInAsP, GaAs, and GaInN, which emit in the spectral interval from the mid-infrared to visible light.