Dynamical simulation of quantum-well structures

For the design and development of optical semiconductor devices based on quantum-well structures, the investigation of saturation phenomena is necessary for high optical power operation. By applying stationary physical models, nonlinear effects cannot be described adequately; hence, transient models are important for an accurate analysis. By utilizing transient models, saturation phenomena, signal delays, and distortions can be investigated. For the analysis of integrated optoelectronic devices, such as lasers and modulators, transient transport or density matrix equations for carriers and photons and the Poisson equation have to be solved self-consistently. A transient model which is useful for the investigation of a wide range of optoelectronic applications is presented. Quantum optical phenomena are included by applying the interband density matrix formalism in real-space representation, where the Coulomb singularity is treated exactly in the limits of the discretization. As we focus on electroabsorption modulators, a drift-diffusion model adequately approximates the transport properties. Here, quantum effects are considered by a quantum correction, the Bohm potential. The model is applied to investigate transport effects in InP-based waveguide electroabsorption modulators including strained lattices.