Quantum-well nonlinear optical response, including valence-band mixing and Coulomb effects

In this paper a complete model to evalute the nonlinear optical response of a semiconductor quantum-well structure is presented. In these structures, excitonic effects are strong also at room temperature; they arise from Coulomb interaction between charged particles, and the corresponding many-body problem is treated in the framework of the second quantization approach, based on the total Hamiltonian of the interacting electron-hole plasma. Moreover Coulomb effects are included, together with a proper description of valence-band states, which accounts for heavy- and light-hole mixing through a variational technique. The computed optical responses, both for TE and TM polarized light, are evaluated by summing up the coupled contributions of the first two transitions; they show a satisfactory agreement with experimental results