QUANTUM-WELL NONLINEAR-OPTICAL RESPONSE, INCLUDING VALENCE-BAND MIXING AND COULOMB EFFECTS

In this paper a complete model to evalute the nonlinear optical respon se of a semiconductor quantum-well structure is presented. In these st ructures, excitonic effects are strong also at room temperature; they arise from coulomb interaction between charged particles, and the corr esponding many-body problem is treated in the framework of the second quantization approach, based on the total Hamiltonian of the interacti ng electron-hole plasma. Moreover Coulomb effects are included, togeth er with a proper description of valence-band states, which accounts fo r heavy- and light-hole mixing through a variational technique. The co mputed optical responses, both for TE and TM polarized light, are eval uated by summing up the coupled contributions of the first two transit ions; they show a satisfactory agreement with experimental results.