Microscopic theory for interband and intersubband optical responses of quantum well laser media

This work analyzes the influence of Coulomb effects with increasing degree of complexity, starting with the Hartree-Fock limit, and evolving to the screened Hartree-Fock case and further on to beyond Hartree-Fock corrections, including non-diagonal dephasing contributions to both interband and intersubband transitions. Electron-electron, hole-hole and electron-hole transitions, correlation and scattering mechanisms are systematically included in our many body Greens functions formalism that consistently includes the nonparabolic electron and hole dispersion relations as well as independent transition dipole elements obtained from a rigorous solution of an 8 × 8 k.p Hamiltonian. The carrier-induced absorption/gain coefficient and refractive index change are directly calculated from the imaginary, χ" and real, χ' parts of the optical susceptibility function.