Non-Markovian gain of strained-layer quantum well lasers with many-body effects

A non-Markovian model for the optical gain of strained-layer quantum-well lasers is studied taking into account the valence-band mixing, strain effects, many-body effects and the non-Markovian relaxation using the time-convolutionless reduced-density operator formalism for an arbitrary driven system coupled to a stochastic reservoir. Many-bode effects are taken into account within the time-dependent Hartree- Fock approximation and the valence-band structure is calculated from the 6 X 6 Luttinger-Kohn Hamiltonian. The optical gain with Coulomb (or excitonic) enhancement is derived by integrating the equation of motion for the interband polarization. It is predicted that the Coulomb enhancement of gain is pronounced in the cases of compressive and unstrained quantum wells while it is negligible in the case of tensile strained quantum well.