OPTICAL GAIN OF A QUANTUM-WELL LASER WITH NON-MARKOVIAN RELAXATION AND MANY-BODY EFFECTS

In this article, a theoretical description of the optical gain of a qu antum-well laser is developed taking into account non-Markovian relaxa tion and many-body effects. Single-particle energies are calculated us ing the multiband effective mass theory, and the valence-band mixing i ncluding the spin-orbit (SO) split-off band coupling is considered in the formulation. The Coulomb enhancement and the band-gap renormalizat ion are also considered within the Hartree-Fock approximation. The gai n spectra calculated with the Lorentzian line shape function show two anomalous phenomena: unnatural absorption region below the band-gap en ergy and mismatch of the transparency point in the gain spectra with t he Fermi-level separation, the latter suggesting that the carriers and the photons are not in thermal (or quasi-) equilibrium. It is shown t hat the non-Markovian gain model with many-body effects removes the tw o anomalies associated with the Lorentzian line shape function. It is also found that the optical gain spectra depend strongly on the correl ation time of the system which can be determined by the intraband freq uency fluctuations.