Non-Markovian gain of a quantum-well laser with many-body effects

The optical gain of a quantum-well laser is studied taking into account the valence-band mixing, non-Markovian relaxation, and the many-body effects. Plasma screening and excitonic effects are taken into account in the time-dependent Hartree-Fock approximation. Conventional gain spectra calculated with the Lorentzian line shape function show two erroneous phenomena: unnatural absorption region below the band-gap energy and mismatch of the transparency point in the gain spectra with the Fermi-level separation, the latter suggesting that the carriers and the photons are not in thermal (or quasi) equilibrium. It is shown that the non-Markovian gain model with many-body effects removes the two errors associated with the Lorentzian line shape function with the proper choice of the correlation time.