Intraband relaxation time effects on non-Markovian gain with many-body effects and comparison with experiment

Momentum-dependent and independent intraband relaxation time effects on a non-Markovian (Gaussian line shape) many-body optical gain spectrum are presented. Our theoretical results are compared with experimental data as well as those obtained from a many-body gain model with a conventional Lorentzian line shape function. We show that a Gaussian line shape gain model with a constant intraband relaxation time gives good agreement with experimental gain spectra and the inclusion of k-dependent intraband relaxation time yields slightly improved agreement. In the case of a Lorentzian line shape function, it is found that the inclusion of the k-dependent carrier-carrier scattering in the intraband relaxation time is important to obtain good agreement with the experiment. This is because the Gaussian line shape function is steeper than the Lorentzian for a constant intraband relaxation time. The Gaussian line shape function with a constant intraband relaxation time requires less computational time than that with a k-dependent intraband relaxation time; therefore, it is an efficient model for comparison with experimental data.