Many-particle effects on the linewidth broadening factor in semiconductor lasers

The linewidth-broadening factor for GaAs under various excitation conditions is computed using an accurate and consistent model of radiative recombination. The results indicate that noticeable contributions to the linewidth can be attributed to many-body effects. It is shown that to obtain gain spectra which possess the salient features of k nonconservation and therefore resemble experimental data, both broadened electron and hole propagators and vertex corrections must be included in the formalism. The alpha factor for different excess carrier concentrations is determined to a reasonable degree of accuracy, although the use of Monte Carlo integration generates a small random error. It is found that while the qualitative behavior of the alpha factor as a function of energy and carrier density is fixed by the general shape of the gain spectrum, the quantitative predictions are somewhat smaller and more slowly varying than those of the one-particle model