Effects of electron-hole Coulomb interaction in semiconductor lasers

The role of electron-hole Coulomb interactions in a semiconductor active medium operating in experimental conditions typically found in semiconductor lasers and their effect on the linewidth enhancement (or index antiguiding) factor were investigated. It was found that bandgap renormalization and Coulomb enhancement in the presence of plasma screening result in a 20-30% change in the calculated local gain and a slightly smaller correction to the carrier-induced refractive index. In particular, a Coulomb enhancement factor was defined as the ratio of the value of a quantity with Coulomb enhancement to that of one without. Plots of this ratio for gain differed from those for index, indicating that the effects of Coulomb enhancement cannot be accounted for simply by changing the dipole matrix element. These effects also lead to significant modifications of the values and functional dependence of the linewidth enhancement factor.