Linewidth enhancement factor and nonlinear gain in ZnSe semiconductor lasers

We have investigated the effects of the Coulomb interaction on the optical gain and the refractive index of ZnSe semiconductor lasers. The Coulomb interaction increases the differential gain, leading to a decrease of the threshold carrier density. Its influence on the linewidth enhancement factor and the nonlinear gain coefficient is relatively small because it increases both the gain and the refractive index simultaneously. We have compared the linewidth enhancement factor alpha and the nonlinear gain coefficient epsilon for ZnSe and GaAs lasers with the effects of the Coulomb interaction taken into account. For typical values of total cavity losses, the values of alpha and epsilon are higher for ZnSe lasers compared with GaAs lasers.