Gain suppression in semiconductor lasers: The influence of dynamic carrier temperature changes

An analytic expression for the gain suppression coefficient of semiconductor laser in terms of carrier temperature and other material parameters is presented. The expression is derived from a density matrix formulation of gain in diode lasers based on a dynamic carrier heating model. We find that in the single mode approximation the theoretical estimate of the gain suppression coefficient is of the order 10−23 m3 in agreement with experimental values. This supports recent direct experimental demonstrations that dynamic carrier heating, rather than spectral hole burning provides the dominant contribution to nonlinear gain in semiconductor lasers.