Analytical vs. Numerical Langevin Description of Noise in Small Lasers

We compare the analytical and numerical predictions of noise in nano- and microcavity lasers obtained from a rate equation model with stochastic Langevin noise. Strong discrepancies are found between the two approaches and these are critically analyzed and explained on the basis of general considerations and through the comparison to the numerical predictions of a Stochastic Laser Simulator. While the analytical calculations give reliable redictions, the numerical results are entirely incorrect thus unsuitable for predicting the dynamics and statistical properties of small lasers.