Computer simulation of laser photon fluctuations: DFB Lasers.

This fourth paper of the series is devoted to photon fluctuations in the light output of distributed feedback (DFB) lasers. Statistics on laser photon fluctuations are collected from numerical solutions of noise driven rate equations. The approximate formula for the variance of the photon fluctuations, presented earlier, is also applicable to the DFB laser. In addition we present in this paper a formula for the variance of the electron fluctuations which can be used to predict refractive index fluctuations of the laser material that can cause random frequency modulation and hence excess spectral broadening of the laser output.