An accurate rate-equation description for DFB lasers and some interesting solutions

Abstract—Starting from the coupled-wave equations, we have derived an alternative set of rate equations which are valid for most single-section distributed feedback (DFB) lasers. These rate equations are in many respects more useful than the conventional rate equations and have also been used to derive the influence of spatial hole burning on characteristics such as the chirp, the linewidth, or the harmonic distortion. Numerical results are presented for a DFB laser with both facets cleaved, AR-coated, and for a =4-shifted DFB laser. Index Terms — Distributed feedback lasers, harmonic distor-tion, modulation. I