Influence of standing waves on DFB lasers including saturable absorptive gratings

The influence of standing waves on the performance of distributed feedback (DFB) lasers is investigated, whereby local changes of the wavenumber as induced by gain compression or inhomogeneous saturation of an absorptive grating are incorporated into the coupled wave equations. With the help of this model, it is shown that gain compression ultimatively limits the maximum output power for monomode operation. As compared to in-phase complex-coupled lasers, it is shown that the worse monomode capability of antiphase complex-coupled lasers is related to the better stability properties of these lasers. Additionally, a characteristic interaction between the saturable absorptive grating and the optical field is found, which furthermore reduces the maximum monomode output power of antiphase complex-coupled lasers with saturable absorptive gratings.