Influence of inhomogeneous injection on sidemode suppression in strongly coupled DFB semiconductor lasers

A longitudinally nonuniform injection counteracting the spatial hole burning in quarter-wavelength shifted DFB semiconductor lasers with strong coupling has been obtained from a quasi-three-dimensional model. This effect enlarges with falling series resistances. It substantially lowers the degradation of sidemode suppression compared with former models that assume homogeneous injection.