A novel mechanism for creating a periodic gain is presented which can be used in the design of complex‐coupled distributed feedback semiconductor lasers. A one‐dimensional longitudinal analysis shows that this gain‐coupling mechanism is characterized by negative differential coupling, which earlier reports have shown can offer the most significant reduction in the linewidth enhancement factor. A linewidth analysis predicts that the linewidth enhancement factor can be reduced by about a factor of 2 because of the negative differential coupling. ©1995 American Institute of Physics.