Theory of optical-waveguide distributed lasers with nonuniform gain and coupling

Abstract

Coupled‐mode theory is applied to distributed feedback lasers having step variations in the longitudinal distributions of both the gain and the coupling. Threshold solutions for the required laser gain and the longitudinal mode spectra are presented for the modified geometries. Numerical computations show that these modifications on the uniform structures considered heretofore allow for optimization of the laser characteristics such as lowering the threshold gains and providing controllable higher‐order‐mode rejection, as well as unidirectional operation.