Abstract: We report numerical results for the above-threshold spectral properties of circular-grating distributed-feedback semiconductor lasers. Our model includes a radially-varying gain and index saturation, as well as a uniformly- distributed grating loss, in the solution of the coupled- mode equations. Our results show a multi-mode spectrum for large coupling strengths, a consequence of mode competition induced by the spatially-varying gain distribution associated with the grating losses. We also find that a single-mode spectrum is possible over a limited power range. !10
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