ANALYSIS OF DISTRIBUTED FEEDBACK SEMICONDUCTOR-LASERS BY 2-DIMENSIONAL THEORY

Two-dimensional theory of distributed feedback (DFB) lasers to take account of the planar waveguide structure, which was presented in a previous paper, is applied to the analysis of the DFB laser threshold conditions with respect to the effects of the waveguide structure and the facet reflection. The asymmetric properties of the transverse functions of the coupled modes with respect to the Bragg frequency in the dispersion relations are found to be enhanced by the asymmetric index waveguide structure and by the asymmetric facet reflectivity. Therefore, the resulting confinement factor differences in the grating layer between the two adjacent lasing modes on both sides of the Bragg frequency give large threshold gain differences. We propose a new design concept of the waveguide for realizing DFB lasers with single-mode operation independent of the corrugation phase at the reflective facet. © 1990 IEEE