1.53 mu m InGaAsP-InP first-order lambda /4-shifted distributed feedback lasers with high coupling coefficients

The authors report on the performance of distributed feedback lasers, revealing coupling coefficients as high as 330 cm/sup -1/. No mode hopping is observed, stable single-mode operation at a high sidemode suppression ratio up to 51.2 dB is obtained, and the linewidths are linear with increasing reciprocal output power. Well-open eyes and no bit-pattern effects are observed in 5 and 8 GB/s nonreturn to zero modulations. In addition, high coupling is found to have several important advantages, e.g. lower feedback sensitivity, lower threshold gain for the Bragg mode, lower relative intensity noise, and lower influence on the facet reflectivity and n the end-facet phase, resulting in a higher yield of single-mode lasers for arbitrary cleaved facets.>