Reduction in reflection-induced chirp from photonic integrated sources

Previously electroabsorption modulated lasers (EMLs) have been demonstrated using source lasers with grating strengths of two or less (k/sub r/L /spl les/ 2.0). Spatial holeburning was believed to limit the magnitude of the optimal grating strength. However, those standard-grating-strength lasers are sensitive to reflections from modulator output facet, integrated amplifiers, combiners, fiber tip, etc. and are a barrier to making integrated modules for long-span transmission. EMLs having record-strength (K/sub r/L > 6) gratings are fabricated. Output power >9.5 dBm, sidemode suppression ratio beyond 50 dB, single-mode yield >60% at high power, and power penalty <0.3 dB at 10 Gb/s for 75 km of fiber are demonstrated.