LAMBDA-4-SHIFTED DFB LASER ELECTROABSORPTION MODULATOR INTEGRATED LIGHT-SOURCE FOR MULTIGIGABIT TRANSMISSION

High-speed, low-chirp, and low voltage driving characteristics of 1.55-mu-m-lambda/4-shifted DFB laser/InGaAsP electroabsorption modulator integrated light sources have been reported. By optimization of the composition and thickness of the modulator waveguide, the driving voltage for a 10-dB extinction ratio was reduced to 1.4-3V, depending on the modulator length in the range of 240-125-mu-m. High-speed modulation up to 10-Gb/s NRZ modulation was achieved by the integrated device with a 125-mu-m modulator length. The linewidth enhancement factor-alpha of the integrated modulator was estimated to be 0.15-0.48. A 2.4-Gb/s-135-km conventional fiber transmission using the integrated light source driven by less than 1V(p-p) was achieved with no power penalty. The first successful conventional fiber transmission over 100 km at 5 Gb/s using the integrated light source was also demonstrated.