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 distributed-feedback (DFB) laser/InGaAsP electroabsorption modulator integrated light sources are reported. By optimization of the composition and thickness of the modulator waveguide, the driving voltage for a 10-dB extinction ratio was reduced to 1.4-3 V, 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 of the integrated modulator was estimated to be 0.15-0.48.<
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