5-Gb/s performance of integrated light source consisting of lambda /4-shifted DFB laser and EA modulator with SI InP BH structure

The fabrication process and characteristics, including 5-Gb/s transmission, of an integrated light source consisting of a lambda /4-shifted distributed feedback laser and an electroabsorption (EA) modulator are discussed. By introducing a semi-insulating (SI) InP on the butt-joint region, both the large electrical isolation resistance (>10 M Omega ) between the laser and the modulator and a high optical coupling efficiency (>80%) between them are achieved. A typical threshold current was 50-70 mA, and single-mode operation at 1.576 mu m was maintained up to 5.5-mW output power. The modulation voltage to swing between 90% transmission and 10% transmission was 6.2-12 V, depending on the modulator length in the range 1000-400 mu m. The 3-dB bandwidth is 7.7 GHz and a linewidth enhancement factor ( alpha ) of 0.9 is estimated from the sideband-to-carrier ratio of the spectra.<
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