An 8 Gbit/s-76 km transmission experiment using a distributed feedback laser at 1.3 μm wavelength

An 8 Gb/s optical transmission experiment was conducted over an unrepeater distance of 76 km. The transmitter used direct modulation of a high-power distributed-feedback laser at a wavelength of 1.3 μm, and the receiver used a high-speed InGaAs avalanche photodiode and a GaAs FET preamplifier. An error rate of 1×10^-10 was obtained at a received power level of -21.8 dBm. Because of operation close to the fiber zero dispersion wavelength, no dispersion penalty from laser chirp was observed. The relatively high laser power obtained (+6.7 dBm coupled into the fiber) helped to overcome the fiber loss, allowing a long unrepeatered distance to be achieved. The experiment demonstrates that long-distance 1.3-μm transmission at multigigabit-per-second rates over conventional fiber is a feasible option for future lightwave systems