DEGRADATIONS IN GBIT/S DFB LASER TRANSMISSION-SYSTEMS DUE TO PHASE-TO-INTENSITY NOISE CONVERSION BY MULTIPLE REFLECTION POINTS

Severe system degradations and bit error rate floors are observed in Gbit/s fiber transmission systems due to the interferometric conversion of laser phase noise to intensity noise by multiple reflections from connectors and splices. Studies of penalties as a function of the magnitude and number of reflections indicate that fiber joints with guaranteed minimum return losses of better than 20 db may be required for high-speed direct detection systems as well as future coherent systems, even though optical isolators may be employed in such systems.