Effects of phase-to-intensity noise conversion by multiple reflections on gigabit-per-second DFB laser transmission systems

Large power penalties and bit-error-rate floors have been observed in some Gb/s systems using distributed feedback (DFB) lasers, which could be attributed to interferometric conversion of laser phase noise to intensity noise by multiple reflections at connectors and splices. The authors calculated the power spectral density of the interferometric noise and its impact on system performance as a function of both the magnitude and number of reflections, and they compare the theoretical predictions with experimental results. Their studies indicate that connectors and splices with return losses of more than about 25 dB are required for the reliable operation of Gb/s fiber transmission systems, even if optical isolators are used.<
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