Receiver analysis for gigabit-per-second non-regenerative optical fibre transmission systems: impact of phase-to-intensity noise conversion by chromatic dispersion

摘要

The interferometric conversion of laser phase noise to intensity noise by fibre chromatic dispersion is of major concern in long-span non-regenerative optical fibre transmission systems. In fact this noise limits the transmission distance in intensity modulation and direct detection (IM-DD) systems operating with external modulators, and may lead to large power penalties and bit-error-rate floors. We investigate the performance of direct detection optical receivers in the presence of phase-induced intensity noise (PIIN). The analysis assumes gaussian noise sources and yields a closed-form estimate of the receiver sensitivity; it allows an immediate physical insight and appreciation of the impact of laser linewidth, fibre dispersion and laser extinction ratio on system performance. Our theory also gives simple approximate (but accurate) expressions to evaluate the power penalty caused by PIIN for both PIN and APD receivers. The results clearly indicate that the penalty stemming from the PIIN is more pronounced when the laser source operates with a relatively high extinction ratio.