The effect of reflections on the system performance of intensity modulated laser diodes

The performance degradation incurred by unwanted external reflections in high-speed digital optical communication systems using intensity-modulated single-longitudinal-mode laser diodes is investigated by numerical simulation of the rate equations. The effects of intensity modulation on the chaotic behavior in the laser output are examined and performance estimates for 0.5, 2.5, and 5 Gb/s systems are made. For example, it is found that to incur less than 0.25-dB power penalty in a 2.5-Gb/s system using a positive-intrinsic-negative photodetector, the reflected light in the laser pigtail should be at least 36 dB below that of the transmitted light.< >