Influence of modulation bit rate of semiconductor lasers on performance of optical communication systems

This paper reports on evaluation of the performance of optical fiber communication systems employing semiconductor lasers subjected to high-speed digital modulation. The evaluation is achieved in terms of the bit error rate and its dependence on the transmission bit rate. The study is based on numerical large-signal analysis of the laser rate equations and counting noise mechanisms in the receiver. Correlation between the bit error rate and the signal-quality factor is presented. The results show that under high speed modulation, the pseudorandom bit-pattern induces enhanced influence of laser noise to the bit error rate. Under low-speed modulation, contribution of laser noise to the bit error rate is mainly due to the intrinsic fluctuations in the "1" and "0" levels.