The effect of semiconductor laser intensity fluctuations on the performance of lightwave transmission systems

The performance of a high-bit-rate lightwave transmission system which uses a dc-operated semiconductor laser with external modulation may be affected by intrinsic intensity fluctuations in the laser output. The effect of such random variations in the transmitted optical pulse stream on the average probability of error is determined. The results indicate that while the effect of the intensity fluctuations is strongly influenced by the average gain of the photodetector, these random variations are not a serious source of transmission errors at a bit rate of 8 Gbit/s.