Multi-path interference in optically pre-amplified lightwave systems

Limitations on optical pre-amplifier performance in presence of crosstalk are due to the combination phase-noise induced intensity noise and crosstalk-spontaneous beat noise during “zeros” and not phase-noise induced intensity noise on “ones”. In this paper, we investigate the power penalties originating from multi-path interference in systems with optically preamplified receivers. At moderate crosstalk levels interference of a “one” with a “one” cause the majority of the errors, analogous to the case of PIN and APD receivers. However, beating between crosstalk and ASE as well as the degradation of extinction ratio lead to increased error levels from “zeros” experiencing crosstalk from “ones” at high levels of multi-path interference