COMPLETE STATISTICAL CHARACTERIZATION OF SIGNAL AND NOISE IN OPTICALLY AMPLIFIED FIBER CHANNELS

A very simple model is found for phase insensitive laser amplification , Signal and noise along the active fiber are modeled as marked Poisso n processes (corresponding to flows of photon bunches of random size) and are dealt with as independent processes, A probabilistic approach, founded on the theory of birth-and-death processes, enables us to giv e a simple characterization of the amplifier in terms of the statistic s of the random gain, of the time intensity of the ASE (amplified spon taneous emission) noise bunches, and finally of the statistics of thei r sizes. The theory is limited to the linear amplification range, whil e is valid also for nonhomogeneous inversion along the active fiber. T he model can be easily applied for the evaluation of the statistics of the global gain and of the accumulated ASE noise in optically amplifi ed links.