Gaussian approach for performance evaluation of optically preamplified receivers with arbitrary optical and electrical filters

A Gaussian approach (GA), which takes into account the influence of arbitrary optical and electrical filters, is proposed to analytically evaluate the performance of optically preamplified receivers. This GA also takes into account the effects of waveform distortion in the signal and in the signal-amplified spontaneous emission beat noise. Exact expressions for the mean and variance of the current at the decision circuit input are derived, which explicitly present the dependence on the optical and electrical filter transfer functions and take into account the presence or absence of a polariser. This GA is computationally much faster and simpler than more rigorous methods and the accuracy of its sensitivity estimates is investigated for different optical and electrical filters. It is shown that the GA predicts the optimal optical filter bandwidth very reasonably. Discrepancies below 1.2 dB are found between its sensitivity estimates and rigorous estimates. The assessment of the optical filter detuning impact on the receiver sensitivity is also investigated with this GA. Discrepancies less than 1 dB are found between the GA estimates and rigorous estimates. The GA sensitivity estimate´s accuracy is also investigated in the presence of intersymbol interference (ISI) and very accurate predictions are obtained by the GA for significant ISI