Bit-error rate of lightwave systems at the zero-dispersion wavelength

The author derives approximate expressions for the bit-error rate of very long lightwave systems with optical amplifiers that are operated at the zero-dispersion wavelength. In this case, the nonlinear interaction of the signal wave with the spontaneous emission noise of the amplifiers corrupts the signal. Its spectrum broadens by several orders of magnitude, and the instantaneous optical power assumes the appearance of bandlimited thermal or spontaneous emission noise. This observation suggests that the bit-error rate should be computed under the assumption that the optical signal and the optical spontaneous emission noise obey Gaussian statistics. The approximate expressions for the bit-error rate are derived under this assumption. The formulas are written in such a way that the signal and the noise may be either completely polarized or completely unpolarized