Performance of DPSK Signals with Quadratic Phase Noise

Nonlinear phase noise induced by the interaction of fiber Kerr effect and amplifier noises is a quadratic function of the electric field. When the dependence between the additive Gaussian noise and the quadratic phase noise is taking into account, the joint statistics of quadratic phase noise and additive Gaussian noise is derived analytically. When the error probability for differential phase-shift keying (DPSK) signals is evaluated, depending on the number of fiber spans, the signal-to-noise ratio (SNR) penalty is increased by up to 0.23 dB due to the dependence between the Gaussian noise and the quadratic phase noise.Comment: 15 pages, 2 figure

Error Probability of DPSK Signals with Intrachannel Four-Wave-Mixing in Highly Dispersive Transmission Systems

A semi-analytical method evaluates the error probability of DPSK signals with intrachannel four-wave-mixing (IFWM) in a highly dispersive fiber link with strong pulse overlap. Depending on initial pulse width, the mean nonlinear phase shift of the system can be from 1 to 2 rad for signal-to-noise ratio (SNR) penalty less than 1 dB. An approximated empirical formula, valid for penalty less than 2 dB, uses the variance of the differential phase of the ghost pulses to estimate the penalty.Comment: 3 pages, 3 figure

Exact Model for Mode-Dependent Gains and Losses in Multimode Fiber

In the strong mode coupling regime, the model for mode-dependent gains and losses (collectively referred as MDL) of a multimode fiber is extended to the region with large MDL. The MDL is found to have the same statistical properties as the eigenvalues of the summation of two matrices. The first matrix is a random Gaussian matrix with standard deviation proportional to the accumulated MDL. The other matrix is a deterministic matrix with uniform eigenvalues proportional to the square of the accumulated MDL. The results are analytically correct for fibers with two or large number of modes, and also numerically verified for other cases.Comment: 7 pages, 2 figures, 2 table