Interaction of Polarization Mode Dispersion and Nonlinearity in Optical Fiber Transmission Systems

Abstract—Aspects of the interaction of the Kerr nonlinearity and polarization mode dispersion (PMD) are reviewed. The basic equation that governs this interaction on the length scale of inter-est in optical fiber communications systems is the Manakov-PMD equation. This equation is derived using multiple-length-scale techniques. The focus of the derivation is the elucidation of com-mon misunderstandings and pitfalls rather than mathematical rigor. It is shown that the scalar nonlinear Schrödinger equation is valid when PMD is absent and the signal is initially in a single polarization state. Two examples are then presented that illustrate the complexity of the interaction between nonlinearity and PMD. The first example considers the interaction of a nonlinearly in-duced chirp with PMD. As the power increases, one can obtain an improved eye opening relative to the case when PMD is absent. The second example considers the effect of nonlinear polariza-tion rotation in a wavelength-division-multiplexed system. When nonlinear polarization rotation is important, the principal states of polarization become time dependent and PMD compensation becomes ineffective. This problem can be mitigated through the use of line codes. Index Terms—Kerr nonlinearity, Manakov-polarization mode dispersion (PMD) equation, optical fiber transmission, PMD