A one-input two-output channel representation of single-mode fibers with PMD

Polarization mode dispersion (PMD) in single-mode fibers is one of the biggest challenges in the design of future high-speed optical communication networks. To mitigate the PMD-induced intersymbol interference (ISI), it has been shown that linear equalization is one of the appropriate approaches . The design of equalizers requires knowledge of the channel. In this paper, we describe a single-mode fiber with PMD as an equivalent baseband single-input two-output channel, which not only conveys an alternative view of the PMD effects on transmitted signals, but also provides explicit information for the design of a PMD compensator based on the technique of linear equalization. Furthermore, we for the first time relate the polarization dispersion vector up to second order to the PMD channel response. This is useful for the theoretical analysis and simulation study aiming at clarifying the system impacts of lower order PMD, such as the effects of depolarization and polarization-dependent chromatic dispersion.