In high-speed long-haul optical transport systems with channel data rates at 40 Gb/s and beyond, polarization mode dispersion (PMD) is one of the major obstacles that limits system performance. It is desired or in most cases required to increase the system tolerance to PMD through PMD compensation and mitigation. In this paper, we review the techniques of PMD compensation and mitigation, including per-channel based optical PMD compensators (PMDCs), analog and digital electronic PMDCs, and all-channel PMD mitigation using distributed fast polarization scrambling and forward error correction (FEC). With the emergence of digital coherent detection, the signal optical field becomes digitally available, enabling powerful digital PMDC techniques to be applied. Digital PMDC techniques in optical single carrier coherent systems and orthogonal frequency division multiplexing (OFDM) systems are briefly reviewed. © 2009 Alcatel-Lucent.
optical and electrical compensation techniques that apply optical signal processing within an optical PMD compensator (PMDC) unit or post-detection electronic signal processing of the photodiode signal by an electronic equalizer within the receiver.
In this paper, we review the advances in optical and electronic technologies for PMD mitigation. We first briefly analyze the impact of installed fiber PMD on a transmission system and how to quantify it. The principle and structure of optical PMDCs are described next. The impact of modulation formats on the design of optical PMDCs as well as the performance of a twostage optical PMDC for 40 Gb/s non-return-to-zero differential phase shift keying (NRZ-DPSK) will be discussed. We follow with a discussion of electronic equalizers, which process the electrical signal provided