Publisher Summary Polarization mode dispersion (PMD) is a linear effect that can be compensated in principle. In an ideal circularly symmetric fiber, the two orthogonally polarized modes have the same group delay. However, in reality, fibers exhibit a certain amount of birefringence because of imperfections in the manufacturing process or mechanical stress on the fiber after manufacture. It is noted that fluctuations in the polarization mode and fiber birefringence produced by the environment lead to dispersion that varies statistically with time and frequency. PMD causes different delays for different polarizations and when the difference in the delays approaches a significant fraction of the bit period, it leads to pulse distortion and system penalties. Environmental changes— including temperature and stress—cause the fiber PMD to vary stochastically in time. PMD, illustrating the basic concepts, the measurement techniques, the PMD measurement, the PMD statistics for first- and higher orders, the PMD simulation and emulation, the system impairments, and the mitigation methods has been summarized in the chapter. Both the optical and the electrical PMD compensations are considered.

Polarization-Mode Dispersion

We show, using simulations, that a combination of orthogonal frequency division multiplexing (OFDM) and optical single sideband modulation can be used to compensate for chromatic dispersion in ultralong-haul wavelength-division multiplexed (WDM) systems. OFDM provides a high spectral efficiency, does not require a reverse feedback path for compensation, and has a better sensitivity than nonreturn to zero. This paper provides design rules for 800-4000-km optical-OFDM systems. The effects of WDM channel number and spacing, fiber dispersion, and input power per channel on the received Q are studied using extensive numerical simulations. These effects are summarized as a set of design rules

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Performance of Optical OFDM in Ultralong-Haul WDM Lightwave Systems

We review recent research related to polarization mode dispersion (PMD) in fiber-optic transmission systems operating at 40 Gb/s and above. We investigate the benefits of using different passive techniques for mitigating the effects of PMD, including more advantageous data formats compared to the conventional nonreturn-to-zero (NRZ) format, soliton transmission, and forward error correction (FEC). We also compare a number of active pre- and posttransmission compensators.

Polarization-mode dispersion in high-speed fiber-optic transmission systems

Adaptive polarization-mode dispersion (PMD) compensation in 10 and 40 Gb/s transmission systems might become necessary if the link PMD causes strong signal distortions, which results in an unacceptable high system outage. The application of PMD compensation has the potential to lead to a drastic improvement of system robustness. Optical and electrical compensators will be reported, their operation principle explained, and their benefits will be quantified. The discussion is focused on the most important structures for practical system application including adaptive feedback loops. Experimental investigations proof compensator concepts which performance conforms with simulations. The electronical feed forward equalizer and the decision feedback equalizer are assessed in comparison to the optical simple and the two-stage compensator and the differences in performance are discussed for statistical PMD limited systems.

Adaptive PMD compensation by electrical and optical techniques

The 25 years since the founding of the Journal of Lightwave Technology have seen more than three orders of magnitude increase in the capacity of optical transmission systems. This dramatic increase was brought about by the deployment of WDM and advances in high-speed transmission technologies.

High-Capacity Optical Transmission Systems

A reduced model to describe self-phase modulation (SPM)-limited fiber transmission in dispersion-managed lightwave systems is presented. By introducing a new figure of merit, the maximum transmission distance versus optical power can be determined without any numerical simulation. Together with simplified models for other nonlinear fiber effects, a useful set of design rules for a first-order performance estimation of wavelength-division multiplexed (WDM) systems is established.

Reduced model to describe SPM-limited fiber transmission in dispersion-managed lightwave systems

Polarisation mode dispersion (PMD) in existing fibres impairs transmission at /spl ges/10 Gbit/s. A 43 ps PMD compensator in X-cut, Y-propagation Ti:LiNbO/sub 3/ with cascaded TE-TM converters is presented and successful operation at 20 Gbit/s demonstrated.

Integrated optical LiNbO3 distributed polarisation mode dispersion compensator in 20 Gbit/s transmission system

Using the distributed under-compensation scheme (DUCS) in every fibre span, the overall transmission distance of 10 Gbit/s NRZ and RZ multiple span systems is doubled The benefits of such a dispersion management scheme are clarified by defining a new figure of merit

http://ieeexplore.ieee.org/iel5/2220/17582/00810028.pdf

Optimised dispersion management scheme for long-haul optical communication systems

With a new simple model for stimulated Raman scattering crosstalk and an 30 dBm system experiment we found that the shortest and longest wavelength channels are affected most by SRS crosstalk independent of the preemphasis.

SRS crosstalk in preemphasized WDM systems

The performance of concatenated codes are improved by generating check bits from information bits, which are represented by an information matrix, by an outer code. The information bits and the check bits are cyclically shifted to obtain an interleaved code matrix. Then, the bits of the interleaved code matrix are coded by an inner code, where at least the outer code, or the inner code, is a product code.

Andreas Färbert

Papers

Reduced model to describe SPM-limited fiber transmission in dispersion-managed lightwave systems

Integrated optical LiNbO3 distributed polarisation mode dispersion compensator in 20 Gbit/s transmission system

Optimised dispersion management scheme for long-haul optical communication systems

SRS crosstalk in preemphasized WDM systems

Method and apparatus for improving the performance of concatenated codes