Effect of Nonlinearities on PMD

satnac.org.za

Intensity induced random varying birefringence leads to nonlinear polarization mode dispersion (PMD) in addition to linear PMD. In this article we investigate the effect of nonlinear PMD on a sideband channels with respect to centre wavelength. It is shown that if three or more channels are launched in the fibre such that the two sideband signals are aligned along the fast and the slow axis respectively, the nonlinear PMD due to change in power of the centre wavelength will affect the two signals differently. The effect will depend on how the State of polarization (SOP) of the centre wavelength are oriented with respect to the fibre axis. Generally we noticed that the sideband signals are little affect with nonlinear PMD if the centre wavelength power is coupled equally into the fibre axes. It was also shown that the nonlinear and linear PMD can be compensated for the effective PMD for each channel by tracking the SOPs of the sideband signals and applying the feedforward technique. The worst channel signal Degree of polarization (DOP) improved by more than 100%.

OSA Continuum

With the extension of the spectral exploitation of optical fibers beyond the Cband, accurate modeling and simulation of nonlinear interference (NLI) generation is of the utmost performance. Models and numerical simulation tools rely on the widely used Manakov equation (ME): however, this approach when considering also the effect of polarization mode dispersion (PMD) is formally valid only over a narrow optical bandwidth. In order to analyze the range of validity of the ME and its applicability to future wide-band systems, we present numerical simulations, showing the interplay between NLI generation and PMD over long dispersion-uncompensated optical links, using coherent polarization division multiplexing (PDM) quadrature amplitude modulation (QAM) formats. Using a Monte-Carlo analysis of different PMD realizations based on the coupled nonlinear Schrödinger equations, we show that PMD has a negligible effect on NLI generation, independently from the total system bandwidth. Based on this, we give strong numerical evidence that the ME can be safely used to estimate NLI generation well beyond its bandwidth of validity that is limited to the PMD coherence bandwidth.

Photonic Network Communications, 2003

Fiber polarization mode dispersion (PMD) is perhaps the most critical transmission impairment in optical networks at transmission rates of 10 Gb/s and higher. Since the bandwidth-distance product, or transparency,of the optical circuit is limited by PMD, the overall network design and cost may be significantly altered by the actual fiber PMD values. The paper has three objectives. First, an accurate model for evaluating the PMD effects is presented and verified experimentally. Second, the cost increase of WDM rings due to PMD in a number of design scenarios—first generation, single-hop,multi-hop, and multi-rate networks—is assessed. Third, the polynomial-time algorithm proposed in Cerutti et al. [1] is modified to provide sub-optimal solutions for the above WDM rings, taking into account the limited bandwidth-distance product imposed by PMD. Presented results reveal that at high transmission rates, the cost of the multi-hop ring is less affected by PMD than the costs of first generation and single-hop rings.

2002

Fiber polarization mode dispersion (PMD) is perhaps the most critical transmission impairment in optical networks at transmission rates of 10 Gb/s and higher. Since the bandwidth-distance product, or transparency,of the optical circuit is limited by PMD, the overall network design and cost may be signi®cantly altered by the actual ®ber PMD values.

Optics Communications, 2005

We experimentally demonstrate the enhanced suppression of nonlinearity-induced crosstalk using polarization-shiftkeying (PolSK) to guarantee constant optical power in a data stream. In a 40-km of LEAF link, PolSK has a 5 times lower nonlinearity-induced crosstalk level in a co-propagating channel with the channel spacing of 100 GHz than return-to-zero (RZ) modulation format. We reduce nonlinearity-induced power penalties by more than 4.6 dB compared with non-return-to-zero (NRZ), and 2.5 dB compared with RZ over the same fiber link at 10 Gbit/s.

IEEE/OSA Journal of Lightwave Technology, 2011

We present a new type of crosstalk in a polarizationmultiplexed ultrahigh-speed transmission caused by polarizationmode dispersion (PMD) in the presence of polarization-dependent loss (PDL). When PMD and PDL are both present, the orthogonality between two principal states of polarization (PSP) is reduced. As a result, crosstalk inevitably occurs between two polarizations and prevents the two channels from being separated completely during polarization demultiplexing. The system impact of these effects in a polarization-multiplexed terabit/s transmission is also demonstrated experimentally.

Journal of Lightwave Technology, 1998

Second-order polarization mode dispersion (PMD) is a major limitation to the transmission capabilities of analog systems and of high bit rate digital systems. Basically, the effect of second-order PMD is the same as that of chromatic dispersion. However, like all polarization effects in standard single-mode fibers, the effects of second-order PMD are stochastic, due to the random polarization mode coupling that occurs in such fibers. Hence, the effects of second-order PMD fluctuate with time. The purpose of this article is to present a description of the phenomenon and of its effects on analog and digital signals, to propose definitions, to discuss some orders of magnitudes and to present some numerical simulations and experimental results. Some general understanding of the phenomena of first-order PMD are assumed. The more mathematical developments are summarized in the Appendixes.

OFC/NFOEC Technical Digest. Optical Fiber Communication Conference, 2005., 2005

We investigate through simulations and experiments inter-channel nonlinear penalties in 2x10Gbit/s NRZ polarization-multiplexed transmission. We show that the inter-channel nonlinear penalties can be partially mitigated by polarization interleaved transmission of the polarization-multiplexed channels.

Modeling Aspects in Optical Metrology II, 2009

With the extension of the spectral exploitation of optical fibers beyond the Cband, accurate modeling and simulation of nonlinear interference (NLI) generation is of the utmost performance. Models and numerical simulation tools rely on the widely used Manakov equation (ME): however, this approach when also considering the effect of polarization mode dispersion (PMD) is formally valid only over a narrow optical bandwidth. In order to analyze the range of validity of the ME and its applicability to future wide-band systems, we present numerical simulations, showing the interplay between NLI generation and PMD over long dispersion-uncompensated optical links, using coherent polarization division multiplexing (PDM) quadrature amplitude modulation (QAM) formats. Using a Monte-Carlo analysis of different PMD realizations based on the coupled nonlinear Schrödinger equations, we show that PMD has a negligible effect on NLI generation, independently from the total system bandwidth. Based on this, we give strong numerical evidence that the ME can be safely used to estimate NLI generation well beyond its bandwidth of validity that is limited to the PMD coherence bandwidth.

satnac.org.za

We demonstrate both experimentally and by simulation nonlinearity-induced depolarization in wavelength-division multiplexing, in which the Stokes vector of each channel rotates around a space-invariant pivot by a time varying angle. The rotation depends on the total instantaneous optical power in the fibre, the angle between the pump and probe, and the channel spacing. These are identified by simulation as the key factors that determine the nonlinear-induced performance degradation on polarization mode dispersion compensators. They are validated by experiments.