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IEEE Photonics Technology Letters 05/2007; · 2.19 Impact Factor
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ABSTRACT: Polarization mode dispersion (PMD), a potentially limiting impairment in high-speed long-distance fiber-optic communication systems, refers to the distortion of propagating optical pulses due to random birefringences in an optical system. Because these perturbations (which can be introduced through manufacturing imperfections, cabling stresses, installation procedures, and environmental sensitivities of fiber and other in-line components) are unknowable and continually changing, PMD is unique among optical impairments. This makes PMD both a fascinating research subject and potentially one of the most challenging technical obstacles for future optoelectronic transmission. Mitigation and compensation techniques, proper emulation, and accurate prediction of PMD-induced outage probabilities critically depend on the understanding and modeling of the statistics of PMD in installed links. Using extensive data on buried fibers used in long-haul high-speed links, the authors discuss the proposition that most of the temporal PMD changes that are observed in installed routes arise primarily from a relatively small number of "hot spots" along the route that are exposed to the ambient environment, whereas the buried shielded sections remain largely stable for month-long time periods. It follows that the temporal variations of the differential group delay for any given channel constitute a distinct statistical distribution with its own channel-specific mean value. The impact of these observations on outage statistics is analyzed, and the implications for future optoelectronic fiber-based transmission are discussed
Journal of Lightwave Technology 01/2007; 24(12):4584-4599. · 2.78 Impact Factor
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ABSTRACT: We derive an engineering methodology and study the impact of polarization-dependent gain (PDG) on the design of cascaded semiconductor optical amplifier (SOA)-based coarse wavelength-division-multiplexing systems. System specifications can be determined based on receiver optical signal-to-noise ratio (OSNR) requirements and cascaded-SOA OSNR penalty calculations that include a simplified model to calculate PDG statistics
IEEE Photonics Technology Letters 11/2006; · 2.19 Impact Factor
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ABSTRACT: We demonstrate the cascading of broad-band semiconductor optical amplifier-Raman hybrid amplifiers which provide nearly flat gain over 70 nm. A coarse-wavelength-division-multiplexing transmission system consisting of three spans of 80 km shows uniform performance and <1-dB power penalty.
IEEE Photonics Technology Letters 02/2006; · 2.19 Impact Factor
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ABSTRACT: This study monitors the polarization activity of operating light wave systems in urban and suburban areas. In 6 months of observation, multiple fast polarization fluctuations are detected, which are, however, not expected to trigger protection, or to affect performance of slower polarization mode dispersion (PMD) mitigating devices.
Lasers and Electro-Optics Society, 2005. LEOS 2005. The 18th Annual Meeting of the IEEE; 11/2005
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ABSTRACT: We study polarization rotations by a dispersion compensation module responding to quasi-periodic room temperature oscillations. The rotations seems to have a functional temperature dependence on short time scales interrupted by rather abrupt shifts occurring, on average, every month.
Optical Communication, 2005. ECOC 2005. 31st European Conference on; 10/2005
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ABSTRACT: We experimentally investigate the polarization-mode dispersion (PMD)-induced system penalty arising from first-order and all-order PMD. We use a measurable quantity, "string" length, to parameterize the penalty, find a deterministic correction to the accepted first-order PMD-induced system penalty approximation, and discuss the implications for system outages. Further, we show that higher orders of PMD introduce an additional penalty scatter that is nearly independent of "string" length, and correlated to the magnitude of the second-order PMD vector.
IEEE Photonics Technology Letters 09/2005; · 2.19 Impact Factor
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ABSTRACT: Using vectorially resolved launch SOP, we show that high order PMD, present in real fibers, introduces a deterministic correction to the accepted first-order system penalty, and an additional uniformly distributed scatter, uncorrelated to the second order PMD vector.
Optical Fiber Communication Conference, 2005. Technical Digest. OFC/NFOEC; 04/2005
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ABSTRACT: We report a 60 nm bandwidth SOA (semiconductor optical amplifier)-Raman hybrid amplifier for CWDM systems in which the Raman section increases overall system gain and reduces SOA gain tilt. The amplifier module is used in a 4-channel, 200-km CWDM transmission experiment.
Optical Fiber Communication Conference, 2005. Technical Digest. OFC/NFOEC; 04/2005
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ABSTRACT: We numerically study polarization-mode dispersion in fiber routes with a finite number of degrees of freedom, show that individual channels in such systems exhibit a non-Maxwellian differential group delay distribution, and analyze the resulting statistics of outage probabilities. We show that a significant number of channels in such systems will be outage-free for long time periods.
IEEE Photonics Technology Letters 03/2005; · 2.19 Impact Factor
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ABSTRACT: PMD for installed systems is well-described as a few static sections connected by dynamic polarization rotators, leading to different (i.e., non-Maxwellian) statistics than the conventional model. This has implications for spectral/temporal dynamics and outage probabilities.
Lasers and Electro-Optics Society, 2004. LEOS 2004. The 17th Annual Meeting of the IEEE; 12/2004
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ABSTRACT: We introduce frequency-resolved in-situ measurements of the output state-of-polarization 'strings' of an optical signal in operating 10 Gb/s channels, and show they permit estimation of the PMD-induced eye penalty, but, paradoxically, not the PMD vector itself.
Lasers and Electro-Optics Society, 2004. LEOS 2004. The 17th Annual Meeting of the IEEE; 12/2004
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ABSTRACT: This paper describes "virtual common space", an access architecture that uses inexpensive "coarse" wavelength-division-multiplexing (CWDM) technology to extend the advantages of wavelength-division multiplexing (WDM) to business access applications. This new approach suggests new operations and diagnostic requirements. A wavelength-selective optical time-domain reflectometer using CWDM sources is demonstrated for such procedures. Some of the potential impairments that could arise from in-service monitoring on these systems are quantified.
Journal of Lightwave Technology 12/2004; 22(11):2641- 2652. · 2.78 Impact Factor
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IEEE Photonics Technology Letters 11/2004; · 2.19 Impact Factor
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ABSTRACT: Fiber to the home in the U.S. market has not been deployed as rapidly as many had hoped or predicted. We examine some of the historical, competitive, and economic reasons for this. We argue that, from a competitive service perspective, it may be difficult to construct compelling business cases for large-scale deployment without either a technical need for fiber, or significant changes in either public policy or industrial organization.
IEEE Communications Magazine 09/2004; · 3.79 Impact Factor
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ABSTRACT: We demonstrate that traffic-bearing signals in coarse wavelength-division-multiplexing systems can limit in-service optical time-domain reflectometry sensitivity on presumably "dark" channels being monitored. This effect is due to spontaneous Stokes and anti-Stokes Raman scattering into the wide spectral bands.
IEEE Photonics Technology Letters 08/2004; · 2.19 Impact Factor
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ABSTRACT: In-service optical time-domain reflectometer measurements will simplify turn-on and fault location procedures for coarse wavelength-division-multiplexing optical network deployments. We describe adverse effects to these measurements due to discretely reflected and Rayleigh backscattered live traffic and discuss implications for multiplexer isolation specifications.
IEEE Photonics Technology Letters 08/2004; · 2.19 Impact Factor
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ABSTRACT: The authors propose a novel technique to improve accuracy in measurements of the mean differential group delay (DGD) of optical fiber. Using the statistics of the second-order polarization-mode dispersion and averaging properly, they find a 30% reduction in measurement uncertainty, which is equivalent to doubling the measurement's optical bandwidth. The authors motivate the necessity for proper averaging by first demonstrating that the conventional conversions of "mean-square" to "mean" DGD lead to (correctable) systematic errors for finite bandwidth measurements.
IEEE Photonics Technology Letters 04/2004; · 2.19 Impact Factor
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ABSTRACT: We performed long-term differential group delay (DGD) measurements on multiple installed fiber spans. Unexpectedly, the statistical distributions of these measurements deviate strongly from existing theory. We offer evidence that analysis of measurement statistics themselves can indicate their validity.
Optical Fiber Communication Conference, 2004. OFC 2004; 03/2004
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ABSTRACT: We propose and demonstrate a method for serving multiple independent "fiber-to-the-floor" customers in large buildings by using emerging CWDM equipment. We demonstrate installation and in-service testing techniques using CWDM OTDR, evaluating "signal-to-OTDR" and "OTDR-to-signal" impairments.
Optical Fiber Communication Conference, 2004. OFC 2004; 03/2004
