With joint contributions from academia and industry, this special issue provides a balanced overview of the area of fiber-optic network capacity scaling.
Advanced optical modulation formats have become a key ingredient to the design of modern wavelength-division-multiplexed (WDM) optically routed networks. In this paper, we review the generation and ...detection of multigigabit/second intensity- and phase-modulated formats and highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, chromatic dispersion, polarization-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity
Based on a variety of long-term network traffic data from different geographies and applications, in addition to long-term scaling trends of key information and communication technologies, we ...identify fundamental scaling disparities between the technologies used to generate and process data and those used to transport data. These disparities could lead to the data transport network falling behind its required capabilities by a factor of approximately 4 every five years. By 2024, we predict the need for 10-Tb/s optical interfaces working in 1-Pb/s optical transport systems. To satisfy these needs, multiplexing in both wavelength and space in the form of a wavelength-division multiplexing × space-division multiplexing matrix will be required. We estimate the characteristics of such systems and outline their target specifications, which reveals the need for very significant research progress in multiple areas, from system and network architectures to digital signal processing to integrated arrayed device designs, in order to avoid an optical network capacity crunch.
Capacity Limits of Optical Fiber Networks Essiambre, René-Jean; Kramer, Gerhard; Winzer, Peter J. ...
Journal of lightwave technology,
02/2010, Letnik:
28, Številka:
4
Journal Article
Recenzirano
We describe a method to estimate the capacity limit of fiber-optic communication systems (or ¿fiber channels¿) based on information theory. This paper is divided into two parts. Part 1 reviews ...fundamental concepts of digital communications and information theory. We treat digitization and modulation followed by information theory for channels both without and with memory. We provide explicit relationships between the commonly used signal-to-noise ratio and the optical signal-to-noise ratio. We further evaluate the performance of modulation constellations such as quadrature-amplitude modulation, combinations of amplitude-shift keying and phase-shift keying, exotic constellations, and concentric rings for an additive white Gaussian noise channel using coherent detection. Part 2 is devoted specifically to the "fiber channel.'' We review the physical phenomena present in transmission over optical fiber networks, including sources of noise, the need for optical filtering in optically-routed networks, and, most critically, the presence of fiber Kerr nonlinearity. We describe various transmission scenarios and impairment mitigation techniques, and define a fiber channel deemed to be the most relevant for communication over optically-routed networks. We proceed to evaluate a capacity limit estimate for this fiber channel using ring constellations. Several scenarios are considered, including uniform and optimized ring constellations, different fiber dispersion maps, and varying transmission distances. We further present evidences that point to the physical origin of the fiber capacity limitations and provide a comparison of recent record experiments with our capacity limit estimation.
Modal dispersion (MD) in a multimode fiber may be considered as a generalized form of polarization mode dispersion (PMD) in single mode fibers. Using this analogy, we extend the formalism developed ...for PMD to characterize MD in fibers with multiple spatial modes. We introduce a MD vector defined in a D-dimensional extended Stokes space whose square length is the sum of the square group delays of the generalized principal states. For strong mode coupling, the MD vector undertakes a D-dimensional isotropic random walk, so that the distribution of its length is a chi distribution with D degrees of freedom. We also characterize the largest differential group delay, that is the difference between the delays of the fastest and the slowest principal states, and show that it too is very well approximated by a chi distribution, although in general with a smaller number of degrees of freedom. Finally, we study the spectral properties of MD in terms of the frequency autocorrelation functions of the MD vector, of the square modulus of the MD vector, and of the largest differential group delay. The analytical results are supported by extensive numerical simulations.
We present two schemes extending the Kramers-Kronig-receiver to polarization multiplexed transmission. One of the schemes relies on the Stokes receiver and allows for complex-valued polarization ...multiplexed transmission without using a local oscillator, and active polarization control at the receiver. It uses three photodiodes and requires three analog-to-digital converters (ADCs). The other scheme uses a local oscillator, and its implementation is suitable in all cases where the transmitter and the receiver operate at the same wavelength, so that the local oscillator signal can be extracted from the transmit laser. It uses only two photodiodes and two ADCs, and does not require optical hybrids. The performance of the first (Stokes-based) scheme is studied numerically, whereas that of the second scheme is studied both numerically and experimentally.
In order to transition multi-core fiber (MCF) technologies from their research state to volume production, the key design specifications have to be broadly agreed upon, first and foremost an ...acceptable level of inter-core crosstalk per unit length. Against common belief, we show that MCF crosstalk requirements per unit length are fairly independent of transmission distance in the context of modern coherent optical communication systems. As a consequence, a single value for the tolerable inter-core crosstalk per unit length can be used to specify MCFs, valid from metropolitan (~100 km) to trans-pacific (~10 000 km) deployment scenarios. The notion of a universal inter-core crosstalk specification allows for application-independent MCF designs (including a distance-independent optimum core density) and will facilitate the standardization and volume manufacturing of MCF.
The papers in this special section were presented at the 2018 Optical Fiber Communications Conference (OFC) that took place in San Diego, CA, March 2018.
We demonstrate transmission of a probabilistically shaped polarization-division multiplexed 3-GBd 4096-QAM signal over up to 200 km of backward Raman amplified Corning® Vascade® EX2000 fiber. The ...3-GBd signal with a root-raised-cosine roll-off of 0.01 has the potential to generate a spectral efficiency of 19.77 bit/s/Hz over 50 km of fiber.
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