This Review summarizes the simultaneous transmission of several independent spatial channels of light along optical fibres to expand the data-carrying capacity of optical communications. Recent results achieved in both multicore and multimode optical fibres are documented.

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Space-division multiplexing in optical fibres

Internet data traffic capacity is rapidly reaching limits imposed by optical fiber nonlinear effects Having almost exhausted available degrees of freedom to orthogonally multiplex data, the possibility is now being explored of using spatial modes of fibers to enhance data capacity We demonstrate the viability of using the orbital angular momentum (OAM) of light to create orthogonal, spatially distinct streams of data-transmitting channels that are multiplexed in a single fiber Over 11 kilometers of a specially designed optical fiber that minimizes mode coupling, we achieved 400-gigabits-per-second data transmission using four angular momentum modes at a single wavelength, and 16 terabits per second using two OAM modes over 10 wavelengths These demonstrations suggest that OAM could provide an additional degree of freedom for data multiplexing in future fiber networks

http://science.sciencemag.org/content/sci/340/6140/1545.full.pdf

Terabit-Scale Orbital Angular Momentum Mode Division Multiplexing in Fibers

The history, fabrication, theory, numerical modeling, optical properties, guidance mechanisms, and applications of photonic-crystal fibers are reviewed

Photonic-Crystal Fibers

We report simultaneous transmission of six spatial and polarization modes, each carrying 40 Gb/s quadrature-phase-shift-keyed channels over 96 km of a low-differential group delay few-mode fiber. The channels are successfully recovered by offline DSP based on coherent detection and multiple-input multiple-output processing. A penalty of ;28 dB.

Mode-Division Multiplexing Over 96 km of Few-Mode Fiber Using Coherent 6 $\,\times\,$ 6 MIMO Processing

This article offers a comprehensive survey of results obtained for solitons and complex nonlinear wave patterns supported by nonlinear lattices (NLs), which represent a spatially periodic modulation of the local strength and sign of the nonlinearity, and their combinations with linear lattices. A majority of the results obtained, thus far, in this field and reviewed in this article are theoretical. Nevertheless, relevant experimental settings are also surveyed, with emphasis on perspectives for implementation of the theoretical predictions in the experiment. Physical systems discussed in the review belong to the realms of nonlinear optics (including artificial optical media, such as photonic crystals, and plasmonics) and Bose-Einstein condensation. The solitons are considered in one, two, and three dimensions. Basic properties of the solitons presented in the review are their existence, stability, and mobility. Although the field is still far from completion, general conclusions can be drawn. In particular, a novel fundamental property of one-dimensional solitons, which does not occur in the absence of NLs, is a finite threshold value of the soliton norm, necessary for their existence. In multidimensional settings, the stability of solitons supported by the spatial modulation of the nonlinearity is a truly challenging problem, for theoretical and experimental studies alike. In both the one-dimensional and two-dimensional cases, the mechanism that creates solitons in NLs in principle is different from its counterpart in linear lattices, as the solitons are created directly, rather than bifurcating from Bloch modes of linear lattices.

Solitons in nonlinear lattices

This erratum amends typographical errors in Eq. (1) and Table 2Table 2Optical properties of each core of the fabricated MCF.Attenuation [dB/km]MFD [µm]Aeff [µm2]λcc [nm]CD [ps/nm/km]D. Slope [ps/nm2/km]Bend loss (R = 5 mm) [dB/turn]PMD [ps/√km]λ [nm]1550162515501550N/A1550155015501625C + LDesignN/AN/A9.8679.6149623.30.0630.0100.021N/ACore 10.1760.1969.8380.2150922.20.0620.0110.0200.132Core 20.1790.1979.7680.2150022.20.0620.0100.0200.134Core 30.1810.2029.8881.3150422.20.0620.0100.0200.044Core 40.1770.1999.8580.8149822.20.0620.0110.0210.093Core 50.1750.1929.7479.0148522.20.0620.0110.0220.205Core 60.1790.2009.8079.9148322.10.0620.0110.0220.116Core 70.1770.1979.7278.2149822.20.0620.0100.0190.106 in Opt. Express 19, 16576 (2011).

Design and fabrication of ultra-low crosstalk and low-loss multi-core fiber: erratum.

All solid photonic bandgap optical fiber comprising a core region and a cladding region is disclosed. The cladding region surrounding the core region includes a background optical material having a first refractive index and elements arranged in a two-dimensional periodic structure. In one embodiment, each of the elements comprises a center part and peripheral part having a higher refractive than the central part. In other embodiments, each element comprises a plurality of rods having a higher refractive index higher than the fist, the rods of each element arranged in a circle or polygon. Light transmission apparatus and methods of using the fiber are also disclosed.

http://www.powag.com/Papers/Luan%20POWAG%20Poster%20July%202004.pdf

All solid photonic bandgap fiber

We experimentally demonstrate multiple-input-multiple-output transmission of a combined 3-space-, and 2-polarization-, and 5-wavelength-division multiplex in a 3-core microstructured fiber over 4200 km. This is the record transmission distance for spatial-division multiplexing in a fiber.

/pdf/space-division-multiplexed-transmission-over-4200-km-3-core-20znxk9zk1.pdf

Space-division multiplexed transmission over 4200-km 3-core microstructured fiber

We demonstrate record 109-Tb/s transmission of spatial division multiplexed (SDM) signals over 16.8 km using a seven-core fiber. Each SDM channel contains 97 WDM channels on a 100-GHz grid and 2×86-Gb/s polarization-multiplexed QPSK signals.

109-Tb/s (7×97×172-Gb/s SDM/WDM/PDM) QPSK transmission through 16.8-km homogeneous multi-core fiber

We describe a newly-developed method to measure inter-core crosstalk of single-mode multi-core fiber (MCF) statistically, and characteristics of the crosstalk of a previously fabricated MCF. To measure the crosstalk lower than -60 dB, we suppressed power floor of the measurement system by employing trench-assisted fiber as launching and receiving fibers. We measured statistical crosstalk distributions by utilizing wavelength dependence of the crosstalk, and the mean crosstalk between the neighboring cores was observed to be about -70 dB after 17.4-km propagation at 1625 nm. The measurement results were in good agreement with the previously proposed model. Based on the measurement results and the model, the crosstalk after 10000-km propagation was estimated to be less than -30 dB. We also confirmed that the crosstalk was varied stochastically depending on polarization state, and on mechanical shock and stress on the MCF.

Toshiki Taru

Papers

Design and fabrication of ultra-low crosstalk and low-loss multi-core fiber: erratum.

All solid photonic bandgap fiber

Space-division multiplexed transmission over 4200-km 3-core microstructured fiber

109-Tb/s (7×97×172-Gb/s SDM/WDM/PDM) QPSK transmission through 16.8-km homogeneous multi-core fiber

Characterization of Crosstalk in Ultra-Low-Crosstalk Multi-Core Fiber