Researchers demonstrate the ability to multiplex and transfer data between twisted beams of light with different amounts of orbital angular momentum — a development that provides new opportunities for increasing the data capacity of free-space optical communications links.

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Terabit free-space data transmission employing orbital angular momentum multiplexing

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

Orbital angular momentum (OAM), which describes the “phase twist” (helical phase pattern) of light beams, has recently gained interest due to its potential applications in many diverse areas. Particularly promising is the use of OAM for optical communications since: (i) coaxially propagating OAM beams with different azimuthal OAM states are mutually orthogonal, (ii) inter-beam crosstalk can be minimized, and (iii) the beams can be efficiently multiplexed and demultiplexed. As a result, multiple OAM states could be used as different carriers for multiplexing and transmitting multiple data streams, thereby potentially increasing the system capacity. In this paper, we review recent progress in OAM beam generation/detection, multiplexing/demultiplexing, and its potential applications in different scenarios including free-space optical communications, fiber-optic communications, and RF communications. Technical challenges and perspectives of OAM beams are also discussed.

Optical communications using orbital angular momentum beams

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

We transmitted 5 wavelength channels and 6 spatial-and polarization modes over a 184 km long hybrid span few-mode fiber span. Low-loss 3-spot mode couplers are used in combination with backward pumped distributed Raman amplification. The 40-Gbit/s QPSK signals with an aggregate line-rate of 1.2 Tbit/s were recovered by coherent multiple-input-multiple-output off-line digital signal processing.

Mode-multiplexed transmission over a 184-km DGD-compensated few-mode fiber span

We will discuss design principles and properties of large effective area, low loss fibers for C+L band transmission. These fibers need to have excellent cabling properties from 1530 to 1610nm.

Optimization of large area, low loss fiber designs for C+L band transmission

We present a novel azimuthal alignment algorithm for multicore fiber splicing that separates the core and marker information in side-view images. For two different 4-core fiber designs, average fusion splice losses of less than 0.03 dB are demonstrated using a 3-electrode arc-discharging fusion splicer.

Less Than 0.03 dB Multicore Fiber Passive Fusion Splicing Using New Azimuthal Alignment Algorithm and 3-Electrode Arc-Discharging System

As deployment of fiber to the home (FTTH) within multiple dwelling units (MDUs) is growing, more technicians will be
involved in the deployment of optical drop cables, and there is a desire to use craft and practice similar to what is used
for copper cables. We introduce a solid bend insensitive fiber in this application that is backwards compatible to G.652D
fiber, and has macrobending, splice loss and system performance to meet the very demanding conditions of these
applications. A closer look at the demands of this environment has made it necessary to re-evaluate reliability in these
critical applications. We apply the Power Law Model to predict reliability in these demanding applications, and provide
experimental evaluation of the model through testing on optical fibers and cables. It will be shown that bends and tension
need to be considered together when evaluating the reliability of the passive optical plant.

Alan McCurdy

Papers

Mode-multiplexed transmission over a 184-km DGD-compensated few-mode fiber span

Optimization of large area, low loss fiber designs for C+L band transmission

Less Than 0.03 dB Multicore Fiber Passive Fusion Splicing Using New Azimuthal Alignment Algorithm and 3-Electrode Arc-Discharging System

Bend Insensitive Fibers for FTTH and MDU

Control of Polarization Mode Dispersion when Building High Bit Rate Optical Transmission Systems