WASHINGTON, Aug. 15—Optical fiber communication is the backbone for the telecommunications infrastructure that supports the Internet. Fueled by emerging bandwidth-hungry applications and increases in computer processing power, Internet traffic has sustained exponential growth and this trend is expected to continue for the foreseeable future.
To highlight research being carried out to ensure that the capacity of fiber optic communication systems can handle this rapidly increasing demand, and thus to address the Internet capacity crunch, the editors of the Optical Society's (OSA) open-access journal Optics Express, today published a special Focus Issue on Space Multiplexed Optical Transmission. The issue is organized and edited by Guifang Li of the University of Central Florida and Xiang Liu of Bell Labs, Alcatel-Lucent.
The Focus Issue describes different approaches to increase the information carrying capacity of optical fibers. One of these, Space-Division Multiplexing (SDM), uses fibers with seven cores, rather than a single one. By using all seven cores, seven independent signals can be carried, and the fiber capacity can thus, in principle, be increased seven-fold. In other approaches, such as Mode-Division Multiplexing (MDM) a single core carries multiple information channels, each of which is associated with a different physical shape of the light field, also increasing the fiber capacity.
According to Liu, "Our goal in producing this focus issue was to provide a comprehensive survey of the state-of-the-art research activities in multiplexed transmission, which holds potential for addressing the challenges of capacity growth in optical communications."
"We hope this collection will stimulate future research on this subject to address the remaining fundamental and practical challenges, potentially enabling dramatic capacity growth in future optical communication systems," said Li.
Summary
It is well known that the capacity of a communication channel is constrained by the Shannon limit. In optical fiber communication, fiber nonlinearity imposes an additional limit in the high power or high signal-to-noise ratio (SNR) regime. Digital coherent detection increases optical signal tolerance to linear noise such as amplified spontaneous emission noise, and sometimes nonlinear phase noise. However, the single-channel capacity increase scales logarithmically with the increase in SNR. This logarithmical single-channel capacity scaling ultimately will not be able to support exponential traffic growth. While it might be impossible to provide exponential single-channel capacity growth in optical communication, multiplicative growth in optical communication capacity has satisfied traffic demand in the past, especially when dense wavelength-division multiplexing (DWDM) with a multiplicative factor on the order of 100 was invented. As today's DWDM coherent optical communication technology has already taken advantage of all degrees of freedom of a light wave in a single-mode fiber, namely frequency, polarization, amplitude, and phase, further multiplicative growth has to explore new degrees of freedom. MDM using few-mode fibers (FMF) and SDM using multi-core fibers (MCF) have emerged as promising candidates for the next multiplicative capacity growth for optical communication. This Optics Express Focus Issue features the state-of-the-art research activities in MDM and SDM aimed at order-of-magnitude capacity growth in future optical communication systems.
Key Findings
The following papers are some of the highlights of the Optics Express Focus Issue on Space Multiplexed Optical Transmission. All are included in Volume 19, issue 17 and can be accessed online at http://www.opticsinfobase.org/oe.
About Optics Express
Optics Express reports on new developments in all fields of optical science and technology every two weeks. The journal provides rapid publication of original, peer-reviewed papers. It is published by the Optical Society and edited by C. Martijn de Sterke of the University of Sydney. Optics Express is an open-access journal and is available at no cost to readers online at http://www.OpticsInfoBase.org/OE .
About OSA
Uniting more than 106,000 professionals from 134 countries, the Optical Society (OSA) brings together the global optics community through its programs and initiatives. Since 1916 OSA has worked to advance the common interests of the field, providing educational resources to the scientists, engineers and business leaders who work in the field by promoting the science of light and the advanced technologies made possible by optics and photonics. OSA publications, events, technical groups and programs foster optics knowledge and scientific collaboration among all those with an interest in optics and photonics. For more information, visit www.osa.org .
Optics Express