22 September 2023

Sumitomo Electric Launches World’s First Mass-produced Ultra-low Loss, Multi-core Fiber

Sumitomo Electric Industries, Ltd. has realized the world’s first mass-production of ultra-low loss, multi-core fiber “2C Z-PLUS Fiber™ ULL,” and will launch its sales in October 2023.

Optical fiber is essential to the infrastructure supporting today’s information and telecommunications network society. With the widespread use of bandwidth-hungry network services including 5G mobile communications and global traffic between large-scale datacenters, it is essential to increase the capacity of optical communication systems. In order to expand transmission capacities further, multi-core fiber (MCF) that has plural cores in a single fiber has been actively studied and highly anticipated as a next-generation fiber.

By applying cutting-edge achievements in MCF R&D activities*1 and low-loss fiber technologies cultivated over 50 years*2, Sumitomo Electric has developed and realized the world’s first mass-production of ultra-low loss MCF “2C Z-PLUS Fiber™ ULL*3.” While a conventional fiber has a single core in which optical signals propagate, 2C Z-PLUS Fiber™ ULL, as the name suggests, has two cores in the same outer dimensions as a conventional fiber. The transmission capacity through the 2C Z-PLUS Fiber™ ULL can be expanded twofold compared to a conventional single-core fiber because the two cores can carry optical signals independently. With a transmission loss of typically 0.158 dB/km at 1550 nm, the new fiber can be considered an ultra-low loss fiber (0.16 dB/km or less) applicable to a transoceanic submarine systems. A small counter-propagating inter-core cross-talk*4 of -43 dB or less is guaranteed. Also, 2C Z-PLUS Fiber™ ULL has equal outer diameters to a conventional single-core fiber (125 μm and 250 μm in glass and coating areas, respectively), and holds excellent environmental reliability and mechanical stability.

Table1 Typical characteristics of 2C Z-PLUS Fiber™ ULL

Glass diameter 125 μm
Coating diameter 250 μm
Transmission loss, at 1550 nm 0.158 dB/km
Effective area (Aeff), at 1550 nm 112 μm2
Cross-talk in counter-propagation,
at C-band
≤ -43 dB

Cross-sectional photo of 2C Z-PLUS Fiber™ ULL.

<Applications of 2C Z-PLUS Fiber™ ULL>
・Broad areas of submarine network systems, from regional to transoceanic distances
・Long-haul, high-capacity terrestrial transmission
・Inter datacenter networks
・Ultra-low loss required applications:
quantum cryptography communications,sensor networks for seismic and fire detection.

Sumitomo Electric will continue to cultivate its world-leading R&D capabilities and mass-production technologies for optical fiber as an essential infrastructure of the information society, contributing to the realization of high-quality optical communications network systems.

*1 Related press releases
The World's First Field Deployed Multi-Core Fiber Testbed for Optical Communications Installed in L'Aquila, Italy.
NEC Corporation, OCC Corporation and Sumitomo Electric Industries, Ltd. complete first trial of submarine cable with multicore fiber
Sumitomo Electric and NICT Develop the World's First 19-core Optical Fiber with Standard Outer Diameter and Set New World Record for Transmission Capacity ーAchieving key technology for beyond 5G long-distance optical communicationー

*2 Sumitomo Electric related page: A 50-Year History of Optical Fibers

*3 Sumitomo Electric products page

*4 Inter-core cross-talk
A signal interference between cores in MCF, in which a portion of optical signal propagating in one core leaks into another. Cross-talk may degrade the signal quality, thus a smaller value is preferable. There are two types of cross-talks in propagating directions of parallel and counter respectively, as shown in the figure below. In principle, a counter-propagating cross-talk has the smaller value than a parallel-propagating one コア間ストローク模式図_en


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