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

*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
https://sumitomoelectric.com/articles/a-50-year-history-of-optical-fibers-part-1

*3 Sumitomo Electric products page
https://global-sei.com/fttx/optical-fibers/z-fiber/

*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