Producer
Sumitomo Electric
Japanese electronics and materials conglomerate (TSE: 5802 / 6502 parent). Co-invented VAD process in 1977 alongside Furukawa and NTT. Consistently top-5 global preform producer; particularly strong in high-performance preforms for submarine cable applications. Primary preform facilities at Yokohama Works (Kanagawa Prefecture, mass production since 1994) and Kiyohara plant (Tochigi Prefecture, since 1999). Achieved world record ultra-low-loss single-mode fiber (0.1397 dB/km, presented OFC 2024); launched world's first mass-produced ultra-low-loss multi-core fiber (September 2023). Also produces copper wire, power cables, automotive parts, and infotainment systems.
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Inputs supplied
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Goods downstream
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Facilities
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Stories
What they make
2 inputs Sumitomo Electric supplies
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Goods downstream
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Where they make it
2 facilities
Sumitomo Electric – Kiyohara Plant (Tochigi) →
JPTochigi Prefecture
Second major Sumitomo Electric optical fiber production plant; Kiyohara Industrial Park, Tochigi Prefecture; operational since 1999. Produces VAD preforms alongside Yokohama Works to serve Japanese domestic and export demand. Together with Yokohama Works, gives Sumitomo Electric the largest Japanese fiber production footprint.
Sumitomo Electric – Yokohama Works (Kanagawa) →
JPKanagawa Prefecture
Mass production preform and fiber drawing plant; primary Sumitomo Electric optical fiber facility completed 1994. Kanagawa Prefecture, near Tokyo. Produces VAD preforms via process co-invented in 1977. Sumitomo has achieved world-record ultra-low-loss fiber at this facility (0.1397 dB/km, OFC 2024); also manufactured world's first mass-produced ultra-low-loss multi-core fiber (September 2023). Primary supply point for Sumitomo's global fiber customers.
What else they do
Business segments
The company's full revenue map — where this supply-chain role fits within their broader business.
Optical Fiber, Preforms & Multi-Core Fiber
20%Automotive Wire Harnesses (Sumitomo Electric Wiring Systems)
38%AutoNetworks Technologies (Infotainment Electronics)
12%Cemented Carbide & Diamond Tools (IGETALLOY)
10%Power Infrastructure & Industrial Cables
20%
Intelligence
What's known
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Did you know2023
Sumitomo Electric Industries — known internationally for high-performance optical fiber and VAD preform technology — derives approximately 40-50% of its total revenue from automotive wire harnesses through its Sumitomo Electric Wiring Systems (SEWS) subsidiary, making it the world's #3 or #4 tier-1 automotive wire harness supplier. Every Toyota, Honda, Nissan, Mazda, and BMW produced in the past 30 years contains Sumitomo Electric copper wire bundles. The same Japanese conglomerate that co-invented VAD optical fiber preform technology in 1977 and achieved the world-record lowest attenuation single-mode fiber in 2024 also installs the copper wiring in the world's best-selling vehicles. The fiber that carries internet data across the Pacific Ocean and the copper wire that connects a Toyota's brake lights were made by the same company.
Sumitomo Electric Industries ↗Capacity2024
Sumitomo Electric presented a world-record ultra-low-loss optical fiber at OFC 2024 with 0.1397 dB/km attenuation — approaching the theoretical silica limit of approximately 0.14 dB/km. Standard single-mode fiber runs at 0.18-0.20 dB/km. The world-record fiber enables submarine cable systems to span greater distances without amplification (amplifiers cost ~$1M each), potentially reducing transatlantic cable costs by 20-30%. Sumitomo Electric also launched the world's first mass-produced ultra-low-loss 19-core multi-core fiber in September 2023 — enabling each fiber strand to carry 19× the data of conventional single-core fiber within the same glass fiber diameter. These advances represent the frontier of optical physics being converted to industrial product — and both came from the same Japanese company that also manufactures Toyota's wiring harnesses.
Sumitomo Electric Industries ↗Origin2023
Sumitomo Electric Industries traces to 1897 in Osaka, when Sumitomo Business Co. (one of Japan's oldest zaibatsu, founded 1590 as a copper smelting business) established a copper wire drawing factory. The Sumitomo zaibatsu's 300-year history in copper gave Sumitomo Electric its foundational material — copper wire — which it still makes in huge volumes for automotive harnesses. The fiber optics breakthrough came from Sumitomo Electric's research partnership with NTT and Furukawa in the 1970s, co-developing the VAD preform process for low-loss silica fiber. Sumitomo Electric's diversification — optical fiber, automotive harnesses, cutting tools — all emerge from the same underlying competency: precise manufacturing of specialty wire/fiber/rod from inorganic materials.
Sumitomo Electric Industries, Ltd. ↗