AFL, Corning Incorporated, Sumitomo Electric Industries, Ltd., and TeraHop PTE. LTD. today announced the completion of the SDM4 Multicore Fiber Multi-Source Agreement (SDM4 MCF MSA) and the public release of the SDM4 Multicore Fiber MSA Technical Specifications, Version 1.0.

The specification defines common geometrical, optical, mechanical and measurement requirements for a four-core multicore fiber intended for AI data centers, campus networks and other short-reach optical links.

By reaching agreement on a common fiber specification, the participating companies have completed the objective established for the MSA: to provide an industry-defined technical foundation for multi-vendor interoperability and future international standardization of four-core multicore fiber.

“This specification establishes a common technical foundation that can help accelerate adoption of multicore fiber across the industry,” said Antonio Castano, Chair, SDM4 MCF MSA. “By aligning around a shared four-core fiber design, we are enabling interoperability while supporting the increasing connectivity demands of AI data centers and campus networks.”

A common fiber design for higher-density optical infrastructure

The continued scale-out of AI infrastructure is increasing the number and density of optical connections required within data centers and across data center campuses. Multicore fiber can provide multiple independent optical paths within a standard fiber cladding, offering a potential path toward greater connection density.

Key elements defined in the SDM4 MCF MSA include:

  • A four-core, square-lattice 2×2 core arrangement with a core pitch of 40 ± 1 µm

  • A nominal cladding diameter of 125 µm

  • Optical characteristics suitable for O-band short-reach applications

  • Crosstalk limits of −40 dB or less at 1 km and 1310 nm for both adjacent and diagonal core pairs

The specification also provides measurement principles and informative guidance on core numbering, rotational alignment, polarization mode dispersion, and marker configurations.

A foundation for broader industry standardization

With publication of the specification, the SDM4 MCF MSA establishes a stable, industry-aligned technical baseline for interoperable SDM4 multicore fiber. The specification is intended to serve as a durable foundation for multi-vendor implementation, industry adoption, and related standards-development activities. Consistent with its role as a stable industry reference, frequent revisions to the MSA specification are not anticipated. Future evolution of requirements for this class of fiber is expected to be advanced through relevant international standards-development organizations, informed by the published specification.

The publicly available specification may serve as a technical reference and foundation for discussions on multicore fiber standardization within ITU-T and IEC, and as a technical reference for discussions on optical transceiver and interface standardization by organizations such as IEEE.

The SDM4 Multicore Fiber MSA Technical Specifications, Version 1.0 are available at:

About the SDM4 MCF MSA

The SDM4 Multicore Fiber Multi-Source Agreement is an industry-led agreement defining common technical requirements for a four-core multicore fiber designed for short-reach O-band optical links. The agreement was created to support multi-vendor interoperability and provide a technical foundation for future international standardization of multicore fiber.

Publication of the SDM4 Multicore Fiber MSA Technical Specifications, Version 1.0, completes the objective of the MSA. The specification will remain publicly available as an industry reference.

About AFL

Founded in 1984, AFL is a global manufacturer providing end-to-end solutions to the broadband, energy, data center, AI, and industrial markets. With products in more than 130 countries, AFL specializes in fiber optic cable and hardware, transmission, compression and substation accessories, connectivity solutions, fusion splicers, and test and inspection equipment. Guided by customer-focused and community-centered values and a strong commitment to safety, the company operates manufacturing facilities worldwide and provides a comprehensive portfolio of services and solutions supporting network infrastructure, data centers, service providers, wireless networks, and power-grid modernization. For more information, visit www.AFLglobal.com.

About Corning Incorporated

Corning (www.corning.com) is one of the world’s leading innovators in materials science, with a 175-year track record of life-changing inventions. Corning applies its unparalleled expertise in glass science, ceramic science, and optical physics, along with its deep manufacturing and engineering capabilities, to develop category-defining products that transform industries and enhance people’s lives. Corning succeeds through sustained investment in research, development, and engineering; a unique combination of material and process innovation; and deep, trust-based relationships with customers that are global leaders in their industries. Corning’s capabilities are versatile and synergistic, allowing the company to evolve to meet changing market needs while helping customers capture new opportunities in dynamic industries. Today, Corning’s markets include optical communications, mobile consumer electronics, display, automotive, solar, semiconductors, and life sciences.

About Sumitomo Electric Industries, Ltd.

Sumitomo Electric Industries, Ltd. was established in 1897. Since then, building on its electric-wire and cable manufacturing technologies, the company has conducted original research and development and worked to establish new businesses. These efforts have enabled Sumitomo Electric to create new products and technologies and diversify its business fields. The company currently operates globally in five segments: Environment & Energy; Infocommunications; Automotive; Electronics; and Industrial Materials. Sumitomo Electric contributes to society through environmentally responsible and fair business activities. For more information, visit https://sumitomoelectric.com/.

About TeraHop PTE. LTD.

TeraHop is a global leading provider of high-speed optical connectivity solutions for AI and data center networking applications. Headquartered in Singapore, the company has a global presence in the United States, Thailand and Taiwan and Suzhou, China. For more information, visit https://terahop.com.

Notes for Editors

Multi-Source Agreement (MSA): An industry-defined, multi-vendor agreement establishing common technical and interoperability requirements so that products from different suppliers can be developed around a consistent specification.

Multicore fiber (MCF): An optical fiber containing multiple light-guiding cores within a common cladding. Each core can provide an independent optical transmission path.

O-band: The “original” optical transmission band, typically covering wavelengths from 1260 to 1360 nm and centered around 1310 nm. It is commonly used for short-reach optical links because chromatic dispersion is low near this wavelength.

AI scale-out: The horizontal expansion of AI infrastructure through the addition of servers, racks, accelerators, or GPUs, allowing workloads to operate across larger multi-node clusters and increasing demand for network interconnects.

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