OIF, where the optical networking industry’s interoperability work gets done, today announced the publication of the Implementation Agreement (IA) for 1600ZR Coherent Interfaces, defining an interoperable 1.6T coherent line interface and frame format for single-span, amplified, point-to-point Dense Wavelength Division Multiplexing (DWDM) links up to 120 kilometers.

The highly anticipated IA doubles the capacity of OIF’s 800ZR specification, enabling a single 1.6T Ethernet client to be transported over a single coherent wavelength. It represents the next major step in OIF’s ZR evolution and provides the common technical foundation needed to bring interoperable 1.6T coherent solutions to data center interconnect applications.

AI training, inference and cloud workloads are driving rapid expansion within and between data centers, creating an urgent need for greater capacity without corresponding increases in power, cost or physical footprint. By combining 1.6T transmission, DCI-class reach and client-optics-equivalent port density, 1600ZR addresses each of these requirements within a framework designed for multi-vendor implementation.

“1600ZR is a defining milestone for coherent networking,” said Karl Gass, OIF Physical & Link Layer Working Group Optical Vice Chair. “It doubles the capacity of 800ZR while preserving the reach, interoperability and client-like density that have made the ZR ecosystem so fundamental. As the AI scale-across application drives unprecedented growth in traffic between data centers, the industry cannot solve the challenge with capacity alone. This IA aligns the ecosystem around a practical 1.6T interface and gives vendors and operators a common foundation for the next generation of coherent DCI.”

Building on the Transformational Success of OIF ZR

OIF’s ZR work has played a central role in moving coherent optics from traditional transport systems directly into routers and switches. The new 1600ZR IA, like 400ZR and 800ZR before it, was developed through a systematic process driven by OIF’s network operator and vendor members. It enables Ethernet client interfaces to be transmitted over a single coherent line interface by specifying the client mapping, frame format, forward-error correction (FEC), modulation, and optical characteristics needed for interoperable implementations.

“1600ZR continues the trajectory OIF set with 400ZR, which fundamentally changed how coherent optics could be deployed,” said Ian Betty, OIF Board Member (Ciena). “The work within OIF has consistently anticipated where networks need to go next, bringing together the technical expertise needed to turn ambitious requirements into practical, interoperable solutions. Delivering 1.6T over a single wavelength marks another major step forward—and provides a critical building block for the AI infrastructure now being deployed.”

OIF members will demonstrate multi-vendor ZR interoperability at ECOC 2026, Sept. 21–23 in Málaga, Spain. The live demonstration at booth #2126 will bring together coherent implementations from across the ecosystem, providing a practical view of the specification’s impact.

For more information or to download the 1600ZR IA, visit the OIF Implementation Agreements page.

About OIF

OIF is where the optical networking industry’s interoperability work gets done. With more than 25 years of effecting forward change in the industry, OIF represents the dynamic ecosystem of 180+ industry leading network operators, system vendors, component vendors and test equipment vendors collaborating to develop interoperable electrical, optical and control solutions that directly impact the industry’s ecosystem and facilitate global connectivity in the open network world. Connect with OIF on LinkedIn, on X, on Bluesky and at https://www.oiforum.com/.

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