OIF defines 1.6T coherent interface
OIF has published a new Implementation Agreement defining an interoperable 1.6T coherent line interface for amplified DWDM links of up to 120km, targeting high-capacity data-centre interconnects driven by AI workloads.
The Optical Internetworking Forum (OIF) has published its Implementation Agreement (IA) for 1600ZR Coherent Interfaces, establishing a common technical framework for transmitting a 1.6T Ethernet client over a single coherent wavelength.
The specification is designed for single-span, amplified, point-to-point Dense Wavelength Division Multiplexing (DWDM) links extending up to 120km. OIF said the agreement doubles the capacity of its 800ZR specification while maintaining the reach and interoperability required for data-centre interconnect (DCI) applications.
The move comes as AI training, inference and cloud workloads drive increasing traffic within and between data centres. Higher optical capacity is needed without proportionally increasing power consumption, cost or equipment footprint.
According to OIF, 1600ZR combines 1.6T transmission with DCI-class reach and high port density, providing a basis for pluggable coherent solutions from multiple vendors.
“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.”
The 1600ZR specification defines the client mapping, frame format, forward-error correction (FEC), modulation and optical characteristics required for interoperable implementations. It follows OIF's earlier 400ZR and 800ZR work, which helped move coherent optics into routers and switches.
“1600ZR continues the trajectory OIF set with 400ZR, which fundamentally changed how coherent optics could be deployed,” said Ian Betty, OIF Board Member at Ciena. “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.”
The specification also highlights the industry's continued effort to increase capacity per wavelength, rather than relying solely on additional wavelengths or increased system footprint.
For photonic system designers, this places greater emphasis on high-speed coherent transmitters, receivers, modulators and associated optical components.
OIF members are scheduled to demonstrate multi-vendor ZR interoperability at ECOC 2026, taking place from 21–23 September in Málaga, Spain. The demonstrations will showcase coherent implementations from across the ecosystem and provide an opportunity to assess the practical deployment of the new 1.6T specification.
