ECOC 2025 Tech Focus: OIF Drives Coherent Standardization and Short-Reach AI Applications

Introduction

As AI and cloud data centers scale rapidly, transmission requirements keep climbing from 400G → 800G → 1.6T. Coherent optics, long established in long-haul transmission (DCI, backbone networks), is now starting to enter short-reach (2–10 km) scenarios inside the data center.

As the core organization driving optical interoperability, OIF shared its latest progress at ECOC 2025, including 400ZR/800ZR applications, interoperability test data, and the next-generation 1.6T/3.2T coherent specs (Coherent Lite).

Content

1. The spread of 400ZR and 800ZR

• 400ZR (released 2020): used mainly for DCI within 120 km; driven by hyperscalers, it has become the market mainstream.

• 800ZR (released 2024): now in commercial deployment, with strong market demand.

• ZR+: offers higher performance than ZR (longer reach / higher OSNR tolerance) and is currently supported by two MSAs, OpenZR+ and Open ROADM.

2. DCI interoperability test results

OIF worked with 10 module vendors on large-scale interoperability testing covering 400ZR and 800ZR:

• Results: modules from different vendors were largely compatible on metrics such as OSNR and receiver sensitivity.

• Issues: in Optical Protection Switch tests, some modules took several minutes for Chromatic Dispersion Compensation (CDC) to reconverge, resulting in excessively long recovery times.

• Improvements: some vendors have tuned the switching hold-off time to 50 ms, successfully improving recovery time.

3. Next-generation specs: 1.6T and 3.2T coherent

• 1600ZR: now in final ballot, to be released in 2026.

  • Spec: supports reach of up to 120 km.

• 1600ZR+: split into two applications:

  • Up to 1000 km.

  • Up to 2000 km (at a reduced rate of 1200G).

• Coherent Lite (CL): targets 2–10 km data center applications, positioned as an alternative to IMDD.

  • Expected to support 2 km LR and 10 km ER scenarios.

  • The goal is to cut power and cost by simplifying the DSP and FEC.

👉 OIF said that even if 1.6T CL doesn't succeed right away, the 3.2T generation will definitely need CL — so the groundwork has to be laid now.

4. OIF's role and goals

• Implementation Agreement (IA): OIF advances projects through member ballots, culminating in implementation agreements (similar to standards).

• Interoperability demos: regular live demos accelerate market adoption and reduce customer risk.

• Goal: ensure next-generation coherent technology interoperates across multi-vendor environments, supporting large-scale deployments by hyperscalers and telecom carriers.

Conclusion

OIF's presentation at ECOC 2025 highlighted three key directions for coherent technology:

1. 400ZR/800ZR are mature and have become standard for DCI, with ZR+ covering higher-performance scenarios.

2. Interoperability remains a challenge, especially in high-reliability scenarios such as protection switching, but OIF's testing has already pushed vendors to improve.

3. 1.6T/3.2T coherent specs are being defined, and Coherent Lite will become a key complement for future short-reach data center links, lowering power and cost.

Overall, OIF's role is not just to set standards but to drive real market adoption through interoperability testing. As AI factories keep scaling, coherent technology will move from long reach to short reach, covering both DCI and intra-data center networks.