TIM DOIRON AI DATA CENTRES
LIGHTING IT UP OPTICAL INFRASTRUCTURE INNOVATION AND ARCHITECTURAL EVOLUTION IN THE AGE OF AI DATA CENTRES In 2025, data centre capital expenditures grew by more than 60%, exceeding $400 billion, and projections indicate spending will surpass $1 trillion by 2030. In parallel, the transition to AI factories underpinned by high-performance XPUs is accelerating connectivity demands between data centres, writes Nokia VP of Solution Marketing Tim Doiron . A lthough data centre interconnect (DCI) remains the fastest growing part of the network, scale-across applications are emerging L band, the capacity of a single fibre pair can be doubled – enabling nearly 100 Tb/s per fibre pair in the combined super C and super L bands. Embedded optical engines remain critical for the most challenging long- haul and subsea applications, but the increasing capabilities of coherent exceeding 1 million by 2030. Vendors are updating their supply chain, processes and partnerships to deliver the production capacity required to support such rapid growth. While 800G ZR/ZR+ coherent pluggable deployments are ramping up, the OIF and the optical industry are already
with AI and cloud providers using optical connectivity to scale XPU clusters and backend networks beyond the physical limits of a single data centre. While xAI’s supercomputer, Colossus, became the world’s largest GPU cluster with 200,000 GPUs in April 2025, multiple companies, including OpenAI, have their sights set on building a one-million-GPU cluster. But one optical networking solution and architecture will not fit all data centre interconnect and scale across needs. Instead, an innovative optical connectivity toolbox is required in order to keep pace, enable deployment flexibility and optimise costs.
pluggables, combined with their relatively small power and space, make them ideal for many data centre interconnect and scale-across networking use cases. While 400G ZR/ZR+ pluggables accelerated the move to coherent pluggables, deployment has been dominated by AI and cloud providers and the IP over DWDM (IPoDWDM) deployment model, with pluggables deployed directly in routers and switches. The general availability of industry-leading 800G ZR/ZR+ coherent pluggables, with their ability to support full rate transmission up to 1,700 km and the programmability to run 400 Gb/s up to 3,000 km (Figure 1), has AI and cloud and telecommunication providers trialling, ordering and planning deployments. Multiple industry analysts more than doubled their forecasts in 2025. Analyst projections now show a rapid ramp – with several thousand units in 2025 growing to more than 100,000 units in 2026 and
defining 800G’s successor – a 1.6 Tb/s coherent pluggable. Although still a few years away, some design directions for 1600G ZR/ZR+ are already emerging. With support for 240+ Gbaud transmission, the higher-performance ZR+ variant will use two digital subcarriers, while the shorter-reach ZR version will use a single subcarrier, similar to its 400G and 800G ZR/ZR+ predecessors. These design considerations align performance and cost with application needs, avoiding problems such as underperformance or overspending seen in one-size-fits-all solutions. ADD THIN TRANSPONDERS While coherent pluggable adoption is accelerating, the IPoDWDM deployment model is not optimal for every network operator or every application. As an example, telecommunication providers that deliver wholesale wave or data
MATCH THE ENGINE TO THE APPLICATION
Since the advent of coherent optical transmission in 2010, sled- or module- based optical engines have dominated deployments. What began with 40 Gb/s and 100 Gb/s wavelengths has given way to 1.2+ Tb/s wavelengths with today’s technology. Industry-leading embedded engines enable 1.2 Tb/s transmission in 150 GHz channels – delivering up to 38.4 Tb/s in the standard 4.8 THz C-band. Using the 6.1 THz super C-band, 48+ Tb/s is achievable. With optical engines available to support both the C and the
Figure 1. 800G ZR/ZR+ coherent pluggable capabilities
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| ISSUE 43 | Q1 2026
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