Scale-Across: Sizing the Optical Layer for Distributed AI

Scale-across, the extension of a single AI training fabric across multiple data center sites, is the most-discussed application in optical transport this year, but the least quantified. This report combines Cignal AI’s coherent pluggable forecasts with a bottom-up model of line systems to size the scale-across opportunity.

• Scale-across optical revenue reaches $9.1 billion in 2030 and $24.6 billion cumulatively from 2026 through 2030.
• Coherent pluggables account for $11.7 billion of the cumulative total and line systems $12.9 billion.
• Scale-across overtakes front-end DCI in 2027. By 2030 it ships over 3x the bandwidth and 2x the pluggable spend compared to front-end DCI.
• Line systems grow from 29% of scale-across revenue in 2026 to 57% in 2030, overtaking pluggables in 2028 despite getting a fraction of the attention.
• Raman amplification is a major cost driver in scale-across line systems and the pump lasers behind it are among the tightest parts of the optical supply chain.

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