The Invisible Backbone of AI: Why Light Powers Intelligence | Lumentum | RAISE Summit 2026

Lumentum's Four-Stage Data Center Evolution Framework

• The speaker outlines a trajectory from the "scale across" (internet backbone) to "scale out," "scale up," and finally "scale in," driven by the physical limitations of copper as bandwidth speeds increase.
• Scale Across (Kilometers): Involves inter-data center communication required to house massive inference models; this historic market relies on optics to maintain full bandwidth over long distances.
• Scale Out (Meters): Connects server racks to switch banks; this phase represents a 10x increase in optical lanes compared to scale across, utilizing pluggable optical transceivers.
• Scale Up (Centimeters/Rack): Replaces internal copper links within compute racks (e.g., NVIDIA racks) with optics to overcome resistance at speeds up to 1.6 terabits per second.
• Scale In (Millimeters): The final stage involves replacing copper traces on Printed Circuit Boards (PCBs) and disaggregating memory from compute blocks with optical interconnects.

Market Growth and Deployment Timelines

• Market Magnitude: The transition from scale across to scale up represents a potential 100x increase in the optical lane market, with scale in potentially reaching a 1,000x expansion.
• Scale Up Deployment: First deployments are expected in the second half of 2027, with full rack integration likely mid-2027; backplane connectivity is projected for 2028.
• Scale In Deployment: Commercial adoption of optical interconnects on PCBs and high-bandwidth memory is projected for the end of the decade (circa 2029).
• Copper Limitations: Copper signals cannot effectively traverse distances beyond one meter at 1.6 Tbps speeds due to resistance and heat generation, necessitating optical solutions even within the rack.

Supply Chain and Laser Manufacturing Challenges

• Volume Surge: The industry is transitioning from deploying hundreds of lasers (telecom era) to requiring hundreds of millions, potentially reaching hundreds of billions annually.
• Manufacturing Scale-Up: Lumentum has ramped five Indium Phosphide wafer fabrication facilities to meet the demand, moving from thousands of wafers to millions.
• Strategic Investments: NVIDIA is investing in both Lumentum and a major competitor to secure Indium Phosphide supply, acknowledging the acute shortage of this specific semiconductor material.
• Laser Density: A single rack in a scale-up network may require 8,000 distinct lasers (eight per light source across 1,000 sources per rack).

Technical Specifications and Applications

• Scale-Up Laser Power: Typically utilizes 400-milliwatt lasers, similar to those used for long-distance scale across and space-based free-space optics.
• Scale-In Laser Characteristics: Requires lower-power lasers designed for array configurations to handle high data rates over very short distances (centimeters).
• Space Applications: The 400-milliwatt lasers developed for scale-up data centers are also viable for space-based optical interconnects due to light's dispersion properties and lack of resistance compared to electrical signals.
• Material Science: Optical systems rely on Indium Phosphide, a non-CMOS material specifically capable of emitting light, distinguishing it from standard semiconductor manufacturing.