Silicon photonics investment surges as AI clusters hit the copper wall
Coherent and Lumentum identified as key beneficiaries in the shift to light-based data transmission, though analysts warn of cyclical risks and high valuations.
Investment in silicon photonics is accelerating rapidly as artificial intelligence clusters expand beyond the physical limitations of traditional copper wiring. As AI workloads swell to encompass tens of thousands of processors, the demand for data transmission has exposed the "copper wall," a bottleneck where signal degradation occurs over distances greater than one metre and power consumption becomes prohibitive. This physical constraint is driving a structural shift towards silicon photonics, which utilises light pulses through fibre optics rather than electrons through metal to move data.
The transition is reshaping the optical interconnect market, with the broader optical transceiver sector projected to reach approximately $26 billion in 2026. This growth represents a significant expansion, driven by the need for co-packaged optics, a cutting-edge approach where optical components are integrated directly next to switch chips. This integration reduces power loss and increases bandwidth, allowing data centres to maintain signal integrity without the excessive heat and energy costs associated with long-distance copper runs.
Coherent and Lumentum are emerging as primary beneficiaries of this industry-wide pivot. Coherent, a global leader in optical technology, has deepened its partnership with Nvidia to pioneer next-generation silicon photonics, positioning itself at the centre of the data centre build-out. The company has seen a surge in demand for its data centre transceivers as cloud providers scale their infrastructure to meet AI training requirements.
Lumentum is similarly positioned to capitalise on the trend, supplying the lasers and optical components essential for data centre networking. The company is currently expanding its manufacturing capacity to address demand that has consistently outpaced supply. As roadmaps for AI hardware push towards lower-power optics and tighter silicon photonics integration, Lumentum remains well-placed to capture spending from major technology firms upgrading their networks.
Despite the clear technological necessity of the shift, investors are being cautioned about the inherent volatility of the optical component sector. The industry is cyclical and lumpy, with fortunes closely tied to a small number of large customers whose orders can fluctuate significantly between quarters. Both Coherent and Lumentum have seen their valuations rise on AI enthusiasm, leaving little room for disappointment, while competition in the optics space remains fierce.
