The copper wire’s days inside an AI cluster are numbered, and the math is not close. At the signaling speeds modern AI systems demand, passive copper quickly runs into signal-integrity and power limits over short reaches. Push it further and you pump in more and more electrical power just to keep the data intact, generating heat and driving up the energy bill. At the scale of a 100,000-GPU training cluster, that problem compounds into a structural barrier.
The Business
Silicon photonics routes data as pulses of light through glass rather than electrons through metal. The real step change is co-packaged optics, or CPO: placing the optical engine directly beside the switch chip rather than plugging it in at the box’s edge. In traditional layouts, electrical path loss can reach roughly the low-20s dB range; with CPO, that loss can fall to about 4 dB.
TSMC’s compact universal photonic engine, a form of CPO technology, is presented as delivering step-change gains versus copper-based approaches. Publicly shared figures around COUPE emphasize major improvements in latency and meaningful power-efficiency gains versus pluggable optics rather than a blanket “more than ten times” power-efficiency claim versus copper across applications, so that comparison should be treated as directional rather than a settled universal multiple.
Coherent Corp. (NYSE: COHR) is the public company most directly in the path of that spending. As Coherent puts it in its own filings: AI runs on compute, but it scales on optical connectivity. The company sits at the center of an extraordinary expansion in optical networking infrastructure, driven by the rapid growth of AI, the transition from copper to optical connectivity, and the increasing need for bandwidth and energy efficiency.
Why Wall Street Is Paying Attention
The clearest signal of conviction came in early March. Nvidia and Coherent announced a strategic partnership to develop optics technology for next-generation data center architecture, with Nvidia committing a $2 billion investment to support R&D, capacity expansion, and U.S.-based manufacturing.
That was one piece of a larger bet: Nvidia has also made major photonics-related commitments in 2026, including a $2 billion investment in Lumentum, a partnership with Corning that includes an investment commitment described as up to $3.2 billion, and participation in Ayar Labs’ $500 million Series E round. The exact “more than $6.5 billion” total depends on whether you include other deals sometimes grouped into the same “replace copper with light” theme, so treat that roll-up as an estimate rather than a precise ledger number.
In September, Coherent launched PhotonLink, a platform selling lasers, silicon photonics, optics, fiber, and assembly as one integrated system. Coherent has said revenue from PhotonLink is expected to begin ramping in Q4 of calendar 2026.
What’s Driving the Opportunity
The industry’s rollout timetable is crystallizing. Industry forecasts and vendor commentary point to sharp growth in optical transceivers during 2026, and to silicon photonics taking a majority share of the optical-transceiver market around 2027 as AI infrastructure drives faster adoption of optical links between processors, switches, and data-center systems.
Standards bodies are following. The Open Silicon Photonics for AI Systems initiative, led by Lightmatter within the Open Compute Project, has formally launched with support that includes Celestica, Dell Technologies, Keysight, and Qualcomm, aiming to create a shared blueprint for CPOs supporting AI clusters from 72 to more than 1,024 nodes.
What Could Go Wrong
The valuation gap cuts both ways. Coherent closed at $288.02 on October 12, 2026. Analysts carry a consensus Buy rating across 24 firms, with a 12-month price target of $412.52, implying about 43 percent upside from that close. Getting there requires execution on a manufacturing ramp at the same moment demand arrives, which is rarely a clean process. Coherent is also expanding indium phosphide capacity in Sherman, Texas, and any delay in that buildout delays revenue.
Competition is intensifying at every layer of the stack. Ayar Labs’ $500 million Series E in 2026 underscores how much capital is chasing the same CPO and optical-interconnect roadmap. Lumentum holds a parallel Nvidia investment-backed relationship in photonics. And Nvidia itself has every incentive to play vendors against each other.
The Bottom Line
Coherent is not a speculative bet on a technology that might arrive. Purchase commitments are in place, manufacturing is expanding, and the physics of copper limitations inside large GPU clusters make the optical transition hard to avoid. The stock fell about 7.9 percent on October 12, 2026, putting it further below a consensus target built on order flow that investors believe is already in motion. That gap between price and target deserves a closer look today.
