Silicon Photonics

Silicon photonics is a way of building optical parts (the lasers, modulators, and waveguides that move data with light) directly onto a silicon chip. By putting optics on the same material as electronics, it promises high bandwidth at lower power, which is why it has become central to wiring AI data centers.

What is silicon photonics?

Traditional optics are assembled from discrete parts; silicon photonics instead fabricates them on a chip using the same processes as semiconductors. In practice that means standard 300mm CMOS wafers: GlobalFoundries, for instance, describes a platform that monolithically integrates high-performance CMOS, RF, and photonic components on the same chip, and calls itself the industry’s only high-volume 300mm CMOS foundry for silicon photonics (GlobalFoundries). Building optics this way makes them smaller, cheaper at scale, and more power-efficient.

The demand pull is real and recent. LightCounting estimates that the optics market serving AI clusters (transceivers plus emerging LPO and CPO) roughly doubled from about $5 billion in 2024 to more than $10 billion in 2026 (LightCounting). Longer-range industry forecasts put the broader silicon-photonics interconnect market on a similar climb, from roughly $3.69 billion in 2025 toward the tens of billions by 2034 (Global Market Insights).

Why does silicon photonics save power?

Moving data with light, rather than pushing it down copper wire, is what makes the technology attractive inside a data center. Copper links lose signal quality and burn power as data rates climb, so the energy cost per bit becomes the binding constraint at hundreds of gigabits. Silicon photonics attacks that number directly. At the 2023 Optical Networking and Communication Conference, the Belgian research center imec demonstrated a ring-based CMOS silicon-photonics transceiver with optical energy consumption as low as 3.5 picojoules per bit, scalable to 800 gigabits per second of bandwidth density (imec). That efficiency is why the technology has moved from the lab to procurement plans so fast:

“The networking bottleneck has created a high sense of urgency, translating into strong engagements for silicon photonics adoption by the industry.” — Joris Van Campenhout, imec Fellow, imec

The point is leverage. A GPU that finishes its math but waits on a slow link is wasted silicon, so a watt saved on the interconnect is a watt freed for compute. As clusters grow to tens of thousands of accelerators, that arithmetic compounds, and it is why hyperscalers treat optical I/O as a first-order design problem rather than a cable choice.

How is silicon photonics used in AI data centers?

It is the foundation under the fastest optical transceivers and under co-packaged optics. As AI clusters demand more bandwidth per watt, silicon photonics is the technology that the Optical Networking & Photonics leaders are racing to scale.

Related terms & concepts

FAQ

Why does silicon photonics matter for AI?

AI clusters need to move enormous amounts of data between chips, and silicon photonics delivers high bandwidth at lower power than electrical links by integrating optics onto a chip, which is why it is central to next-generation data-center networking. LightCounting estimates the optics market serving AI clusters roughly doubled from about $5 billion in 2024 to more than $10 billion in 2026.

How is silicon photonics different from co-packaged optics?

Silicon photonics is the underlying chip technology; co-packaged optics is a way of deploying it, placing the photonic engine right next to the switch chip rather than in a separate pluggable module.

How is silicon photonics actually manufactured?

It is fabricated on standard 300mm CMOS wafers, the same platform used for mainstream chips. GlobalFoundries, for example, monolithically integrates high-performance CMOS, RF, and photonic components on a single chip, which is what lets silicon photonics scale at semiconductor volumes and cost.

Sources & references

  1. Silicon Photonics Market Size, Share & Forecast · Global Market Insights, 2025-10-01
  2. AI creates a new wave in demand for optical transceivers and accelerates LPO/CPO adoption · LightCounting, 2025-01-15
  3. Silicon Photonics technology platform · GlobalFoundries, 2025-11-01
  4. How silicon photonics technology can address the networking bandwidth demand in cloud datacenters and AI/ML applications · imec, 2023-06-01