What is silicon photonics, and why is AI completely dependent on it? If you have been hearing about this technology and wondering what it actually means, here is the clearest explanation you will find.
Quick Answer: Silicon photonics uses light rather than electrical signals to transmit data within computers and AI systems. Copper wires — which have powered computing for decades — are hitting physical limits that light can solve. This switch is one of the most important technology transitions happening right now, and it affects everything from your favourite AI tools to the biggest investment opportunities in tech.
The Problem With Copper Wires
Every time you use ChatGPT, Google Gemini, or any AI tool, thousands of computer chips work together to generate your response.
Those chips need to communicate with each other constantly — sharing data at extraordinary speeds. For decades, copper wires have handled this job.
But copper has hit a wall. Three specific walls, actually:
Wall 1 — Heat: Copper wires generate heat when electricity passes through them. A single NVIDIA AI chip generates around 700 watts of heat — about the same as a small electric heater. A data centre running 50,000 of these chips generates more heat than a small power plant. Cooling this costs billions and is environmentally devastating.
Wall 2 — Speed: AI systems now need to move data at 800 Gigabits to 1.6 Terabits per second between chips. Copper wires physically cannot carry this much data at these speeds reliably.
Wall 3 — Distance: At very high speeds, copper signals degrade rapidly over distance. Reliable copper connections at AI speeds only work across a few metres — but AI data centres span entire buildings.
Physics has caught up with copper. You cannot engineer your way past the laws of nature.
What Is Silicon Photonics?
Silicon photonics is the technology of using light — photons — instead of electricity to carry data.
Instead of electrons moving through copper wires, pulses of light travel through hair-thin glass fibres. The same basic principle as the undersea internet cables that connect continents, but miniaturised to work inside computers and data centres.
The name comes from the two key elements:
- Silicon — the material used to make the chips that generate and detect the light
- Photonics — the science of generating, controlling, and detecting photons (light particles)
Think of it this way. Copper is like a busy motorway at rush hour — congested, slow, generating heat from all the traffic. Silicon photonics is like replacing that motorway with a network of high-speed rail — carrying far more passengers, faster, with a fraction of the energy.
Why Light Is Better Than Electricity for AI
The advantages of using light instead of electricity for data transmission are significant:
| Copper Wires | Silicon Photonics | |
|---|---|---|
| Speed | 400G maximum | 800G to 1.6T and beyond |
| Heat generated | Very high | Near zero |
| Power consumption | Baseline | Up to 40% less |
| Reliable distance | Under 3 metres | Kilometres |
| Interference | High | None |
For AI, specifically, the power saving is critical. AI data centres already consume as much electricity as some small countries. A 40% reduction in power consumption at scale represents billions of dollars in savings and a massive reduction in carbon emissions.
What Is Co-Packaged Optics — The Next Step?
Today, most data centres use separate optical transceivers — plug-in modules that convert electrical signals to light at the edge of chips. The signal is still electrical inside the chip itself.
Co-packaged optics — or CPO — takes this further by embedding the light conversion directly onto the chip package. The signal becomes optical immediately, before any degradation occurs.
NVIDIA unveiled its first CPO-enabled switches at its GTC 2025 conference. Broadcom, Intel, and others are following. Volume deployment is expected by 2027.
This is not a future technology. It is in production now.
Which Companies Are Leading This Transition?
Several companies sit at the heart of the silicon photonics revolution:
The laser makers — Coherent Corp (COHR): make the lasers that go inside photonic chips. Every company building optical transceivers buys components from companies like Coherent. Dominant supplier position with real pricing power.
The testers — Aehr Test Systems (AEHR): Every silicon photonics chip must be stress-tested before deployment. Aehr has the dominant wafer-level burn-in technology. Unique position in the supply chain — no photonics at scale without testing.
The validators — Viavi Solutions (VIAV) makes the instruments that test optical networks after they are built. The quality control layer of the entire photonics infrastructure.
The platform players — Marvell Technology (MRVL): Acquired optical computing startup Celestial AI for $5.5 billion in late 2025 — a direct bet on photonics becoming standard in every AI data centre.
The hyperscalers — Microsoft, Amazon, Google, Meta: The companies are buying all of the above to build AI infrastructure. If you already own shares in these companies, you already have indirect photonics exposure.
⚠️ Disclaimer: The companies mentioned above are for educational purposes only. This is not financial advice. Always do your own research and consult a qualified financial advisor before making any investment decisions.
What Comes After Silicon Photonics?
Silicon photonics solves the data movement problem — getting information between chips faster and more efficiently.
The next frontier is using light not just to move data but to actually perform calculations. This is called optical computing, and early commercial products are expected between 2027 and 2030.
After that, neuromorphic computing — chips designed to mimic the human brain — and eventually quantum computing using photons as quantum bits.
Each transition follows the same pattern as every major computing era before it. The companies that build the essential infrastructure — not the flashiest products — tend to generate the most consistent returns.
Conclusion
Why is AI replacing copper wires with light? Because copper has hit the limits of physics, and AI keeps growing. Silicon photonics is not a future concept — it is happening now, driven by the insatiable demand of AI data centres for faster, cooler, more efficient data movement. Understanding this transition helps you make sense of where technology — and the companies building it — are heading next.
The same principles that make photonics secure also apply to everyday internet security — read our guide on public WiFi safety.
Just as health myths persist despite evidence, many technology myths about AI are equally misunderstood.
Sources:
National Cyber Security Centre — AI Infrastructure
IEEE — Silicon Photonics Overview
Yole Group — Photonics Market Research
Frequently Asked Questions
What is silicon photonics in simple terms? It is the technology of using light instead of electricity to move data inside computers and AI systems. Faster, cooler, and more efficient than copper wires.
Why does AI need silicon photonics? AI requires thousands of chips working together at extraordinary speeds. Copper wires cannot handle the bandwidth, heat, or distance requirements of modern AI data centres. Light can.
Is silicon photonics already being used? Yes — it is already deployed in data centres and ramping rapidly. NVIDIA, Broadcom, and Intel all have products in production or near production using silicon photonics principles.
Will silicon photonics replace all copper wiring? Not entirely — copper will remain for short-range, low-speed connections. But for high-performance AI applications, the transition to optical connections is already underway and accelerating.
How does this affect everyday users? Indirectly but significantly. Faster, more efficient AI infrastructure means AI tools become more capable, more accessible, and cheaper to run. The electricity savings also reduce the environmental impact of the AI industry.
