Will Data Center Photonics Finally Kill Copper?

“I think we’re at the end of copper,” says Chris Sharp, chief technology officer at data center giant Digital Realty. Sharp is not suggesting that copper will vanish overnight. Instead, he and a growing cohort of hardware engineers, chip designers, and infrastructure operators are betting that data center photonics will systematically dismantle copper’s dominance in high-speed data transmission. The goal is simple yet incredibly complex: replace the flow of electrons through metal with the flow of photons through glass, cutting power use and unlocking a new era of computational scale.

The Heavy Metal Burden of Modern Compute

To understand the scale of the problem, one must look at the sheer volume of metal currently buried inside modern infrastructure. A typical 100-megawatt (MW) data center—the standard unit of measurement for modern facilities—requires roughly 400 tonnes of copper to function. The vast majority of this metal is used in heavy electrical infrastructure, such as transformers, power distribution units, and massive cooling systems. However, a significant and highly problematic portion is dedicated entirely to moving data.

Up to 70 tonnes of copper are locked inside the computer servers themselves, soldered onto motherboards and woven into the architecture of central processing units (CPUs) and graphics processing units (GPUs). Another 20 tonnes of copper are consumed by the dense, spaghetti-like network wiring that snakes through the back of server racks, connecting individual machines into a unified computing grid. It is here, in these short-reach connections, where copper wiring limitations have become a critical barrier to progress.

“The wires between these GPUs, CPUs, and all this compute are what’s slowing us down,” Sharp explains. “We are spending too much energy just fighting the physical resistance of metal.”

When electrons travel through copper, they encounter resistance. This resistance generates heat. As data rates climb to support massive AI models, the frequency of the electrical signals must increase. Higher frequencies lead to exponentially higher resistance, worse signal degradation, and a massive spike in thermal output. The industry has reached a point where pushing more data through copper requires unsustainable amounts of power, not just to transmit the signal, but to run the air conditioning and liquid cooling loops needed to keep the wires from melting.

The Physics of Light: How Photonics Rewrites the Rules

The alternative is photonics—the science of using light waves instead of electrical currents to transmit information. While electrons crawl through copper, photons travel through optical fibers at the speed of light, experiencing virtually zero resistance and generating no heat along the way.

For decades, fiber optics have been the standard for long-distance telecommunications. The data delivering this very article likely traveled across continents and oceans via undersea fiber-optic cables. However, the challenge has always been bringing this optical technology inside the server chassis itself. This requires silicon photonics technology, an intricate engineering discipline where optical components like lasers, modulators, and photodetectors are fabricated directly onto silicon substrates, sometimes alongside traditional electrical transistors.

By bringing optics directly to the chip level, operators can bypass copper entirely for inter-server communication. “You can save so much energy,” says Callum Littlejohns, deputy director of silicon photonics foundry Cornerstone Labs. Because light does not suffer from resistive heating, the energy required to transmit a gigabit of data drops by orders of magnitude. This directly impacts data center energy consumption, which has become a primary regulatory and operational concern worldwide. According to reports by Reuters, the power demands of AI data centers could double by the end of the decade, making efficiency gains a non-negotiable priority for operators.

The AI Catalyst and the Thermal Wall

The transition to optical networking is no longer a theoretical luxury; it has become an operational necessity driven by the rise of generative artificial intelligence. Modern AI training clusters, such as those powered by Nvidia’s latest architectures, require thousands of GPUs to work in perfect synchronization. These chips must constantly share massive datasets, creating a level of network traffic that traditional copper switches simply cannot handle.

To maintain signal integrity over copper at these speeds, cables must be kept incredibly short—often less than a few meters. This forces data centers to pack servers closer together, creating intense thermal hotspots. By replacing these copper links with optical interconnects, system architects can separate server racks by tens or even hundreds of meters without experiencing latency penalties or signal loss. This physical decoupling allows for more efficient cooling designs and prevents localized thermal runaways.

The performance benefits of this transition are detailed in the comparison below, illustrating why the industry is aggressively moving away from legacy copper systems:

Beyond heat reduction, photonics offers a massive boost in bandwidth density. Using a technique called wavelength division multiplexing, engineers can transmit multiple streams of data down a single optical fiber simultaneously, using different colors (wavelengths) of light. This allows a single fiber to carry the equivalent data of a thick, heavy bundle of copper cables, drastically reducing physical clutter behind the server racks.

The Manufacturing Bottleneck: Why the Swap Isn’t Simple

If the benefits of photonics are so overwhelming, why hasn’t copper been completely phased out? The answer lies in the complex, highly specialized world of semiconductor manufacturing and global supply chains.

Peter O’Brien, head of research for photonics packaging and systems integration at Ireland’s Tyndall Research Institute, notes that while academics and commercial labs have been working with photonics for decades, scaling the technology has proven to be an uphill battle. “What’s happening now with optics and photonics is there’s kind of a reset,” O’Brien says. The technology is finally ready to make the leap from specialized labs into high-volume manufacturing, largely because industry giants like Nvidia have thrown their immense financial weight behind it.

However, building an optical supply chain is vastly different from building an electrical one. “We’ve really gotten good at bringing the cost down on the electrical side—how to design it, how to manufacture it, how to test it, how to deploy it,” says Andrew Wheeler, senior vice president at Hewlett Packard Labs. The silicon industry has spent sixty years optimizing the production of copper-based microchips. Photonics, by contrast, requires aligning microscopic lasers with optical fibers to tolerances of less than a micron.

Furthermore, the manufacturing process is highly fragmented. While silicon wafers can be printed in advanced fabs in the United States or Europe, the final assembly—known as “packaging”—is heavily concentrated in specialized facilities in Taiwan. This geographic concentration introduces geopolitical risks and supply chain vulnerabilities that major technology companies are eager to mitigate, as documented in market analyses by Bloomberg.

The Thermal Paradox of Optical Components

While optical networks generate far less heat than their copper counterparts, they suffer from a unique vulnerability: they are highly sensitive to external temperature fluctuations. The lasers used to generate light signals require precise thermal environments to maintain their specific wavelengths.

This creates a paradox within the data center. Even if the optical interconnects themselves run cool, they are plugged directly into motherboards sitting next to screaming-hot GPUs that can reach temperatures of over 80 degrees Celsius. If the local environment gets too hot, the lasers can drift in frequency, leading to data corruption or complete link failures. Keeping these optical components within strict thermal limits requires sophisticated engineering, sometimes involving dedicated cooling systems just for the optical transceivers, which can offset some of the energy savings.

The Human Element: Retraining the Workforce

Another often-overlooked hurdle is the human element. Installing and maintaining optical networks requires a completely different skillset than handling copper cables. Copper is rugged; it can be bent, pulled, and stepped on with relatively little consequence. Glass fiber, however, is delicate.

“You can’t take tight turns,” warns Chris Sharp. “There are little nuances on how to structure that.” If a technician bends an optical fiber too sharply, the light escapes the core of the cable, causing signal loss. Furthermore, even microscopic specks of dust on the end of an optical connector can completely block the light path, requiring specialized cleaning tools and inspection microscopes. Data center operators must retrain their field support engineers and installation crews to handle these delicate components at scale, a process that takes time and money.

The Ultimate Goal: All-Optical Computing

For some industry visionaries, simply replacing copper cables with optical fibers is just the first phase of a much larger revolution. Ofer Shapiro, CEO of optical networking firm Resolight.ai, argues that the true benefits of photonics will only be realized when we eliminate the constant conversion of data between the electrical and optical domains.

Currently, when a server processes data, it does so electrically. To send that data to another server, it must convert those electrical signals into light waves, transmit them over fiber, and then convert them back into electrical signals at the receiving end. These electro-optical conversions consume a significant amount of power and introduce latency.

“It doesn’t make sense to constantly convert data from photons to electrons and back,” Shapiro argues. “We need an architecture where data remains in the optical domain from start to finish.”

Resolight.ai and other pioneering startups are developing all-optical switches that route light signals using tiny mirrors or liquid crystal displays, bypassing the need for electrical conversion entirely. If successful, this approach could slash networking power consumption by up to 90%, providing a massive relief valve for grid-stressed data centers.

Repurposing the Past to Power the Future

Despite the high-tech nature of photonics, the path to scaling the technology involves some surprisingly retro solutions. Because optical wavelengths are significantly larger than the nanometer-scale transistors used in modern computer chips, photonics components do not require the ultra-advanced, multi-billion-dollar lithography machines used to make the latest AI processors.

Instead, photonics manufacturers can repurpose older silicon fabrication equipment that has been retired by mainstream chipmakers. For example, Cornerstone Labs utilizes manufacturing tools originally used on Intel production lines to make Pentium 4 processors back in the early 2000s.

This ability to reuse legacy equipment and manufacturing knowledge drastically lowers the capital expenditure required to scale photonics production. “We know we can make it at a huge scale,” says Littlejohns. “That’s why it’s such an interesting technology, because it can underpin many applications without requiring us to reinvent the wheel.”

As the industry stands on the precipice of an AI-driven energy crisis, the transition to light-speed data transmission is shifting from a long-term research project to an immediate operational priority. While copper will likely remain the backbone of power delivery for decades to come, its reign as the primary medium for data transmission is drawing to a close. The future of computing belongs to light, and the data centers that embrace photonics first will be the ones that survive the coming power crunch.

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