"I think we're at the end of copper," says Chris Sharp, chief technology officer at data centre operator Digital Reality. He doesn't mean that copper supplies are running out, but that the industry is moving toward using less of it. Data centres use vast amounts of copper—around 400 tonnes in a typical 100MW facility. Much of this is used in electrical systems, cooling, and servers, with up to 70 tonnes dedicated to servers and 20 tonnes to network wiring. This wiring, often described as "spaghetti-like," is a prime candidate for replacement. "The wires between these GPUs, CPUs, and all this compute are what's slowing us down," Sharp explains. Researchers and companies are exploring the use of light, in the form of photons, to transmit data more efficiently. Light is already used in long-distance communications via optical fibre, and now there is growing interest in applying this technology within data centres. This field is known as photonics, and its main advantage is that light doesn't produce the heat associated with electricity, potentially reducing the energy needed to cool data centres. "You can save so much energy," says Callum Littlejohns, deputy director of silicon photonics foundry Cornerstone Labs. Photonics could also increase data capacity by allowing multiple data streams to travel through the same channel. Despite the promise of photonics, the technology is still evolving. Researchers and companies have worked on it for years, but manufacturing challenges have slowed progress. Now, however, experts say the technology is ready to move from the lab to real-world use. "What's happening now with optics and photonics is there's kind of a reset," says Peter O'Brien, head of research for photonics packaging at Ireland's Tyndall Research Institute. The support of major companies like Nvidia has also helped. However, the shift to photonics is not a simple swap—it involves different engineering approaches and supply chains. Photonics components are generally larger than traditional silicon components, which might seem counterintuitive. However, this allows companies like Cornerstone Labs to repurpose older manufacturing equipment used for earlier generations of processors. For instance, one of Cornerstone's tools was originally from an Intel production line that made Pentium 4 chips in the early 2000s. While the benefits of optical networking are clear, the full potential of using light for both data transmission and processing remains a future goal. For now, the focus is on scaling up photonics manufacturing and reducing costs, with the hope that this technology will eventually underpin a wide range of applications.