A robot hums along a library shelf, but instead of books, the shelf holds small, flat squares of clear glass. The robot picks up a piece and takes it to a microscope. The microscope examines the glass, revealing a speckled pattern, invisible to the naked eye. This pattern was etched by a high-speed laser, and now a computer can read the digital information stored within it.

Figure 1. High-Speed Lasers Etch Data in Glass to Last for Millennia.

Each glass plate is like a futuristic book, capable of storing 7 terabytes of data — the equivalent of about two million books. Figure 1 shows High-Speed Lasers Etch Data in Glass to Last for Millennia.

The library, robot, laser, microscope, and glass plates are all part of a research initiative called Project Silica, directed by Richard Black at Microsoft Research in Cambridge, England. "Project Silica offers a new way of storing data," he explains.

Current computer hard drives can hold terabytes of data but only last around three to five years. Most common methods for storing digital data tend to degrade quickly, Black points out. “Every few years, you’ve got to buy a new [storage medium] and copy,” and the cycle repeats: “buy and copy, and buy and copy.”

In contrast, the data encoded in the glass can last “thousands of years,” or possibly even longer, according to Black.

“It’s a very neat and clever idea,” says Deep Jariwala, an electrical engineer at the University of Pennsylvania in Philadelphia, who wasn’t involved in the project.

Glass is known for its durability. These glass platters can survive various harsh conditions. "You could leave [the glass platter] in boiling water,” says Black. “You can put it in the oven. You can microwave it.” Even if the surface gets scratched, the data inside remains intact.

How to write inside glass

“It’s fun to think about talking to aliens,” says Jon Lomberg, an artist based in Kona, Hawaii. While that may be an intriguing thought, these glass platters could soon serve significant purposes here on Earth. People generate and rely on an enormous amount of information every day, from medical data and scientific experiments to banking records, Hollywood movies, and much more.

Much of this information, Black explains in the podcast, “needs to be kept for a long time,” and it’s coming in at enormous volumes every day.

In 2014, researchers at the University of Southampton in England made a breakthrough by using lasers to record data inside glass for the first time. “We were very happy,” says Jingyu Zhang, a physicist at Huazhong University of Science and Technology in Wuhan, China, who was part of that team.

The laser pulses used are incredibly fast, measured in femtoseconds. One femtosecond is one-thousandth of one-millionth of one-millionth of a second, Black explains. By concentrating even, a small amount of energy on a tiny point for such a brief moment, surprising things happen. “The intensity at that point is just so mind-bogglingly high,” he says. “You get something called a plasma nano explosion.”

This explosion creates a tiny divot in the glass structure, known as a voxel. Voxel formation is predictable — whenever the laser is fired in the same way, the voxel forms consistently, Zhang explains. These voxels can function as 1s and 0s to represent digital data. Additionally, multiple layers of voxels can be stacked within a sheet of glass. To read the data, a microscope is used to focus on a small area of a single layer inside the glass. A camera then captures the pattern of voxels in that area.

In the decade following Zhang's team's discovery, Microsoft has been advancing the technology. They've developed methods to write and read voxels more quickly and reliably. Additionally, they now use machine learning, a form of AI, to convert voxel patterns back into digital data. They've also created a library of these data-storing glass sheets, which includes robots called shuttles that are responsible for shelving and retrieving the glass platters.

So far, a robot has never dropped a platter. But if one were to break or get lost, Black explains, its data could always be recovered from the other platters, thanks to a technique commonly used in data storage across various media.

At present, this is the only library of its kind, but Black has big ambitions. Microsoft operates hundreds of data centers, and “the goal,” Black says, “would be for a library like this to be in every data center.”

For data that needs to be accessed or worked with frequently, traditional hard drives will still be necessary. That’s because voxel patterns can't be altered once they’re written. “This is an archival form of data storage,” Jariwala explains. It’s designed to last for a long time without change, making it ideal for projects like the golden record.

Moreover, being unchangeable makes the data stored in glass nearly hack-proof, Black adds. This contrasts sharply with magnetic tape, which can be rewritten while it's being read.

Source: Explore Science News

Cite this article:

Priyadharshini S (2025), “High-Speed Lasers Inscribe Data in Glass to Endure for Millennia,” Anatechmaz, pp.109