How can you save data in glass? Data can be saved in glass by using an ultrafast laser to write tiny permanent marks inside it. It is also called 5D storage. Those marks are far too small to see with the naked eye, but they can still be read later because they change the way light passes through the glass.
Human beings have always wanted to leave information behind. For most of history, that meant writing on materials like paper, papyrus, wood, clay, or stone. Some of those materials lasted surprisingly well. Clay tablets from ancient Mesopotamia have survived for thousands of years, and inscriptions cut into stone can still be read long after the people who made them are gone. But even the most durable old materials had weaknesses. Paper rots, burns, and gets eaten. Wood decays. Stone can break, weather, or be buried and forgotten. Preserving information for a very long time has never been as easy as simply writing it down.
Modern storage devices have a different problem. Hard drives, CDs, magnetic tape, USB drives, and solid-state memory can hold a huge amount of data, but none of them are ideal for extremely long-term storage. Some wear out physically. Some become unreadable because the format becomes obsolete. It was not so long ago that floppy disks and cassette tapes were common, but many people now have no way to read them. Even if the data survives, the machine needed to access it may disappear first. That is why researchers are interested in finding new ways to preserve important information for the distant future.
Glass is attractive because it is stable, durable, and does not need electricity to hold information once it has been written. It is resistant to water, heat, and electromagnetic interference, and the data is stored inside the material rather than on the surface. A scratch on the outside does not necessarily destroy what is held within. Glass also changes very little over time, which makes it useful for archiving. The goal is not to replace ordinary computer memory for everyday use, but to create a medium that could safely preserve valuable information for an extremely long time.
The writing process uses a femtosecond laser. A femtosecond is an unbelievably short length of time, one quadrillionth of a second. Because the pulses are so brief and so precisely controlled, the laser can deliver energy into a tiny point inside the glass without significantly affecting the rest of the material. That is the part that can seem strange at first. It is easy to imagine a laser beam burning all the way through whatever it touches, but that is not what happens here. The beam is focused so precisely that the real effect happens at the exact point where the energy is concentrated.
At that tiny point, the structure of the glass is altered. It is not really a large explosion in the ordinary sense. It is more like a microscopic change being made at a carefully chosen location. That tiny written point is called a voxel, which is basically the three-dimensional version of a pixel. By moving the glass or adjusting the focus of the laser in tiny X, Y, and Z steps, researchers can place these voxels exactly where they want them. In that way, the glass can be filled with layers of microscopic marks.
This is where the idea of 5D storage comes in. The “5D” does not mean five dimensions in the science-fiction sense. It means that the data is stored using five measurable properties. Three of those are simply the position of the voxel in space: X, Y, and Z. The other two are the orientation of the tiny structure and the strength of its optical effect. In other words, a voxel is not just a dot. It also has a certain internal arrangement and a certain optical character. That means one mark can carry more information than a simple yes-or-no signal.
A useful comparison is handwriting on paper. A written mark carries information because of where it is on the page, the angle of the stroke, and how heavily it has been made. Glass storage works in a somewhat similar way. A voxel can be located at a certain point, formed at a certain angle, and made with a certain optical strength. When many such voxels are arranged together, they can represent a large amount of digital information in a very small space.
Reading the data back involves shining light through the glass and measuring how those tiny internal marks affect it. The written regions interact with light differently from the untouched regions around them, and sensitive equipment can detect those differences. A computer then interprets the pattern and converts it back into digital data. So the information is not stored as visible writing, but as microscopic changes in the material that can be recognized optically.
The result is a storage system with remarkable potential. A small piece of glass can hold a surprising amount of information, and because the marks are written inside a stable material, the data may survive far longer than it would on conventional media. At the moment, the process is still expensive and technically difficult, so it is not something that will replace everyday storage devices any time soon. Still, as a way of preserving human knowledge far into the future, it is a fascinating idea. In a sense, it brings the story of information storage full circle. After thousands of years of writing on clay, stone, paper, and plastic, one of the most promising ways to preserve the future may be to write it into glass. And this is what I learned today.
Sources
https://www.theguardian.com/technology/2026/feb/18/scientists-new-way-preserve-data-microsoft
https://en.wikipedia.org/wiki/5D_optical_data_storage
https://en.wikipedia.org/wiki/Mode_locking
https://www.sandisk.com/topics/ssd/how-long-do-ssds-last
https://en.wikipedia.org/wiki/Solid-state_drive
https://en.wikipedia.org/wiki/Cuneiform
Photo by Magda Ehlers: https://www.pexels.com/photo/diamond-on-top-of-a-disc-4198863/