Storing Data in Glass: Southampton's 5D Optical Storage

November 11, 2021

Researchers at the University of Southampton in the UK have been working since the early 2010s on a way to store data in glass that, by their estimate, could last for billions of years. In 2021 the team, led by Professor Peter Kazansky, reported a much faster way to write such data, a step towards archives that could preserve human knowledge far longer than today's storage media.

What 5D optical storage is

The method uses a femtosecond laser, which fires extremely short pulses, to write tiny nanostructures inside fused silica glass. Each written point, or voxel, carries information in five "dimensions": its three spatial coordinates plus the orientation and size of the nanostructure, which change how it affects polarised light. The data is read back with an optical microscope and a polariser. Because fused silica is very stable, the researchers estimate that the data could survive for billions of years.

The 2021 result

Earlier versions of the technique were too slow to be practical. In a paper published in Optica in October 2021, doctoral researcher Yuhao Lei, Peter Kazansky and colleagues described a writing method based on near-field enhancement: a single laser pulse creates a tiny void, which then concentrates the energy of a few weaker pulses that form the data-carrying nanostructure. This limits heat damage to the glass. The method reached 1,000,000 voxels per second, about 230 KB of data per second, and the team wrote 5 GB of text to a silica glass disc and read it back with nearly 100% accuracy.

At this density, a glass disc the size of a CD could in theory hold about 500 TB, which the researchers described as more than 10,000 times denser than a Blu-ray disc. With planned parallel writing, the researchers estimated that filling such a disc would take about 60 days.

What happened next

In September 2024 the team announced that it had stored the full human genome on a 5D "memory crystal", now kept in the Memory of Mankind archive in a salt cave in Hallstatt, Austria. According to the University of Southampton, the largest crystals can hold up to 360 TB.

The technology is being commercialised by SPhotonix, a start-up that came out of stealth in late 2024 with Peter Kazansky as chief scientific officer. In November 2025 it raised $4.5 million in pre-seed funding for the final technology-readiness steps needed to bring 5D optical memory into data centres.

Microsoft has worked on similar technology. Its Project Silica stored the 1978 film Superman on a small piece of glass with Warner Bros. in 2019, and in 2023 the team presented a design for a cloud archival storage system built on glass. In February 2026 Microsoft researchers reported in Nature that data can also be written into ordinary borosilicate glass, the material used in oven doors, with an expected lifetime of at least 10,000 years. Microsoft said the research phase was complete, without announcing a product. Scientists are also recording information in DNA, which is even denser but still slow and costly to write and read.

Why it matters for businesses

Magnetic tape is still widely used for long-term archives. The current generation, LTO-10, holds 30 TB or 40 TB per cartridge without compression, according to the LTO Program. Tape is cheap, but each drive reads only a limited range of tape generations, and LTO-10 drives cannot read older cartridges at all, so archives have to be migrated to new media from time to time.

Glass is attractive for data that must be kept for decades: compliance records, medical and scientific data, cultural archives, and the "cold" tier of data-centre storage that is written once and rarely read. Once written, it needs no power to keep the data intact. The limits are just as clear: writing is still slow compared with tape, reading requires specialised optical equipment, and data in Project Silica's glass cannot be rewritten. With SPhotonix still at the pre-seed stage in late 2025 and no product in Microsoft's 2026 update, glass storage is a technology to watch rather than buy. As the data centre market keeps growing, so will the pressure to find more durable archive media.