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A new method of writing data onto glass using lasers could store 500 terabytes on a single optical disc – but it takes so long to create that its applications may be limited.

The technique uses similar technology to existing optical media, but can store 10,000 times more data than Blu-ray discs. It involves a laser that sends out pulses every femtosecond – 1 quadrillionth of a second – to etch minute holes into glass.

at the University of Southampton, UK, and his colleagues call the method five-dimensional (5D) optical data storage because it uses two optical dimensions, based on the polarisation and intensity of light, along with the usual three spatial dimensions, to record data.

In tests, the researchers managed to write 6 gigabytes of data onto a 1-inch square of glass. They could read the data back with between 96.3 and 99.5 per cent accuracy, which could be improved to 100 per cent with an error correction algorithm, says Lei.

“The major challenge for us is writing speed,” he says, as they could only write 225 kilobytes a second, meaning the 6 gigabytes took around 6 hours. “We are not currently doing parallel writing [where multiple laser beams write onto the material]. We’re working on improving that.”

“This data storage is very durable and can withstand high temperatures, which means it can live almost forever,” says team member at the University of Southampton.

With small tweaks, the writing speed could become four times faster, says Kazansky – though he isn’t yet sure whether that could materially increase the chance of errors. The intention is to provide a storage method for national archives, says Lei.

“It’s great to see the apparently vast improvements that have been made in the write speeds and general performance of this storage technology in a lab environment in just a few years” says of Small Data Industries, a New York archiving firm, pointing to a 75 times improvement over an earlier version of the technique that could only write at 3 kilobytes per second . “What remains unclear is what practical role 5D glass storage could hypothetically play in the future.”