Data Storage That Could Outlast the Human Race

Researchers’ “Superman memory crystal.”

Just in case you haven’t been keeping up with the latest in five-dimensional digital data storage using femtocell-laser inscription, here’s an update: it works.

A team of researchers at the University of Southampton have demonstrated a way to record and retrieve as much as 360 terabytes of digital data onto a single disk of quartz glass in a way that can withstand temperatures of up to 1000 C and should keep the data stable and readable for up to a million years.

“It is thrilling to think that we have created the first document which will likely survive the human race,” said Peter Kazansky, professor of physical optoelectronics at the Univ. of Southampton’s Optical Research Centre. “This technology can secure the last evidence of civilization: all we’ve learnt will not be forgotten.”

Leaving aside the question of how many Twitter posts and Facebook updates really need to be preserved longer than the human species, the technology appears to have tremendous potential for low-cost, long-term, high-volume archiving of enormous databanks.

Optical storage—in the form of CDs and DVDs—were the medium of choice for data archives for decades, until the 4.7GB capacity limits on DVDs made them impractical for storage volumes measured in petabytes.

The quartz-glass technique relies on lasers pulsing one quadrillion times per second though a modulator that splits each pulse into 256 beams, generating a holographic image that is recorded on self-assembled nanostructures within a disk of fused-quartz glass.

The data are stored in a five-dimensional matrix—the size and directional orientation of each nanostructured dot becomes dimensions four and five, in addition to the usual X, Y and Z axes that describe physical location. Files are written in three layers of dots, separated by five micrometers within a disk of quartz glass nicknamed “Superman memory crystal” by researchers (after the glass crystals that stored video of Kal-El’s flight from Krypton in the first Superman movie).

Data is read using an optical microscope and a polarization filter similar to those found in sunglasses, which limits the viewing angle to one that allows the nanodots to be read correctly.

The idea of using femtocell lasers to write data on transparent material has been around since 1996, but has not been demonstrated in practical form until now, according to a paper describing the technique (PDF), presented in June at the photonics-industry Conference on Lasers and Electro-Optics in San Jose, Calif. (Hitachi has also been researching the technique, but hasn’t yet created a commercial version.) If the technique turns out to be practical outside the laboratory, the glass disks will offer a number of advantages in addition to storage capacity, according to Jingyu Zhang, a Univ. Southampton graduate student and lead researcher on the project.

“At the moment companies have to back up their archives every five to ten years because hard-drive memory has a relatively short lifespan,” Jingyu wrote in a press release announcing the experiment. The long lifespan of data recorded in glass would make data archives more stable, not to mention more manageable than relying on tens of thousands of optical disks.

“Museums who want to preserve information or places like the national archives where they have huge numbers of documents, would really benefit,” Zhang added.

 

Image: Jingyu Zhang et al., ORC, Univ. Southampton

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