Femtosecond lasers enable data storage in quartz
Researchers at the University of Southampton and Cambridge have been working with Microsoft on a long term quartz data storage system.
Long-term storage costs are driven up by the need to repeatedly transfer data onto newer media before the information is lost. Hard disk drives can wear out after three to five years. Magnetic tape may only last five to seven. File formats become obsolete, and upgrades are expensive. Film companies such as Warner Bros proactively migrate content every three years to stay ahead of degradation issues.
Quartz storage has the potential to become a lower-cost option as the data is stored just once. Femtosecond lasers developed at Southampton permanently change the structure of the material, so the data storage can be preserved for decades, even centuries.
The quartz glass developed in Project Silica also doesn’t need air conditioning to keep material at a constant temperature or humidity, reducing the cost of long term cloud data storage.
“We are not trying to build things that you put in your house or play movies from. We are building storage that operates at the cloud scale,” said Ant Rowstron, partner deputy lab director of Microsoft Research Cambridge in the UK.
“One big thing we wanted to eliminate is this expensive cycle of moving and rewriting data to the next generation. We really want something you can put on the shelf for 50 or 100 or 1,000 years and forget about until you need it,” he said.
Microsoft and Warner Bros. have copied a digital version of Superman to the quartz storage. The infrared lasers encode data in voxels, the three-dimensional equivalent of the pixels that make up a flat image. Unlike other optical storage media that write data on the surface, Project Silica stores data within the glass itself. A 2-mm-thick piece of glass can contain more than 100 layers of voxels.
Data is encoded in each voxel by changing the strength and orientation of the laser pulses that physically deform the glass. To read the data back, machine learning algorithms decode the patterns created when polarized light shines through the glass.
Early on, the research team tried baking one in an oven at 500ºC – hence the use of quartz glass rather than a more fluid vesion, microwaving, boiling it and scouring it with steel wool. When they read the data back, it was all still there.
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