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New ultrafast lasers needed for alternative Microsoft cloud storage

Opportunities could soon be on the horizon for laser manufacturers thanks to a new type of cold storage technology under development by Microsoft Research and the University of Southampton, in which ultrafast lasers are being used to scribe digital information into silica glass.

Introducing the new storage technology in his keynote presentation at the University of Southampton’s Future Photonics Hub industry day, Dr Benn Thomsen, senior researcher at Microsoft Research, explained how scribed glass could serve as an alternative to the current technologies used to store information – such as the photos taken with our smartphones – on the cloud.

‘At the moment we store that information on tape. The reason for that is because using lots of hard disks is too expensive,’ Thomsen said. ‘Tape has a short lifetime, however, it lasts about three to five years, meaning if we’ve stored a petabyte of information on tapes, in three years’ time we’re going to have to read that information back off the tape and put it on new tape. In addition, we’ve got many petabytes of new data coming in all the time, so this problem is getting exponentially worse.’

Microsoft Research has therefore been working with the University of Southampton on using lasers to write and store information in silica glass, which unless heated to an excess of a thousand degrees will likely last forever.

‘We’ve been using ultrashort laser pulses to store the information in little voxels in the glass,’ Thomsen explained. ‘The nice thing about this is that it’s a three-dimensional storage technology, you can actually control the orientations of nanogratings and use that to record information. You don’t have to store one bit per voxel, you can record three or five bits per voxel just by changing the angle.

‘For the first time the cloud has really given us as a company the opportunity to really put this into practice.’

At the moment the collaborators are using fairly expensive, research-style femtosecond lasers wielding 100-300fs, 1µm pulses at 1-50nJ in their initial explorations of the technique. However, Thomsen highlighted that a new range of laser technology would be needed if this new method of cold storage were to become widely adopted.

‘Going forward, because of the scale that we’re going to roll this out, new laser technology that is really optimised for these kinds of applications will be needed that is a lot less expensive, more compact and more reliable than the technology we are using today. So, there’s real opportunities there in the laser technology used,’ he said.

The application will also require new types of high-speed modulator, Thomsen added. ‘We have lots of these in the 1,500nm regime where we work in comms. However, not so many in the 1µm or the 500nm regime, where you’d like to work when writing in silica glass.’

The collaborators are currently using optical microscopy to read the information off the glass, and have been exploiting recent developments in camera technology for consumer electronics to improve the rate at which they can do this.

‘The developments in the cameras going into the back of phones is really pushing the technology both in terms of the number pixels and the frame rates available,’ Thomsen said. 'This is very good for us as it drives the IO rate – how fast you can read data back off silica glass.’

Image: Lasers can be used to inscribe information into silica glass in the form of three-dimenisional voxels. (Credit: University of Southampton).

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