Holographics set to feed a market hungry for data backup

It has taken 40 years, but our insatiable appetite for data has finally led to holograms for storage - if you've got the cash

Could magnetic tapes, hard drives and optical disc formats like Blu-ray be replaced by a data storage format that uses holograms? The world's first commercial holographic storage system is launched this autumn, with the product able to store the equivalent of 64 DVD movies on a disc about the size of a CD.

Holographic storage has been talked about since the 1960s, but it's taken more than 40 years for technology to catch up.

InPhase Technologies, based in Longmont, Colorado, is the latest company to get behind holographic storage. InPhase has spent 13 years developing materials, systems and processes. Its first products - marketed under the Tapestry brand - will be a 600GB write-once disc and a drive.

Biggest challenge

Wolfgang Schlichting, a research director at IDC, the analysis group, says: "The biggest challenge was developing the media. There was a lot of work on complex crystalline rewritable media, but the success of CD-R showed that write-once media could succeed, so then there was a switch to photopolymer materials. The cost and complexity of the optics has also decreased - you're now talking of technology that's similar to a digital camera."

The increasing demand for data storage makes it necessary to look beyond conventional forms of storage technology, such as optical discs or magnetic tape. The storage capacity of optical discs has increased over successive generations, from CD-Roms, which store around 700MB of data, to DVDs (18GB), and now next-gen formats such as Blu-ray and HD-DVD, which each hold upwards of 25GB. And there are plans for even larger capacity discs.

But despite this, optical disc technology has struggled to keep up with our insatiable appetite for data. That's why many archival systems still use magnetic tape, which offers large storage capacities at a cost-effective price. However, tape has its problems. Wlondek Mischke, director of research at technology company DaTARIUS, says: "Magnetic tape is very difficult to handle and very expensive [and] is waiting for something to replace it. Holographic storage could be the one."

But how successful will holographics be? Jim Porter, president of market research company Disk/Trend, says: "Any holographic storage system will have to be reliable, easy to use and be sold at a price that is considered by prospective buyers to be appropriate for the application."

The first holographic products are certainly not mass-market - a 600GB disc will cost around $180 (£90), and the drive costs about $18,000. Potential users include banks, libraries, government agencies and corporations.

Kevin Curtis, InPhase's chief technology officer, says: "Very large companies are showing the most interest, which is interesting, because large companies tend to be technology laggards. The amount of data they're getting through is becoming unmanageable." However, Bill Foster of consultancy Understanding & Solutions, says: "Tape technology is well established. It will be difficult to sweep aside."

What's more, tape technology is still evolving. Last year, IBM and Fuji Photo Film showed that it was possible to pack data on to magnetic tape with a density of 6.67bn bits per square inch - or 15 times the data density of standard tape. And magnetic hard disk capacity is also increasing thanks to perpendicular recording.

Nor does holographic storage look like replacing optical disc formats any time soon. "Any storage system with the capability to supersede today's optical discs will have to have rewritable versions and be offered at more attractive prices. Holographic products will not reach these objectives in the foreseeable future," says Porter. Jean-Paul Eekhout, TDK's corporate strategy director, adds: "Holographic storage will be complementary to formats like Blu-ray. It's more a B2B [business-to-business] technology and will find a place in the archival market. But I don't expect holographics in its current shape or form to cross over to the commercial market."

Even InPhase acknowledges that we are unlikely to see pre-recorded videos on holographic discs for a long time - if ever. "We're not looking at [packaged] content," admits Curtis. Conventional optical discs and drives are cheaper to produce and there is a huge hardware and software infrastructure based around them.

But Walden says: "We believe the technology lends itself to both business and consumer applications. Almost every company involved in optical storage is also looking at holographics as a potential candidate for the next generation of optical disc." IDC thinks that by 2011, the holographics drive market will worth around $200m globally, a small portion of the multibillion-dollar data storage market.

David Mercer, principal analyst at research group StrategyAnalytics, says: "The challenges will revolve around production economics and industry standards, and these alone are likely to delay the emergence of significant consumer volume opportunities."

Consumer applications

Mercer believes holographic technology will play some role in storage devices aimed at consumer applications, such as content archiving and creation, but adds that: "It will be more challenging to develop a video distribution and publishing standard around holography, as this will involve the coordination of interests in content ownership and protection, device manufacturers and others. By the time these pieces fall into place, video distribution will have migrated to some degree towards online models so the need for a physical media platform may be in doubt."

Indeed, Microsoft chairman Bill Gates thinks that formats such as Blu-ray and HD-DVD represent the last generation of physical video formats, with future generations downloading videos on demand.

But Foster says that holographic storage might stand a better chance at challenging another storage medium - flash memory. "Holographic storage doesn't have to be on a disc - it can also be on solid state medium," he says. So perhaps holographic storage's day has finally come.

· How holograms work

The source material (such as a photographic image or video footage) is encoded with error correction and channel data, but instead of the encoding being carried out on a bit-by-bit basis (as with say, CD or DVD), around 1m bits are generated at one time, which are recorded as a single page. The process uses light from a single laser split into two - a signal beam, which carries the data, and a reference beam. Where the two beams intersect, the interference pattern (hologram) is recorded within a photosensitive storage medium. Note "within" - because holographic storage is a 3D process that uses the entire recording layer and not just the surface of the medium.

The data is recorded throughout the depth of the media uniformly, and multiple pages of information can be recorded in the same volume by changing the angle of one of the two beams. To read the data, a reference beam with the same characteristics used during the recording process is shone on to the holographic disc and the deflected beam is read by a digital camera detector.

Holographic storage offers extremely fast data transfer rates - currently up to 160Mbit/sec, though there are plans to increase this.

An alternative system uses micro-holograms to record discrete recording layers, like a multi-layer DVD.

Liz Murphy, of InPhase, says: "You only have one opportunity to introduce a product and there's so much anticipation about this. We want holographic storage to be successful."
