Work on the technology began more than 40 years ago, and two companies -- InPhase Technologies of Longmont, Colo., and Japan's Optware Corp. with its Holographic Versatile Disc (HVD) -- will finally ship the first commercial offerings late this year. InPhase's first Tapestry drive, the HDS-300R, will use 300 GB write once disks designed for professional archiving, complete with RFID
But in the meantime, both the Optware and InPhase drives are targeted at the enterprise storage market, with drives priced at approximately $12,000 and media at $120. Archival life is specified at greater than 50 years. Consumer-grade disks will probably not appear until after 2009, according to Optware founder and chief technology officer Hideyoshi Horimai.
The promise of holographic storage lies in its volumetric approach. Data isn't stored on the medium's surface; instead, it uses the third dimension by employing inverted cones approximately 500 microns thick at the top. Superimposed holograms share the same 3D space; the recording beam distinguishes them via different angles, phases or wavelengths. The theoretical limit is storing one bit in a cubic block the size of the light's wavelength. Practical densities will always remain much lower, but 10 TB or more on a CD-sized disk is feasible. Holographic drives don't store bits, but pages of 60 Kbit or more, writing one page with a single laser flash. They can read and write in parallel: To achieve higher transfer rates, the orange-colored disk doesn't have to spin any faster.
Though not currently championed by any standards bodies, Optware's technology could greatly expand the reach of holographic storage by enabling things like combination holographic/DVD drives, physical on-disk encryption or the use of holographic storage as an alternative to flash memory in consumer-device manufacturer items, like cell phones and camcorders.
While other systems require separately angled signal and reference beams, Optware's beams are collimated (parallel) on the same axis, reducing the bulk and complexity of a read/write mechanism. This so-called collinear system can use preformatted disks with address "pits" that are similar to today's CD and DVD technology. While a blue-green laser reads and writes, a red laser ensures accurate positioning. Because the servo positioning is so similar to today's DVD, it's conceivable that future drives might be able to use both. Collinear technology is also capable of physical on-disk encryption, which holds great promise for digital rights management and other sensitive applications, the company says.
For now, the challenge is to get holographic storage into the hands of the enterprise. "With a little bit of luck, they'll make their ship date," said Dr. Hans Coufal, manager, science and technology at IBM's Almaden Research Center. Then the real issue becomes gaining "credibility for a new technology."