06 May 2009
After six years of development, GE has demonstrated materials that could store 500 gigabytes of data in a standard DVD-sized disk.
The ability to store 1 terabyte of information on an optical disk, a long-standing Holy Grail of the data storage world, has moved a step closer. GE Global Research, the technology development arm of General Electric, has demonstrated a microholographic storage material that it claims could support 500 gigabytes of storage capacity in a standard DVD-sized disk.
Holographic data storage involves the creation of optical interference patterns in a photosensitive medium, using two separate laser beams derived from a single source. By adjusting variables such as the beam angle, wavelength or media position, a large number of holograms can be stored on a single disk, and can be positioned throughout the volume of the storage media.
The GE team successfully recorded microholographic marks with a diameter of approximately one micron and reflectivity approaching 1% in a storage material. It is this level of reflectivity that provides the key.
"We are creating chemical changes in microscopic patterns that will generate higher reflectivity when read by a low-power laser," said programme leader Brian Lawrence. "Recently we have made dramatic increases in the amount of light that can be reflected by the holograms. Reflectivities as high as 1% represent a 100–200× improvement in performance. When we scale the holograms down in size to those that would correspond to the marks created using standard DVD or Blu-ray optics, the reflectivities will be sufficient to enable the storage of up to 500 gigabytes of data in a single CD-sized disk."
GE's holographic storage programme has now turned the corner, according to Bill Kernick of GE's Technology Ventures team: "With this milestone we can now intensify our efforts in commercialization opportunities," he said. Those opportunities will lie initially in the commercial archival industry, with consumer applications following at a later stage.
• Other techniques to approach the 1 terabyte goal include a range of optical methods such as chromophore poling and deliberate void formation in optical materials, although progress to date has been mixed. Israeli developer Mempile told optics.org about reaching the 300 gigabyte mark using its Teradisk process based on two-photon absorption of light-sensitive chemicals, but developments beyond that level appear to have slowed.