Denser DVDs

Toshiba has developed a working prototype of a high capacity dual-layer, single-sided, blue-laser rewritable optical disk.

Toshiba claims that the new disk can be brought to mass production with only minimal adjustments to current DVD production facilities, and that its current capacity can also be increased significantly.

In August 2002, Toshiba and NEC jointly proposed a format to the DVD Forum for a new high-definition DVD system based on a high-capacity, blue-laser DVD. That format covers a 15GB single-layer, single-sided read-only disk, a 30GB dual-layer, single-sided, read-only disk, and a 20GB single-layer, single-sided read-and-write disk. These capacities significantly improve on the 8.5GB capacity of current dual-layer, single-sided read-only DVD disks and 4.7GB single-layer, single- sided read-and-write DVD disks.

The proposed format uses a short wavelength blue laser and the same disk structure used in current DVDs – back-to-back bonding of two 0.6mm thick, 120mm disks. The Toshiba-NEC format also employs an objective lens with a numerical aperture of 0.65, very close to that of current DVD.

Since proposing the format, Toshiba has continued development work and has now achieved and demonstrated the practicality of a 36GB dual-layer, single-sided read-and-write disk that can be used in both consumer electronic and computer applications.

Toshiba’s new high-capacity dual layer disk employs Germanium-Tellurium-rich Germanium-Antimony-Tellurium-Bismuth (GeSbTeBi) alloy recording layers and is backwards compatible with current CDs and DVDs.

Toshiba will present details of the new disk and the technology behind this week at ‘Optical Data Storage 2003’ at the Hyatt Regency of Vancouver, BC Canada, and will propose the dual-layer format to the DVD Forum in the latter half of this year.

On a related note, Microsoft Corporation has said that it plans to provide native support for all major recordable formats including DVD-RAM, DVD-R and DVD-RW in the next version of the Windows operating system.

With this announcement, all major DVD recordable formats standardised by the DVD Forum will receive native support from Windows, along with DVD-RAM, which is currently supported.

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