Toshiba's New Dual-Layer, Single-Sided, Blue-Laser Rewritable Optical Disc Needs Only Current Production Facilities

9-May-03

Toshiba Corporation announced that it has developed a working prototype of a high-capacity dual-layer, single-sided, blue-laser rewritable optical disc. The new disc is said to offer key advantages in that it can easily be brought to mass production with only minimal adjustments to current DVD production facilities, and that its current capacity can be increased significantly. The new disc is also expected to promote lower production costs for next-generation optical discs, while offering simple implementation of backward compatibility with today's generation of DVD formats.In August 2002, Toshiba and NEC jointly proposed to the DVD Forum a format for a next-generation, high-definition system based on a high-capacity, blue-laser DVD. This is now under discussion. That format covers a 15 GB single-layer, single-sided, read-only disc; a 30 GB dual-layer, single-sided, read-only disc; and a 20 GB single-layer, single-sided read-and-write disc.The proposed format utilizes a short-wavelength blue laser and the same disc structure used in current DVDs--back-to-back bonding of two 0.6mm-thick 120mm discs. This approach not only supports continued use of today's DVD disc manufacturing equipment, but is claimed to deliver higher production yields than alternative disc structures based on stacked discs. The Toshiba-NEC format also employs an objective lens with a numerical aperture of 0.65, very close to that of current DVD technology.Since proposing the format, Toshiba has continued development work and has now achieved and demonstrated the practicality of a high-capacity, 36 GB dual-layer, single-sided read-and-write disc that can be applied to both consumer electronics and computer applications.Toshiba's new high-capacity dual-layer disc employs Germanium-Tellurium-rich, Germanium-Antimony-Tellurium-Bismuth (GeSbTeBi) alloy recording layers that support improved signal processing and erasability. The disc's dual-layer structure has a high level of manufacturability and a capacity that can be pushed to higher levels.In summing up the advantages of the new disc, Toshiba noted pluses in the manufacturing process from maximizing similarities with current DVD. The working prototype allows use of the same manufacturing infrastructure as current DVD, supporting manufacturers by limiting the need for new investments, while also minimizing disc production costs and delivering high yields. The new disc also assures backward compatibility with current CDs and DVDs, and supports fabrication of discs that do not need a cartridge--an essential feature for slim drives that can be integrated into portable equipment.Toshiba will present the disc technology at Optical Data Storage 2003 on May 13. The company will propose the dual-layer format to the DVD Forum in the latter half of this year.

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