Matsushita Electric Industrial Co. Ltd. has developed a rewritable optical disc with a capacity of 50G bytes, the company announced Monday.
The breakthrough uses a blue laser to store the data on a dual-layer optical disc 120 millimeters in diameter, said Yoshinari Takemura, a spokesman for Matsushita.
Until now, this dual-layer approach, which allows one side of a disc to hold two recording layers, was only possible using red lasers. Currently, a red laser with wavelength of 850 nanometers is used for optical discs. However, a laser beam with a shorter wavelength can register smaller dots on a disc, meaning more data can be stored. When a blue laser, which has a 425 nanometer wavelength, is used for recording data on an optical disc, it can record more data -- in this case five times more -- than a red laser, which can store up to 4.7G bytes on one layer. Using a blue laser, it is possible to make discs with two layers, each of which can store around 25G bytes of data on a 120 millimeter disc, according to the company statement.
Matsushita, better known by its Panasonic brand name, developed a new material called a GeSbTe (germanium antimony tellurium) film for the recording layer of the disc which can record information at the high densities possible with blue lasers, Takemura said.
The disc records and retrieves data at up to 33M bps (bits per second), making it three times faster than "conventional" DVD (digital versatile disc) technology, the company said. Its speed and capacity make it possible for a 50G-byte disc to record more than four hours of high-definition digital TV pictures, which have a data transfer speed of 25M bps, according to the statement.
The company hopes the new optical disc will be used as a recording medium for high-definition digital TV programs, and hopes to have the product on the market by the time broadcasting of such programs starts in Japan, expected to be in 2003, Takemura said.