Hitachi has developed a new technology that is capable of storing up to 500GB of data onto discs that have a super-resolution film on their substrate.

The company said that the new technology can be applied to the next-generation optical discs. Hitachi's achievement takes advantage of a new signal processing technology that is capable of increasing the S/N (signal-to-noise ratio) ratio of the playback signal of a multi-layer "super-resolution" optical disc. This paves the way to the development of optical systems capable of storing up to 500GB of data on 12cm discs.

A super resolution optical disc uses a nonlinear optical thin film formed on a substrate. The nonlinear optical thin film comprises an amorphous alloy or a mixture of the amorphous alloy and an oxide glass component. The film has a refractive index which changes in response to a change of intensity of a laser beam incident thereto.

In addition, Hitachi developed a new signal processing circuit that was essential in order to filter the low-frequency noise that was introduced in the reading signal. The noise was related to the low-temperature areas of the super-resolution substrate.

Story filed 28.05.07