Japanese scientists have proposed a new method for storing more data on optical discs by using arrays of multidirectional V-shape pits.

Current high-density optical recording systems in combination with a blue laser diode and a high numerical aperture (NA) optics have increased the capacity of optical disks to a 20 Gbits level in the Blu-ray system. For further increase of the data storage capacity, technologies such as a holographic data storage, a polarization multiplex recording system, a multilayer optical disk have now been developed. However, these technologies have not the simplicity enabling mass-production by simple stamper processing applied in the production of current CD and DVD media. Other methods proposed for the increase of the capacity of discs include multi-bits configurations of depth controlled single pits. Although these methods enabled stamper reproduction, they require high precision in the pit shape reproduction since the principle is based on the optical multiplexing involving the reflection phase modulation by the pit geometry.

Toshihide Tsuru and Masaki Yamamoto of Tohoku University in Japan, proposed a new concept of high-density recording by imprinting an array of V-shape pits composed of mirror facets of specified directions and slopes on a media surface.

The method can increase the capacity of CD and DVD media by nine times, according to the scientists.



Reading the stored data on the CD or DVD media (1 and 0) requires the read out of the direction of the facet. This has been achieved by determining the parameters of the reflected light, which appears as elliptically polarized . Scientists claim that they have successfully read out the stored data with very high accuracy.

Scientists said that structure of this single layer geometry is compatible to current mass-production of optical storage discs by stamping.

The technology may also help realizing a variety of high density memory applications. However, it cannot be applied on Blu-ray discs and of course, the V-pit cd /DVD discsc are not compatible with current CD/DVD ROM drives.

More information is available in the Japanese press release of the Tohoku University.