Yesterday we brought you what could be the DVD-killer, Blu-ray, but Japanese firm Optware has gone one step further with an optical disc that can store more than 1TB (one terabyte, or 1,000 gigabytes).

Optware says the discs and an associated disc player should be available later this year. The disc and player are based on the standard 12cm size optical disc, but the new disc will be able to store about 120 DVD-format movies, according to Atsushi Machida for Optware.

The high capacity — around 20 times the storage available on existing discs — and a data transfer speed of 1Gbps (gigabit per second) was originally achieved by using digital volume holography read/write technology and developed by the US' Darpa (Defense Advanced Research Project Agency), according to Optware.

But in this form the technology is costly, unreliable and not compatible with existing disc media.

But, says Optware, it has developed a reliable method of storing data in 3D on existing CD/DVD media. It will start sample shipping of the disc and the replay device in the third quarter of this year. Its first product will be a write-once disc, to be followed by rewritable discs, Machida said.

Here comes the science bit

So you want to know how to stuff a million megabytes on to a CD? Read on, but don't say we didn't warn you.

  • Darpa's system:

    The system firstly splits a laser source into two beams, signal (data-carrying) and reference beams.

    The signal beam goes through a spatial light modulator, which has pages of data arranged in a checkerboard pattern.

    The pattern either blocks or transmits light, therefore the signal beam will encode data via the spatial light modulator.

    This encoded beam then interferes with the reference beam via an optical lens to record on to a photosensitive volumetric recording medium.

    By changing the angle or wavelength of the reference beam, the technology allows many different data pages to be recorded in three dimensions and read out in the same recording medium, allowing for enormous storage capacity.

  • Optware's development:

    Conventional optical disc systems use a single red laser beam to write a dot, containing one bit of information, to a disc surface.

    Optware's technology, known as polarised collinear holography, splits the signal laser beam into one million narrower beams.

    It creates data pages in the same way as the Darpa system and, with the help of a separate reference laser beam, writes the data in 3D to the disc's volumetric recording layer.

    One million bits of information can be stored for each dot, Optware said.