How to fit 300 DVDs on one disc

A new optical recording method could pave the way for data discs with 300 times the storage capacity of standard DVDs, Nature journal reports.
The researchers say this could see a whopping 1.6 terabytes of information fit on a DVD-sized disc.
They describe their method as "five-dimensional" optical recording and say it could be commercialised.
The technique employs nanometre-scale particles of gold as a recording medium.
Researchers at Swinburne University of Technology in Australia have exploited the particular properties of these gold "nano-rods" by manipulating the light pointed at them.
The team members described what they did as adding three "dimensions" to the two spatial dimensions that DVD and CD discs already have.
They say they were able to introduce a spectral - or colour - dimension and a polarisation dimension, as well as recording information in 10 layers of the nano-rod films, adding a third spatial dimension.
The scientists used the nanoparticles to record information in a range of different colour wavelengths on the same physical disc location. This is a major improvement over traditional DVDs, which are recorded in a single colour wavelength with a laser.
Also, the amount of incoming laser light absorbed by the nanoparticles depends on its polarisation. This allowed the researchers to record different layers of information at different angles.
The researchers thus refer to the approach as 5-D recording. Previous research has demonstrated recording techniques based on colour or polarisation, but this is the first work that shows the integration of both.
As a result, the scientists say they have achieved unprecedented data density.Their approach used 10-layer stacks composed of thin glass plates as the recording medium. If scaled up to a DVD-sized disk, the team would be able to record 1.6 terabytes - that is, 1,600 gigabytes - or over 300 times the quantity stored on a standard DVD.
Significant improvements could be made by thinning the spacer layers and using more than two polarisation angles - pushing the limits to 10 terabytes per disc and beyond, the researchers say.