News

posted on 30 July 2008 10:11

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University of California Irvine researchers have devised a way to have a DVD-size optical disk store a terabyte of data.

A paper in the Applied Optics journal (subscription required) describes their work. It is based on creating 200 layers in a 120mm x 1.2mm format disk.

The disk is made from a polymethylmethacrylate (PMMA) matrix that contains dye precursor (DP) molecules and light-sensitive photoacid generator (PAG) molecules. If the PAG molecules are exposed to one ultra-violet or two visible light photons from a 532nm laser then they change into a strong acid which converts a nearbye DP molecule into a flourescent dye called Rhodamine 700. If a 635nm laser is then shone on the Rhodamine its flourescence can be detected and signals a binary zero or one.

(This Rhodamine fluorescence is also the basis of Call/Recall's 1TB optical disk technology.) The Rhodamine dots, with a 5 micron separation between them, are in one of 200 layers and the recording and reading laser beams can be focussed on each layer.

A demonstration disk has been recorded with 5GB of data capacity per layer. The paper's authors think a 200-layer disk is possible, hence the 1TB capacity. Follow-on technology might achieve a five-fold increase in capacity. It is a write-once technology for now.

There is no imminent prospect of productisation at all.

^{[Martin Edwards, news writer.]}