Pioneer claims that a 20-layer optical disc is now viable, following research by our team of engineers at Pioneer HQ, Tokyo. Each layer of the disc can store 25GB of information to provide a mammoth 500GB of storage.

The multi-layered method is compatible with Blu-ray devices providing a long term future for the technology and is more easily produced when compared to competing technologies such as holographic storage.

One of the technical issues addressed was the problem of ‘crosstalk’ between the separate layers of optical media. Due to the close proximity of the layers, data from one layer could interfere with that from another layer. By applying proprietary technology developed for its BD products and by stacking two different thickness of layers alternatively, interlayer crosstalk was reduced, thus further confirming the feasibility of 20-layer optical discs.

more here