Stacked Volumetric Optical Disc

The Stacked Volumetric Optical Disc (or SVOD) is an optical disc format developed by Hitachi/Maxell, which uses an array of wafer-thin optical discs to allow data storage.

Each "layer" (a thin polycarbonate disc) holds around 9.4 GB of information, and the wafers are stacked in layers of 100 or so, giving overall data storage increase of 100× or more.

SVOD might likely be a candidate, along with HVDs, to be a next-generation optical disc standard.