Holographic data storage

Abstract

Both magnetic and conventional optical data storage technologies store individual bits of information as distinct magnetic or optical changes of the surface of the recording medium. Currently, both of these techniques approach physical limits of storage density beyond which the bits are either too small to detect or the tolerances imposed on the storage media become too stringent. In magnetic storage, the superparamagnetic limit seems to be not far away, and recording head scaling becomes a growing problem. Optical storage technology, such as blue DVD, is reaching its practical limits of capacity (25 gigabytes per layer in a CD-size disk). To further improve capacity and transfer rates, several options are available, including increasing the NA beyond 0.85, reducing the wavelength below 400 nm, or adding more layers. All these options present significant challenges.