Recent advances in optical data storage have led
to the development of a five-dimensional device
that could hold up to 2,000 times more data than a
conventional DVD. These authors discuss this and
other milestones on the road to multi-dimensional
optical memory with petabyte capacity.
Bit-by-bit optical data storage. Inset: Bits are pre-recorded by a photoinduced physical
or chemical change in a recording medium. Information is retrieved back by detecting
the intensity variation of a reading beam when the optical disc is scanned.
Optical data storage has led to revolutionary advances in informa- tion technology and storage. One of the challenges in this field is to meet the rapid growth in demand for storage capacity. Bit-by-bit optical data storage systems such as compact discs (CDs), digital video discs
(DVDs) and Blu-ray discs (Blu-rays) have emerged as compact, portable devices
that have high memory density and high resistance to intense electromagnetic
radiation. Given its high tolerance to vibration and robust reliability, bit-by-bit
optical storage has been shown to be superior to holographic memory.
Each technological breakthrough comes with a new expansion of the storage
capacity but also with its own limitations. Bit-by-bit optical data storage uses
photons to introduce a localized physical or chemical property change—such
as photoinduced fluorescence or reflectance modulation—as information storing processes. When an optical disc is scanned, pre-stored information can be
retrieved back by detecting the intensity variation of the reading beam; the “on”
or “off” state corresponds to a “ 1” or “0.”
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