Holographic storage has been bandied around as a potential replacement for magnetic and solid state storage for quite a while, but new advances made by a research group in Melbourne, Australia are the first indication that the technology may be developing to a point at which its use will be practical.
Traditional magnetic storage encodes data on the surface of some medium with a series of ones and zeros. The density of such storage media is constantly improving but the physical limitations of the process means that in time we’ll reach a hard limit beyond which the technology cannot be significantly improved.
Holographic media has the potential to encode data at significantly higher densities because, rather than encoding data only on the surface, it can be encoded throughout the medium using lasers with a different wavelength or beam angle. That means the whole volume of the storage medium is available for writing data, which can then be read using differently focused lasers.
The team in Australia are working with graphene oxide suspended in water and mixed with a polymer then spread over the surface of a disk. The mixture of the polymer and graphene oxide is highly fluorescent, but, using a laser, areas of the disk can be altered so that their fluoresce is reduced and their refractive index altered. The differences between highly fluorescent and low fluorescent areas can be used to encode data, which can then be read using another laser and a photodetector.
What’s really significant is that the thickness of the GO polymer allows for data to be recorded and read over multiple layers and modulating the refractive index of the polymer allows for true holographic storage, where multiple holograms can be stacked and read by lasers at different angles and wavelengths.
These qualities lead to holographic media being much more data dense than magnetic media or solid state devices. The Australian team estimate that they have reached data densities of around 3.2 terabytes per cubic inch, which is about 3 times the current upper limit for storage per square inch on magnetic media.
Of course, it’s still very early days, but holographic technology has the potential to make an enormous impact on how we think about data storage in the data center. Currently, SSDs are the fastest forms of storage that are available to us, but if holographic storage proves a viable technology, we will be able to store huge amounts of information in less space, retrieve it extremely quickly, and have more faith in the reliability of our storage devices — it’s estimated that holographic media has a lifespan of over 50 years, compared to 3 or 4 for current hard drives.