5d optical memory crystals
In 2018, The Arch Mission Foundation delivered the first library in space, with SpaceX, when it launched a small quartz crystal containing the three books of the Isaac Asimov Foundation Trilogy, into 30 million year solar orbit, in the glove compartment of Elon Musk’s tesla.
This “Superman memory crystal” was developed by the lab of Professor Peter Kazansky — the inventor of “5D” optical storage technology — at the Optoelectronics Research Centre at the University of Southampton.
The 5D optical storage medium works by using an extremely fast and precise femtosecond laser to create tiny pits within the fused silica glass containing self-assembled nanostructures (nanogratings).
Quartz silica glass is the same material used to make spacecraft windows and is extremely durable in space. Data written into nanogratings in quartz has a projected lifetime of 14B years.
The nanogratings, with features as small as 20 nm, are the smallest embedded structures ever produced by light. They change how light travels through them much in the same way that polarized sunglasses do, allowing scientists to read information about each depending on how the light is transformed.
The changes to the light convey five ‘dimensions’ of information (thus the name), based on each nanostructure's orientation, the strength of the light that it refracts, and its location in space on the x, y, and z axes.
The nanongrating produces birefringence in glass, which is characterized by two parameters: slow axis orientation (4th dimension, coinciding also with the orientation of nanograting), and strength of retardance (5th dimension coinciding also with the size of nanograting).
During recording the slow axis orientation and strength of retardance are controlled respectively by the polarization and intensity of light. If you add the two optical dimensions to three spatial co-ordinates the result is "5D data storage”
By comparison, CDs only have two "dimensions" of information — reflecting or not reflecting laser light to convey the 1s and 0s of binary data in a single layer of plastic.
In DVDs, the data is stored by burning tiny pits on multiple layers on the plastic disc, which means you are using three spatial dimensions to store information. With our technology, we exploit two additional, optical dimensions with fused silica glass.
Despite all technological progress it is still difficult to securely store large amounts of information over even relatively short timescales of 100 years. Our 5D data storage technology eliminates this problem by storing high capacity digital information that could survive the human race.
The current achievable density is several TB per disc (CD size of 12 cm, 1.2 mm thickness), which is of the same order as magnetic disk data storage. In a couple of years, the team hopes to achieve about 20 TB per disc. We estimate the ultimate capacity of 360 TB per disc using this technology.
HOW CAN THE CONTENT OF THE QUARTZ DISCS BE RETRIEVED?
The Arch Mission sends data using different media for different purposes. One of these media is quartz discs, written with a femtosecond laser. Here is a diagram with the decoding key for the Isaac Asimov Foundation disc we sent with SpaceX in early 2018 that is now orbiting the Sun for 30 million years: