Researchers have found a five-dimensional (5D) digital data disc that can store 360 terabytes ( that would be 500000 movies each of 700mb in size ) of data for some 13.8 billion years.
To create the data disc, researchers from the University of Southampton used a process called femtosecond laser writing, which creates small discs of glass using an ultrafast laser that generates short and intense pulses of light. These pulses can write data in three layers of nanostructured dots separated by 5 micrometres .The data recording was significantly simplified by replacing the conventional control of the writing beam energy and polarization with a spatial light modulator and a specially designed laser imprinted half-wave plate matrix.
The idea of the optical memory based on femtosecond laser writing in the bulk of transparent material was first proposed in 1996 . More recently self-assembled nanogratings produced by ultrafast laser writing in glass were proposed for the polarization multiplexed optical memory, where the information encoding would be realized by means of two birefringence parameters, i.e. the slow axis orientation (4th dimension) and strength of retardance (5th dimension), in addition to three spatial coordinates . The slow axis orientation and the retardance can be controlled by polarization and intensity of the incident beam respectively . The unprecedented parameters including 360 TB/disc data capacity, thermal stability up to 1000°C and practically unlimited lifetime . However the implementation of digital data storage, which is a crucial step towards the real world applications, has not been demonstrated by ultrafast laser writing. Here we successfully recorded and retrieved a digital copy of the text file in 5D using polarization controlled selfassembled ultrafast laser nanostructuring in silica glass.
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