Data storage

5D data storage technology scales up to 500TB on CD-sized glass

Researchers at the University of Southampton in the UK have developed a laser writing method to produce high density nanostructures in silica glass. These tiny structures can be used for long-term five-dimensional (5D) optical data storage that is more than 10,000 times denser than Blue-Ray optical disc storage technology.

Photo credit: Yuhao Lei and Peter G. Kazansky, University of Southampton

“Individuals and organizations are generating increasingly large data sets, creating a desperate need for more efficient forms of data storage with high capacity, low power consumption and long lifespan,” said doctoral student Yuhao Lei from the University of Southampton. “Although cloud-based systems are designed more for temporary data, we believe 5D data storage in glass could be useful for longer-term data storage for national archives, museums, libraries. or private organizations. “

In Optica, the Optica Publishing Group journal for high-impact research, Lei and colleagues describe their new method of writing data that encompasses two optical dimensions and three spatial dimensions. The new approach can write at speeds of 1,000,000 voxels per second, which is equivalent to recording approximately 230 kilobytes of data (over 100 pages of text) per second.

“The physical mechanism we use is generic,” Lei said. “Thus, we predict that this energy efficient writing method could also be used for rapid nanostructuring in transparent materials for applications in 3D integrated optics and microfluidics. “

Although the storage of 5D optical data in transparent materials has already been demonstrated, writing data fast enough and with a density high enough for real applications has proven difficult. To overcome this hurdle, the researchers used a femtosecond laser with a high repetition rate to create tiny pits containing a single nanolaminate-like structure measuring just 500 by 50 nanometers each.

Rather than using the femtosecond laser to write directly into glass, the researchers harnessed light to produce an optical phenomenon known as near-field enhancement, in which a nano-lamella-like structure is created by a few pulses of light. weak, from an isotropic nanovide. generated by a single micro-pulse explosion. The use of near-field enhancement to fabricate the nanostructures minimized thermal damage that has been problematic for other approaches using high repetition rate lasers.

Because nanostructures are anisotropic, they produce birefringence which can be characterized by the orientation of the slow axis of light (4th dimension, corresponding to the orientation of the nano-lamella-like structure) and the retardation force (5th dimension, defined by the size of the nanostructure). As the data is recorded in the glass, the orientation of the slow axis and the strength of the delay can be controlled by the polarization and intensity of the light, respectively.

“This new approach improves the speed of writing data to a practical level, so that we can write tens of gigabytes of data in a reasonable amount of time,” said Lei. “Highly localized precision nanostructures allow for higher data capacity because more voxels can be written in a unit volume. In addition, the use of pulsed light reduces the energy required for writing.

The researchers used their new method to write 5 gigabytes of text data onto a silica glass disc the size of a conventional compact disc with almost 100% read accuracy. Each voxel contained four bits of information, and both voxels matched a text character. With the write density available through the method, the disk could hold 500 terabytes of data. With system upgrades that allow parallel writing, the researchers say it should be possible to write this amount of data in about 60 days.

“With the current system, we have the ability to preserve terabytes of data, which could be used, for example, to preserve information from a person’s DNA,” said Peter G. Kazansky, head of the team of researchers.

Researchers are now working to increase the writing speed of their method and make the technology usable outside the lab. Faster methods of reading data will also need to be developed for practical data storage applications.