Data storage

Laser Write Method Facilitates 10,000 Times More Data Storage Than Blu-Ray Discs | Research & Technology | October 2021

SOUTHAMPTON, England, November 1, 2021 – Researchers at the University of Southampton have developed a fast, energy-efficient laser writing method to produce high-density nanostructures in silica glass. The resulting tiny structures can be used for long-term five-dimensional (5D) optical data storage that is more than 10,000 times denser than Blu-ray optical disc storage technology.

“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. “While cloud-based systems are designed more for temporary data, we believe 5D data storage in glass could be used for longer-term data storage for national archives, museums, libraries. or private organizations. ”

Researchers at the University of Southampton have developed a fast, energy-efficient laser writing method to produce nanostructures in silica glass. They used the method to save 6 GB of data in a 1-in. silica glass sample. The four squares shown each measure only 8.8 × 8.8 mm. The group also used the laser writing method to write the logo and brand of the university on the glass. Courtesy of Yuhao Lei and Peter G. Kazansky, University of Southampton.

Storing five-dimensional optical data in transparent materials has already been demonstrated, although the ability to write data at sufficiently fast speeds and with sufficiently high density for real-world applications has proven to be a challenge. To overcome the 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 × 50 nm each. The approach wrote at speeds of 1 million voxels per second, which is equivalent to recording approximately 230 KB of data (over 100 pages of text) per second.

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

Rather than using the femtosecond laser to write directly into the glass, the researchers harnessed light to produce a near-field enhancement, in which a nano-lamella-like structure is created by a few weak pulses of light, from a nanovide. isotropic generated by a single pulse microexplosion. 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 (fourth dimension, corresponding to the orientation of the nano-lamella-like structure) and the retarding force (fifth dimension, defined by the size of the nanostructure). As data is recorded in the glass, the orientation of the slow axis and the strength of the retardation 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 team used the method to write 5 GB of text data to a silica glass disc the size of a conventional compact disc with near 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 drive could hold 500TB 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 Kazansky, team leader for research.

The team aims to increase writing speed and make the technology usable outside of a laboratory setting. Faster methods of reading data should also be developed for practical data storage applications.

The research was published in Optical (