High-speed Laser Writing Method Could Pack 500 Terabytes of Data into CD-sized Glass Disc Advances make high-density, 5D optical storage practical for long-term data archiving
From:
Optica, October 28, 2021
WASHINGTON — Researchers have developed
a fast and energy-efficient laser-writing method for producing 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.
“Individuals and organizations are
generating ever-larger datasets, creating the desperate need for more efficient
forms of data storage with a high capacity, low energy consumption and long
lifetime,” said doctoral researcher Yuhao Lei from
the University of Southampton in
the UK. “While cloud-based systems are designed more for temporary data, we
believe that 5D data storage in glass could be useful for longer-term data
storage for national archives, museums, libraries or private organizations.”
In Optica, Optica Publishing Group’s journal for
high-impact research, Lei and colleagues describe their new method for writing data
that encompasses two optical dimensions plus three spatial dimensions. The new
approach can write at speeds of 1,000,000 voxels per second, which is
equivalent to recording about 230 kilobytes of data (more than 100 pages of
text) per second.
“The physical mechanism we use is
generic,” said Lei. “Thus, we anticipate that this energy-efficient writing
method could also be used for fast nanostructuring in transparent materials for
applications in 3D integrated optics and microfluidics.”
Faster, better laser writing
Although 5D optical data storage in
transparent materials has been demonstrated before, writing data fast enough
and with a high enough density for real-world applications has proved
challenging. To overcome this hurdle, the researchers used a femtosecond laser
with a high repetition rate to create tiny pits containing a single
nanolamella-like structure measuring just 500 by 50 nanometers each.
Rather than using the femtosecond laser
to write directly in the glass, the researchers harnessed the light to produce
an optical phenomenon known as near-field enhancement, in which a
nanolamella-like structure is created by a few weak light pulses, from an
isotropic nanovoid generated by a single pulse microexplosion. Using near-field
enhancement to make the nanostructures minimized the thermal damage that has
been problematic for other approaches that use high-repetition-rate lasers.
Because the nanostructures are
anisotropic, they produce birefringence that can be characterized by the
light’s slow axis orientation (4th dimension, corresponding to the orientation
of the nanolamella-like structure) and strength of retardance (5th dimension,
defined by the size of nanostructure). As data is recorded into the glass, the
slow axis orientation and strength of retardance can be controlled by the
polarization and intensity of light, respectively.
“This new approach improves the data
writing speed to a practical level, so we can write tens of gigabytes of data
in a reasonable time,” said Lei. “The highly localized, precision
nanostructures enable a higher data capacity because more voxels can be written
in a unit volume. In addition, using pulsed light reduces the energy needed for
writing.”
Writing data on a glass CD
The researchers used their new method to
write 5 gigabytes of text data onto a silica glass disc about the size of a
conventional compact disc with nearly 100% readout accuracy. Each voxel
contained four bits of information, and every two voxels corresponded to a text
character. With the writing density available from the method, the disc would
be able to hold 500 terabytes of data. With upgrades to the system that allow
parallel writing, the researchers say it should be feasible 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, leader of
the researcher team.
The researchers are now working to
increase the writing speed of their method and to make the technology usable
outside the laboratory. Faster methods for reading the data will also have to
be developed for practical data storage applications.
Paper: Y.
Lei, M. Sakakura, L. Wang, Y. Yu, H. Wang, G. Shayeganrad, P. G. Kazansky,
“High speed ultrafast laser anisotropic nanostructuring by energy deposition
control via near-field enhancement,” Optica, 8, 11, 1365-1371
(2021).
No comments:
Post a Comment