Tech Briefs Magazine - September 2021 - PIT-26

Say Goodbye to the Dots and Dashes to Enhance Optical
Storage Media
Purdue University (West Lafayette, IN)
P
urdue researchers have created technology
aimed at replacing Morse code
with colored " digital characters " to modernize
optical storage. They are confident
the advancement will help with the explosion
of remote data storage during and
after the COVID-19 pandemic.
Morse code has been around since the
1830s. The familiar dots and dashes system
may seem antiquated given the
amount of information needed to be
acquired, digitally archived, and rapidly
accessed every day. But those same basic
dots and dashes are still used in many
optical media to aid in storage.
The new technology is aimed at modernizing
optical digital storage. This
advancement allows for more data to be
stored and for that data to be read at a
quicker rate. Rather than using the traditional
dots and dashes as commonly
used in these technologies, the information
is encoded in the angular position
of tiny antennas, allowing them to store
more data per unit area.
" The storage capacity greatly increases
because it is only defined by the resolution
of the sensor by which you can
determine the angular positions of
antennas, " said Professor Alexander
Kildishev. " We map the antenna angles
into colors, and the colors are decoded. "
Not all optical data storage media
needs to be laser-writable or rewritable.
The majority of CDs, DVDs, and Blu-Ray
discs are " stamped " and not recordable
at all. This class of optical media is an
essential part of disposable cold storage
with a rapid access rate, long-lasting shelf
life, and excellent archival capabilities.
The making of a Blu-Ray disc is based
on the pressing process, where the siliCCD
Images
Antenna
Orientation
CCD Cameras
π
Z
y Analyzers
x
Flip Mirrors
Obj. Lenses
Polarizers
0° 45° 90° 135°
8
8
2π
3π
4π
45°
8
8
8
8
8
5π
6π
7π
000
001
010
011
π
100
101
110
111
45° 90° 135°
Color Codes
Analyzer Angle
0°
State
500 nm
300 nm
200 nm
The proposed anisotropic metasurface from Purdue University innovators has significant potential for
high-density optical data storage, dynamic color image display, and encryption. (Image courtesy of the
researchers)
con stamper replicates the same dot-anddash
format the final disc is getting. A
thin nickel coating is then added to get a
negative stamp. The Blu-Rays, as well as
DVDs and CDs, are just mass-produced.
According to the researchers, their
metasurface-based 'optical storage' is
just like that. Although in their demo
prototype, the information is 'burnt in'
by electron-beam lithography, it could
be replicated by a more scalable manufacturing
process in the final product.
This new development not only allows
for more information to be stored but
also increases the readout rate. " You can
put four sensors nearby, and each sensor
would read its own polarization of light, "
Kildishev said. " This helps increase the
speed of readout of information compared
to the use of a single sensor with
dots and dashes. "
Future applications for this technology
include security tagging and cryptography.
To continue developing these capabilities,
the team is looking to partner
with interested parties in the industry.
For more information, contact Alexander
Kildishev at kildishev@purdue.edu.
Standard Digital Camera and AI to Monitor Soil Moisture
University of South Australia
he United Nations predicts that by
2050 many areas of the planet may
not have enough fresh water to meet
the demands of agriculture if we continue
our current patterns of use. One
solution to this global dilemma is the
development of more efficient irrigaT
26
Cov
ToC
tion,
central to which is precision monitoring
of soil moisture, allowing sensors
to guide 'smart' irrigation systems
to ensure water is applied at the optimum
time and rate.
Current methods for sensing soil
moisture are problematic - buried
sensors are susceptible to salts in the
substrate and require specialized hardware
for connections, while thermal
imaging cameras are expensive and can
be compromised by climatic conditions
such as sunlight intensity, fog, and
clouds.
Photonics & Imaging Technology, September 2021
Movement
Direction
White-Light Sources

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Tech Briefs Magazine - September 2021

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