Tech Briefs Magazine - December 2023 - 23

Communications
Making Satellite, Ground Communication More Effective
Ultrafast, femtosecond lasers cut through the clouds and rain that commonly cause losses in
free-space optical communication.
Rensselaer Polytechnic Institute, Troy, NY
R
ensselaer Polytechnic Institute's Moussa
N'Gom has devised a method to
make communications between satellites
and the ground more effective - regardless
of the weather. N'Gom and his team
used ultrafast, femtosecond lasers to cut
through the clouds and rain that commonly
cause losses in free-space optical
communication (FSO).
" The lasers we use are so energetic that
they change the environment in which
they propagate, " N'Gom said. " The environment
starts to change the laser that is
changing it, and they have a light-matter
interaction. It becomes a cascading effect
that creates a long filament of light. "
The filament of light is accompanied
by a shockwave, akin to a sonic
boom. The laser filament propagates
through clouds, and the accompanying
shockwave clears the space around
the filament, providing an open pathway
for visible light. N'Gom uses structured
light, in the form of a spiral with
a hole at its center, to propagate
through the pathway.
" The Laguerre-Gauss beam travels
through this empty space without interacting
with the filament and is unobstructed
by the clouds, " N'Gom said.
" Normally, light travels in one, flat wave,
but the light we create travels in a spiral.
Imagine it like curling a flat piece of paper
with scissors. "
In addition to facilitating transmission
through clouds, the light's spiral
Robust Serial Communications
Although Ethernet is the modern networking technology of choice, proven serial RS232/
RS485 communications are useful for many applications, preferably when supported by
industrial-grade platforms.
AutomationDirect, Cumming, GA
S
erial data transmission has served as a
mainstay of digital communications
since the standard was introduced in the
1960s. Variants of RS232/RS485 have
been commonplace in many types of laboratory
instruments, industrial devices,
and other intelligent electronics. But because
the newest devices commonly feature
wired Ethernet or Wi-Fi capability,
some may think that serial communications
are simply not relevant anymore.
In reality, many scientific, commercial,
and industrial electronics continue to offer
proven RS232/RS485 communications
because the technology is inexpensive and
sufficient for a significant number of applications.
This means users will continue to
need robust solutions for linking RS232/
RS485 devices to other host equipment for
performing configuration/setup, diagnostics,
and data acquisition.
For some users, especially those familiar
with " homebrew " tech projects, an immeTech
Briefs, December 2023
shape allows for more information to
be transmitted.
N'Gom's work presents a significant advance
for FSO; previous attempts to overcome
the persistent obstacle of rain and
clouds required substantial energy, large
investments, or were less effective.
" Dr. N'Gom's innovative research
shows how to overcome a fundamental
barrier in free-space optical communication, "
said Dean of the Rensselaer
School of Science Curt Breneman. " I
expect free-space optical communication
technology of this type to enable
hyper-speed secure worldwide quantum
communications. "
For more information, contact Katie
Malatino at malatk@rpi.edu; 838-240-5691.
Figure 1: An Arduino microcontroller hardened for industrial use, such as the AutomationDirect
ProductivityOpen platform, provides the networking, open-source programming, and expandability
needed for users to implement serial communications, along with other control and networking
applications. (Image: AutomationDirect)
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