Page 18 - Winter 2025

In October 2024 JAXA and NEC successfully opaque white resin structures with a low scattering
achieved the optical inter-satellite communication
between DAICHI-4 equipped with the Optical Leo
Laser Communication Terminal (OLLCT) dedicated
to an Earth observation satellite, and the Optical
Data Relay Satellite equipped with the Optical Geo
Laser Communication Terminal (OGLCT) dedicated
to a geostationary satellite. As a result DAICHI-4
observation data was successfully transmitted using
optical communication. The success of this data
transmission utilising LUCAS facilitates immediate
downloading of a large amount of observation
data, which is difficult to achieve through direct
communication to groundstations in areas that lack
accessible groundstations.
In LUCAS optical communication has been adopted
in the data relay system onboard the geostationary
satellite. By using optical communication between
the Earth observation satellite and the geostationary
satellite, LUCAS enables data transmission from the
Earth observation satellite at 1.8 Gbps, 7.5 times faster
than the 240 Mbps transmission rate of the Data
Relay Test Satellite KODAMA (DRTS) (4) using previous
generation radio waves. As light has a bandwidth
far wider than that of radio waves (5THz in the
1.5µm wavelength band), it can transmit a lot more
information. The use of the 1.5µm band was derived
from NEC’s development achievements in terrestrial
and underwater optical fibre communication
systems, and whilst the 1.5µm band is relatively
deficient in power efficiency, the recent success in
long-distance high-speed transmission between the
geostationary satellite and the low Earth orbit satellite
is expected to accelerate its utilisation in space-
based optical communication.
Reference: Gittins, C., ‘JAXA and NEC achieve Transmission of Mission
Data’, Electronic Specifier, 27th. January
New Method for controlling and guiding Light
Researchers at the University of Glasgow have
pioneered a new method for controlling and guiding
light based on the way in which sunlight passes
through clouds.
The ‘waveguiding’ effect that has been discovered
is analogous to fibre optic cable, which carries light
through its core by means of total internal reflection.
This is achieved through the use of cladding around
the core that has a lower refractive index such that
the light continues to ‘bounce’ along the length of the
core enabling it to travel long distances with minimal
loss.
The team has refined this effect so that light is
transported through a solid core of weakly scattering
material which is in turn encased in a material that
scatters much more strongly. The contrast between
the scattering properties of the materials confines the
light to the core and enables it to be guided with very
high precision.
A 3D-printer was used to produce highly scattering
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New First for Infrared Imaging
core through which light was passed. It was found
that it was possible to transmit over a hundred
times more light through the low-scattering core
than in structures without it. The phenomenon
was demonstrated using both straight and curved
structures.
A comprehensive mathematical model was devised
to explain the physical processes of diffusion which
underpins the results. As the resulting equations are
similar to those representing the conduction of heat
through solid materials, it is postulated that the new
technique may have wider usage than just with light.
Leader of the University of Glasgow Extreme Light
Research Group, Professor Danielle Faccio, is quoted
as follows:
“ Tall cumulus clouds are often bright white at their
tallest point and dark grey at their lowest because
sunlight is scattered through the countless water
droplets which are contained in the cloud’s interior.
The light decays exponentially as it scatters
through the cloud, making the lower part darker,
and is reflected at the top, which makes it white.
We started to wonder whether it might be possible
to harness that scattering effect in a controlled way,
and to use it to create a path to guide light through
scattering materials.
We’re still learning new tricks about light, in this case
by a process that we were surprised to discover has
more in common with our understanding of the way
heat travels than light.
That means that we can expect to use this technique
to find new ways to see inside opaque biological
tissue using light, but also that we can apply it to
guide more than just photons. We could create new
ways to carry heat through systems which need to
be cooled, like data centre computers, or to transport
particles like neutrons, which could open up new
applications for nuclear power plants, for example”.
Reference: West, P., ‘Sky’s the Limit for Cloud-inspired Method of
guiding Light’, Electronic Specifier, 4th. November
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Avalanching Nanoparticles create new
Researchers at Nottingham Trent University have
pioneered new camera technology that will bring
high resolution to the entire range of infrared
imaging for the first time.
The new technique will make it possible to detect,
view and switch between the full infrared range in
one place, which is currently not possible.
Visual cameras, such as those in smartphones,
offer high resolution and clarity, but cannot be used
for infrared or thermal imaging as the images are
blurred due to less developed sensors working in the
infrared ranges.
Infrared sensors are, however, critical from the near-
infrared range, just beyond the visible spectrum,
through to the long infrared range, with applications
in areas such as food quality control, night vision,
medical imaging and inspection for heat and gas
leakages.
The new technique involves deployment of a layer
of engineered arrays of nanoparticles, known as
metasurfaces, that can absorb all infrared bands and
convert them into visible light. These metasurfaces
can be configured to be pixelated so as to offer
higher resolutions and independently controlled
to switch between different infrared bands. The
objective is for this Universal Platform for Infrared
Imaging to offer an inexpensive alternative to the
present complex semiconductor technology that is
required for infrared imaging.
Mohsen Rahmani, Professor of Engineering at the
Nottingham Trent University School of Science and
Technology, states:
“ Our ambition is to have all of the visible and
infrared bands together in high resolution in one
inexpensive device. Infrared cameras are critical
for many applications, but these rely on cameras
to work at different infrared sub-bands. No single
camera can detect all bands. They are also low in
pixels with poor image quality, are expensive and
heavy on energy consumption.
We aim to generate a new addition to visible
cameras, technology which is not currently
compatible with our everyday technologies but
can be easily incorporated. We can do this with the
creation of a compact nanoscale layer which sits
between the other layers of a standard camera”.
Reference: Gittins, C., ‘NTU Research Team developing new Infrared
Imaging Tech’, Electronic Specifier, 3rd. December
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Possibilities for Optoelectronics
Scientists at Oregon State University have
discovered a new type of nanocrystal that has
the ability to be toggled from light to dark and
back again, which is envisaged to have major
implications for optoelectronics offering a way to
rapidly process and store information using light
particles.
These avalanching nanoparticles exhibit extreme
non-linearity in their light-emission properties with
the result that they emit light the intensity of which
can increase significantly with a small increase in the
intensity of the laser light that is exciting them.
Nanocrystals composed of potassium, chlorine and
lead, doped with neodymium were studied and it
was found that whilst the potassium lead chloride
crystals do not interact with light themselves, as
hosts they can enable neodymium guest ions to
handle light more efficiently, making them useful for
optoelectronics, laser technology and other optical
applications.
Artiom Skricka, Associate Professor at the Oregon
State University College of Science, explains:
“ Normally, luminescent materials give of light
when they are excited by a laser and remain dark
when they are not. In contrast, we were surprised to
find that our nanocrystals live parallel lives. Under
certain conditions, they show a peculiar behaviour:
they can be either bright or dark under exactly the
same laser excitation wavelength and power.
If the crystals are dark to start with, we need a
higher laser power to switch them on and observe
emission, but once they emit they remain emitting
and we can observe their emission at lower laser
powers than we needed to switch them on initially.
It’s like riding a bike - to get it going you have to
push the pedals hard, but once it is in motion
you need less effort to keep it going. And their
luminescence can be turned off really abruptly, as
if by pushing a button intrinsic optical bistability.
Integrating photonic materials with intrinsic optical
bistability could mean faster and more efficient
data processors, enhancing machine learning
algorithms and data analysis. It could also mean
more efficient light-based devices of the type used
in fields like telecommunications, medical imaging,
environmental sensing, and interconnects for
optical quantum computers”.
Reference: Gittins, C., ‘OSU Researchers investigate new
Nanocrystals’, Electronic Specifier, 6th. January
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