Tech Briefs Magazine - June 2022 - 30

Optics
Diffraction Suppressed Mirror
Applications include infrared detection and space-based observation.
Goddard Space Flight Center, Greenbelt, MD
P
recise optical systems, especially those
sensitive to information loss, are typically
designed to minimize the use of
mirrors. This is due to the Airy disk effect
inherent to all conventional mirrors,
which is a result of diffraction of the incident
light. This effect represents information
loss between the incident light
and the reflected image. In applications
such as space-based observation or lithography
information, loss is a serious
concern.
NASA Goddard developed a diffraction
suppressed mirror to eliminate the
problem of undesirable diffraction in
optical system mirrors. The impedance
mismatch between the edge of the mirror
and the vacuum beyond it is responsible
for the occurrence of diffraction.
To eliminate diffraction, the impedance
mismatch must be eliminated.
To achieve this, a gradient of wavelength
scale via nanostructures is fabricated
on the surface of the mirror substrate.
The via nanostructure gradient
density is highest at the edge of the mirror
and decreases linearly or in a stepwise
fashion toward the center of the
mirror where the density is the lowest.
This technique effectively matches the
impedance of the mirror to that of free
space and allows for 100 percent transmission
of incident light to the reflective
layer of the mirror. This is effective for a
wavelength of choice. Broadband capability
can be achieved by multiple layers
of via nanostructures decreasing in feature
size from top to bottom layer.
NASA is actively seeking licensees to commercialize
this technology. Please contact NASA's
Licensing Concierge at Agency-PatentLicensing@mail.nasa.gov
or call at 202-3587432
to initiate licensing discussions. For
more information, visit https://technology.
nasa.gov/patent/SC-TOPS-172.
Platform for Quantum Technologies Using Gold
This new approach may help develop new materials for secure communications and
sensing technologies.
Naval Research Laboratory, Washington, DC
S
cientists discovered a new platform for
quantum technologies by suspending
two-dimensional (2D) crystals over pores
in a slab of gold. When heated, the metal
reflows to form a porous structure and
the gold atoms lock into registry with the
atoms in the 2D layer on top. Instead of
droplets forming on the glass base underneath
the gold, heating caused a reorientation
of the underlying metal slab. The
gold became porous throughout and this
physical change led researchers to test for
other side effects of the merger.
They also discovered that the combination
can create a large number of
quantum light sources in a ready-made
network. The alignment between atomic
layers may facilitate energy transfer between
the emitters through the gold
framework that connects them.
Researchers verified that light emanating
from the 2D semiconductors comes
out as single light particles, or photons.
These emitters can transfer energy to
each other through the gold layer. The
light shines on one part of the sample
and researchers look at the light coming
off at another part. This shows how energy
can be coupled into the gold layer at
one point, propagated to a different
quantum emitter site far away, and
re-emitted as visible light.
Suspended 2D crystals over pores in a slab of gold (center image) allow scientists to connect quantum
light sources (inset images) in a ready-made network. (Image: Jeremy Robinson/U.S. Naval Research
Laboratory)
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The ability to remotely control the
piping of energy to a single-photon emitter
makes this an attractive system for
quantum technology. Sensors are a first
application; they can take advantage of
the atomically thin membranes stretched
across the porous metal framework.
While researchers conducted this
work using a gold slab underneath the
thin semiconductor layer, other metals
can respond the same way as the gold.
The team continues to investigate how
various material combinations and structures
can create single photon sources
with unique properties, a key component
of secure communications.
For more information, contact the NRL at
nrlpao@nrl.navy.mil; 202-767-2541.
Tech Briefs, June 2022
TB Optics 0622_1.indd 30
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Tech Briefs Magazine - June 2022

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