Invisibility devices may soon no longer be the stuff of science fiction. A
new study published in the De Gruyter journal Nanophotonics by lead authors
Huanyang Chen at Xiamen University, China, and Qiaoliang Bao, suggests the
use of the material Molybdenum Trioxide (α-MoO3) to replace expensive and
difficult to produce metamaterials in the emerging technology of novel
optical devices.
The idea of an invisibility cloak may sound more like magic than science,
but researchers are currently hard at work producing devices that can
scatter and bend light in such a way that it creates the effect of
invisibility.
Thus far these devices have relied on metamaterials—a material that has been
specially engineered to possess novel properties not found in naturally
occurring substances or in the individual particles of that material—but the
study by Chen and co-authors suggests the use of α-MoO3 to create these
invisibility devices.
Possessing some unique properties, this material can provide an excellent
platform for controlling energy flow. The team's simulation results showed
that when cylindrical or rolled up α-MoO3 materials replace metamaterials,
the simplified invisibility concentrator can gain the effects of
electromagnetic invisibility and energy concentration that would be
demonstrated by a near perfect-invisibility device.
As a result, the study shows that hyperbolic materials such as α-MoO3 and
Vanadium pentoxide (V2O5) could serve as a new basis for transformation
optics, opening the possibility of photonic devices beyond invisibility
concentrators, including improved infrared imaging and detection systems.
Transformation optics has been a hot topic in physics over recent decades
thanks to the discovery that the path light takes through a continuous
medium can be the same as its propagation through a curved space that has
undergone a coordinate transformation.
The consequence of this is that the behavior of light can be manipulated as
it passes through a material, something that has led to the creation of a
multitude of novel optical devices, such as invisibility cloaks—a camouflage
material that could cover an object and bend light around it making it
almost disappear—and other optical illusion devices.
"It is the first time that 2D materials have been used for transformation
optical devices. Usually, we need metamaterials but this is much simpler,"
says Chen. The researcher continued by explaining that the first application
for the results of this study might be a large size energy concentrator
capable of improving such devices. "We are now performing experiments by
rolling up the α-MoO3, the results of which we hope will appear very soon."
Reference:
Tao Hou et al, Invisibility concentrator based on van der Waals
semiconductor α-MoO3, Nanophotonics (2021).
DOI: 10.1515/nanoph-2021-0557