Experts are getting ever closer to making real-life Harry Potter-style invisibility cloaks, and in the latest breakthrough, scientists have reportedly developed an ultra-thin skin that can conform to an object’s shape while concealing it from detection in visible light.
This new technology, which was developed by researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California, Berkeley, is just microscopic in size at this point, but the principles behind it could be scaled up for use on larger items as well.
As Xiang Zhang, director of the Berkeley Lab’s Materials Sciences Division, and his colleagues explained in the latest edition of the journal Science, they took blocks of gold nanoantennas and created a “skin cloak” that was about 80 nanometers thick. They then wrapped this cloak around a three-dimensional object roughly the same size as a handful of biological cells.
The object had been arbitrarily shaped with multiple bumps and dents, the researchers explained, and the cloak’s surface had been meta-engineered in order to redirect reflected light waves, thus rendering the object invisible to optical detection as long as the cloak had been activated.
Objects cannot be seen, even using phase-sensitive detection
According to Zhang, who is corresponding author of the study as well as a member of the Kavli Energy NanoSciences Institute at Berkeley, this represents “the first time a 3D object of arbitrary shape has been cloaked from visible light. Our ultra-thin cloak now looks like a coat. It is easy to design and implement, and is potentially scalable for hiding macroscopic objects.”
Ordinarily, objects can be observed due to the scattering of light as it interacts with the matter, but this can be circumvented in metamaterials that have optical properties due to their physical structure and not their chemical composition, the study authors explained. Zhang and his group have been conducting experiments involving these interactions for over a decade.
Previously, they have been able to curve the path of light, bend it backwards, and render objects optically undetectable. Their previous attempts to build an invisibility cloak were bulky and hard to scale-up, the researchers said, but their new technique is smaller and reflects light in much the same way as a flat mirror, making objects undetectable to even phase-sensitive detection.
“A phase shift provided by each individual nanoantenna fully restores both the wavefront and the phase of the scattered light so that the object remains perfectly hidden,” explained co-lead author Zi Jing Wong, who is a member of Zhang’s research group. Their work could also result in a new class of high resolution optical microscopes and superfast optical computers, the author said.
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Feature Image: A 3D illustration of a metasurface skin cloak made from an ultrathin layer of nanoantennas (gold blocks) covering an arbitrarily shaped object. Light reflects off the cloak (red arrows) as if it were reflecting off a flat mirror. (Credit: Lawrence Berkeley National Laboratory)
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