Based on transformation optics.
First, it’s worth pointing out that this invisibility cloak isn’t like the one made famous in J.K. Rowling’s Harry Potter novels. Sadly, recent research found that a human-sized invisibility cloak is theoretically impossible.
Still, researchers at Queen Mary University of London (QMUL) managed to make an object disappear with a composite material with nano-size particles that enhance certain properties on the object’s surface — demonstrating for the first time that a practical cloaking device can make curved surfaces appear flat to electromagnetic waves.
Publishing their work in Scientific Reports, the researchers coated a curved surface with a nano composite medium that contains seven distinct layers. The electric property of each layer varies depending on its position, and the effect “cloaks” an object which would have normally caused a wave to be scattered.
The authors write that novel mixing techniques were used to fabricate the device.
Below is a graphic of the “cloak” in action:
Incoming light waves (left) do not cast a shadow. Credit: Dr. La Spada
"The design is based upon transformation optics, a concept behind the idea of the invisibility cloak,” study co-author Professor Yang Hao, from QMUL’s School of Electronic Engineering and Computer Science, said in a press release.
"Previous research has shown this technique working at one frequency. However, we can demonstrate that it works at a greater range of frequencies making it more useful for other engineering applications, such as nano-antennas and the aerospace industry.”
Further, the researchers say the underlying design approach has even wider applications, from microwave to using optics to control any kind of electromagnetic surface waves.
"We demonstrated a practical possibility to use nanocomposites to control surface wave propagation through advanced additive manufacturing,” first author Dr. Luigi La Spada, also from QMUL's School of Electronic Engineering and Computer Science, said in the release.
“Perhaps most importantly, the approach used can be applied to other physical phenomena that are described by wave equations, such as acoustics. For this reason, we believe that this work has a great industrial impact."
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