Harry Potter-style invisibility cloak comes closer to reality

An Indian-origin scientist has developed a larger swath of material that can bend light, a breakthrough that could pave way for Harry Potter-style invisibility cloaks.
Controlling and bending light around an object so it appears invisible to the naked eye is the theory behind fictional invisibility cloaks, researchers said.
It may seem easy in Hollywood movies, but is hard to create in real life because no material in nature has the properties necessary to bend light in such a way.
Scientists have managed to create artificial nanostructures that can do the job, called metamaterials.
But the challenge has been making enough of the material to turn science fiction into a practical reality.

The work of Debashis Chanda at the University of Central Florida, however, may have just cracked that barrier.

Chanda and fellow optical and nanotech experts were able to develop a larger swath of multilayer 3-D metamaterial operating in the visible spectral range.
They accomplished this feat by using nanotransfer printing, which can potentially be engineered to modify surrounding refractive index needed for controlling propagation of light.
"Such large-area fabrication of metamaterials following a simple printing technique will enable realisation of novel devices based on engineered optical responses at the nanoscale," said Chanda, an assistant professor at University of Central Florida (UCF).

The nanotransfer printing technique creates metal or dielectric composite films, which are stacked together in a 3-D architecture with nanoscale patterns for operation in the visible spectral range.
Control of electromagnetic resonances over the 3-D space by structural manipulation allows precise control over propagation of light.
Following this technique, larger pieces of this special material can be created, which were previously limited to micron-scale size, researchers said.
By improving the technique, the team hopes to be able to create larger pieces of the material with engineered optical properties, which would make it practical to produce for real-life device applications.
For example, the team could develop large-area metamaterial absorbers, which would enable fighter jets to remain invisible from detection systems.

The research was published in the journal Advanced Optical Materials.