An invisibility cloak that is made more convenient for use due to its ultrathin material has just been invented by a group of researchers from the Lawrence Berkeley National Laboratory of the US Department of Energy and the University of California (UC) Berkeley.

The said invention also has the ability to follow the shape of the object being covered, as well as hide it from detection in visible light. According to the researchers, the microscopic size of the cloak does not hinder it from concealing macroscopic materials with the technology used to make it.

Dubbed as a "skin cloak," this invention boasts an 80-nanometer thickness and a surface meta-engineered to divert the reflected light rays. As a result, the material becomes invisible to optical identification when the cloak is powered.

For the experiment, the scientists worked with chunks of gold nanoantennas and wrapped the cloak around a microscopic 3D object with a number of dents and irregular shapes. When a red light hit the wrapped object, the light bounced back off the surface of the cloak, much like how it would also occur in a flat mirror. With this, the material beneath the cloak becomes invisible even if phase-sensitive identification was present. The cloak may be deactivated by reversing the polarization of the nanoantennas.

The wavefront and the phase of the scattered light are restored through a phase change initiated by each antenna, said Zi Jing Wong, co-lead author of the study. With this, the material stays flawlessly concealed, he added.

Objects can be observed through the scattering of light after it has made contact with matter. Regardless of the type of light emitted, objects may be perceived. While this may be the case in natural materials, such principles may be thwarted in metamaterials that rely on the physical rather than chemical properties for optical features.

Over the last decade, the team of researchers has been investigating about the mechanisms that surround the way light interacts with metamaterials - backward bends, path light curves and other phenomena not observed in natural objects. Aside from that, the researchers wanted to make materials optically concealed.

Previously, the researchers worked on a metamaterial optical cloak that is carpet-based and bulky. This invention was also a challenge to scale and involved a phase discrepancy between the hidden area and the surrounding space that rendered the cloak detectable.

But now, finally, a three-dimensional material with irregular shapes can be hidden from visible light, said Xiang Zhang, the director of Berkeley Lab's Materials Sciences Division. The newly invented cloak is ultrathin, easy to use and able to conceal macroscopic objects.

Applications of this new invention include enhancement of high-resolution microscopes, high-performance optical computers and 3D displays.

Photo: Andrew Gustar | Flickr

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