Invisibility Cloak 

Brian M. Santiago Busutil

A group f investigators in Berkeley have achieved partial success in what is being called an “invisibility cloak”. The team leader, Xiang Zhang, is also the director of UC Berkeley’s Nano-scale Science and Engineering Center. He has been able to create what he calls a “carpet cloak” from nanostructered silicon that hides any object from visual detection. Even though the “carpet” can be seen, the object that lies under it disappears from sight. Zhang mentions that this discovery presents a new solution towards developing invisibility based on the use of “dielectric (nonconducting) materials”. This discovery  represents a huge step forward and the hope that true invisibility is at our grasp.

This is not the only device that Zhang and his teams have developed. They also created a “fishnet” of alternating layers made out of silver and magnesium floride, and another device constructed out of silver and nanowires grown inside porous aluminum oxide. The true success of this research is that the group was able to manipulate light and make it “bounce back”. This was not successful before because metals absorb too much light, but these new materials work in a differenty way. The device functions  by bending light waves so they curve around the object and then “reconnect”, making it seem like it is unaltered.  This light-bending effect is based on reversing refraction, similar to the effect that makes a straw placed in water appear bent.

The developed device was able to cover an area of 3.8 microns by 400 nanometers and it was able to demonstrate invisibility at several angles. At its current stage, it operates for light between 1,400 and 1,800 nanometers in wavelength, one that is far longer than humans can see. These wavelengths are the ones used around the telecommunications industry, which are near to the visible part of the spectrum. Even though the device at its current stage is on a nano scale, the team hopes that in the future it can be large enough to work on bigger objects including humans

Even more impressive is the fact that this cloak is easy to fabricate.  Zhang mentions that after using a refined and more precise fabrication, they should be able to develop a material that can be truly invisible to the human eye. Professor Ortwin Hess, of the Advanced Technology Institute at the University of Surrey says that there could be immediate applications for the cloaking device in telecommunications. This research also benefits other areas of interest, including transformation optics, light manipulation, powerful and new microscopes and faster computers.

This discovery might remind us of the movie “Harry Potter”, in which the main character has a cloak which renders him completely invisible to the human eye.  Even though this is fiction, Zhang and his team have proved that the development of a similar device might just be something real. Proffessor Hess said, “In order to have the ‘Harry Potter’ effect, you just need to find the right materials for the visible wavelengths”.  It’s just a matter of time until we bridge the gap between fiction and reality.