TechTheDay

This blog has already featured a couple of invisibility cloak inventions. There was one created with an inexpensive optical material and another intended for large scale invisibility cloaking. Recently, another invisibility has been developed and unlike any other invisibility technology developed previously, it is extremely thin and small.

Invisibility at the Microscopic Level

This new invisibility invention is different because it is not only ultra thin, it also ultra small.  In fact, its effect can be observed with a microscope. Developed by a team of scientists from the United States Department of Energy’s Berkeley Lab and University of California-Berkeley, this new invisibility cloak can be wrapped around an object to make it disappear from sight. Being barely 80 nanometers in thickness, it is so small you will need a microscope to observe its effect.

This nanoscale invisibility device was wrapped around a microscopic 3D object with the size of just a few biological cells. The object is also arbitrarily shaped with several dents and bumps. Once the microscopic invisibility cloak was in place, as it conformed to the shape of the 3D object, it successfully prevented the observers from detecting the object under visible light.

First Time

One of the most notable feats of this new microscopic invisibility cloak is that it is the first invisibility invention to have successfully cloaked a 3D object with an arbitrary shape from visible light. This is at least the claim of Xiang Zhang, a metamaterials expert and the director of Berkeley Lab’s Materials Sciences Earlier invisibility technologies were limited to mostly creating some form of invisibility from a few angles. The one created by researchers from the University of Central Florida as well as the one invented Canadian camouflage design company Hyperstealth Biotechnology Corp, for example, are not as effective this new invention.

Ultra-Thin Invisibility Cloak

The paper on this new invisibility invention was published on the journal Science entitled “An Ultrathin Invisibility Skin Cloak for Visible Light.” It lists as authors Xingjie Ni, Jing Wong, and Michael Mrejen of the NSF Nanoscale Science and Engineering Center (NSEC); Yuan Wang of the Lawrence Berkeley National Laboratory’s Materials Science Division, and Xiang Zhang of the King Abdulaziz University Department of Physics.

According to Xiang Zhang, their invention is easy to design and implement. One of its highlight features is its potential scalability for hiding macroscopic objects. Although it has only been demonstrated on microscopic objects, it has the potential to be used on much larger objects. It is by far the thinnest implementation of a cloaking device.

How Does It Work

Just like how every other invisibility cloak works, this invention creates the effect by guiding light around the object being cloaked. What makes it better, though, is that it’s a lot thinner and that it can be wrapped around an object regardless of its shape. This is made possible through the creation of a two-dimensional metamaterial surface that is highly reflective. The metamaterial manages to curve the path of light or bend it, making the objects cloaked become optically undetectable.

Research co-author Xingjie NI, in an interview with Phys.org, emphasized how metamaterials technology has vastly improved that it is now possible to manipulate the phase of a propagating wave directly by employing subwavelength-sized elements. These subwavelength-sized elements locally tailor electromagnetic response at the nanoscale, which results in dramatic light confinement. In short, it makes cloaking devices less bulky (extremely thin in the case of this latest invention) by taking away the need for a dielectric prism that introduces an added phase in the reflected light to remove phase-sensitive detection. Phase sensitive detection, by the way, refers to a method of detecting minute signals in the midst of overwhelming noise, using a lock–in amplifier.

As presented on the study paper, when red light was made to illuminate a cloaked arbitrarily shaped object with a surface area of around 1,300 square microns, the light reflected by the cloaked surface turned out to be similar to the light reflected off a flat mirror. This made the object below the surface of the ultra-thin cloak invisible even with phase-sensitive detection.

Applications

You might be wondering what purpose does a nanoscale invisibility cloak serve. Don’t be worked up, though, as this invention does not deserve to be lined up among science’s hall of ridiculousness. Given the size of this new invisibility technology, it is expected to become valuable in hiding the detailed layout of microelectronic components as a form of security encryption. This technology is also believed to be useful for the development of the next generation of 3D displays. Additionally, it can be used in high resolution optical microscopes and extremely fast optical computers. It is in fact a useful technology and not just created for the whimsical pursuit of making Harry Potter’s invisibility cloak a reality.

Unfortunately, for now, the researchers have yet to demonstrate how this ultra-thin cloak can be scaled up to come up with something that can really match the fictional Harry Potter cloak. There’s also no word on the timeline regarding the possible developments for commercial applications.