We're One Step Closer to Invisibility Cloaks Thanks to Digital Metamaterials
Harry Potter-style invisibility cloaks (minus the magic) may be within our reach, thanks to a novel type of material called "digital metamaterials." Researchers from the University of Pennsylvania have devised a method for building metamaterials using binary code that allows for both the elegance and complexity needed to build a revolutionary structure like an invisibility cloak.
Metamaterials are artificially engineered materials, specifically created to have properties that cannot be found in nature. They can be built from conventional materials such as metal or plastic, because they acquire their unique properties through their structure rather than their composition. The geometry and orientation that results from the materials being arranged in artificially exact repeating patterns allows them to interact with light and sound in unconventional ways.
"The idea behind metamaterials is to mimic the way atoms interact with light, but with artificial structures much smaller than the wavelength of light itself," said Boris Kuhlmey, associate professor of photonics and optics at the University of Sydney. "This way, optical properties are no longer restricted to those of the constituent materials, and can be designed almost arbitrarily."
The researchers proposed a new way to build these metamaterials that's based on the binary system of computing. Binary code is simple, as it is based entirely on sequences of 1 and 0, but can yield complex results, as the most advanced technologies, like state-of-the-art computers and smartphones, are based on binary code. In order to create digital metamaterials, the research team created two different types of "metamaterial bits" that are analogous to the 1's and 0's of the binary system, and arranged the structure of the metamaterials like a binary code.
"The beauty of the new method is its simplicity," said Min Gu, professor of optoelectronics at Swinburne University of Technology.
Using 2-D simulations, the researchers were able to afford nanoscale pieces of silver and glass with unusual properties, specifically in their interactions with light. Kuhlmey said, "What this [research] really does is put a new spin on the idea that with only two set materials arranged with the right portions – one metal, one insulator, here silver and silica – almost any optical property can be achieved. The authors… showed in simulations that nano-patterned glass/silver structures can then bend light, which is also the principle behind invisibility cloaking."
While creating a full invisibility cloak would be difficult (and would more likely resemble military-grade armor than a soft, comfortable cloak) these simulations show that it is theoretically possible, as these digital metamaterials were shown to be capable of bending light around them. "You guide the light around the object. Light would follow around the object and continue as if the object was never there," researcher Ventsislav Valev said to Newsweek. "Through this technology it is possible to not only hide something but also make it appear as something else."