One step closer to an invisibility cloak
Using 3D photonic crystals of their own design, researchers at the University of Twente’s MESA+ research institute have achieved a world first, revealing the signature of a photonic band gap. This is one of the holy grails of physics.Their study brings the development of an invisibility cloak - as well as more efficient lasers, LEDs and solar cells - a step closer.The results of the study will soon be published in Physical Review B, a leading American scientific journal.
In 1987, the American scientist Eli Yablonovitch predicted the existence of a photonic band gap. This is a phenomenon in which light of specific wavelengths is unable to pass through a three dimensional structure. The structure behaves as if it is out of bounds to light of that colour. Regardless of the angle at which you shine light into the structure, it will always be reflected. Using entirely new three-dimensional crystals, which they developed themselves, researchers at the University of Twente achieved a world first by observing the signature of the photonic band gap. According to researcher Prof. Willem Vos, the photonic band gap is one of the holy grails of physics.
Crystals
The crystals created by the researchers consist of silicon, the familiar semiconductor. They contain air-filled cavities, which have been etched into the material. This material has the same structure as the crystal lattice of a diamond, except that it is larger by a factor of 10 000. The dimensions of the unit cells in the photonic crystals’ lattice are of the same order of magnitude as the wavelength of the “forbidden light”. The three-dimensional photonic crystals may lead to many different applications and features, such as tiny light sources and lasers on chips, more efficient solar cells, and even invisibility cloaks.
Research
The study was conducted by researchers at the department of Complex Photonic Systems (COPS), in collaboration with the Center for Nanophotonics at the FOM Institute for Atomic and Molecular Physics (AMOLF). COPS is part of the "Advanced Nanophotonics" research field within the University of Twente’s MESA+ research institute. The study’s sponsors included the Netherlands Organization for Scientific Research (NWO) and Smartmix Memphis.