METAFLEX - Metamaterials on Flexible optically transparent substrate

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Metamaterials (MMs) are man made materials with unusual electromagnetic properties that are not typically found in Nature. They are the key to achieving such extraordinary properties as invisibility cloaks and perfect lenses. At present, they are bulky and confined to laboratories. If they were flexible, they could become much more versatile and practical. Here, I propose a novel concept for flexible MMs that will turn current cloaking devices from suits of armour into true cloaks.The concept of index of refraction underpins the physics of MMs, which can be illustrated with an example. The direction that light takes when it crosses the interface between two media depends on its initial direction with respect to the surface and on the refractive indices of the media. This is the reason why a pencil appears to kink when immersed in water. In nature, all transparent materials have a positive refractive index, like water. As a result, the image of the pencil always kinks in the same direction. Conversely, MM are manufactured with a negative refractive index, thus in a MM the kink of the pencil would appear in the opposite direction. This effect, which may seem to be a mere curiosity, drives the extraordinary behavior of MMs.The technological requirements of currently fabricated optical MMs impose a flat rigid geometry. This impedes the realistic implementations of an optical cloak made of soft fabric, for example. I aim to overcome such limits.The aim of this project is to fabricate MMs in flexible, extremely thin membranes (METAFLEX).Metaflex will retain all the power of material design typical of MMs and their ability to control light, in a more flexible framework. I have already achieved the first milestone of the project and printed MMs on polymer flexible membranes with thickness down to few nanometers.The physics of Metaflex is a rich and unexplored field of research. This ambitious project is structured around their most striking properties:-Metaflex can be wrapped around objects and stacked, a vital step to realistic cloaking applications.-Metaflex stacks can be easily fine tuned after fabrication, e.g. via deformation, hence light can be controlled with additional degrees of freedom. The flexibility of Metaflex permits the design and fabrication of a camouflaging system, as the material response can sense and adapt to the surrounding environment. This offers a remarkable example of smart fabrics and intelligent textiles, currently a thriving area of research in academia and industry.-Metaflex provide a new framework to study the interaction between optical and mechanical forces, as in Optical Trapping or the new field of Optomechanics. Potential applications include very small optical microphones.-Metaflex are very light. They could take advantage of the attractive and repulsive forces triggered by optical beams in order to levitate and behave as nano-flying carpets. This would be a breakthrough in biomedical nano-applications such as drug-delivery and single molecules manipulation.My interest in Metaflex arises from diverse theoretical and experimental projects in photonic structures and nanofabrication and from the knowledge gained throughout these projects, including the physics and applications of MMs. This project contains many exciting scientific challenges, which offer the possibility of developing the extraordinary properties of MMs for every-day life applications that were unimaginable only a few years ago.