The advent of invisibility cloaks for electromagnetic (EM) waves has arisen from clever theoretical advances in transformation optics, for which exit EM waves can be made identical to incident waves even after they are guided around a concealed object. Transformation optics can be used to achieve other optical effects, as well. For example, they can be tailored to create nonreflecting boundaries at the edge of a specific domain—an effect that could become practically useful. Existing theoretical limitations, however, such as the requirement for EM waves incident from a vacuum (which in ordinary Earthly life would require the addition of a reflecting dielectric layer to the construct), create practical drawbacks.
Researchers at Australian National University (Canberra, Australia) and the Russian Academy of Sciences (Nizhny Novgorod, Russia) have sidestepped these limitations by designing an EM cloak with an “inside-out” structure (transforming infinity and far distances to the design surface) that will allow the design of practical nonreflecting interfaces with no unwanted dielectric layers. One-and two-dimensional simulations, for example with an impinging Gaussian beam, show complete absorbence. The constructs work simultaneously for all polarizations. Contact Ilya Shadrivov at
[email protected].