Cell phone antennas, radio receivers and GPS devices may one day go incognito. In a paper to appear in Physical Review Letters, Andrea Alù and Nader Engheta propose a new cloaking method that cancels out the electromagnetic waves bouncing off an object. The concept may ultimately lead to surreptitious sensors that can collect and send messages without detection.
The new cloak manipulates electromagnetic waves — including light — not by blocking out the waves, but by working with them. Previous cloaks worked by diverting waves around an object. We have shown how plasmonic materials and metamaterials may overcome a general and fundamental limit of currently available sensors, in that they are necessarily required to scatter around, affecting their own measurement, says Alù. In our paper, we have set the ground for a new general class of sensing devices that may see without being seen. This may have fundamental implications in conceiving novel non-invasive probing devices for a wide range of biological, optics, physics, and engineering applications.