Designing metasurfaces of unusual shapes
CRHEA, in collaboration with the center of the CNRS International NTU THALES Research Alliance in Singapore, presents a method for designing ultrathin optical components - commonly called metasurfaces - of arbitrary shapes. The method relies on an optical transformation technique used in the field of metamaterials. With this results, it is now possible of predicting and designing the optical response of metasurfaces conformal to non-planar objects. This method would enable new design opportunities for free-form optics, illusion optics, radar and military camouflage.
Surfing a wake of light
When a duck paddles across a pond or a supersonic plane flies through the sky, it leaves a wake in its path. Wakes occur whenever something is traveling through a medium faster than the waves it creates — in the duck’s case water waves, in the plane’s case shock waves, otherwise known as sonic booms (see picture on the left).
Wakes can exist wherever there are waves, even if those waves are light. While nothing travels faster than the speed of light in a vacuum, light isn’t always in a vacuum. It is possible for something to move faster than the phase velocity of light in a medium or material and generate a wake. The most famous example of this is Cherenkov radiation, wakes produced as electrical charges travel through liquids faster than the phase velocity of light, emitting a glowing blue wake.
For the first time, we have created similar wakes of light-like waves moving on a metallic surface, called surface plasmons, and demonstrated that they can be controlled and steered. The angle of incidence of the light shining onto the metamaterial provides an additional measure of control and using polarized light we can even reverse the direction of the wake relative to the running wave — like a wake traveling in the opposite direction of a boat.
The discovery was recently published in the journal Nature Nanotechnology, see also the Harvard press release here