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Phoenix666 writes:

For the first time, Harvard researchers have created wakes of light-like waves moving on a metallic surface, called surface plasmons, and demonstrated that they can be controlled and steered. The creation and control of surface plasmon wakes could lead to new types of plasmonic couplers and lenses that could create two-dimensional holograms or focus light at the nanoscale.

[...] Surface plasmons are confined to the surface of a metal. In order to create wakes through them, Capasso's team designed a faster-than-light running wave of charge along a one-dimensional metamaterial — like a powerboat speeding across a lake.

The metamaterial, a nanostructure of rotated slits etched into a gold film, changes the phase of the surface plasmons generated at each slit relative to each other, increasing the velocity of the running wave. The nanostructure also acts like the boat's rudder, allowing the wakes to be steered by controlling the speed of the running wave.

The team discovered that the angle of incidence of the light shining onto the metamaterial provides an additional measure of control and using polarized light can even reverse the direction of the wake relative to the running wave — like a wake traveling in the opposite direction of a boat.