These curved rays are called ‘Airy beams’ after the astronomer Sir George Biddell Airy who studied what appears to be curved light in rainbows.

The US Lawrence Berkeley National Laboratory (Berkeley Lab) has demonstrated real-time control of the curved trajectories of Airy beams over metallic surfaces.

“This development paves the way for fast-as-light compact communication systems and optoelectronic devices,” said the Berkeley lab. “The key to this work was the team’s ability to directly couple free-space Airy beams, using a grating coupler, to quasi-particles called surface plasmon polaritons [SPPs].”

Directing a laser beam of light across the surface of a metal nanostructure generates electronic surface waves – plasmons – that roll through the metal’s conduction electrons.

The resulting interaction between plasmons and photons creates SPPs, and by coupling Airy beams to SPPs, the researchers can manipulate light at a small scale, beyond the diffraction limit.

“Dynamic controllability of SPPs is extremely desirable for reconfigurable optical interconnections,” said research head Processor Xiang Zhang. “We have provided a novel approach of plasmonic Airy beam to manipulate SPPs without the need of any waveguide structures over metallic surfaces, providing dynamic control of their ballistic trajectories despite any surface roughness and defects, or even getting around obstacles. This is promising not only for applications in reconfigurable optical interconnections but also for precisely manipulating particles on extremely small scales.”

According to collaborator Professor Zhigang Chen of San Francisco State University: “With the reconfigurability of our plasmonic Airy beams, a small number of optical devices can be employed to perform a large number of functions within a compact system. In addition, the unique properties of the plasmonic Airy beams open new opportunities for on-chip energy routing along arbitrary trajectories in plasmonic circuitry, and allows for dynamic manipulations of nano-particles on metal surfaces and in magneto-electronic devices.”

There is a paper on the subject titled ‘Plasmonic Airy beams with dynamically controlled trajectories’ in the journal Optics Letters.

A simulation of dynamical control of light by Professor Xiang Zhang at Berkeley Lab. The team has also demonstrated it physically.