Sculpting super-fast light pulses: Nanopillars shape light precisely for practical applications

Imagine being able to shape a pulse of light in any conceivable manner—compressing it, stretching it, splitting it in two, changing its intensity or altering the direction of its electric field. Controlling the properties of ultrafast light pulses is essential for sending information through high-speed optical circuits and in probing atoms and molecules that vibrate thousands of trillions of times a second.

Researchers at the National Institute of Standards and Technology (NIST) and the University of Maryland’s NanoCenter in College Park have developed a novel and compact method of sculpting light. They first deposited a layer of ultrathin silicon on glass, just a few hundred nanometers (billionths of a meter) thick, and then covered an array of millions of tiny squares of the silicon with a protective material. By etching away the silicon surrounding each square, the team created millions of tiny pillars, which played a key role in the light sculpting technique.

The flat, ultrathin device is an example of a metasurface, which is used to change the properties of a light wave traveling through it. By carefully designing the shape, size, density and distribution of the nanopillars, multiple properties of each light pulse can now be tailored simultaneously and independently with nanoscale precision. These properties include the amplitude, phase and polarization of the wave.