Electrical Signals Dictate Optical Properties

A new type of metamaterial that can be controlled by electrical signals has optical properties that are three orders of magnitude faster than previous electrically reconfigurable materials.

Photonic metamaterials, created by precise and extremely fine structuring of conventional media using nanotechnology, offer numerous applications from cloaking to radically improved solar cells, but the properties of these materials are usually fixed.

Now researchers at the University of Southampton’s Optoelectronics Research Centre (ORC) have created an artificial material with optical properties that can be actuated by electrostatic forces of only a few volts to its nanoscale building blocks — the plasmonic metamolecules — that are supported by pairs of parallel strings cut from a flexible silicon nitride membrane of nanoscale thickness.

“We shift [the strings] by distances smaller than the diameter of a human hair,” said Dr. Eric Plum, a research lecturer at the ORC. “These minute rearrangements are sufficient to radically change the transmission and reflection characteristics of the metamaterial. We do this by engaging the same force that sticks a small piece of paper to a comb after brushing. In essence, we dictate the movement of metamaterial building blocks with electrical signals, and we can do this very fast.”

“Thanks to nanotechnology, we need not depend only on natural materials; we can now engineer optical properties and change them at will,” said professor Nikolay Zheludev, director of the university’s Center for Photonic Metamaterials. “Light-enabled technologies are vital to the 21st century, and photonic metamaterials will have a broad impact.”

The research was published in Nature Nanotechnology (doi: 10.1038/nnano.2013.25).

For more information, visit: www.southampton.ac.uk