A decade ago, people were impressed that their cellular phones could send a simple text message. Now smartphones send and receive high-resolution photographs, videos, emails with large attachments, and much more. The desire for endless data has become insatiable.
"The ability to deliver information from one location to another has played a very important role in advancing human civilization," said Robert Chang, professor of materials science and engineering at Northwestern University’s McCormick School of Engineering. "Today, we live in a digital world where the demand for the ability to transmit large amounts of data is growing exponentially."
To meet this high demand, Chang and his team have developed a new surface for modulating light signals in the near-infrared wavelength region. Their work, which is reported in Nature Photonics, demonstrates a novel scheme for controlling infrared plasmons and could form the basis for faster, more efficient ways of transmitting massive amounts of information.
A plasmon is a quantum particle that arises from collective oscillations of free electrons. By controlling plasmons, researchers can work optical switches, potentially permitting signals in optical fibers to be switched from one circuit to another – with ultimate high speeds in the terahertz.
"Today, we live in a digital world where the demand for the ability to transmit large amounts of data is growing exponentially."Robert Chang, Northwestern University’s McCormick School of Engineering
Researchers have already demonstrated active plasmonics for light at ultraviolet to visible wavelengths using noble metals such as gold. But controlling plasmons in the near- to mid-infrared spectral range – where noble materials suffer from excessive optical losses – is largely unexplored. Research in this area has recently attracted significant attention for its importance to telecommunications, thermal engineering, infrared sensing, light emission and imaging.
Chang's team successfully controlled plasmons in this technologically-important wavelength range by using nanorod arrays of indium-tin-oxide (ITO). The low electron density of ITO produces a substantial redistribution of electron energies, which results in light signal modulation with very large absolute amplitude. By tailoring the geometry of the ITO nanorod arrays, the researchers could further tune the spectral range of the signal modulation at will, opening the door for improved telecommunications and molecular sensing.
"Our results pave the way for robust manipulation of the infrared spectrum," Chang said.
This story is adapted from material from Northwestern University’s McCormick School of Engineering, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.