image: Overlaid scanning electron microscopy (SEM) and optical images showing an ENGRAVE nanowire that is periodically modulated at one end. Light of one select color (green) from a broad rainbow background enters at the modulated segment (false-colored red), traverses the uniform wire (false-colored blue), and is emitted at the end. Insets are magnified SEM images of the modulated segment and end of the nanowire, where the end contains a spherical gold particle that was used to grow the nanowire by the ENGRAVE process. view more
Credit: UNC-Chapel Hill
Researchers from the University of North Carolina at Chapel Hill have reached a new milestone on the way to optical computing, or the use of light instead of electricity for computing. They explored a new way to select and send light of a specific color using long silicon wires that are several hundred nanometers in diameter (about 1,000 times smaller than a human hair) and their work enabled a new type of nanoscale "light switch" that can turn on and off the transmission of one color of light over very long distances.
The research paper, written by chemistry professor James Cahoon and graduate student Seokhyoung Kim at the University of North Carolina at Chapel Hill, along with collaborators at Korea University, was published in the journal Nature Communications on July 17.
Optical computing technology promises many benefits. Swapping electrons for light-based technology would mean that the computers of the future won't overheat and will run much faster.
"In the past there hasn't been a controlled method for selectively sending light down nanoscale wires, so optical technology has either used much larger structures or wasted a lot of light in the process," said James Cahoon, senior corresponding author and associate professor of chemistry in the College of Arts and Sciences at UNC-Chapel Hill. "We found a way to turn on and off the transmission of a specific color of light, and it represents an important step towards the more controlled, effective use of light that would enable optical computing."
The research team developed the Encoded Nanowire Growth and Appearance through VLS and Etching (ENGRAVE) technique, which can create complex shapes in nanowires. They then achieved selective light transmission through precise diameter modulation with the ENGRAVE technique. This was the first report of direct use of a Mie resonance, a light scattering property of nanowires, for guiding light in a nanowire.
This work is a step forward for optical computing and will help enable further advances in the technology. The team's findings can enable downsizing of the optical components needed to develop computers based on light instead of on electricity. By miniaturizing these components, they can be more easily integrated with the existing electronic components in computers. Additionally, the color of light conducted by the wires in this study is sensitive, with the color changing as the environment changes. Thus, these structures can be used as a new type of sensor, in which the color of the conducted light senses the environment of the wire.
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About the University of North Carolina at Chapel Hill
The University of North Carolina at Chapel Hill, the nation's first public university, is a global higher education leader known for innovative teaching, research and public service. A member of the prestigious Association of American Universities, Carolina regularly ranks as the best value for academic quality in U.S. public higher education. Now in its third century, the University offers 77 bachelor's, 111 master's, 65 doctorate and seven professional degree programs through 14 schools and the College of Arts and Sciences. Every day, faculty, staff and students shape their teaching, research and public service to meet North Carolina's most pressing needs in every region and all 100 counties. Carolina's more than 323,000 alumni live in all 50 states, the District of Columbia and 149 countries. More than 169,000 live in North Carolina.
Journal
Nature Communications