IBM Researchers Use Silicon Waveguides to Slow Light

IBM researchers have found a way to slow light with a silicon chip, a discovery that could lead to ultra-compact optical communications circuits integrated into computer systems.
Researchers have long known that light could be controlled in laboratory conditions but this is the first time scientists have used silicon, with micro and nanoelectronic fabrication technology. The findings, announced Thursday, are a major advance that could lead faster information delivery and less data traffic congestion in computers and other electronics systems, according to IBM.

Researchers said complex light-based circuits with footprints close in size to semiconductor circuits could one day be used to create nanophotonic components like optical delay lines, optical buffers and optical memory, all of which could be used to build computer systems linked by powerful optical communications networks.

IBM scientists slowed light to about 600 miles per second, less than 1/300th of its usual speed, by channeling it through a silicon photonic crystal waveguide that scatters the light and makes it highly refractive. The speed can be tuned quickly over a large range by applying low voltage electricity to the guide.

The IBM researchers believe that it should be possible to fabricate such waveguides in the form of silicon-on-insulator integrated circuits — a feat which would make the whole effort practical. The Defense Advanced Research Project Agency paid for some of the research, done by Yurii A. Vlasov, Martin O’Boyle, Hendrik F. Hamann and Sharee J. McNab at IBM’s T.J. Watson Research Center.

The findings have been published in the journal Nature. Though the Nature paper isn’t available online, insight into the IBM work can be gleaned from a separate, recent paper coauthored by one of the IBM researchers. The paper, entitled “Transmission of Slow Light through Photonic Crystal Waveguide Bends,” explains the importance of two-dimensional photonic crystal waveguides to the work.

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