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10-03 :: March 2010

nanotimes

News in Brief

Computer Chips //

Ultra-Fast Device Which Uses Light for Communication

I

BM (NYSE: IBM) scientists unveiled a significant step towards replacing electrical signals that com-

municate via copper wires between computer chips with tiny silicon circuits that communicate using pulses of light.

The device, called a nanophotonic avalanche pho- todetector, is the fastest of its kind and could enable breakthroughs in energy-efficient computing that can have significant implications for the future of electro- nics.

The IBM device explores the “avalanche effect” in Germanium, a material currently used in production of microprocessor chips. Analogous to a snow ava- lanche on a steep mountain slope, an incoming light pulse initially frees just a few charge carriers which in turn free others until the original signal is amplified many times. Conventional avalanche photodetectors are not able to detect fast optical signals because the avalanche builds slowly.

“This invention brings the vision of on-chip optical interconnections much closer to reality,” said Dr. T.C. Chen, vice president, Science and Technolo- gy, IBM Research. “With optical communications embedded into the processor chips, the prospect of building power-efficient computer systems with performance at the Exaflop level might not be a very distant future.”

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Optical microscope photographic image of an array of nanophotonic avalanche photodetectors on a silicon chip. © IBM Research

The avalanche photodetector demonstrated by IBM is the world’s fastest device of its kind. It can receive optical information signals at 40Gbps (billion bits per second) and simultaneously multiply them tenfold. Moreover, the device operates with just a 1.5V vol- tage supply, 20 times smaller than previous demons- trations. Thus many of these tiny communication devices could potentially be powered by just a small AA-size battery, while traditional avalanche photo- detectors require 20-30V power supplies.

Solomon Assefa, Fengnian Xia, and Yurii Vlasov: Rein- venting Germanium Avalanche Photodetector for Nano- photonic On-chip Optical Interconnects, In: Nature, Vol. 464(2010), Number 7285, March 04, 2010, Pages 80-84, DOI:10.1038/nature08813: http://dx.doi.org/10.1038/nature08813 Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69