The March 2010 issue of Nature has published a report by scientists at IBM Research who have engineered a device called the nanophotonic avalanche photodetector that can take energy-efficient computing to advanced levels and affect the future of electronics significantly. This development replaces electrical signals that communicate via copper wires between PC chips with tiny silicon circuits that communicate by implementing light pulses.
The device explores the ‘avalanche effect’ in germanium, in which an incoming light pulse frees a few charge carriers that free others in turn until the original signal is amplified manifold times. IBM’s new device is capable of receiving optical information signals at 40GB/s and multiplying them by tenfold simultaneously. The report titled ‘Reinventing Germanium Avalanche Photodetector for Nanophotonic On-chip Optical Interconnects’ was submitted by Solomon Assefa, Fengnian Xia, and Yurii Vlasov of IBM, T.J. Watson Research Center in Yorktown Heights, N.Y.
“This invention brings the vision of on-chip optical interconnections much closer to reality. 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,†elaborated Dr. T.C. Chen, VP of Science and Technology at IBM Research.
Its small size results in the device emitting a multiplication noise which is suppressed by nearly 50% to 70% as placed against currently existing avalanche photodetectors. The device may be powered by an AA-sized battery since its energy requirements are calculated at a mere 1.5V. It is built out of materials used in microprocessor chips such as silicon and germanium with standard processes used in chip manufacturing. Accordingly, these devices can be produced in volume quantities along with silicon transistors for high-bandwidth on-chip optical communications.
Dr. Solomon Assefa, lead author of this report, explained, “This dramatic improvement in performance is the result of manipulating the optical and electrical properties at the scale of just a few tens of atoms to achieve performance well beyond accepted boundaries. These tiny devices are capable of detecting very weak pulses of light and amplifying them with unprecedented bandwidth and minimal addition of unwanted noise,â€
The nanophotonic avalanche photodetector will be part of the ‘nanophotonics toolbox’ by IBM Research that will assist in engineering on-chip optical interconnects.
