At the Frontiers in Optics conference on October 14 ,2009 Jeffrey Kash of IBM Research gave a presentation on the road to Exascale supercomputering He gave a projection of the necessary timeline for the shift from electrical communication in supercomputers to optical in order to support exascale supercomputing.
VCSEL-based optics have displaced electric cables today in supercomputers, but with power, density and cost requirements increasing exponentially as the systems get powerful, the need increases to move to on-chip optics.
Because a 10x increase in performance means the machine will consume double the power, to make future supercomputers feasible to build and to operate optics will need to be more widely used he said. In 2008 a 1-petaflop computer cost $150 million to build and consumes 2.5 MW of power. Using the same technology, by 2020 a 1 exaflop machine would cost $500 million to build and consume 20 MW of power.
Kash gave a timeline that would find optics replacing electrical backplanes by 2012 and replacing electrical printed circuit boards by 2016. In 2020, optics could be directly on the chip. In a less aggressive scenario, by 2020 all off-chip communications need to be optical, he said.
But for that to happen, to get optics up to millions of units in 2010, the price needs to drop to about $1 per Gb/s, he said. Today, Gb/s processing costs about $10.
Photonics in Supercomputing: The Road to Exascale, Jeffrey Kash; IBM Res., USA. Optical interconnects in present and future supercomputers are reviewed, emphasizing Exaflop performance circa 2020, which is 1000X today’s Petaflop computers. Power, density and cost requirements become increasingly stringent, ultimately driving the need for on-chip optics. (Integrated Photonics and Nanophotonics Research and Applications, 2009)