IBM researchers build supercomputer-on-a-chip

by Agam Shah

December 6, 2007 —

Supercomputers may soon be the same size as a laptop if IBM
brings to market research detailed on Thursday, in which pulses of light replace
electricity to make data transfer between processor cores on a chip up to one-hundred
times faster.

The technology, called silicon nanophotonics, replaces some of the wires on
a chip with pulses of light on tiny optical fibers for quicker and more power-efficient
data transfers between cores on a chip, said Will Green, research scientist
at IBM.

The technology, which can transfers data up to a distance of a few centimeters,
is about 100 times faster than wires and consumes one-tenth as much power, Green
said. The lower power requirement should reduce operational costs for supercomputers,
he said.

"The silicon nanophotonic effort is a high-bandwidth, low-power technology
for cores to communicate," Green said.

The technical basis of this research is the same science that led to the development
of optical fiber and Internet communications. Silicon nanophotonics brings similar
optical communication on chips for centimeters instead of miles, Green said.

The improved data bandwidth and power efficiency of silicon nanophotonics will
bring massive computing power to desks, Green said. "We'll be able to have
hundreds or thousands of cores on a chip," Green said. Users will be able
to render virtual worlds in real-time and have a better gaming experience, he
said.

Modulators sitting in each core convert light into pulses that travels over
optical fibers in the silicon chip. The modulators don't take up too much space
on the chip, Green said.

Silicon nanophotonics is part of a long-term research project and could be
implemented in chips within 10 to 12 years, he said.

More cores are being added to chips to boost performance, but electrical wiring
that connects cores on current chips doesn't transfer data effectively in these
situations, Green said. Electrical wiring suffers from overheating and data
signals travel only a few millimeters from one core to another before breaking
down, Green said. Silicon photonics sends signals for many centimeters in a
power-efficient mode without an attempt to reconstruct the signal, Green said.

Though the technology shows potential to replace copper wires for data transfer
on chips, electrical wiring still does well over short distances. Copper wire
is essential for transistors in chips to communicate, while silicon nanophotonic
technology is used for cores to communicate. "We're complementing the capabilities
of copper with our optical technology," Green said.

In addition to IBM, there are a couple of start-up companies and labs in the
U.S. that are working on silicon nanophotonics technology, Green said. The IBM
project was funded partly by Defense
Advanced Research Projects Agency (DARPA), a division of the U.S. Department
of Defense.

IDG News Service