"Get on the Optical Bus"
IBM's light-powered links overcome the greatest speed bump in
supercomputing: interconnect bandwidth
By CLINT SCHOW, FUAD DOANY, JEFFREY KASH,
IBM T. J. Watson Research Center in Yorktown Heights
SEPTEMBER 2010, IEEE Spectrum
"At IBM, we have now developed a first-of-its-kind optical data-transfer
system, or bus, built right onto the circuit board. With it, we will
soon unveil computer systems 100 times as fast as anything available
Anatomy of An Optomodule (解説図)
"We are developing parallel optical devices that will soon have the
kind of speed, density, and cost profile we are seeking. We call them
optochips. Optochips are transceivers: They convert signals from
electrical to optical form and back again."
"We have built two quite different optochips, one operating on optical
signals at 985 nanometers and the other at 850 nm. They both use
vertical-cavity surface-emitting lasers (VCSELs) as the light source.
These lasers can be modulated at speeds of up to 40 Gb/s, and they emit
light vertically through mirrors, along a path perpendicular to the chip.
The lasers are particularly inexpensive to manufacture, in part because
they are fabricated in two-dimensional arrays and so can be tested right
on the wafer, before it has gone through further processing steps.
(VCSELs are so inexpensive - just pennies per device?that they're now
found in nearly all optical mice.)"
"Within five years, we hope to connect microprocessors and memory chips
right to the optochip, producing the optical analogue to the electrical
multichip modules in today's big-iron machines. In these near-future
supercomputers, electrical connections will supply only the power, the
ground, and the control signals. All the data will shoot through optical
interconnects at the speed of light."
About the Author
"Their mission is not to speed up processors but to deal with the
shortage of bandwidth between them - an irksome problem that must be
solved if future generations of supercomputers and servers are to be
more powerful than today's."
"Optical PCB Overview",
Printed circuit board symposium, IBM Research, November 2009
Printed circuit board symposium, November 18 and 19, 2009
"The theme of this worldwide conference was high speed, high bandwidth
challenges for future technologies. The meeting brought together key
PCB and interconnect?related suppliers, along with IBM employees
representing development, research, and the integrated supply chain.
Eleven countries and twenty-six suppliers were represented at this