IBM Shines Ray of Light on Processor Technology

Researchers at IBM announced Thursday the development of a technological breakthrough known as a “silicon Mach-Zehnder elctro-optic modulator.” The device would replace the copper wires normally used to transmit information between the multiple cores in a microprocessor. IBM’s optical modulator would convert the electrical signals and send that information using pulses of light through silicon instead of electrical signals on wire.

“We believe this is a major advancement in the field of on-chip silicon nanophotonics,” said Dr. Will Green, the lead IBM scientist on the project. “Just like fiber optic networks have enabled the rapid expansion of the Internet by enabling users to exchange huge amounts of data from anywhere in the world, IBM’s technology is bringing similar capabilities to the computer chip.”

The team of IBM scientists published details of their work in this month’s issue of the journal Optics Express.

At the Speed of Light

The IBM modulator is 100 to 1,000 times smaller than previously demonstrated modulators, and according to IBM, will pave “the way for many such devices and eventually complete optical routing networks to be integrated onto a single chip.” The modulator could substantially reduce cost, energy and heat while increasing communications bandwidth between the cores more than a hundred times over wired chips.

The goal of the technology is to enable a power-efficient method to connect hundreds or thousands of cores together on a tiny chip by eliminating the wires required to connect them. Using light instead of wire-bound electrical impulses to send information between the cores can be 100 times faster and use 10 times less power.

“Work is underway within IBM and in the industry to pack many more computing cores on a single chip, but today’s on-chip communications technology would overheat and be far too slow to handle that increase in workload,” said Dr. T.C. Chen, vice president of science and technology at IBM Research. “What we have done is a significant step toward building a vastly smaller and more power-efficient way to connect those cores, in a way that nobody has done before.”

It works by converting electrical signals into a series of light pulses carried on a silicon nanophotonic waveguide. The process begins when an input laser beam is delivered to the optical modulator. The modulator acts like a very fast shutter, controlling whether the input laser is blocked or transmitted to the output waveguide.

As digital electrical pulses from a computer core arrive at the modulator, a short pulse of light is allowed to pass through at the optical output. This allows the device to modulate the intensity of the input laser beam, and the modulator converts a stream of 1s and 0s from electrical signals into light pulses

Future of Computing

IBM’s announcement highlights a field of research that began several years ago. Companies including Intel, Primarion, Luxtera and IBM have invested millions of dollars into research that could solve the industry’s heat-related problem.

“There is in general a fair bit of interest and work going on in various ways to integrate optical links with silicon technology. For example, Intel has a number of projects in this area,” Gordon Haff, senior analyst at Illuminata, told TechNewsWorld.

“One of the big problems right now is power and heat,” said Rob Enderle, principal analyst at Enderle Group. “The more power you put into something the hotter it gets. And of course the more processing you’re doing on an ever-denser envelope, the hotter it’s going to get. Gordon Moore talked about at some point these things were going to be hotter than the sun, if we didn’t do something. This is the kind of thing we need to do to keep that from happening.”

Once it is put into practice, this latest technology could significantly cut back on the power requirements of computers and and reduce heat, allowing for even higher densities and more practical power requirements for a device we might carry in a pocket or for an ultra-dense super computer, Enderle told TechNewsWorld.

“This is one of those things that will make advanced computing late in the next decade possible. Without something like this, we would probably hit a pretty heavy wall in the next five to seven years,” he explained.

If IBM can productize the technology it will revolutionize not only desktop computers, but also handheld device, for which the power savings requirement is even greater.

“You could do everything on your phone that you now do on your laptop,” Enderle pointed out.

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