A new IBM process uses pulses of light through silicon to send information between multiple cores on a chip

R E L A T E D C O N T E N T

IBM plans laptop-sized supercomputer

Breakthrough using light removes the need for wires

Matt Chapman, vnunet.com 06 Dec 2007

Supercomputers that consist of thousands of individual processors connected by miles of copper wires could one day fit into a laptop PC, according to IBM.

The company claims that a breakthrough by its scientists uses pulses of light through silicon, rather than electrical signals on wires, to send information between multiple cores or 'brains' on a chip.

This could lead to tiny 'supercomputers-on-a-chip' that expend the energy of a light bulb, compared with today's enormous machines that use enough energy to power hundreds of homes.

The process, published today in Optics Express, uses a silicon Mach-Zehnder electro-optic modulator to convert the electrical signals into pulses of light that are carried on a silicon nano-photonic waveguide.

IBM said that the modulator, a video of which has been posted on YouTube, is 100 to 1,000 times smaller than previously demonstrated modulators.

"Work is underway at IBM and in the industry to pack many more computing cores onto a single chip," said T C Chen, vice president of science and technology at IBM Research.

"But today's on-chip communications technology would overheat and be far too slow to handle that increase in workload.

"What we have done is a significant step towards building a much smaller and more power-efficient way to connect those cores, in a way that nobody has done before."

Chen explained that the process uses an input laser beam. The optical modulator acts as a very fast 'shutter' controlling whether the laser is blocked or transmitted to the output waveguide.

When a digital electrical pulse arrives at the modulator from a computer core, a short pulse of light is allowed to pass through at the optical output.

This 'modulates' the intensity of the input laser beam, and the modulator converts a stream of digital ones and zeros from electrical signals into light pulses.

"Just like fibre 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," said Will Green, lead IBM scientist on the project.

Using light instead of wires to send information between the cores can be 100 times faster and use 10 times less power than wires, IBM claimed.

See also: