Sun aims to replace wires with laser beams

The technology, part of a field of computer science known as silicon photonics, would eradicate the most daunting bottleneck facing today’s supercomputer designers: moving information rapidly to solve problems that require hundreds or thousands of processors.

Processor and memory chips are currently made by etching hundreds or thousands of identical circuits onto a single wafer of silicon and then slicing that wafer into fingernail-size chips. That manufacturing process ensures that if there is a defect at a single spot on the giant wafer it will not ruin the entire batch of chips.

The drawback in the approach is that wires have to connect the chips in a computer. This causes a fundamental limit in processing power because data moves between chips at lower speeds, creating significant bottlenecks.

The wires that connect chips are analogous to the on and off ramps that cars use to move between freeways — just as cars slow down as they move onto city streets from multilane highways, electrical signals run more slowly between chips. The bottlenecks also generate additional electrical current and heat.

“All of a sudden it’s better to have an optical superhighway,” said Greg Papadopoulos, chief technology officer and executive vice president of research and development for Sun.

Computer scientists have long sought a way to make faster and cheaper computers by making larger chips on a single wafer of silicon, a manufacturing process called “wafer scale integration.” If the Sun researchers’ idea can be proved technically feasible and manufactured commercially, it would be possible to create more-compact machines that are a thousand times faster than today’s computers, the company said. Each chip would be able to communicate directly with every other chip in the array via a beam of laser light that could carry tens billions of bits of data a second.

The Sun researchers acknowledge that their project is a significant gamble.

“This is a high-risk program,” said Ron Ho, a researcher at Sun Laboratories who is one of the leaders of the effort. “We expect a 50 percent chance of failure, but if we win we can have as much as a thousand times increase in performance.”