Sun tries to replace wire with laser
Sun Microsystems is trying to do for computing what all the king's horses and men failed to do for Humpty Dumpty.
For decades, the semiconductor industry has broken silicon wafers into smaller chips to improve manufacturing yields.
Now Sun has found a way to reconnect the chips so they can communicate with each other at such high speeds that computer designers can build a new generation of computers that are faster, more energy-efficient, and more compact.
The company, which is based in Santa Clara, Calif., plans to announce today that it has received a $44 million contract from the Pentagon to explore the high-risk idea of replacing the wires between computer chips 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 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. 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 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."
Silicon photonics has become hot recently with major semiconductor and computer companies as well as start-ups investing heavily in efforts to build optical networking directly into processors to replace electrical wires.
The Sun researchers refer to their new system as a "macrochip." They said that the technology would make it possible for computer architects to completely rethink the organization of circuitry on a computer.
"It's like the difference between having someone next door and having to get on an airplane to fly across the country," said Alan Huang, an optical networking designer at the Terabit Corp. in Menlo Park, Calif.
