IBM researchers have built a device that can delay the flow of light on a silicon chip, a key step toward faster computers based on optical communications.
Researchers agree that using optical instead of electrical signals for moving data within a computer chip will probably mean better performance because light signals can carry more information faster. But speed isn't the only issue.
"Buffering," or temporarily holding data on the chip, is critical in controlling the flow of information. The IBM work outlines a means for buffering optical signals on a chip.
"Today's more powerful microprocessors are capable of performing much more work if we can only find a way to increase the flow of information within a computer," said Dr. T.C. Chen, vice president of Science and Technology for IBM Research. "As more and more data is capable of being processed on a chip, we believe optical communications is the way to eliminate these bottlenecks. As a result, the focus in high-performance computing is shifting from improvements in computation to those in communication within the system."
One way to delay light is to pass it through optical fibers.
However, current "delay line" devices are too big to fit on a microchip. IBM control the light signal by passing it through a new form of silicon-based optical delay line built of up to 100 cascaded "micro-ring resonators." With the optical waveguide curved to form a ring, it forces light to circle multiple times, delaying its travel. The resonators are built using current silicon complementary metal-oxide-semiconductor (CMOS) fabrication tools and will fit on a microchip.