Researchers have effectively delayed light's travel for the purpose of chips
IBM has announced that its researchers have built a device capable of delaying the flow of light on a silicon chip, which could lead the further development of using light instead of electricity to transfer data. Researchers have known that the use of optical instead of electrical signals for transferring data within a computer chip might result in significant performance enhancements since light signals can carry more information faster. The engineering challenge is buffering data on the chip, which is difficult given light’s speed. Thus, a means of using light effectively is to delay its travel.
Long delays can be achieved by passing light through optical fibers. IBM scientists were able to delay light by passing it through a new form of silicon-based optical delay line built of up to 100 cascaded "micro-ring resonators," built using current silicon complementary metal-oxide-semiconductor (CMOS) fabrication tools. When the optical waveguide is curved to form a ring, light is forced to circle multiple times, delaying its travel. The optical buffer device based on this simple concept can briefly store 10 bits of optical information within an area of 0.03 square millimeters. This advancement could potentially lead to integrating hundreds of these devices on one computer chip, an important step towards on-chip optical communications.
a) Cleaved coupling section of a bent waveguide bus and a resonator; b&c) Delay line consisting of several ring resonators
"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."
The report on this work, "Ultra-compact optical buffers on a silicon chip," is published in the premiere issue of the journal Nature Photonics. This work was partially supported by the Defense Advanced Research Projects Agency (DARPA) through the Defense Sciences Office program "Slowing, Storing and Processing Light."