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
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
"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."