Cynthia L. Atwood, Science Correspondent
Yale University Office of Public Affairs
433 Temple St.
New Haven, CT 06520
(203) 432-1326, fax (203) 432-1323
[email protected]
CONTACT: Cynthia L. Atwood #129
For Immediate Release: Jan. 9, 1997
Yale Discovery Could Help Expand Fiber-optic Network Traffic,
Speed Up Computers, Improve Video Displays and Laser Printers
New Haven, CT -- Today, a single fiber-optic cable barely wider than
a human hair can carry half a million phone calls simultaneously,
making fiber-optic technology perhaps the single most important factor
in the phenomenal success of the information superhighway. Now this
technology is moving into the realm of computers and printers,
where microlasers and optical-fiber interconnects are expected
to boost performance dramatically in the near future.
A new approach for manipulating laser light on the microscopic scale
that could be useful for all of these applications was announced Jan. 2
in the journal Nature in a cover story by Yale University applied
physicist A. Douglas Stone and his former graduate student Jens Noeckel.
"All lasers require a component called an optical resonator,
which traps light after it is generated, allows it to be amplified, and
selects out a specific frequency of light to be emitted in a desired
direction," said Professor Stone, who proposes a radically new desig
for a resonator that could be more efficient, more powerful and cheaper
to produce on a microscopic scale.
He and Dr. Noeckel, along with Yale physicist Richard Chang, have
applied jointly with Yale for a patent on the resonator design, called
an asymmetric resonant cavity (ARC). The discovery, which is based on
computer simulations, has attracted the interest of fiber-optic giant
Corning Inc. "The collaboration with Corning is a natural one because
the accepted approach for sending even more information on fiber-optic
networks is to pack the information into different frequencies, or
colors, of light, all transmitted at the same time on the same cable,"
Professor Stone said.
The ARC resonator can be used to detect each of the arriving light
frequencies, much like a radio receiver sorts out different radio
frequencies. "This approach could save millions of dollars by making
it possible to send high-quality video and audio signals at greater
speeds on existing fiber-optic networks without installing new cable,"
he said, adding that a tenfold increase in speed might be possible
eventually.
The Yale discovery is based on the principles of chaotic motion
illustrated by the path of a billiard ball bouncing off the wall of a
table that is round instead of rectangular. Professor Stone had been
using computer models of such motion in his study of chaos theory and
realized that rays of light bouncing inside an oval chamber, such as a
pill box or glass bead, would behave the same way.
"Light can be thought of either as a ray or a wave, although most
scientists today rely on James Clerk Maxwell's wave theory of light,
developed at the end of 19th century, which led to the invention of
radio," Professor Stone said. "However, the wave theory of light is
very difficult to use in this case. By retreating to the old-fashioned
ray theory, which dates back to the 1600's, combined with new-fangled
chaos theory, we were able to get an insight into this problem that no
one else had."
Like Sound in a "Whispering Gallery"
The Yale computer simulations showed that a light ray could be
trapped inside a perfectly round optic resonator, where it would bounce
along the perimeter. "This is analogous to sound trapped in a circular
'whispering gallery,' such as the famous one in St. Paul's Cathedral in
London, where sound flows along the walls," Professor Stone said.
"A whisper can be heard by someone standing against the opposite wall,
but not by someone standing in the center of the room."
However, trapped light eventually escapes equally in all
directions from a perfectly circular resonator, making it useless for
practical applications, he said. A slightly asymmetrical resonator,
on the other hand, traps light of a certain frequency and emits it in
a specific direction, making 'whispering gallery' resonators -- like
the ARC resonator -- useful as micro-lasers and as detectors of
fiber-optic signals.
Because Professor Stone's theory can predict the directions that
light will be emitted from an ARC detector of a given shape, he
believes he can find the best shape for each application. (Initially
the theory was tested by observing and predicting how laser light
interacted with deformed water droplets in Professor Chang's
experiments.) Corning Inc. now is fabricating glass resonators only
80 millionths of a meter across that are deformed to Stone's
specifications. They will be tested at Yale for suitability as ARC
detectors in research funded by the National Science Foundation.
"We have to build up our understanding of these completely new
devices very systematically so we know what to expect from different
shapes," said Professor Stone, who joined the Yale faculty in 1986 and
was named a Presidential Young Investigator the following year.
"Scientists already know how to make microresonators, although no one
had thought of the ARC design before. People are getting excited
about it. Hopefully in the next five years there will be a lot of
research at Yale and elsewhere to understand exactly how it works."
###
NOTE TO EDITORS: A. Douglas Stone received his bachelor's degree in
social studies from Harvard University in 1976 and a master's degree
in physics and philosophy from Oxford University in 1978, where he was
a Rhodes Scholar. He received a Ph.D. degree in theoretical physics
from MIT in 1983 and spent several years at IBM's Watson Research
Center before coming to Yale. His earlier research at Yale was in
theoretical solid-state physics, where he predicted the existence of
fluctuations in the electrical resistance of all tiny conductors due
to wave-like interference of electrons moving in solids. In addition
to a Presidential Young Investigators award, Professor Stone has
received a Sloan Fellowship and has been elected a Fellow of the
American Physical Society.
He is continuing his research on ARC microresonators in collaboration
with Richard K. Chang, the Henry Ford II Professor of Applied Physics
at Yale, who is an internationally recognized leader in optical physics.
Their research is being funded by a $727,000, three-year NSF grant.
For interviews, call Professor Stone at (203)-432-4279.
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