Nanovation Technologies, Inc. develops a photonic chip useful in WDM demltiplexing, as well as other areas:
newsbytes.com
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Success Reported In Revolutionary Photon Chip
Tests
17 Dec 1998, 3:07 AM CST
By Craig Menefee, Newsbytes.
CHICAGO, ILLINOIS, U.S.A.,
Florida-based high tech start-up
Nanovation Technologies, Inc. says its
lab at Northwestern University has made
a working, fully integrated optical circuit
that could have revolutionary effects on computing. The
circuit works with photons instead of electrons.
According to the firm, a light-operated or photonic chip would
be up to 1,000 times smaller than electron-based
semiconductor circuits and could boost chip speed and data
capacity by a factor of 100 to 1,000.
Unlike conventional electron-based switched, a photonic
switch uses no bias voltages or currents. Instead, it controls
a light-borne signal using frequency harmonics, photon
tunneling, microcavity lasers and atomically smooth optical
wave guides called "photonic wires."
Such terms may sound like the technical baffle-gab of a Star
Trek script but the results are real enough. The university
has even taken an equity position in the patented technology
-- the first time it has not just settled for royalties on
inventions made in its facilities.
Inventions this far out on the bleeding edge of technology
can take 10 years to appear in high-end commercial
applications. It can be 15 years before they appear in homes
or in gadgets like cellular flip-phones.
But Bob Tatum, Nanovation's chief executive officer (CEO),
says photonic switching -- he does not use the term "light
switches" -- will be widely used much faster than that. In
fact, he told Newsbytes, Nanovation is already having
proof-of-concept sessions with major technology companies.
Tatum says devices using optical logic chips, based on the
switch circuit announced this week, could start to appear as
early as the year 2,000.
Tatum has some good credentials. He is a former senior vice
president of technology at General Electric's information
services division and others in the industry take him
seriously.
Still, it will take more than pure speed and capacity to drive
such fast adoption, even though performance at 100 times or
more the speed of electronic circuits hardly hurts.
Just as importantly, Tatum says, the process for making
photonic circuits is "consistent with current semiconductor
fabrications – it is silicon based, using materials like gallium
arsenide that are not terribly exotic."
Creating the wave guides requires methods that are well
understood by the semiconductor industry. The processes
have formidable names like reactive ion beam etching and
inductively coupled plasma processing.
Northwestern University's prototype production line was
designed virtually from scratch by the UK's Oxford
Instruments, which Tatum says has called Northwestern's
etching line the most advanced in North America for
sub-micron lines.
The term "advanced" understates what Oxford Instruments
achieved. Tatum says the connections or "wires" between
features in a photonic circuit are as small as 0.02 microns --
not 0.20 microns, like some fairly advanced electronic
circuits, but ten times finer.
Such etching takes precision right down to the atomic level,
says Tatum, but wires that tiny are needed because photons
travel best in much more confined spaces than electrons.
"Our patents all refer to strongly confined space, meaning
the light travels in very narrow, very confined space with very
little leakage or loss," Tatum explained. "As a result, we can
bend the light in a quarter-micron radius, which is necessary
in a dense integrated circuit -- or in our case, integrated
optics."
Tatum says the actual processes used by the working
circuit are proprietary but in layman's terms, they resemble
the resonance that causes a tuning fork, when brought near
a second, vibrating tuning fork, to start to vibrate in
sympathy.
"Instead of a tuning fork, we use a photon resonator cavity,
called a quantum well, that resonates at a particular
frequency," he told Newsbytes. "When you pass a wire
close to the well and a photon is in the wire at the same
precise frequency as the well, the two will couple. It's called
tunneling -- the photon will disappear from the photonic wire
and tunnel into the resonator well."
He continued, "Now, if there is a second photonic wire on
the other side of the well, another photon at the same
frequency will tunnel from the quantum well into the second
wire."
In effect, the resonating well frequency determines whether a
photon tunnels into the well or continues on its merry way.
And that becomes the basis of logic devices that use light
instead of electrons.
Tatum added, "Now here's where it gets beautiful. Take 32
channels, like in wave division multiplexing, and run it down
that first wave guide. The light in one of those multiplexed
channels is at the resonant frequency of the quantum well. It
will be picked off that stream and coupled into the other
wave guide while the rest of the light continues on its way. In
electronics terms, they call that de-multiplexing. "
He paused. "It is a huge breakthrough. Huge. We have here,
in a single, passive device, a working de-multiplexer. With
32 different frequencies you could de-multiplex 32
frequencies from a single wave guide. Without any
electronics."
A scramble has begun among corporations and universities
to research the use of photonic technology, largely because
of its speed and information-carrying capacity. Tatum says
one obvious use is to replace computer processors.
"Because photonic circuits are smaller and more efficient,
they don't use as much power," Tatum said. "A laptop could
run for three weeks on the same battery. And you know
what? You don't have to put a fan on top of our circuits like
you do on an IC (integrated circuit) because they don't heat
up."
Nanovation holds patent rights on the photonic technology,
which was developed initially at Cornell University and later
refined at Northwestern by a team led by Dr. Seng Tiong Ho.
Ho is a professor in the Electrical Engineering and Computer
Sciences Department at Northwestern but came there from
the advanced quantum physics laboratory at Bell Labs, the
home of the original transistor.
Tatum says the earliest uses for light-operated logic will
most likely be found in industries that need ever greater
bandwidth, such as telecommunications, large networks and
data storage.
Nanovation is on the World Wide Web at
nanovation.com .
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