Re: new discovery may lead to the first optical microchip, where light instead of electricity moves through tiny circuits.
Hi All,
Wondering if anyone has seen this announcement or the Nature article cited:
ciar.ca
Text Follows:
Toronto – May 26, 2000 - Researchers affiliated with The Canadian Institute for Advanced Research
(CIAR) and the University of Toronto, have produced a silicon-based material that can "cage", or trap
light, controlling it in the same way that microchips control electrons. This new discovery may lead to the
first optical microchip, where light instead of electricity moves through tiny circuits. If this new material
can be reliably mass produced, and incorporated into telecommunications networks and computers, it
can be a major technological revolution. Information would travel at light-speed, the fastest in the
universe, allowing smaller and faster communications devices to be built.
This novel material is the result of collaboration between Sajeev John, a theoretical physicist and
Geoffrey Ozin, a materials chemist. Both are professors at the University of Toronto and Associates of
CIAR's newest program – Nanoelectronics, the science of developing and using circuits and devices only
a few nanometers (1 billionth of a meter) in size. Their results appear in this week's issue of the British
science journal, Nature.
Dr. John first developed the idea of "caging" light in his PhD. thesis at Harvard in 1984. "I realized that if
you could cage it, then you could perform functions with light, similar to the way in which electrons
behave in semiconductors." While at Princeton in 1987, he refined his idea by introducing the concept of
a "photonic band gap" material that could control light in the same way that today's semiconductor chips
control electrons.
A worldwide effort has been going on for a decade to produce this photonic material. Ideally, it needed to
meet four criteria: First, it had to be silicon-based, the most common microchip material. Second, it had
to control light at the same wavelength used in today's fibre optics. Third, there had to be a way taking the
micro-scale structures and building them into larger structures. Fourth, the material should be
inexpensive to make, and the only way to do this was to find a way for molecules to assemble themselves
naturally into the required 3-D structure, rather than having to build the structure piece by piece.
"Going from the idea to developing an actual material," says Dr. John "has been the biggest bottleneck in
the field up to now."
The breakthrough emerged from a collaboration at the University of Toronto that would not have been
possible without the CIAR. First, Dr. John would still have been in Princeton, not Toronto. "CIAR's offer to
be part of one of their programs was the edge that ultimately made me leave Princeton in 1989 to come
to Toronto," recalls Dr. John. Second, about a year ago CIAR was instrumental in convincing Dr. Ozin to
stay in Toronto, and turn down a prestigious appointment in the United Kingdom. Finally, both
researchers were invited to join CIAR's new nanoelectronics program at about the time that a
collaboration between them would be critically needed to move forward.
/ . . .2
Dr. Ozin had been working independently in the building next door to Dr. John's, creating new techniques
for growing silicon into porous materials. In traditional microelectronics, silicon chips are "grown" on flat
surfaces. Dr. Ozin's techniques for growing silicon in holes were just what Sajeev John needed.
"When Sajeev first approached me and asked if I could use my techniques to grow this material," says
Dr. Ozin, "I thought it was impossible." Their discussions continued during early meetings of CIAR's
nanoelectronics group. "This CIAR interaction catalyzed our collaboration," says Ozin. "I became
motivated to 'try the impossible.'" "I think meeting Geoff at this particular time was destiny," says John.
Researchers knew that opals have an orderly crystal structure with some of the earmarks of the materials
that Dr. John had predicted. The idea was to use opals to create a template (a regularly spaced lattice of
tiny cavities, or holes) on which to grow the new material. Sajeev John found a group of physicists in
Spain who had developed a technique for producing just such a template. The group, knowing about
John's theoretical work and Ozin's materials research, were happy to collaborate by providing a template.
"We knew that unless the templates were really good it would be very hard to get silicon to infiltrate their
tiny cavities. In our initial trials my worst fears were confirmed," recalls Ozin. "Our yield was only a few
percent, while Sajeev's theoretical road map called for 90 per cent!"
The Spaniards perfected their templates, and finally Ozin's group was able to get the yields that John
needed. With this obstacle removed, they began to work with a laser group at the University of Toronto,
led by Dr. Henry van Driel. "We had a unique, three-way collaboration," says Ozin. "My group would use
Sajeev's specifications to produce some material. Henry's people would measure its optical properties.
Sajeev would look at the numbers, crunch them in his computer, and tell us precisely what to change.
Then we would start again." Finally, in November 1999, they produced their magic material.
"There have been two technological revolutions that have come out of condensed matter physics in this
century," explains Dr. John. "The first was the semiconductor revolution for electronics. The second
revolution was the invention of the laser. But even with the laser and all the things it can do, there has not
been any real material that can micro-manipulate the flow of light in the same way that the semiconductor
does to electrons. And that's why this line of research, and in particular this breakthrough, is really
important."
Founded in 1982, The Canadian Institute for Advanced Research is Canada's research university without
walls. Over 190 renowned scholars work within the Institute's eight major research programs. Their
collaboration within and among the programs influences health, social and economic policies as well as
science and technology in Canada and abroad.
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For more information contact Jeffrey Crelinsten or Janet Sandor at 416-481-7070.
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Holy Grail or Holy Cow? Opinions solicited.
Ciao, Ray |
