~e; photo-speedometer

From bc <human@electronetwork.org>
Date Wed, 27 Mar 2002 21:18:26 -0600

  [this seems to go beyond fiberoptics and switching and into
  realms of the unknown (applications), so it is exciting. there
  is mass in light, i thought, when it is moving. so the immaterial
  is even more of a question then, than with electronics. but from
  one person's post-hype perspective, it may be vaporware for a
  while (decades if not centuries) before these mysteries unfold
  in this lifetime's timetable. but maybe. still seems there are a
  lot of things lacking in today's miracle tech, to believe that an-
  other will solve all problems with things not having to do with
  speed. such as quality. purpose in design. basic human stuff.
  the nature of light is one of the more fascinating areas which
  is so absolutely strange and wondrous and hard to imagine,
  yet the basic work is being done so someday we will all know
  more about it, and hopefully be able to do things now impossible.]

Posted on Mon, Mar. 25, 2002
Moving slowly toward light-speed technology
By Robert S. Boyd
Mercury News Washington Bureau (referenced on NewsScan)

WASHINGTON - A major technological transformation -- potentially as 
significant as the electronics revolution of the 20th century -- is 
creeping up on a largely unsuspecting world.

Light, in the form of tiny, weightless particles called photons, is 
on its way to succeeding electrons as the high-tech workhorse of the 
21st century, scientists say.

Practical applications of the coming photonics revolution are still a 
ways off, but researchers offer the prospect of much faster 
communications, more powerful computers, sharper display screens, 
more effective ways to convert sunlight to energy and many other 

For example, the Pentagon is experimenting with photonics for future 
military technologies, such as night vision, early warning sensors 
and automatic target recognition, according to Anthony Tether, 
director of the Defense Advanced Research Projects Agency.

By shooting photons through the air instead of pushing electrons 
along wires, information networks can move data at trillions of bits 
per second instead of millions or billions, as networks do now. In 
addition, Tether said, photonic links can provide a thousandfold in 
savings of size and power needs.

Photons and electrons are very different creatures. Photons are the 
smallest carriers of energy. They make up the electromagnetic 
spectrum, an array of forces that includes X-rays and ultraviolet, 
infrared and radio waves, as well as visible light.

Electrons, in contrast, are a basic component of matter. They are an 
essential part of every atom and the principal tool of the 
information age. But they are beginning to run into size and speed 
limits in some fields, such as computing and telecommunications.

Gradual takeover

``You'll see enormous advances in optical components and devices,'' 
he said. ``Miniaturization will lead to many-orders-of-magnitude 
increases in performance. You can do a lot more in a lot less real 

In laboratories around the world, physicists and optical engineers 
are practicing ingenious tricks to control light. They have learned 
how to make photons follow straight paths, split, rejoin, turn sharp 
corners, change speed, even stop in their tracks.

Lene Hau, an optical physicist at Harvard University, in Cambridge, 
Mass., has slowed a beam of light to the sluggish pace of about one 
mile per hour, a tremendous drop from its normal speed of 186,000 
miles per second. Peter Zoller, a physicist at the University of 
Innsbruck in Austria, has brought a bunch of photons to a complete 
stop, then set them free to zoom off again at their original pace.

``It's thrilling to think we can control light,'' Hau said, adding 
that many research groups ``all over the world are pouring into the 

According to Hau, scientists put the brakes on photons by slamming 
them into a cloud of sodium atoms that have been cooled to almost 460 
degrees below zero Fahrenheit.

``When the light enters the cloud, it slows down and compresses like 
a concertina,'' she said. ``When it exits the cloud, it expands and 
goes on its way, exactly like it was before.''

Unimaginable benefits

The first commercial beneficiaries of the photonics research probably 
will be computing and telecommunications. They stand to benefit from 
the blinding speed and minute size of particles of light.

Computer scientists have dreamed for years of being able to compute 
with photons instead of electrons. Current technology is nearing its 
physical limit as computer-makers cram more and more transistors onto 
silicon chips.

To get around the limits on the chips' capacity, government, academic 
and private researchers are turning to photonics. Photonic crystals 
-- tiny cages or honeycombs constructed of silicon -- trap, guide and 
switch light much the way semiconductors manipulate electrons in 
today's computers.

``The optical world will slowly creep its way into the electronics 
world by replacing devices on a chip,'' said Axel Scherer, an 
electrical engineer at the California Institute of Technology in 

In the communications field, most long-distance telephone and 
computer networks already transmit digital information -- zeroes and 
ones -- in the form of pulses of light racing along optical fibers.

Overcoming drawbacks

In contrast, researchers say future optical-communications systems 
will use fibers composed of tiny mirrors that direct photons down a 
desired path without using wires.

Yoel Fink, a physics professor at MIT, invented ``photonic fibers,'' 
which he said can deliver up to 1,000 times more photons than today's 
fiber-optic cables. Fink and colleagues started a company, Omniguide 
Communications, based in Pasadena, to commercialize their invention.

At least a dozen other firms are entering the field, despite the 
slump in high-technology companies that includes the Jan. 28 
bankruptcy of Global Crossing, a big fiber-optics communications 

Major corporations such as IBM, Lucent and Agilent Technologies are 
developing ``photonic switches,'' systems of mirrors that redirect 
photons like freight cars in a railroad yard.

Scherer said photonic crystals can be manufactured at a reasonable 
cost using the same basic technology as today's silicon-chip 
factories. He predicted that such devices ``will be ready for 
commercial applications very soon.''

``Right now, it's mostly baby steps in the lab,'' said Mikhail Lukin, 
a Harvard physicist. ``But there is hope for something practical 

For more information about photons and photonics, go to:

* The Massachusetts Institute of Technology Joannopoulos Research 
Group's Web page on Photonic Crystal Research, at 

* The Online Photonics Resource, at http://optics.org

* Photonics.com, an optical, laser and fiber-optics resource, at 

Contact Robert Boyd at rboyd@krwashington.com.

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