TIME: Almanac 1993/TIME Almanac 1993.iso/time/021290/0212310.000

Text File | 1992-08-28 | 5.6 KB | 120 lines

                                                                                TECHNOLOGY, Page 71

Harnessing the Speed of Light


AT&T moves closer to creating superfast optical computers

By THOMAS MCCARROLL


    When Alan Huang revealed his plans to build an optical
computer, most of his fellow scientists dismissed the idea as
hopelessly quixotic. It was impractical, if not impossible,
they said, to create a general-purpose computer that could use
pulses of light rather than electrical signals to process data.
During one of Huang's lectures on the subject, a third of the
audience walked out. At another talk, some of the scientists in
attendance laughed and heckled the researcher, calling him a
quack and a dreamer. Recalls the 41-year-old engineer at AT&T
Bell Laboratories: "I began to have computer nightmares, but
I never doubted that it could be done. I wanted the last
laugh."

    That was several years ago. Few of the doubters were
smirking last week when Huang and AT&T unveiled an experimental
computing machine based on optics rather than electrons, the
first of its kind. The device -- a crudely configured
collection of lasers, lenses and prisms -- could serve as the
basis for future optical computers 100 to 1,000 times as
powerful as today's most potent supercomputers. The potential
applications are stunning: robots that can see; computers that
can design aircraft from scratch; processors that can swiftly
convert spoken words into written text and vice versa. Such
practical optical computers are still years -- some would say
light-years -- away. Yet many scientists are already predicting
that the device will have an impact similar to that of the
integrated circuit, which made small personal computers
possible. David Casasent, director of Carnegie Mellon
University's Center for Optical Computing, calls Huang's work

new technology.

    Photons, the basic unit of light beams, can in theory be
much better than electrons for moving signals through a
computer. For one thing, photons can travel about ten times as
fast as electrons. And while electrons react with one another,
beams of photons, which have no mass or charge, can cross
through one another without interference. Thus while electrons
must be confined to guide wires, photons can move in free
space. This could open the door to radically new and different
computer designs, including so-called parallel processors that
could work on more than one problem at a time instead of one
after another, as today's serial computers do.

    But harnessing the computing power of light has proved to
be a daunting challenge. The earliest attempts to build an
optical computer date back to the late 1950s, when researchers
experimented with mercury-arc lamps and even sunlight. Not much
happened until the early 1960s brought the invention of lasers,
devices that could concentrate light into powerful,
high-precision beams. IBM spent four years and $100 million
trying to develop a machine that could use laser beams to
operate the multiple "on-off" switches that are the heart of all
computers. Unfortunately, the switching operations required
too much energy, and the devices often overheated. Eventually
the company virtually abandoned the project as unfeasible.

    The field of optical computing faded into relative
obscurity, but it was revived in 1986 by a breakthrough at AT&T
Bell Labs. Research scientist David Miller developed the
world's tiniest optical switch, a thin chip that in its latest
version measures no more than 10 micrometers (0.00004 in.) on
a side. Made of advanced synthetic materials, the device can
turn on and off a billion times a second without overheating.

    Miller's switches became the building blocks for Huang's
optical processor, which took five years to develop. His team
finished construction around Christmas but did not get the
machine to work until last month. The device is far cruder than
even the most basic computers: it has no permanent memory, and
the only function it can perform is counting simple numbers.
Just a small fraction of the thousands of switches are
connected. Nonetheless, Huang insists, the machine proves that
his principle works. He thinks computer makers will soon
replace wiring inside their machines with optical circuits. By
1995, he contends, some 30% of supercomputers will use optical
interconnections.

    Huang has not convinced everyone, however. Says one
scientist: "Huang is like the boy who cried wolf. He's been
promising an optical computer for years, and he's still
promising. I'm waiting for him to prove that it's practical
rather than it's possible." Others are skeptical that optics
can compete with electronic computers. Says Bernard Soffer,
senior scientist at Hughes Aircraft Research: "Optical computers
would have to be ten to 100 times better than electronic ones
to justify retooling." Even enthusiasts are guarded. Says
optical-computing pioneer Joseph Goodman, a Stanford
electrical-engineering professor who was once Huang's teacher:
"The first commercial general-purpose optical computer will
appear between the year 2000 and infinity, and it may be closer
to infinity."

    When it finally does appear, it may not be American. A group
of 13 Japanese companies, including Mitsubishi and Nippon
Electric, has teamed with the government's Ministry of
International Trade and Industry to launch a ten-year
optical-research program. Given the Japanese record in
electronics, their interest in optical computers may be the
best evidence that Huang and AT&T are on to something big.