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From: dennis@cpac.washington.edu (Dennis Gentry)
Newsgroups: comp.society.futures
Subject: Optronics & optical computers
Message-ID: <9003010548.AA02812@yang.cpac.washington.edu>
Date: 1 Mar 90 05:48:50 GMT
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Steve Snodgrass writes:

    I'd like to get a few opinions or a discussion going on this:
    What does everyone think about the possibility of optronics or
    optical computers?

I'll break with Usenet tradition and offer no opinion, only
excerpts from an article (from "OE Reports, The Internation
Newspaper of Optical and Optoelectronic Applied Science and
Engineering", published by SPIE, The Internations Society for
Optical Engineering", March, 1990, p.1)

    OPTICAL COMPUTER:  Is concept becoming reality?

    Digital optical processor demonstrated.

    AT&T scientists announced on January 29 that they had succeeded
    in building the world's first digital optical processor.  "The
    digital optical processor is a technological milestone," said
    William H. Ninke, director of the Information Systems Research
    laboratory at AT&T Bell Labs.  "This wireless processor uses
    lasers to transmit information internally and employs optical
    devices to process the information."  The optical processor
    demonstrated at Bell Labs operates at 1 million cycles per
    second, less than most personal compuuters.  But AT&T scientists
    are optimistic that an optical computer operating at serveral
    hundred million cycles per second--faster than most
    supercomputers--is possible in the near future.

    The switching is handled by S-SEEDs (Symmetric
    Self-Electro-optic Effect Devices), optical switches with a
    potential speed of 1 billion operations per second using a
    switching energy of about 1 picojoule.  They are based on
    GaAs-AlGaAs technology and are fabricated by molecular beam
    epitaxy.  Each device is 5um squar and contains two mirrors with
    controllable revlectivity.  There are 32 S-SEEDs on each of four
    arrays within the processor.  Each S-SEED can drive two inputs.

The article goes on to interview Alan Huang, head of the Optical
Computing Research Department at Bell Labs.  Mr. Huang thinks
that the chief advantage of optical processing technology is
that processors will become 1,000 or 10,000 bit processors,
rather than the current 16 or 32 bits.

Mr. Huang also describes the S-SEEDS as essentially light-
operated RS flipflops: incoming photons change the state of a
mirror from 10 percent to 60 percent reflectivity.  To make
logic gates, the S-SEEDS are reset to "0" before use.  And
although they are currently running the logic at 1 million
cycles per second, the devices are said to be capable of a
billion cycles per second.

Dennis Gentry
(dennis@cpac.washington.edu)