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From: miles@vax135.UUCP (Miles Murdocca)
Newsgroups: net.research
Subject: Re: Photonics - replacing eletronics?
Message-ID: <1247@vax135.UUCP>
Date: Thu, 12-Dec-85 10:15:56 EST
Article-I.D.: vax135.1247
Posted: Thu Dec 12 10:15:56 1985
Date-Received: Fri, 13-Dec-85 08:35:09 EST
References: <57100003@hpcnof.UUCP>
Organization: AT&T Bell Labs, Holmdel, NJ
Lines: 28

>         Photonics, on the other hand, has not only the advantage of a
> zero mass particle (a photon) but also, by using optical fibers, can
> have the photons travel essentially arbitrary paths without encountering
> ANY resistance.  Other advantages accrue too - including a complete freedom
> from electrical interference and noise.  The fiber optic cables are also much
> smaller than the similar amount of traditional electrical wires (the article
> states that "a single [electrical] coaxial cable is as thick as a whole array
> of optical fibers").

>        My question to the net is simply - Does anyone have any further
> information on this technological breakthrough?

One problem with using fiber optic cables is that you are limited to serial
computation, e.g.: 1 bit per fiber.  2-dimensional optical logic elements
exist that allow for wavefront propagation.  An example is the nonlinear
Fabry-Perot etalon (U. Arizona and AT&T Bell Labs) with an absorption time
of ~5ps and a relaxation time of ~100ps.  It is hoped that the population
of the devices will go as high as 1K x 1K elements per array.  An entire
array can be imaged onto another array.  If the free space between the arrays
is filled with simple glass devices like a few beam-splitters and mirrors,
then array scale logic can be done essentially at the speed of light.

A major win in going to optical computing is the enormous communication
capability of using a free-space interconnect.  Optical fibers don't allow
this.

    Miles Murdocca, 4G-538, AT&T Bell Laboratories, Crawfords Corner Rd,
    Holmdel, NJ, 07733, (201) 949-2504, ...{ihnp4}!vax135!miles