NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/comp/arch/10948

Text File | 1992-11-19 | 2.0 KB | 46 lines

Newsgroups: comp.arch
Path: sparky!uunet!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!agate!rsoft!mindlink!a684
From: [e-mail] (Nick Janow)
Subject: THz Clock Lines
Organization: MIND LINK! - British Columbia, Canada
Date: Fri, 20 Nov 1992 06:35:29 GMT
Message-ID: <[e-mail]>
Sender: [e-mail] (Usenet)
Lines: 35

[e-mail] (Roger Arnold) writes:

>+ If that distance is small enough, it might be possible to do a "flash"
>+ conversion, with sensor elements in a linear optical path, each detecting
>+ whether there was a positive optical pulse within it at the time of a
>+ central clock pulse.
>
> About .2 mm, if it worked that way.  But it doesn't.  What you'd actually
> have would be 128 light frequency channels carried in one fiber, each
> channel modulated at 10 GHz.  Or 256 channels modulated at 5 GHz, or
> whatever works. Heavy duty frequency multiplexing, at any rate.  The
> receiving end has a corresponding number of tuned receivers, one per
> frequency channel.

That doesn't disqualify the "flash" conversion idea.  As the multi-frequency
optical signal enters a chip, it is split into channels via diffraction
grating or whatever.  Each channel converts one train of pulses into a
digital word. If you don't like long chips, yet need to stretch the pulses
out (by whatever means), you can wind the channels into spirals on the chip,
with little mirrors on the corners.  You can machine these optical channels
in two dimensions, or three (maybe stacked).

The point is, the optical pulses exist as physically serial information
measured from one single point in space...and as parallel information
measured from one single point in time.  The former requires a length of time
to acquire an entire word; the latter requires a length of space to acquire
an entire word.

Eventually, someone will develop the tools to make use of the parallel aspect
of optical signals in space to make fast optical>binary-word and
binary-word>optical interfaces.

--

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