From: Bill Stewart <stewarts@ix.netcom.com>
Date: Tue, 20 Feb 1996 12:42:14 +0800
To: cypherpunks@toad.com
Subject: Re: Optical repeaters
Message-ID: <199602200205.SAA23957@ix8.ix.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


>> > > Optical repeaters have to pass your signal through an intermediate
electronic
>> > > stage anyway, since we have no purely optical valve/transistor
>> > > equivalents (bosons don't interact with each other at all).

>> > 	This is not true.   There is now a whole technology of optical
>> > amplifiers for fiber communications systems that used Ettrium doped
>> > fibers pumped with strong light from a laser at a slightly shorter
>> > wavelength. These fiber optical amplifiers have gains in the order of
>> > 10-12 db in a section of special doped fiber only about 10 feet long.

>Very nice! ;-)  Flouride based amplifiers should be able to handle up
>to 16 channels.  Using state of the art time-multiplex stuff of 10 Gb/sec
>gives a total throughput of 160 Gb/Sec.... smoking!

The flavor of optical amplifier and end equipment being deployed by one 
large telecomm company (ahem) over the next couple of years 
uses 8 colors, each at 2.4 Gbps (OC-48), giving about 20 Gbps,
which is about 10 times the current capacity (1.7 Gbps.)
(Some other telecomm companies are deploying 3-colors of OC-48.)
A nice thing about the optical amplifiers is that they have about triple
the range of the current regenerators, so one amplifier can replace about
16-24 regens,
reducing the amount of equipment that can fail and produce downtime.
Because of this increased capacity, it's a good time to upgrade to SONET rings
(which are dual rings that provide self-healing similar to FDDI's;
SONET self-repair typically takes 60 ms instead of the several minutes
to cross-connect the equivalent pile of T3s using current equipment.)

If the FBI wants to wiretap this stuff, they'll have to get on the ball :-)

#--
#				Thanks;  Bill
# Bill Stewart, stewarts@ix.netcom.com / billstewart@attmail.com +1-415-442-2215
# http://www.idiom.com/~wcs     Pager +1-408-787-1281

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