transcievers/amplifiers for 150 km fiber run

Francois Menard francois at
Sun Oct 12 12:16:19 UTC 2008

or you buy some boxes from BTI Photonics that specialize into taking  
GigE around the world...


François D. Ménard
francois at

On 11-Oct-08, at 12:25 PM, Lamar Owen wrote:

> On Friday 10 October 2008 14:50:11 Fletcher Kittredge wrote:
>> We are looking to light a two strand fiber link of about 95 miles (or
>> 150km).   It would be worth a lot to us not to have repeaters.   We  
>> are
>> hoping for Gigabit Ethernet.   Sonet is possible but a less  
>> attractive
>> solution.  Are there options for this sort of distance?   The longest
>> current link we have is about 65 miles.  I understand the  
>> transmission
>> characteristics of the fiber will effect distance of transmission.
> EDFA's can extend your power budget a few dB.  Chromatic dispersion  
> could
> still be an issue, though.
> Used units that had previous homes in CATV supertrunk applications  
> should work
> well, at least for GigE; up to 120mW is easily possible (I have a  
> few 65mW
> (18.1dBm) EDFA's that came as part of a donation).  You hit the  
> input of the
> EDFA with your ZX (1550nm) transceiver's transmit on each end, and  
> don't look
> at the lit fiber or even a reflection of the lit fiber (IOW, wear  
> laser
> safety goggles).  And don't even think about looping the EDFA output  
> back
> around without many dB of attenuation.
> At this power level you will have to use angle polish connectors at  
> the EDFA
> output (the green SC/SPC or FC/APC ones) or you can burn out the  
> pump laser
> with the reflections.
> You also will need to notify your carrier's tech department of the  
> power level
> with which you're lighting that fiber, as even several km down fiber  
> from an
> EDFA is in Class IIIB laser territory.
> A bare Cisco ZX GBIC or SFP is rated to light 70km of ordinary  
> singlemoder
> fiber, and up to 100km of either premium (low-loss) or dispersion- 
> shifted
> (which is also low-loss) singlemode fiber.  The rated output is  
> between 0 and
> +5dBm (1 and 3.2 mW) for the ZX laser.  The link budget is 23dB for  
> the
> standard ZX optics.  With a high-gain EDFA outputting 13 more dBm of  
> power
> (20 times the power) you can get a link budget for loss of 36dB;  
> which could
> increase your range 40km, on ordinary fiber.
> So, in a nutshell, you'd take the TX from a ZX SFP or GBIC, a few  
> feet worth
> of jumper to an EDFA, and light the fiber (with APC connectors only)  
> from the
> EDFA output.  You do this at both ends.

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