Insertion Loss of fiber connectors

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I am trying to find a reference or similar information on estimating
the amount of gap a fiber optic connector would need to generate an
insertion loss of approximately 6 dB.

We are having some problems with erratic connectors that appear to not
fully mate when plugged in.  I am trying to explain to the boss that
this is not something we can adjust that we need to replace the
connectors...

I am assuming the required gap is very small but my guess is not going
to prove it to the boss so I would like to be able to cite a
reference.

Regards
Larry

Re: Insertion Loss of fiber connectors
Larry Mackey wrote:
Quoted text here. Click to load it

Is this single- or multimode?  Fibre type and core diameter?


Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

Re: Insertion Loss of fiber connectors
In article

Quoted text here. Click to load it

I'm nobody's expert, but have been diving into building a system, and as
far as I understand it, most modern connectors assume physical contact,
ie - no gap at all. Filth is always an issue, as well. Filth is about
the first, second and third issue to check, and while checking for
filth, you could look for things like fiber endface damage (usually from
filth not removed before connecting, causing hard filth to damage the
polished faces when they touch) as well.

While air gap variable attenuators are on the market, I think they are
generally set by using a power meter to get the desired attenuation, not
set to a particular distance for a particular attenuation.

But, here is a possible source of "gap" information.

http://www.freepatentsonline.com/5734778.html

Quoted text here. Click to load it

Unfortunately the figure is not there, since the site is one of those
that don't actually exist to provide information as much as to host ads.
The raw numbers indicate 21.7 dB in 0.065" - if linear (and I have no
idea if it is without the figure), that would indicate 18 thousandths
for 6db. Or about 5 sheets of standard 20lb copy paper.

Hopefully someone else can get you a better reference, but this is a
somewhat slow newsgroup much of the time.

--
Cats, coffee, chocolate...vices to live by

Re: Insertion Loss of fiber connectors
EyesLight had written this in response to
http://forums.cabling-design.com/fiberoptics/Insertion-Loss-of-fiber-connectors-887-.htm
 :

Larry Mackey wrote:


Quoted text here. Click to load it





-------------------------------------


Early connectors like the biconic and SMA,  which did not have keyed
ferrules and could rotate in mating adapters, always had an air gap
between the connectors to prevent them rotating and grinding  scratches
into the ends of the fibers.

Connectors of today are call “PC” or “physical contact”
connectors. No air gap



Type of connector and fiber type would be helpful in answering your
question but I'll give it a try.

Does the problem exist across all connectors or just one?

If you think it is a mating issue simple use a different jumper and test
your theory. Change out the bulkhead. Borrow it from another spot.

You can all so "hold" the mated pair together with pressure and check
power and the release the pressure and check again.

I had this problem once or twice. Both were a result of two different
jumper manufactures which meant slightly different connectors (SC) front
and rear. Pigtails on termination were Corning, Jumpers were from
FyberDyne.

The Fiberdyne connector has a slightly raised ferrule while Corning was a
flush surface.

If your kimwipe tears when cleaning either connector look for the raised
ferrule

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Re: Insertion Loss of fiber connectors
EyesLight had written this in response to
http://forums.cabling-design.com/fiberoptics/Insertion-Loss-of-fiber-connectors-887-.htm
 :

Larry Mackey wrote:


Quoted text here. Click to load it





-------------------------------------


Early connectors like the biconic and SMA,  which did not have keyed
ferrules and could rotate in mating adapters, always had an air gap
between the connectors to prevent them rotating and grinding  scratches
into the ends of the fibers.

Connectors of today are call “PC” or “physical contact”
connectors. No air gap



Type of connector and fiber type would be helpful in answering your
question but I'll give it a try.

Does the problem exist across all connectors or just one?

If you think it is a mating issue simple use a different jumper and test
your theory. Change out the bulkhead. Borrow it from another spot.

You can all so "hold" the mated pair together with pressure and check
power and the release the pressure and check again.

I had this problem once or twice. Both were a result of two different
jumper manufactures which meant slightly different connectors (SC) front
and rear. Pigtails on termination were Corning, Jumpers were from
FyberDyne.

The Fiberdyne connector has a slightly raised ferrule while Corning was a
flush surface.

If your kimwipe tears when cleaning either connector look for the raised
ferrule

--
+----------------------------------------------------------+
|            http://forums.cabling-design.com/             |
|              *** a better way to USENET ***              |
| no-spam Web and RSS interface to your favorite newsgroup |
|      sci.optics.fiber - 835 messages and counting!       |
+----------------------------------------------------------+



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