High attenuation with multimode fibers
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Posted by Dennis on April 10, 2008, 1:24 pm
Please log in for more thread options I have a problem with multimode fibers. The attenuation of the fibers is about 1.5 db/km @ 1300nm and about 3.2 db/km @ 850 nm. I haven't had such a problem before. Normally, the attenuation of the fibers is less then 0.6 dB/km @ 1300nm and less then 2.4 dB/km @ 850 nm. It's no problem with hydrogen. I've checked it. On my OTDR are no events displayed. The curve is normal. In my opinion, it looks for micro- or macrobending. Does anyone has experience with this topic? Is it possible to measure it or to make it "visible". BTW, there are 4 fibers in a metallic tube with a diameter of 1.42 mm. Greeting, Dennis | ||||||||||||||||||||||
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Posted by Walter Gryder on April 10, 2008, 11:06 pm
Please log in for more thread options measuring a fiber with a larger core diameter than you typically encounter? A larger fiber core region (62.5 microns rather than 50 microns, for example) would display higher attenuation characteristics. | ||||||||||||||||||||||
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Posted by Dennis on April 11, 2008, 4:41 am
Please log in for more thread options > Dennis wrote:
> > Hello,
>
> > I have a problem with multimode fibers. The attenuation of the fibers
> > is about 1.5 db/km @ 1300nm and about 3.2 db/km @ 850 nm. > > I haven't had such a problem before. Normally, the attenuation of the > > fibers is less then 0.6 dB/km @ 1300nm and less then 2.4 dB/km @ 850 > > nm. > > It's no problem with hydrogen. I've checked it. > > On my OTDR are no events displayed. The curve is normal. > > In my opinion, it looks for micro- or macrobending. Does anyone has > > experience with this topic? > > Is it possible to measure it or to make it "visible". >
> > BTW, there are 4 fibers in a metallic tube with a diameter of 1.42 mm.
>
> > Greeting,
>
> > Dennis
>
itierten Text ausblenden -
> What is the diameter of the fiber core? =A0Could it be that you're > measuring a fiber with a larger core diameter than you typically > encounter? =A0A larger fiber core region (62.5 microns rather than 50 > microns, for example) would display higher attenuation characteristics.- Z= >
> - Zitierten Text anzeigen - It is a fiber with 50 =B5m core! | ||||||||||||||||||||||
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Posted by Arnie Berkers on April 11, 2008, 6:27 am
Please log in for more thread options > Hello,
> > I have a problem with multimode fibers. The attenuation of the fibers > is about 1.5 db/km @ 1300nm and about 3.2 db/km @ 850 nm. > I haven't had such a problem before. Normally, the attenuation of the > fibers is less then 0.6 dB/km @ 1300nm and less then 2.4 dB/km @ 850 > nm. > It's no problem with hydrogen. I've checked it. > On my OTDR are no events displayed. The curve is normal. > In my opinion, it looks for micro- or macrobending. Does anyone has > experience with this topic? > Is it possible to measure it or to make it "visible". > > BTW, there are 4 fibers in a metallic tube with a diameter of 1.42 mm. > > Greeting, > > Dennis The excess length of the fibres in the metallic tube could be too high. This would result in microbending problems. To check this you can cur a piece of tube of 5 to 10 meters, measure it exactly and then measure the exact length of the fibre in the tube. Normally the fibres should be about 0.1 to 0.4 % longer than the tube. Arnie | ||||||||||||||||||||||
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Posted by Dennis on April 14, 2008, 10:47 am
Please log in for more thread options >
> > > > Hello,
>
> > I have a problem with multimode fibers. The attenuation of the fibers
> > is about 1.5 db/km @ 1300nm and about 3.2 db/km @ 850 nm. > > I haven't had such a problem before. Normally, the attenuation of the > > fibers is less then 0.6 dB/km @ 1300nm and less then 2.4 dB/km @ 850 > > nm. > > It's no problem with hydrogen. I've checked it. > > On my OTDR are no events displayed. The curve is normal. > > In my opinion, it looks for micro- or macrobending. Does anyone has > > experience with this topic? > > Is it possible to measure it or to make it "visible". >
> > BTW, there are 4 fibers in a metallic tube with a diameter of 1.42 mm.
>
> > Greeting,
>
> > Dennis
>
> The excess length of the fibres in the metallic tube could be too > high. This would result in microbending problems. > To check this you can cur a piece of tube of 5 to 10 meters, measure > it exactly and then measure the exact length of the fibre in the tube. > Normally the fibres should be about 0.1 to 0.4 % longer than the tube. > > Arnie The supplier send us test certificates of every single tube, where the excess length is specified between 0.09% to 0.15%. I have 2 FIMT laying in the same way with nearly the same excess length. But you're right, we have had a problem with the excess length before and we have to check the excess length again. Dennis | ||||||||||||||||||||||
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>
> I have a problem with multimode fibers. The attenuation of the fibers
> is about 1.5 db/km @ 1300nm and about 3.2 db/km @ 850 nm.
> I haven't had such a problem before. Normally, the attenuation of the
> fibers is less then 0.6 dB/km @ 1300nm and less then 2.4 dB/km @ 850
> nm.
> It's no problem with hydrogen. I've checked it.
> On my OTDR are no events displayed. The curve is normal.
> In my opinion, it looks for micro- or macrobending. Does anyone has
> experience with this topic?
> Is it possible to measure it or to make it "visible".
>
> BTW, there are 4 fibers in a metallic tube with a diameter of 1.42 mm.
>
> Greeting,
>
> Dennis
>