From the corning leaf spec:
Environmental Test Induced Attenuation
Condition (dB/km)
1550 nm /1625 nm
Temperature Dependence
-60°C to +85°C* ? 0.05
Temperature Humidity Cycling
-10°C to +85°C* and up to
98% RH ? 0.05
Water Immersion, +23°C ? 0.05
Heat Aging, +85°C* ? 0.05
*Reference Temperature = +23°C
Operating Temperature Range: -60°C to +85°
I just checked the daily variation of optical loss, and it seems to be about
+-0.15dB
over a 90km DWDM system that operates in the NY,NJ metro area. It's slightly
larger
from summer to winter. Clearly measuring delay through a loop would be a more
accurate
metric, but this should give you a ballpark of real-world environmental
influence. All
of the electronics are in cooled rooms (typical CO or datacenter), all the
fiber was
buried and in building risers.
And don't forget about back-hoe induced phase shifts.
Scott
Bruce Griffiths wrote:
> Scott Mace wrote:
>> I think for singlemode LEAF fiber you see something around 100ps/km per
>> degree C.
>> Hopefully the fiber is buried and the temperature changes are more gradual.
>>
>> Scott
>>
> Most of it may be buried, however the ends of the fiber run may not be.
> There are expensive fibers available with much smaller tempcos, at least
> over limited temperature ranges.
> The thermal expansion tempco of fused silica fibers is relatively low
> (0.5ppm/C or so depending on exact composition) so most of the
> propagation delay tempco is due to the refractive index tempco.
>
> Bruce
>
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