[time-nuts] 10 MHz over optical fiber?

[Bruce Griffiths]

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