The biggest concern with temperature effects in the fiber would be thermal expansion. Potentially, as well, changes in waveguide shape, which could add more waveguide dispersion as well as potential polarization mode dispersion. Jeff
Jeffrey K. Okamitsu, PhD, MBA +1-609-638-5402 --- On Wed, 11/26/08, Bruce Griffiths <[EMAIL PROTECTED]> wrote: From: Bruce Griffiths <[EMAIL PROTECTED]> Subject: Re: [time-nuts] 10 MHz over optical fiber? To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Date: Wednesday, November 26, 2008, 2:13 PM [EMAIL PROTECTED] wrote: > All: Sorry for jumping in abruptly on this ongoing thread. I have been meaning to chime in ever since the discussion got started. > > I apologize in advance if I am dragging up an issue that has already been discussed and put to rest. > > That being said, have you given consideration to the effects of chromatic dispersion in the fiber? > > A good, telcom grade, dispersion shifted (designed for the 1550nm wavelength band, where absorption of the light by water is small), single mode fiber has a chromatic dispersion of approximately 1 to 10 ps/nm/km. The concern therefore is changes in timing induced by changing wavelength content of the laser or LED used to drive the fiber - for example, due to temperature changes, etc. > > If you've already considered this, then please ignore this. Otherwise, it would be interesting to work through a "what if"? > > jeff > > Jeffrey K. Okamitsu, PhD, MBA > +1-609-638-5402 > > Without compensation, the delay tempco of 34 km of fiber will be somewhat more problematic unless the temperature of the entire run is constant and/or expensive low delay tempco fiber is used. Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.