The Kerr effect is Proportional to the square of the field so one would expect a strong 100Hz component from this.
The magneto optical Kerr eefect which rotates the plane of polarisation is linear however. Bruce On Wednesday, August 24, 2016 07:04:31 AM Bob kb8tq wrote: > Hi > > I would not rule out line noise into the electronic side of things. > > Bob > > > On Aug 23, 2016, at 7:06 PM, Magnus Danielson <mag...@rubidium.dyndns.org> > > wrote: > > > > Don't over-interpret the 50 Hz aspect, I don't remember those details from > > 4.5 months back or so, as I already indicated. I can ask on the details > > tomorrow. I think they discussed the Kerr effect: > > https://en.wikipedia.org/wiki/Kerr_effect > > The PTB folks asked me the same question essentially. > > > > Would be nice to verify it. > > > > Cheers, > > Magnus > > > >> On 08/24/2016 12:11 AM, David wrote: > >> I could not find it in the links but Magnus mentions 50 Hz instead of > >> 100 Hz. > >> > >> I would expect a 100 Hz noise signal if it was vibration coupled from > >> magnetostriction in a transformer; magnetostrictive strain depends on > >> the magnitude of the magnetic field strength and not the sign which is > >> why 50/60 Hz transformers hum at 100/120 Hz. 50 Hz however fits with > >> piezomagnetism if the optical fiber was in an oscillating magnetic > >> field and antiferromagnetic; for piezomagnetism, the strain does > >> follow the sign. > >> > >> https://en.wikipedia.org/wiki/Magnetostriction > >> https://en.wikipedia.org/wiki/Piezomagnetism > >> > >> I do not know if optical fibers are even slightly antiferromagnetic > >> but maybe doping can make them susceptible? > >> > >>> On Wed, 24 Aug 2016 09:31:57 +1200, you wrote: > >>> > >>> What is the coupling mechanism giving rise to the 50Hz disturbance? > >>> DaveB, NZ > >>> > >>> ----- Original Message ----- > >>> From: "Magnus Danielson" <mag...@rubidium.dyndns.org> > >>> To: <time-nuts@febo.com> > >>> Cc: <mag...@rubidium.se> > >>> Sent: Wednesday, August 24, 2016 8:54 AM > >>> Subject: Re: [time-nuts] Optical link connects atomic clocks over 1400 > >>> km of fibre > >>> > >>>> ... > >>>> > >>>> These links is in principle not very complex, but they are regardless > >>>> somewhat sensitive. One link experienced excessive 50 Hz disturbance, > >>>> which they could trace to the fact that for a short distance the fibre > >>>> was > >>>> laying alongside the house 400V three-phase feed-cable with quite a bit > >>>> of > >>>> current in it. > >>>> > >>>> ... > >>>> > >>>> Cheers, > >>>> Magnus > >> > >> _______________________________________________ > >> 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. > > _______________________________________________ > 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.