On Thursday, 23 February 2017 3:09 PM, Bruce Griffiths <bruce.griffiths@xtra.co.nz> wrote:

On Thursday, 23 February 2017 3:02 PM, Attila Kinali <attila@kinali.ch> wrote:

Perhaps one could use a laser stabilised to an atomic absorption line to interrogate an atomic absorption cell or equivalent in the other location via optical fiber using the absorption cell as a frequency discriminator. Trapped ion or Bose-Einstein condensates could be used in the absorption "cells". Bruce  On Thursday, 23 February 2017 3:09 PM, Bruce Griffiths <bruce.griffiths@xtra.co.nz> wrote: It would be better to lock the laser to a suitable optical absorption line or other optical transition.Long term stability can be better than an optical cavity provided the absorption cell parameters are stabilised. Other techniques such as using  a Bose Einstein condensate can be helpful. Bruce  On Thursday, 23 February 2017 3:02 PM, Attila Kinali <attila@kinali.ch> wrote: On Wed, 22 Feb 2017 00:54:34 -0800 Hal Murray <hmurray@megapathdsl.net> wrote: > How stable is a good laser and/or how hard do I have to work (or how much do > I have to pay) to get one stable enough for this experiment?  What's the line > width on a typical laser?  How much does it wander with temperature and > supply voltage and phase of the moon? A normal ECDL system gets a line width sub 1MHz pretty easily, the better ones are in the order of 10-100kHz. With the right stabilization system sub 1Hz linewidths can be achieved [1,2]. Stability is in the order of 10^-14 to 10^-16 (ADEV/MDEV) from 1s to a few 100s. Long term seems to be limited by temperature stability, creep of spacer material and mirror aging (no particular order). I haven't had a look at this topic in a while so I cannot tell you what the current state of the art is.             Attila Kinali [1] "Sub-hertz-linewidth diode laser stabilized to an ultralow-drift high-finesse optical cavity", by Hirata, Akatsuka, Ohtake, Morinaga, 2014 http://dx.doi.org/10.7567/APEX.7.022705 [2] "A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity", Kessler, Hagemann, Grebing, Legero, Sterr, Riehle, Martin, Chen, Ye, 2012 http://dx.doi.org/10.1038/nphoton.2012.217 -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation.                 -- Miss Matheson, The Diamond Age, Neil Stephenson _______________________________________________ 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.