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Entry  Sat Jan 6 05:18:12 2018, Kevin, Update, PonderSqueeze, Displacement requirements for short-term squeezing displacement_noise.pdfnoise_budget.pdf
    Reply  Sat Jan 6 13:47:32 2018, rana, Update, PonderSqueeze, Displacement requirements for short-term squeezing 
       Reply  Sat Jan 6 23:25:18 2018, Kevin, Update, PonderSqueeze, Displacement requirements for short-term squeezing displacement_noise.pdfnoise_budget.pdfangles.pdf
          Reply  Sun Jan 7 03:22:24 2018, Koji, Update, PonderSqueeze, Displacement requirements for short-term squeezing 
             Reply  Sun Jan 7 11:40:58 2018, Kevin, Update, PonderSqueeze, Displacement requirements for short-term squeezing 
                Reply  Sun Jan 7 17:27:13 2018, gautam, Update, PonderSqueeze, Displacement requirements for short-term squeezing 
                   Reply  Sun Jan 7 20:11:54 2018, Koji, Update, PonderSqueeze, Displacement requirements for short-term squeezing 
                      Reply  Thu May 3 00:42:38 2018, Kevin, Update, PonderSqueeze, Coil driver contribution to squeezing noise budget 
Message ID: 13514     Entry time: Sun Jan 7 17:27:13 2018     In reply to: 13513     Reply to this: 13515  
Author: gautam 
Type: Update 
Category: PonderSqueeze 
Subject: Displacement requirements for short-term squeezing 

Maybe you've accounted for this already in the Optickle simulations - but in Finesse (software), the "tuning" corresponds to the microscopic (i.e. at the nm level) position of the optics, whereas the macroscopic lengths, which determine which fields are resonant inside the various cavities, are set separately. So it is possible to change the microscopic tuning of the SRC, which need not necessarily mean that the correct resonance conditions are satisfied. If you are using the Finesse model of the 40m I gave you as a basis for your Optickle model, then the macroscopic length of the SRC in that was ~5.38m. In this configuration, the f2 (i.e. 55MHz sideband) field is resonant inside the SRC while the f1 and carrier fields are not.

If we decide to change the macroscopic length of the SRC, there may also be a small change to the requirements on the RoCs of the RC folding mirrors. Actually, come to think of it, the difference in macroscopic cavity lengths explains the slight differences in mode-matching efficiencies I was seeing between the arms and RCs I was seeing before.

Quote:

Yes, this SRC detuning is very close to extreme signal recycling (0° in this convention), and the homodyne angle is close to the amplitude quadrature (90° in this convention).

For T(SRM) = 5% at the optimal angles (SRC detuning of -0.01° and homodyne angle of 89°), we can see 0.7 dBvac at 210 Hz.

 

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