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Tue Apr 30 01:15:26 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO
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Thu May 2 03:03:48 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO
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Thu May 2 23:40:46 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 6x
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Mon May 6 03:11:44 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO
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Mon May 6 17:08:25 2013, Matt A., Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO
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Tue May 14 02:06:15 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO
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Wed May 15 20:07:12 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 
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Tue May 21 01:06:43 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO
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Wed May 22 00:04:48 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO
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Fri May 24 04:04:58 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO
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Fri May 24 23:57:27 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 6x
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Wed Jun 5 22:25:28 2013, tara, Notes, NoiseBudget, TO calculation review
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Thu Jun 6 22:28:46 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO
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Tue Jun 11 00:45:48 2013, tara, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity 
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Tue Jun 11 16:46:52 2013, tara, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity
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Wed Jun 12 01:34:27 2013, Koji, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity
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Wed Jun 12 14:32:22 2013, not Koji, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity
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Wed Jun 12 14:49:47 2013, Koji, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity
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Fri Jun 14 02:36:22 2013, tara, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity
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Tue Jun 18 11:53:17 2013, tara, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity
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Mon Jul 15 10:55:40 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 
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Message ID: 1177
Entry time: Wed May 15 20:07:12 2013
In reply to: 1176
Reply to this: 1178
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Author: |
tara |
Type: |
Notes |
Category: |
NoiseBudget |
Subject: |
AlAs/GaAs layer structure optimized for TO |
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We checked the half wave cap solution for minimizing TO noise. WIth a half wave cap of nl, the TO noise is smaller by ~ a factor of 2 in Hz^2/Hz unit.
Matt and I checked the calculate the TO noise for a half wave cap solution. The noise goes down by a factor of 2.
A few issues that we still have to investigate:
- A thin layer of nh: we talked to Mike, he said that to prevent the oxidation that occurs on GaAs layer (nL), a thin layer of AlGaAs(nH) has to be applied on top. We are not sure how thick the layer will be, we should ask G Cole, so that we can estimated the effect before hand.
- The TO noise with half wave cap may already be lower than substrate thermoelastic (TE) noise. I'm checking the TE calculation and find out that the value for thermal expansion of fused silica is 3.9e-7 in Gwinc, but 5.5e-7 elsewhere (add sources). If it is really 5.5e-7, this will be higher than the current TO noise already. I'll look into it.
- A factor of 2 : This comes from double sided PSD or either 2 mirrors. I'll change that to our standard here (1-sided PSD, with single mirror).
- The cancellation might change for different numbers of doublet. Since we plan to have ~ 100-200 ppm, the actual TO noise may be different than this calculation (2ppm). I try using 56 layers (1/2 lambda cap of nL included) which give us 100ppm, and TO noise is below coating brownian from DC to 200 Hz. This is a pretty good result which should be expected. Since we reduce the number of doublet, the effect from TE becomes smaller, (still larger than TR). Thus the different between the two (the total TO noise) is smaller.
- Different cap thickness may bring down TO noise more than half wave cap does. I just try the cap with 0.1 wavelength of nL (for 40 doublet stack), and TO noise goes down by another factor of 2. This might apply for 56 stack as well. I'll check.

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