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Entry  Tue Apr 30 01:15:26 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 
    Reply  Thu May 2 03:03:48 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 
       Reply  Thu May 2 23:40:46 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 6x
          Reply  Mon May 6 03:11:44 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO RefCav_AlGaAs_TOnoise.png
             Reply  Mon May 6 17:08:25 2013, Matt A., Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 
             Reply  Tue May 14 02:06:15 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 
                Reply  Wed May 15 20:07:12 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO TO_compare_cap.pngTO_compare_cap.fig
                   Reply  Tue May 21 01:06:43 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 
                      Reply  Wed May 22 00:04:48 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 
                         Reply  Fri May 24 04:04:58 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 
                            Reply  Fri May 24 23:57:27 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO 6x
                               Reply  Wed Jun 5 22:25:28 2013, tara, Notes, NoiseBudget, TO calculation review 
                         Reply  Thu Jun 6 22:28:46 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO eighth.png
                            Reply  Tue Jun 11 00:45:48 2013, tara, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity sk2009nb.pngsk2009nb.fig
                               Reply  Tue Jun 11 16:46:52 2013, tara, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity getCoatBrownian2.m.zip
                               Reply  Wed Jun 12 01:34:27 2013, Koji, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity 
                                  Reply  Wed Jun 12 14:32:22 2013, not Koji, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity 
                                     Reply  Wed Jun 12 14:49:47 2013, Koji, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity 
                                        Reply  Fri Jun 14 02:36:22 2013, tara, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity 
                                           Reply  Tue Jun 18 11:53:17 2013, tara, Notes, NoiseBudget, noisebudget for 8" SiO2/Ta2O5 cavity spacer_br_8_edge.png
                            Reply  Mon Jul 15 10:55:40 2013, tara, Notes, NoiseBudget, AlAs/GaAs layer structure optimized for TO alGaAsnb.pngalGaAsnb.fig
Message ID: 1170     Entry time: Mon May 6 03:11:44 2013     In reply to: 1169     Reply to this: 1171   1176
Author: tara 
Type: Notes 
Category: NoiseBudget 
Subject: AlAs/GaAs layer structure optimized for TO 

I checked the calculation for TO noise in Cole etal people and found a few problems that I didn't understand.

  • In the paper, they have two solutions for TO-noise, at low and high frequency. The solution for high frequency is similar to that in Evan etal paper, but I'm not sure where the solution for low frequency are from.  I don't see this kind of calculation in Evans etal paper.
  •  I repeated and plotted the TO noise calculation as used in Cole etal's paper. The TO noise plotted in their paper mostly came from the low frequency part.
  • Some parameters reported in the paper might not be accurate, for example their beam radius is 250 um. However, with their 35mm spacer, 1.0 m RoC mirrors, the spotradius on the mirror should be 212 um. I haven't checked how much their materials parameters and what I used in my codes differ.
  • For low frequency solution (solid blue line), with the materials parameter given in the paper, it is a factor of 1.5 higher than their result (I got 3e-3, they report ~2 e-3 around 1-10 Hz).
  • For high frequency solution (solid yellow line), with the materials parameters given in the paper, the result is about a factor of 10 higher than that from Gwinc code (dashed blue line). The formulas are the same, but I used different material parameters. The two lines should be close, but they are a factor of 10 apart, just because of the material parameters. We should really make sure that the numbers are correct. Before trying to do the optimization.

 

RefCav_AlGaAs_TOnoise.png

 

My GWINC code for TO calculation can be found here. (other modified functions are in /GwincDev/ ).The main code is plotTO_algaas.m. This code uses getCoatThermoOpticsAGS.m which calls out other other functions in /gwincdev/

  1. getcoatTOposAGS.m (calculated effective alpha and beta in coatings.) This function uses getcoatLayers.m to generate the layer structure. The original one started with nL, I modified it to start with nH, and end with nH.
  2. getcoatThickCorrAGS.m, which computes the correction factor (gamma TO).
  3. getcoatavgAGS.m, this code compute the average material parameters in coatings.
  4. in /coating/AlGaAs_Refcav, I created a database file for material parameters called algaasmodels.m.

 

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