40m
QIL
Cryo_Lab
CTN
SUS_Lab
TCS_Lab
OMC_Lab
CRIME_Lab
FEA
ENG_Labs
OptContFac
Mariner
WBEEShop
|
PSL |
Not logged in |
 |
|
Thu Jan 10 10:39:27 2019, anchal, DailyProgress, NoiseBudget, New noise budget code is ready, but
|
Mon Aug 12 11:56:21 2019, anchal, DailyProgress, NoiseBudget, Adding specifics of discepancy
|
Tue Aug 13 11:59:56 2019, anchal, DailyProgress, NoiseBudget, Checking the differences between old and new noisebudget 
|
Tue Aug 13 17:05:53 2019, aaron, DailyProgress, NoiseBudget, Checking the differences between old and new noisebudget
|
Tue Sep 24 15:40:33 2019, anchal, DailyProgress, NoiseBudget, Adding specifics of discepancy 2
|
Tue Sep 24 17:11:13 2019, anchal, DailyProgress, NoiseBudget, Adding specifics of discepancy 2 (More)
|
Tue Sep 24 19:39:06 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Loss Angles 
|
Fri Sep 27 16:40:49 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Loss Angles Better Plots 
|
Mon Sep 30 11:14:41 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Loss Angles 2D Plots 
|
Mon Sep 30 12:25:24 2019, rana, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Loss Angles 2D Plots
|
Mon Sep 30 20:08:42 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Beam Radius 
|
Tue Oct 1 13:46:49 2019, anchal, DailyProgress, NoiseBudget, Using bayesian inference to estimate loss Angles 
|
Wed Oct 2 15:13:27 2019, anchal, DailyProgress, NoiseBudget, Checking variation in estimated Coating Brownian Noise with Beam Radius 
|
Wed Oct 23 13:21:12 2019, anchal, DailyProgress, NoiseBudget, Fixed all discrepancies.  
|
Fri Jun 12 12:34:08 2020, anchal, DailyProgress, NoiseBudget, Resolving discrepancy #1 concretly
|
|
Message ID: 2390
Entry time: Tue Aug 13 11:59:56 2019
In reply to: 2388
Reply to this: 2391
|
Author: |
anchal |
Type: |
DailyProgress |
Category: |
NoiseBudget |
Subject: |
Checking the differences between old and new noisebudget |
|
|
I saved the traces of old and new noise budgets as txt files and then plotted them together to understand the differences between the codes. One can refer to CTN:2250 for a summary of calculations of old noise budget.
Coating Brownian Noise:
- Old noise budget uses a simple formula from Harry et al. (2001) Eq 21.
- New noise budget uses analysis of Hong et al . PRD 87, 082001 (2013) which takes into account different bulk and shear loss angles for each layer.
- In this run, I used the same values of bulk and shear loss angles of both AlGaAs and GaAs, equal to 2.41e-5 +/- 0.482e-5 rad. This is the same value used in old calculations as well.
- It is interesting to see that there is almost no difference (<5% mostly) in the prediction of two methods even though they were done with vastly different methods.
- In the future, however, I would try to use different values. But there is no proper source for them. I can try using the coating loss angle values mentioned in Penn et al JOSA B Vol 36, Issue-4 (2019).
Coating Thermo-optic Noise:
- Both new and old methods use the same formula from Evans et al. (2008), Eq 4.
- But to calculate the effective coefficient of thermo-refractive effect, the old method used a complex matrix calculation which I'm unable to follow. The value was 8.61e-5 1/K.
- The new noise budget follows Evans et al. (2008) Appendix B to the best of my knowledge and generates a slightly different value of 8.2e-5 1/K.
- However this changes the coating thermo-optic contribution by almost 50%!
- IF ANYONE IS WILLING TO LOOK INTO THIS DISCREPANCY FOR A SANITY CHECK, I'LL BE REALLY HAPPY. CONTACT ME FOR MORE SPECIFICS.
Photothermal Noise:
There is no distinction in the calculation of this contribution after the changes made in CTN:2388, but there is still a difference (which reaches to around 20% above 1 kHz). This is maybe because of interpolation errors when taking the differences. But I'm not sure about this. This can take a sanity check from others as well.
No differences in:
The following calculations had no differences between the two noise budgets and the contribution differences are also none or minimal.
- Substrate Thermo-elastic Noise
- Substrate Brownian Noise
- Seismic Noise
- PDH Shot Noise
- PLL Oscillation Noise
- PLL Readout Noise
- Residual NPRO Noise
|
|
|
|