40m
QIL
Cryo_Lab
CTN
SUS_Lab
TCS_Lab
OMC_Lab
CRIME_Lab
FEA
ENG_Labs
OptContFac
Mariner
WBEEShop
|
PSL |
Not logged in |
 |
|
Fri Nov 1 17:54:47 2019, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD RF Ouput under inspection   
|
Tue Nov 5 18:37:59 2019, anchal, DailyProgress, FSS, FSS Diagnostics - TTFSS Testpoint Spectrum Data
|
Sat Nov 9 19:28:36 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Loop nonlinearity Test  
|
Mon Nov 11 20:42:49 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Two Tone Test  
|
Tue Nov 12 18:36:59 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Two Tone Third Order Intermodulation Test
|
Thu Nov 14 12:19:32 2019, rana, DailyProgress, FSS, FSS Diagnostics - Two Tone Third Order Intermodulation Test
|
Tue Nov 19 18:51:02 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Second-order Distortion Calculation 
|
Mon Dec 9 19:54:44 2019, anchal, DailyProgress, FSS, FSS Diagnostics - How much distortion affects the functioning of PDH?
|
Wed Nov 27 13:59:24 2019, anchal, DailyProgress, FSS, FSS Diagnostics - TTFSS TP1 TimeSeries
|
Wed Nov 27 15:17:51 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Quick HF OLTF of NFSS
|
Wed Nov 27 16:31:20 2019, rana, DailyProgress, FSS, FSS Diagnostics - Quick HF OLTF of NFSS
|
Wed Dec 4 18:11:09 2019, anchal, DailyProgress, FSS, Free running laser frequency noise spectrum
|
Thu Dec 5 18:25:11 2019, rana, DailyProgress, FSS, Free running laser frequency noise spectrum
|
Tue Dec 17 18:29:58 2019, anchal, DailyProgress, FSS, Need for ISS?
|
Wed Dec 18 18:40:32 2019, anchal, DailyProgress, FSS, Maybe the NPRO Laser isn't bad after all
|
Wed Dec 18 22:03:17 2019, rana, DailyProgress, FSS, Maybe the NPRO Laser isn't bad after all
|
Fri Dec 20 15:00:30 2019, anchal, DailyProgress, FSS, PZT, EOM to RIN TF Measurement
|
Fri Dec 20 18:08:44 2019, anchal, DailyProgress, FSS, PZT, EOM to RIN TF Measurement Through FSS
|
Tue Jan 7 17:59:20 2020, anchal, DailyProgress, FSS, NPMC TF
|
Thu Dec 12 19:15:55 2019, anchal, DailyProgress, FSS, FSS Diagnostics - Beatnote Spectrum wrt Laser Power and Modulation Index
|
Tue Dec 17 16:55:07 2019, anchal, DailyProgress, FSS, FSS Diagnostics - TTFSS North U7 Boost Stage Input-Output TimeSeries
|
Tue Nov 12 11:39:48 2019, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD RF Ouput under inspection
|
Fri Dec 13 16:24:02 2019, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD Circuit Latest Available Photos   
|
Fri Dec 13 17:44:05 2019, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD RF Coupled Output Offset
|
Mon Jan 13 19:04:38 2020, anchal, DailyProgress, FSS, FSS Diagnostics - SN009 (North RFPD) Notch Improvement Attempt  
|
Tue Jan 14 18:19:33 2020, anchal, DailyProgress, FSS, FSS Diagnostics - SN009 (North RFPD) Notch Improved!  
|
Thu Jan 16 11:17:15 2020, anchal, DailyProgress, FSS, FSS Diagnostics - SN010 (South RFPD) Notch Improvement Attempt  
|
Thu Jan 16 20:18:44 2020, anchal, DailyProgress, FSS, FSS Diagnostics - SN010 (South RFPD) Notch Improved  
|
Mon Jan 27 18:29:19 2020, anchal, DailyProgress, FSS, FSS Diagnostics - RFPD RF Out Spectrum
|
|
Message ID: 2502
Entry time: Wed Dec 18 18:40:32 2019
In reply to: 2500
Reply to this: 2503
|
Author: |
anchal |
Type: |
DailyProgress |
Category: |
FSS |
Subject: |
Maybe the NPRO Laser isn't bad after all |
|
|
Today I inserted two photodiodes, Thorlabs PDA10CS at (110,44) at dumped end of a PBS before PMC and at (64,28) at dumbed end of INput PBS of Faraday Isolator after PMC. These photodiodes were set at 20dB gain which according to the manufacturer gives us a bandwidth of 1.9 MHz.
Then, I just took Noise Spectrums using AG4395A with the parameter file attached in the data directory, from 0 to 1 MHz at 1 kHz ResBW and 50 averages. The output was divided by the DC level of the photodiode which was measured using TDS 3052B averaged over 10s. This measurement was done with FSS ON or OFF.
Inference
- Whenever FSS is ON, the loop is completed, so noise due to PMC and FSS is present in the measured RIN.
- But when FSS is OFF, before PMC, the noise should be just of free running laser even though PMC is locked downstream.
- The most important observation is that when FSS is OFF, before PMC, the RIN is pretty small with no peaks in 100s kHz, particularly the notorious 433 kHz peak.
- The dome from 1kHz to almost 100kHz peaks at 10kHz is most probably due to FSS as it goes away whenever FSS is OFF.
- The peak at 433 kHz persists even after switching off FSS and is present only after PMC. So this peak is clearly due to PMC and not due to laser as was thought before.
- Conclusion is, that laser is free of any large RIN and most of the RIN introduces is due to FSS or PMC.
- I've left the PDs in there with termination. I'll change some PMC loop and FSS loop parameters tomorrow to see nature of their contribution to RIN.
North Laser is hereby acquitted.
Data
|
|
|