Sheila, Matt, Camilla
We repeated the HD data set taken in 82202 as in 83022 we found we had pump depletion during these measurements so that the OPO trans powers were actually lower than reported. We had some issues at first which ended up being that with HAM7 ISI tripped the optics were moving around too much, plot of optics here. After we fixed that, we retook the data, so that our real data set is in 83039. Below documents the steps taken and initial data that we ended up not trusting.
- Checked LO shot noise (LO on HD, Seed blocked) and HD dark noise (both beams blocked)
- Sheila increased Seed power form 0.5mW to 70mW.
- SQZ_MANAGER to LOCKED_SEED_DITHER. Went onto SQZT7, plugged oscilloscope into the outside of the table. Adjusted LO power to match.
- Then both Seed and LO beams on the HD Seed PZT scanning, starting visibility 89% (max-min/max+min), adjusted SQZ path optics to increase visibility to 98.6%
- Sheila decreased Seed power to 0.2mW.
Then started data taking:
- NLG measured at (Toggle SQZ/HD path and follow 76542)
- Took SQZ_MANAGER to SQZ_READY_HD (FC2 misaligned) and take data on HD DTT
- Change opo_grTrans_setpoint_uW in sqzparams.py, reload OPO guardian, take it to NO_ISS and then back to LOCKED_CLF_DUAL to check it can reach opo_grTrans_setpoint_uW
- Repeat
Sheila and Matt measured the LO OLG as 2.5kHz 80deg phase margin is LO loop with gain -12 LO on LOCKED_HD with opo_grTrans_setpoint_uW = 80uW before we started.
One we got to the 110uW measurements, we felt the squeezing was unstable, moving independently of the SQZ angle, steps taken to help this:
- Sheila and Matt measured the LO OLG, it was the same as before, so it's changing significantly with OPO trans power
- OPO loop measured, 1.7kHz was UGF last week this week looks very different, changed gain from -8 to - 14 plots in 83039.
- CLF loop had 13.7kHz UGF with plenty of phase margin, was 12kHz last week.
- Realized that the ZM optics were noisy with HAM7 tripped and the increased (60mph!! wind), see plot.
- Then Sheila and Matt rechecked balancing and visibility after HAm7 was untripped, started at 98.3% but noisy, improved to 99.0%.
Data saved to camilla.compton/Documents/sqz/templates/dtt/20250225_HD.xml
FC2 is misaligned during this dataset.
| Type | NLG | SQZ dB @ 1kHz | Angle | DTT Ref | Notes |
| Dark Noise | N/A | N/A | ref 0 | This and shot noise was noisy <300Hz at times when the OPO was locking or scanning, unsure why. | |
| Shot Noise | N/A | N/A | ref 10 |
Blocked SEED, LO only.
|
|
| SQZ | 12 | -7.1 | 157 | ref1 |
opo_grTrans_setpoint_uW = 80uW
Amplified Max = 0.0107mW
Amplified Min = 0.00037mW
UnAmp = 0.00095
Dark = 6.5e-5
NLG = 11.9(max/min) and12.0 (usual method)
|
| ASQZ | 12 | 14.7 | 243 | ref2 | |
| Mean SQZ | 12 | 11.8 | N/A | ref3 | |
| SQZ | 66 | -6.6 | 167 | ref4 |
opo_grTrans_setpoint_uW = 120uW
Amplified Max = 0.05347mW
Amplified Min = 0.0002933mW
UnAmp = 0.00095
Dark = 6.5e-5
NLG = 66 (max/min) and 60.3 (usual method)
|
| ASQZ | 66 | 22.6 | 229 | ref5 | |
| Mean SQZ | 66 | 19.7 | N/A | ref6 | |
| SQZ | 23 | -7.0 | 156 | ref7 |
opo_grTrans_setpoint_uW = 100uW
Amplified Max = 0.0210425mW
Amplified Min = 0.00034922mW
NLG = 23.0 (max/min) and 23.7 (usual method)
|
| ASQZ | 23 | 18.1 | 236 | ref8 | |
| Mean SQZ | 23 | 15 | N/A | ref9 | |
| SQZ | 36 | -7.2 | 165 | ref11 |
opo_grTrans_setpoint_uW = 110uW.
Amplified Max = 0.033029mW
Amplified Min = 0.00033752mW
NLG = 36.0 (max/min) and 37.2 (usual method)
OPO gain reduced -8 to -14. HAM7 WD untripped. Visibility again measured. |
| ASQZ | 36 | 19.9 | 230 | ref12 | Rechecked after visibility adjusted, no change |
| Mean SQZ | 36 | 16.9 | N/A | ref13 | |
| SQZ | 36 | -7.2 | 165 | ref14 | Remeasured after visibility again measured. |
