Sheila, Naoki, Camilla
We took FDS, Anti-SQZ and Mean SQZ data at different NLGs: 14, 17, 43, 82 and 123. We think we see evidence of frequency noise. We see less squeezing at high NLGs: around 4.5dB of SQZ at NLG < 43.1 but at NLG 81.9 and 122.8, squeezing at 1kHz reduced to 3.6 and 3.1dB. Attached Plot.
Each time we optimized SQZ angle around 1kHz. Because of this, the low frequency increased noise at high NLGs could be due to incorrect rotation, rather than phase noise.
|
Time (UTC)
|
Demod phase
|
DTT ref#
|
NLG |
SQZ dB at 900Hz
|
|
|
FDS
|
21:23:40-21:26:00
|
152.25
|
3
|
13.9
|
-4.3
|
|
FDAS
|
21:27:30- 21:32:30
|
228.10
|
6
|
13.9
|
15.2
|
|
Mean
|
21:33:47- 21:38:00
|
-
|
7
|
13.9
|
12.7
|
|
No SQZ
|
21:40:00 -21:44:50
|
-
|
0
|
-
|
|
|
FDS (not optimized)
|
21:51:20 -21:54:30
|
164.57
|
Deleted
|
43.1
|
-4
|
|
FDAS (Left ASC off)
|
21:56:00 -21:59:45
|
226.2
|
5
|
43.1
|
19.1
|
|
FDS (retake)
|
22:03:00 -22:06:13
|
167.42
|
4
|
43.1
|
-4.3
|
|
Mean
|
22:06:45 -22:09:52
|
-
|
8
|
43.1
|
16.9
|
|
FDS
|
22:37:50- 22:41:00
|
172.16
|
9
|
122.8
|
-3.1
|
|
FDAS
|
22:42:43-22:45:45
|
217.67
|
10
|
122.8
|
24.7
|
|
Mean
|
22:46:35 - 22:49:55
|
-
|
11
|
122.8
|
|
|
FDS
|
22:57:30- 22:59:40
|
169.31
|
12
|
81.9
|
-3.6
|
|
FDAS
|
23:01:20 - 23:02:55
|
219.56
|
13
|
81.9
|
22.7
|
|
Mean sqz
|
23:03:26 - 23:05:45
|
-
|
14
|
81.9
|
20
|
|
FDS (left IFO here)
|
23:19:38
|
154.14
|
15
|
17.1
|
-4.5
|
Data saved in /camilla.compton/Documents/sqz/templates/dtt/20231025_GDS_CALIB_STRAIN.xml
|
Time (UTC)
|
Unamplified OPO OPO_IR_PD_LF
(Scan Seed)
|
OPO trans (uW)
|
OPO Temp (degC)
|
Amplified (maxium) H1:OPO_IR_PD_LF
(Scan OPO PZT)
|
NLG
(Amplified / (Unamplified Peak Max - Unamplified Dark Offset))
|
|
| Peak Maximum | Dark Offset | |||||
|
21:15
|
786e-6
|
-16e-6
|
80.54 uW
|
31.446
|
0.0112
|
13.9
|
|
21:44
|
|
|
100.52
|
31.414
|
0.0346
|
43.1
|
|
22:17
|
|
|
120.56
|
31.402
|
0.160
|
199.5 (SQZ loops went unstable)
|
|
22:30
|
|
|
110.5
|
31.407
|
0.06617
|
82 (didn't use)
|
|
22:36
|
|
|
115.46
|
31.405
|
0.09853
|
122.8
|
|
22:52
|
|
|
110.5
|
31.407
|
0.0657
|
81.9
|
|
22:09
|
769e-6
|
-15e-6
|
80.5
|
31.424
|
0.0137
|
17.1
|
Vicky and Naoki did an NLG sweep on the Homodyne in 73562.
Edits to NLG table in above alog: Last measurement was at 22:09 23:09 UTC. For measuring unamplified we scanned OPO PZT and for amplified we scanned SEED PZT.
Setup for each SQZ Measurement:
- SQZ_MANAGER to NO_SQUEEZING and SQZ_OPO to DOWN
- Scan the OPO PZT with PZT_1 Enable, Use trigger: No (via SQZ Overview > HAM7 > OPO IR > OPO PZT1)
- Should see mode scan on H1: SQZ-OPO_IR_PD_LF_OUT. Measure the highest peak as "Unamplified" and the zero level as "Unamplified Dark Offset".
- Only need to this once (we did at start and end)
-
SQZ_MANAGER to NO_SQUEEZING
-
Change opo_grTrans_setpoint_uW in sqzparams.py (higher power = higher NLG)
-
Reload SQZ_OPO
-
SQZ_OPO to LOCKED_CLF_DUAL_NO_ISS then LOCKED_CLF_DUAL
-
Check it locks with correct OPO TRANS power, may need to adjust SHG power with waveplate
-
-
SQZ_OPO to LOCKED_SEED_NLG
-
SQZ_CLF to DOWN
-
Adjust temperature to maximize SQZ-OPO_IR_PD_LF_OUT (with SEED_PZT scanning enabled)
-
Record SQZ-OPO_IR_PD_LF_OUT maximum it is "Amplified" signal.
-
Can now calculate NLG = Amplified / (Unamplified - Unamplified Dark Offset).
-
-
SQZ_MANAGER to SQZ_READY_IFO (with swap back from SEED to CLF)
Attached are fits of squeezing loss, phase noise, and technical noise to this NLG sweep on DARM: we can infer 25-30% total SQZ losses, ~25 mrad rms phase noise, with technical noise almost -12 dB below shot noise.
Losses are tracked in the SQZ wiki and gsheet. Of the 30% total inferred loss, we expect 20%: that is 7.5% injection loss, and 13.7% readout loss.
Remaining ~10% mystery loss is compatible with mode-mismatch: in sqz-omc single bounce mode scans, LHO:73696, we estimate 8-15% mismatch, and we observe the frequency-dependence of the mismatch as we vary squeezer beam profile using PSAMS: 73400, 73621.
In the fits, [loss, phase noise, technical noise] are fit to the measured SQZ and Anti-SQZ, given the measured NLG, using equations from the aoki paper. "Loss from mean sqz" is the calculated loss from the measured NLG and measured mean-sqz dB; it is not a fit, but depends on the calibration from NLG to generated SQZ dB.
Some summary slides here show the progression of our loss hunting, which are so far lining up with Sheila's projections from 73395.
