NAOJ GW Elog Logbook 3.2
Yao-Chin and Yuhang
For the optimization of homodyne, we basically align again the homodyne. Including the matching of IRMC/AMC and OPO/AMC, the balance of homodyne, the beam height regulation.
The situation of IRMC/AMC matching is 99.95% while OPO/AMC is 99.7%.
The balance of homodyne now is done without aligning its BS but by aligning the lens before homodyne.
Benefit from not aligning homodyne BS, we could make squeezing go to homodyne flatly. Also, in this case, the balance of homodyne is easier.
After this work, we characterize squeezing again. We measured squeezing and anti-squeezing for power from 20mW to 60mW with an interval of 5mW. The result is shown in the attached first figure.
In the attached figure 2, we see there was a peak appearing. I need to mention that this peak appears after we did several measurements.
By fitting the squeezing and anti-squeezing, we could find out the loss and phase noise information. However, this time, the fitting and raw data has a larger discrepancy.
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I am sorry that I forgot to put the information about the Green power and demodulation phase.
| green pump power | MZ offset | OPO temperature | p-pol locking frequency | CC2 demodulation phase(sqz) | CC2 demodulation phase(asqz) |
| 20 | 4.1 | 7.166 | 175 | 75 | 160 |
| 25 | 4.2 | 7.167 | 175 | 90 | 170 |
| 30 | 4.3 | 7.18 | 175 | 100 | 175 |
| 35 | 4.4 | 7.18 | 175 | 120 | 170 |
| 40 | 4.5 | 7.19 | 180 | 120 | 160 |
| 45 | 4.6 | 7.19 | 170 | 125 | 155 |
| 50 | 4.7 | 7.19 | 150 | 125 | 160 |
| 55 | 4.8 | 7.195 | 150 | 125 | 155 |
| 60 | 4.9 | 7.2 | 150 | 135 | 155 |
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In the last attached figure, we can see the fit without considering the sqz-asqz for 55, 60mW.
Note: the anti-squeezing level is lower than the measurement did last week. This may come from the alignment issue of green pump.
Did you tune CC2 demodulation phase for each green power?