M. Todd, S. Dwyer
This morning Sheila and I went out to HAM7 to move the OPO crystal to try and get rid of some loss, continuing from this work.
We got the translation stage driver out of the SQZ cabinet and after a bit of fiddling with the connector, we were able to see a response in the IR and Green transmission.
From here we moved the OPO to the right and then back to the left, measuring the NLG and Threshold Power at each position:
| Position | Max | OPO Therm. | Green Launch | Unamp. | Dark | NLG | P_thres[uW] | P_set [uW] | Notes |
|---|---|---|---|---|---|---|---|---|---|
| 0 | 0.0577 | 30.698 | 0.00663 | 0.0000232 | 8.73 | 90.35 | 80 | 8:58 AM | |
| 20 | 0.052 | 30.647 | 7.87 | 91.65 | 80 | 9:06 AM | |||
| 40 | 0.049 | 30.618 | 20.7 | 7.41 | 92.47 | 80 | 9:15 AM | ||
| 60 | 0.0477 | 30.593 | 19.85 | 7.22 | 92.87 | 80 | 9:21 AM | ||
| 0 | 0.0494 | 30.61 | 20.5 | 7.47 | 92.36 | 80 | 9:25 AM | ||
| -10 | 0.0498 | 30.612 | 20.6 | 7.53 | 92.24 | 80 | 9:33 AM | ||
| -20 | 0.0499 | 30.613 | 20.7 | 7.55 | 92.22 | 80 | 9:37 AM | ||
| -40 | 0.0502 | 30.616 | 20.8 | 7.59 | 92.13 | 80 | 9:41 AM | ||
| -60 | 0.0508 | 30.624 | 21 | 7.69 | 91.97 | 80 | 9:45 AM | ||
| -80 | 0.0512 | 30.63 | 21.2 | 7.75 | 91.86 | 80 | 9:52 AM | ||
| -100 | 0.0515 | 30.634 | 21.3 | 7.79 | 91.78 | 80 | 9:55 AM |
As you can you see when we "returned" to our starting position our NLG never returned to its starting point. Sheila and I went back into the control room to try and recover the NLG via adjusting the OPO temp, but in un-plugging the driver before digitally closing the connection, we think we kicked the OPO into a very different position than expected. To even get something sensible we had to change the OPO temp by over one degree celcius -- far more than should be necessary to get the Green and IR to be coresonant.
So after lunch, we back into the LVEA and connected the driver again as well as a function generator to the OPO PZT, reading the IR and Green transmissions onto a scope. We also increased the seed power to 2W so that we could see it on the scope more easily. Ensuring the connector was more properly setup, we moved the OPO a BUNCH to the left to get the Green and IR to be co-resonant. After awhile the driver would not let me move it to the left anymore, (though it would let me move to the right a couple steps but then NOT retrace my steps back left...), so we decided to leave it as it was. At the end of it we had moved 22 x 50 steps (+ 1 x 10 steps) to the left, and decided to do the rest of the actuation with the OPO temp.
We measured the NLG in the final position and it was disappointingly low but we decided to regroup and think about things.
| Position | Max | OPO Therm. | Green Launch | Unamp. | Dark | NLG | P_thres[uW] | P_set [uW] | Notes |
|---|---|---|---|---|---|---|---|---|---|
| -1110 | 0.00186 | 30.46 | 15.5 | 3.40E-4 | -2.70E-5 | 5.137 | 99.34 | 80 | |
| -1110 | 0.00280 | 3.48E-4 | -2.70E-5 | 7.539 | 121.06 | 105 |
More to come, and more to think about!