Daniel, Dhruva, Sheila

Daniel rigged a couple of breakout boards at the HAM7 feedthrough so that we could lock the OPO (drive it's PZTs) and connect the translation stage controller near the chamber (photos in first two attachments).  With this set up we were able to drive the stage to find a new spot in the crystal and improve the nonlinear gain. This is great news since it means we will not need to replace the translation stage during the upcoming vent.

This table shows nonlinear gain (max IR/ IR when green is blocked), corresonance temperature and the max IR PD counts (for reading off the ndscope).  Haocun did a similar adjustment for the O3 OPO in 43292. We don't know what the calibration of steps or direction on the translation stage, I am just reporting what the software says for steps and direction. Moving the stage back to the left we saw some hysterises. When we started these measurements we had 11mW injected into the pump fiber, 2.37mW on the REFL diode ( meaning 4.74mW reflected from the OPO before the 50/50 SK:BS1), and 0.08mW.  When we first moved the crystal, the OPO green transmission nearly doubled, while the reflected power increased by about 10% see 3rd attachment. 

When we finished adjusting the crystal position Dhruva reduced the green power into the fiber so that we have a nonlinear gain of about 14, with 7.4mW injected into the fiber, 0.11mW on the OPO green trans diode, and about 3mW reflected from the locked OPO.  The final attachment shows that over the last 4 hours, the OPO transmission is dropping, previously we have seen that when we find a low loss spot in the crystal there is a degredation in the first few days of operating at that spot.