daniel.sigg@LIGO.ORG - posted 11:54, Tuesday 17 December 2019 - last comment - 12:39, Tuesday 17 December 2019(53943)
New OPO Crystal Position
Sheila Marc Daniel
We changed the OPO crystal position by a random amount.
New OPO parameters:
- T = 33.316°C (before 33.296°C)
- OPO REFL DC unlocked = 2.1 mW
- OPO REFL DC locked = 0.53 mW (25%)
- SHG Launch ~ 5.3 mW
Before the crystal move we were at the maximum SHG launch power of 20mW with 2.6 mW on OPO REFL DC and weren't able to maintain the OPO green pump power anymore. We now need 4x less power.
Before moving the crystal, we set up the OPO scanning with the Thorlabs PZT driver (so that we can scan quickly), and saw that the red and green were co-resonant for a scannin cavity. We then moved the crystal using 100 count steps on the controller, the first direction that we tried moving (toward the right according to the UI) we found the edge of the crystal (red transmission peaks nearly disappeared) before we found an additional co-resonance. We went back in the other direction (left arrows) until we found our first co-resonaonce, then stopped at the next one. We after locking the cavity there we measured the nonlinear gain of 2.56 for a normalized OPO trans of 1 (OPO Refl is 0.5mW, fiber launch is 5.4mW).