The initial degradation seems to have slowed down. Initially we needed 5.3mW at launch, but within the first 4 days this increased to ~7.5mW. Currently we need ~8.5mW of green pump light to mainatain the OPO intra-cavity power.
Here is a plot that shows that as the crystal absorption has increased, (roughly shown by the increase in the reflected power since the transmitted power is in loop), the nonlinear gain has dropped, and the DARM noise from 100-450 Hz, shown by OAF RLP 5 has gotten worse. In the first few days after the crystal move, we adjusted the crystal temperature set point to compensate for the increased local heating from absorption, which recovered the NLG. We probably need to do this again.
We adjusted the crystal temperature using the seed while the IFO was relocking. The nonlinear gain is now 2.7
H1 lost lock right after the SQZ BDV was closed for the above mentioned adjustment (thus "while the IFO was relocking").
After the IFO relocked but before we started injecting squeezing I checked the "dark" offsets of AS_A_RF42 and AS_B_RF42 (which is not really "dark" dark, it's "full IFO without SQZ" dark) we set last year (alog 54013) to see if they changed, and they didn't.
Since the offset comes from IFO light though nobody knows why, another question is if these change while the IFO is thermalizing.