[Anchal, Paco, Shruti]

• Today we found out that the laser controller at the Yend had it's inputs disconnected for the FAST PZT input and the Slow temperature control input. The cables were also not labeled that were lying nearby.
• I tracked the cables and connected the Fast input adn the slow input.
• We then adjusted the temperature slider to go to previously marked laser crystal temperature of 40.1 degrees celsius. But we could not find the the beatnote of Y end IR with teh Main laser IR.
• We scanned the laser crystal temeprature until we could see a beatntoe with the main IR laser and stopped in that region.
• Then we continued looking for flashing and HOM, but no luck.
• It was interesting that when the PDH loop was closed, we saw fluctuations in relfection photodiode DC value, but not so much when the loop was not closed.
• We tried flipping the sign of the loop with no luck and we tried changing the gain of the loop as well, but no luck.
• The behavior of this Yend laser and its controller is still suspicious to us. When the loop is closed, the PZT feedback signal should not cause a change in amplitude of the light so much as we see it.
• Also the fact that when loop is clsoed we do not see signs of flashing in the reflection photodiode is interesting. If anyone has any ideas, that would be good.