Sheila, Nutsinee

We went back and took some data today while the roughing pump was still running just to see if we could see the sqz turn around that would be an indication of phase nosie. We didn't look at any of the loop spectra and assumed that most of the phase noise came from the running pump. With the current non linear gain we have we barely reach the bottom of 80 mrad phase noise sqz curve. Assuming that the actual squeezing with the IFO has much lower phase noise than this we are going to need more non linear gain. I think the way to achieve that is to move the crystal to a new co-resonance position and hopefully we would gain some of the nlg back (given we can get the threshold power back to where it used to be, which is ~20mW). Even with 20mW threshold power we would only have the max non linear gain of 7-9 given we can only put in 20 mW into the fiber coupler. This is still not enough to see the turn around if the phase noise during the operation is really low (our rough noise budget predicted phase noise to be no more than 20 mrad). 

It is also unclear at the moment that 80mrad came from the roughing pump alone. LO lock was iffy during all the measurement.

The date on these plots should be Oct 23.