Previously in alog46336 I felt like I was bottomed out on some of the measurements phase delay wise. To get more phase delay so we can be more confident in our measurement I gave 3MHz phase delay box to CLF (I have a feeling that phase delay box hooked up to LO/OMC gives me a bit less phase, not sure if that make sense, I will post more detail alog on the ellipse rotation later). Add CLF sign flip on top of that (which gives us extra 90 degree as Daniel suggested) I was able to go from OK to GOOD then back to OKAY measurement on both squeezing and anti squeezing. Flipping LO sign didn't help (180 deg). And using Q error signal to lock the CLF seems to have given me some extra phase adjustment (not sure why, CLF common mode board input 2 now has Q error signal goes into it). This way I know that I've seen the best sqz/asqz (by monitoring LO Q error signal go up and down while adjusting the phase, we locked with I).
After correcting for some of the minor loss typos and added data taken yesterday after I've acquired more phase delay, here I attached another loss estimate plot. I also give phase noise of 10 mrad this time since assuming that what we measured out of the LO IMON isn't all the phase noise there is. The result hasn't changed. We have more loss compared to when Haocun took a measurement here. We are still in the process of checking red transmission then and now.
Fringe visibility during Jan14 measurement was 99%. In the model I use 97%.
Before the measurement our laser was running multimode again. To get away from multimode I moved the current knob from 2.193A to 2.207A. Temperature stays the same (29.65C). This gives 158MHz without having to put a lot of offset to the control loop (ended up with -7MHz).
I went back to double check if my nlg was correct and found that the dark noise was actually negative (I missed a minus sign when I subtracted the DN). So here attached a revised plot. That didn't change the result (sadly). I also attached a plot projecting how much phase noise would you need in order to explain what we observe if we were to let efficiency by 86%. You need at least >250 mrad to explain what we have (which is not what we observed in LO error signal).
