NAOJ GW Elog Logbook 3.2
Based on the measurement we did before, we have dark noise of CC PD. We use this PD to lock the green pump phase, at the same time, we have bandwidth lower than 80Hz. So we could use this dark noise to evaluate the phase noise we have for coherent control loop 1. The calibration method is to use pk-pk value when we scan the green phase, which corresponds to radians of pi/2. In the case of that entry, 25mV corresponds to pi/2. The estimated phase noise(RMS) is attached as follows.
While it will be better to measure the spectrum and do RMS integration. And according to Emil thesis, this 200mrad of phase will degrade ~15dB of squeezing to ~5dB. And it seems to be close to the squeezing situation we saw in the past few days.
According to Emil's thesis P. 42 figure 2.10 or P.48 figure 2.13 (b), 200 mrad of phase noise seems to degrade 15 dB of squeezing to almost 0 dB of squeezing. Our situation seems around 100 mrad of phase noise. Did you consider the effect of control bandwidth when you calculated rms phase noise? As you noted, it's better to measure the spectrum and integrate it within control bandwidth.