[Aritomi, Yuhang]

First we moved position of green phase shifter closer to GRMC since effect of misalignment of green phase shifter was large due to rubber and also there was no space to put additional clamp to fix green phase shifter.

Then we measured free running and closed loop phase noise of CC1,2 (attached pictures). We measured EPS2 of servo as error signal. Note that EPS2 of servo is larger than real error signal by a factor of 15.

As you can see, phase noise above 400Hz is very large and rms phase noise is mostly accumulated at high frequency where phase noise is not suppressed by CC loop. When we close the CC loop, phase noise at high frequency becomes larger and rms phase noise becomes even larger. This measurement is consistent with recent noisy squeezing measurement.