Matteo and Yuhang

Based on Aritomi-san's code, I add the degradation from mode-matching to the CCFC error signal. The simulation result is in attached figure 1. From this simulation, worse mode-matching makes CCFC error signal degrade around resonance. But mode-matching doesn't affect the CCFC error signal's offset.

Based on this simulation, we sent BAB to the filter cavity and checked the mode-matching was about 0.75. We found the IR drift happened only in the yaw direction. After optimizing yaw, mode matching increased to about 0.9. When we checked the CCFC error signal's pk-pk value, we found some issues with this signal's demodulation. After optimizing the mixer, we saw an even better CCFC error signal. The comparison of CCFC error signals before and after optimization is in attached figure 2.

I compared the mm-optimized/mm-original CCFC error signal's minimum. In the simulation, the ratio is 0.64. While in measurement, it is 0.58.