Yuefan and Yuhang

Recently, we always have a problem of filter cavity green transmission power drop. It dropped from 5000 to 1500 recently. We figured out this problem today although we are always checking with the same method. The reason for GRtra power drop is too high gain.

After reducing the gain of filter cavity control loop while looking at filter cavity green transmission, we found the indicator of GRtra goes to 5000.

The incident power to filter cavity is 12.5mW, setting of the filter cavity loop is attached in figure 1 and 2(attenuation:1.68, gain:2.28). The locking bandwidth is 21kHz.