Participant: Marco, Aritomi, and Yuhang

1. We replaced the OPO transmission PD by PDA10CS. The new PD has a bandwidth of 17MHz so that we can see the oscillation of coherent control error signal(should be 14MHz).

2. Then we brought back BAB and aligned it with OPO scanning and green phase scanning. Here the green phase scanning with 1kHz and 2Vp-p. This parametric amplification effect is not obvious when the modulation magnitude around 1Vp-p. However, we see many fringes within 1ms. This means 2 Vp-p corresponds to the scanning depth is more than 1 period. See attached figure 1.

We also make BAB and p-pol peak overlap when we scanning OPO. We wrote down the p-pol PLL frequency shift. It is 30.5MHz. In this case, green power is 51mW. OPO temperature is 7.03kOm. In principle, this frequency difference will be always like this if we keep green power and OPO temperature. Then we lock p-pol PLL.

3. Then we replace BAB with coherent control beam. Lock PLL with 7MHz. As soon as we did that, we found a phenomenon in the attached picture 2. It seems there is a very clear oscillation at high frequency. After we lock OPO and we look into the detail of this oscillation. We found this oscillation is around 14MHz. See attached picture 3. It seems the coherent control signal we are looking for. However, we found a not understandable error signal after we did the demodulation. Because we found the error signal didn't change oscillation frequency after we changed the green phase scanning frequency. So further investigation needs to be done.

4. We didn't see any useful information from OPO reflection.

We have noticed the nonlinear effect became worse for the second time of CC error signal checking. This proofs that we should consider more about how to apply coherent control.