Marc and Yuhang
We checked OPO CC power in transmission with different green power injected.
The injected CC power is 1.52mW. In transmission, 3.9uW of offset has been removed (coming from p-pol).
Reflected CC power (no green) is picked out by a 25:75 (R:T) BS. The pick-off power reaching CC1 PD is about 133uW, which is strange. Since we know that OPO makes 99.7% CC reflected and 25% of pick-off, we expect 379uW reaching CC1 PD.