Turning down the LO power ends up hurting squeezing. Very strange. We see 4.3dB with 2mW LO and 3.4 with 0.1mW. HD dark noise is still 8dB below the Low LO SQZ level. LO loop gains were adjusted to compensate for the change in power.
The 10dB clearance between the dark noise and the shot noise with low LO is equivalent to 10% of optical loss. Ignoring the phase noise and assuming 15dB generated squeezing, 3.4dB squeezing corresponds to 44% loss and 4.3dB squeezing corresponds to 35% loss. The additional ~10% loss could be explained by this effect. We should have more than 20dB clearance to make the loss due to the dark noise below 1%.
The calculation of loss due to the classical noise is shown in P.40 of P1800001. The loss due to the classical noise is the ratio of the classical noise and the observed shot noise in PSD (10dB in ASD correponds to 20dB in PSD, which means 10% of loss).