[Aritomi, Yuhang, Eleonora]

First we measured shot noise spectrum with sensor card in squeezing path to see LO back scattering. Then we reduced LO power from 1.86mW to 0.158mW by putting ND filter after IRMC. Pic. 1 shows shot noise with different LO power. Shot noise reduced by 10.5dB and 13Hz peak from LO back scattering reduced by 21dB as expected.

Then we measured shot noise with filter cavity. At the beginning we saw low frequency bump in shot noise spectrum, but after some alignment of homodyne, the low frequency bump somehow reduced a lot. Pic. 2 shows shot noise with filter cavity.