[Aritomi, Yuhang, Michael]

First we replaced mirrors and mirror mounts in the IR reflection and LO path.

We replaced 1 mirror mount (FMD MM1000S) and 3 mirrors (layertec) in the reflection path. We also replaced 2 mirror mounts (FMD MM1000S) in the LO path.

Then we moved a lens in the reflection path to improve the reflection mode matching. We moved a lens which is closer to homodyne in the reflection path.

Before moving the lens, we checked reflection alignment with AMC. TEM00 was 872mV and mode mismatch was 54.4mW, which means mode matching without misalignment is 94%. This value is consistent with the previous visibility measurement.

We moved the lens and reduced the mode mismatch from 54.4mV to 4mV as follows. 

Now the effect of mode mismatch is only 0.5% and the misalignment is larger than the mode mismatch.