In order to mitigate back reflection noise we plan to install an additional  Faraday isolator (FI-1060-5SC-HP) on the squeezing path in reflection from FC, at the edge of the optical bench. See pic 1 and 2.

To finalize the istallation we need to modify a bit the custom support: drill holes for the screws and reduce the hight of about 2.5 mm. (ATC will do it by next Wednesday afternoon)

The Faraday should bring additional 3% of propagation losses, the associated squeezing degradation (simulated in pic 3) doesn't seem too bad.

The drawback is that the faraday will prevent to close one side of the bench cover. But so far we have never closed it.

The beam waist is ~1mm and FI aperture is 5 mm in diameter, so clipping losses shoud be negligible.