Marc, Matteo, Yuhang

We found out that we were only rotating the PBS circular dump and not the PBS itself..

We removed the circular dump and could see some beam. After a little realignment of the LO back-reflection to the FI, we measured :

Pinc = 3.54 mW, 12.6 uW and 8.4 uW rejected by the first PBS respectively towards top and bottom, 3.5 mW rejected by the second PBS toward the top and 0.4 uW transmitted by the FI.

This is closer to what we expect, especially because the 8.4 uW and 3.5 mW measured have some error due to space constraints to place the power-meter.

With this measurement, we can estimate the FI isolation to be about 40 dB which is in agreement with the specsheet.

We reinstalled the ND filters on the LO path, realigned the LO into the AMC, removed the steering mirror we used to increase the back-scatter light of LO (ie recovered the usual situation) and measured 3nW incident on the FI. It means that the LO seed should be about 0.3 pW.

Then, we measured the FI transmission using the BAB. We optimized the PLL frequency to be at maximum OPO transmission and got 342 uW incident on FI and 328 uW transmitted.

Finally, we were also able to remove one titled HWP on the squeezing path towards the Homodyne because we were able to use the HWP just after the FI to remove the p pol as seen in the AMC scan.