Marc and Yuhang

I measured frequency independent squeezing on Thursday (20210408), the difference between this measurement and last measurement is the improvement of IRPS. The result is shown in the attached figure 1.

After this, I also flipped lens inside homodyne. The minimum ROC of gaussian beam with w=390mm is (x_R+x_R^2) = 650mm. This fits better the flat surface of lens, which makes it reasonable to make light hits on lens flat surface. After this work and tilting lens a bit (few degrees), I got squeezing spectrum as the attached figure 2.

Figure 2 represents the cleanest squeezing spectrum we have ever got.