R&D (FilterCavity)
NaokiAritomi - 07:14, Monday 22 July 2019 (1494)
DC balance of LO and BAB

[Aritomi, Yuhang]

This is work on July 20th. First we made LO and BAB overlap and more or less DC balanced at homodyne. CMRR at 1 kHz is 82 dB which is similar to before. Then we measured shot noise and squeezing spectrum (data is not saved). Shot noise is worse below 100Hz and squeezing spectrum was very bad. 

After that we found large 7 MHz peak at homodyne DC signal (attached pictures). LO and CC before homodyne BS is 1.2 mW and 8 uW respectively. This 7 MHz seems beat between LO and CC.

Images attached to this report
1494_20190722001354_7mhzoscilloscope.jpg 1494_20190722001400_7mhzspectrum.jpg