R&D (FilterCavity)
NaokiAritomi - 22:38, Monday 29 July 2019 (1522)
Recovery of good squeezing

[Aritomi, Yuhang]

Recently we turned off lasers when we leave. We accidentally kept lasers ON from last Friday and today we found that squeezing spectrum is very flat and phase noise is much less (attached pictures). Green power is 40 mW and error signal of CC1 and CC2 is 76 mVpp and 120 mVpp. Phase noise is smaller almost by a factor of 10. We guess large phase we had so far is due to unstable lasers. When we achieved good squeezing in May, lasers were always ON. We'll keep lasers on and see what happens.

Images attached to this report
1522_20190729153749_sqz20190729.png 1522_20190729153755_cc120190729.png 1522_20190729153759_cc220190729.png
Comments related to this report
EleonoraCapocasa - 10:40, Tuesday 30 July 2019 (1526)

The large increase of phase noise above 300 Hz when the CC2 is closed (pic 3) is very strange and we need to investigate it. The loop should have a UGF of few kHz, but it doesn't seem to work correctly.