Craig, Georgia, Nutsinee
It seems like we have non-linear coupling from CLF to DARM. The coherence plot wasn't very obvious but we clearly saw out injection showed up everywhere in DARM as we swept. Lockloss before we could inject more squeezing measurement (it's not the squeezer!).
Hmm. How hard were you driving? I suppose it's either fringe-wrapping or nonlinear upconversion of the backscatter. At LLO, driving the ZM's also shows such nonlinear conversion into DARM LLO43807
The relevant ZM1 drive plot in DARM.(DARM calibration not setup here, but you can clearly see the 2F and even 3F harmonics for a small 1F drive)
I assume we are modulating the back scattered light, so the phase wanders around. We will have to repeat this with a power spectrum peak height ratio measurement.