Spectra attached.

Coherence (modulation on)

Using 2600 V/W for the demod gain and transimpedance, and 29 mW of dc PD power, this implies the following AM depths:

Using 0.22 rad and 0.28 rad for the 9 MHz and 45 MHz modulation depths, this implies the following AM/PM ratios:

The attachment contains a budget of the expected CARM residual. The in-loop error point is taken from the CM board control signal, as was done previously. Here I used 2600 V/W for the transimpedance and demod gain.

The other measured traces are taken from the REFL9I readback (not from the CM board), so in principle there could be some extra dark noise at the error point from the summing node board or CM board. However, based on the O1 level this is of the same order as the shot noise (so we are not missing a huge amount of extra noise in this estimate).

Attaching earlier RAM plot, this time with informative labels

Here is a time series of REFL LF during the modulation depth reductions that happen during lock acquistion.

During the 9 MHz depth reduction (from 0.22 rad to 0.11 rad), the dc power changes from 4.83(3) mW to 4.27(3) mW. That means that after the modulation depth reduction, 4.08(4) mW of the dc light is from the carrier and 0.19(2) mW of the dc light is from the 9 MHz sideband (this assumes the 45 MHz contribution is negligible).

Note that the dc level is still settling to its final value of ~3.7 mW, so it's possible that these power ratios are evolving during the lock.