From the last comment on https://mccullerlab.com/logs/lab/index.php?callRep=11650 we can clearly see some additional process decaying at the tail end of the cavity ringdown measurement. Attached is a screenshot of a quick check I performed where I repeat the cavity ringdown measurement process with no cavity. This is pure reflection from the input coupler. Attached is a screenshot of triggering on the decay. There are three distinct time frames:

1) -375.4 ns to -294.2 ns - This is the first moment where the total light on the PD is changing. Note that this portion is flatter than the following one. Probably some initial slow process on the AOM. This looks like the AOM is slowly becoming less efficient immediately after the power is cut.

2) -294.2 to -234.2 ns - Rapid decay of light on the photo detector. This could be the light travel time? 60 nanoseconds is order of magnitude how long the light is taking to travel to the PD (don't know the exact refractive index of the fiber).

3) -234.2 ns and on - This is the same shape as the tail end of the cavity ringdown measurement. This seems like some residual voltage produced by the PD on short timescales.

Also note that we don't see the large blip that is in every cavity ringdown measurement perhaps suggesting it is not from the AOM but some interaction with the cavity.