[Jon, Yehonathan]

We carried out a set of cavity ringdown measurements of the PMC. The 1/e decay time scale is found to be 35.2 +/- 2.4 (systematic) μs. The statistical error is negligible compared to the systematic error, which is taken as the maximum absolute deviation of any measurement from the average value.

To make the measurement, we injected the first order deflection beam of an 80 MHz AOM, then extinguished it quickly by cutting the voltage offset to the AOM driver provided by an RF function generator. A 100 MHz oscilloscope configured to trigger on the falling voltage offset was used to sample the cavity in transmission as sensed by a PDA55. We found the detector noise of the DC-coupled output of the 35.5 MHz REFL PD to be too high for a reflection-side measurement.

Further loss analysis is forthcoming.