What I Did

• Lock the laser to the folded cavity
• Did ringdown measurement for rough estimation of the finesse

First, I tried to lock the laser with the servo by adjusting the offset.
Then I could lock and transmitted power was 60 uW.

After that, I turne off the AOM in order to test the ringdown measurement.
The decay time was about 2.5 usec.
It should be noted that the decay time of diffracted beam power by AOM was about 100 nsec.
Therefore, the impact of AOM can be negligible.

From this result, the finesse can be estimated about 1.4-1.5*10⁴.
Next time, I will record the result and calculate the decay time by fitting.

Next Step

• Measure the OLTF
• Ringdown measurement test
• Thermometer installation