The measurement of CC2 loop opto-mechanical transfer function, CC2 open loop tranfer function and CC2 error signal spectrum is attached as attachement.

The good news is that the OMTF is very flat.

The first obvious oscillation we could find is ~23kHz(the last attachement). While we could see from the error singal spectrum, we have two narrow peaks at ~15.5kHz and ~22kHz.