To become more familiar with TCS, I've taken open loop transfer functions (OLTF) for the TCS lasers. These maintain the CO2 laser output powers at some reference level by feeding back to the laser PZT and the chiller temperature.

The UGF is 0.7 Hz and ITMY_CO2 and 0.4 Hz for ITMX_CO2, which is the same order of magnitude as presented in llo-alog-14338. I didn't wait to go down to mHz where the chiller servo takes over.

Transfer functions attached for reference, with the OLTF shown in red. Note that I took the TFs from TSC-ITMX_CO2_LSRPWR_ERR_SIGNAL_EXC, with 0.05 amplitude which gives ~4Vpk-pk to the laser PZT.