I measured PMC open loop transfer function (OLTF) with the current high power laser(HPL) and the new HPL.

Unity gain frequency (UGF) of PMC loop with current laser is 25% higher than the last measurement (klog 16367) if comparing Moku graph.

Actual UGF is 10dB higher than Moku's data according to circuit,  so UGF is something like 1.637kHz * 3.16 ~ 5.2kHz.

On the other hand, UGF of PMC with the new laser is much lower: 614Hz * 3.16 ~ 1.9kHz.

This result means that we need some modification on servo gain controlled by Gardian for each laser.

Since actual gain is normalized by transmitted light, if power changed or even if laser it self changed, the UGF should be kept to the same value. However the new HPL still have a lot of higher order mode, and the reflected power is much higher than the current HPL when PMC is locked. I guess this imbalance introduces some gain difference.