I have analyzed the scan made in CARM null. It is not very linear, as it is a scan of one FSR, while we usually have to scan two FSRs to get a linear scan, as during the first FSR the temperature inside the OMC is too delayed.

Figure 1 shows the region around the carrier TEM00 highlighting the sidebands TEM00 modes. The +/- 6MHz, +/-56MHz and +/-81MHz, the frequencies do not match as the scan is not linear enough.

Figure 2 highlight the carrier HOM from 1 to 11

Figure 3 highlights the carrier HOM from 12 to 21.

Figure 4 shows the order 2 mode, that peaks at 50mW. Note that OMC astigmatism is already noticable, adding both peaks the power is ~85mW. On figure 2 and 3, as the HOM order increase the modes become more and more wide.

Adding all the modes highlighted (from 1 to 21) and doubling the power to take into account astigmatism yields a power of 755mW which is comparable to the ~1000mW detected on B1p.