[Sheila, Craig, Koji]
We performed OMC scans at 50 W (alog 62514) and we would like to know how much higher input power OMC scans we can do without burning the DCPDs. We are not able to lower the modulation depth of the RF45 band (alog 62507) past a certain point without losing lock.
At 50 W input we put 30 mA of current on the DCPDs. At 60 W we would put 40 mA.
We contacted Koji to ask what the maximum power the DCPDs can tolerate. This is the PD we are using in the OMC. Although the DCC says that we are using Excelitas 30655, we are actually using lasercomponents IGHQEX3000. Koji has tested both PDs up to 332 mW of incident power (IGHQEX3000 high power test).
At 100 W we would likely be putting 60 mA which may be pushing it, but it not entirely impossible.
However, we may saturate the amps. We do not have information about the response of the DCPD amps with continuous saturation.
Craig has documented all of this at: https://git.ligo.org/aligo_commissioning/labutils/-/tree/master/omc_scan
I think it's clear, but just to remind myself, these are all per-PD currents (so, at 50W for example, it's 30 mA per photodiode, for a total of 60mA).