We (rana, yehonathan and i) briefly talked about having high power going into the IFO. I worked on some calcs a couple of years ago, that are summarized here. There is some discussion in the linked page about how much power we even need. In summary, __if__ we can have
- T_PMC ~85% which is what I measured it to be back in 2019
- T_IMC * T_inputFaraday ~60% which is what I estimate it to be now
- 98% mode matching into the IMC
- power recycling gain of 40-45 once we improve the folding mirror situation in the recycling cavities
- and a gain of 270-280 in the arm cavities (20-30ppm round trip loss)
then we can have an overall gain of ~2400 from laser to *each* arm cavity (since the BS divides the power equally between the two arms). The easiest place to get some improvement is to improve T_IMC * T_inputFaraday. If we can get that up to ~90%, then we can have an overall gain of ~4000, which is I think the limit of what is possible with what we have.
We also talked about the EOM. At the same time, I had also looked into the damage threshold as well as clipping losses associated with the finite aperture of our EOM, which is a NewFocus 4064 (KTP is the Pockel medium). The results are summarized in **Attachments #1** and **#2 **respectively. Rana thinks the EOM can handle factor of ~3 greater power than the *rated* damage threshold of 20W/mm^2. |