karmeng.kwan@LIGO.ORG - posted 09:15, Tuesday 23 April 2024 - last comment - 13:54, Tuesday 23 April 2024(77343)
OPO fiber rejected power high, SQZT0 waveplate adjust
Karmeng, Camilla. H1:SQZ-SHG_FIBR_REJECTED_DC_POWERMON power was high. Adjusted the 1/2 and 1/4 waveplate to reduce rejected power from 0.3 to 0.03. Instruction
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Vicky questioned if we need to realign the pump AOM /SHG fiber eg.74479.
With the OPO guardian DOWN, OPO REFL DC POWER is 2.26V, our max is around 2.9V 75270.
With SQZ MANAGER DOWN, SHG fiber shutter closed and H1:SQZ-OPO_ISS_DRIVEPOINT at 0V:
SHG_LAUNCH + SHG_REJECTED = 37 + 7 = 44mW, with 106mW out of SHG. ~75% of SHG output should go to pump (other 25% to FC launch). So we expect 106mW * 75% = 80mW. We are only getting 44mW so 55%.
Launched powers been increasing for the same Green REFL, plot attached.
We should plan on realigning AOM and fiber next week.
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