camilla.compton@LIGO.ORG - posted 12:19, Wednesday 19 October 2022 - last comment - 16:23, Tuesday 25 October 2022(65392)
SEED/CLF Fiber Switch installed back into SQZT0 and tested
Naoki, Wen, Camilla
After removing the SEED/CLF Fiber Switch in alog 65063 we installed a new one into SQZT0. Thorlabs MEMS Switch SN1x2-7N 2015-08-37731 soldered to board D1700376 by Fil.
This fiber switch has some bare optical fibers at both input ends, see photo. We have a spare one with no bare fibers coming in the next few weeks if we need to swap it in future.
Output (port 2) is on the same side as CLF (port 4), the opposite side has SEED (port 3).
We measured the coupling from free space at the fiber coupler to the output of the fiber switch to be:
SEED: input 20mW, output 10mW = 50%
CLF: input 1mW, output 0.15mW = 15%
We got light into HAM7 too.
Wen also secured the cable he found blocking the FCGS path in alog 65371.
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This afternoon Naoki adjusted the two steering mirrors before the SQZT0 CLF fiber coupler to double to power seen at CLF REFL. Now we expect we are getting 2 x 15% = 30% throughput from free space to out of the fiber coupler.