Dan Gould, Daniel S., Vicky

Several small SQZT0 tweaks today, see updated photo attached with current on-table measurements on SQZT0.

1. Replaced broken green pump AOM (+GAOM1) with a new green AOM that Daniel brought. We optimized the AOM diffraction effiency to reach ~60%, and then tweaked up pump fiber coupling ("POPO on diagram"). Finished ~16:06 PT. For H1:SQZ-SHG_LAUNCH_DC_POWERMON = 6.22, we now have see H1:SQZ-OPO_REFL_DC_POWER ~ 2.41. All seems good, this should resolve LHO:63217.
2. Swapped CLF 5:95 BS for a mirror to increase CLF power (from D1201210, this is "MR5, 95:5"). Finished ~15:10 PT. Old 5:95 BS now is stored in a labelled optics box in the SQZ cabinet. CLF_REFL_DC is up from 0.002 --> 0.014, and a first pass saw HD_DIFF_RF3_RFMON ~ -22.9.
   1. Note: this mirror mount has the retaining surface on the front of the mount, so the optic is replaced from the back. So, should be relatively easy to swap this optic back later.
3. Increased SHG output green power from ~24 to ~31mW, by increasing input IR power to SHG (ie, manually turning HW9). Daniel took the SHG transfer function at this higher IR power. Almost all the IR power on that path now goes to SHG; IR power measured after PBS1 is up from ~260mW (on 5/9) to ~400mW now. Hopefully this will allow us to explore sqz with pump powers at threshold.
    

Small SQZT7 side note: we measured the very dim reflected spot powers from the HD PD's. For ~0.6mW LO light incident on each PD, we measure reflected powers ~1.2uW (left pd) and ~1.8uW (right pd). These are only losses of about 1.5/600 ~ 0.25%, so not enough for our large mystery homodyne losses.